ASTRONOMICAL POLARIMETRY 2014
Abstract Booklet
Contents
1 Session I.
New Instrumentation, Facilities & Techniques: OPTICAL / NIR

1

2 Session II.
New Instrumentation, Facilities & Techniques: FIR / Radio

9

3 Session III. Particle properties, Lab Measurements, modelling15

4 Session IV. Results: ISM , Molecular Clouds, Star Formation

20

5 Session V. Results: Circumstellar matter31

6 Session VI. Results: Solar & Stellar Magnetic Fields

40

7 Session VII. Results: Solar System & Exoplanets

46

8 Session VIII. Results: Cosmological Microwave Background52

9 Session IX. Results: External Galaxies, Active Galactic Nuclei

56

10 Session X. Results: High Energy Astrophysics,
Gamma-Ray Bursts, Supernovea

63

11 POSTERS

67

Grenoble, France, 26-30 May 2014i

ASTRONOMICAL POLARIMETRY

2014

Grenoble, France, May 26-30 2014*** CONFERENCE PROGRAMME ***I	  	
  Invited	
  talk	  S	  	
  Solicited	
  talk	  C	  	
  Contributed	
  talk	  DAY 1 : Monday, May 26th
08:30-­‐09:30	
  	
  	
  Arrival,	
  Registration	
  	
  	
  
	
  	
  09:30-­‐09:45	
  	
  	
  Welcome	  words.

SESSION I: New Instrumentation, Facilites, and Techniques :Optical and Near-Infrared	
  	
  09:45-­‐10:05	
  	
  M.	
  Perrin	
  –	  Polarimetry	
  with	  Gemini	  Planet	
  Imager	
  (C)
	
  	
  10:05-­‐10:25	
  	
  D.	
  Mouillet	
  –	
  Polarimetry	
  with	  VLT	  /	  SPHERE	
  (C)	  	  	
  10:25-­‐10:45	
  	
  T.	
  Fujiyoshi	
  –	
  N-­‐band	
  polarimeter	
  for	  SUBARU/COMICS	
  (C)	
  10:45-11:20

Coffee and Posters	  	
  11:20-­‐11:40	
  	
  H.-­M.	
  Schmid	
  –	
  Concept	
  and	
  test	  results	  for	  ZIMPOL	
  (C)	  	  
	  	
  11:40-­‐12:00	
  	
  M.	
  Rodenhuis	
  –	
  The	
  EXtreme	
  POlarimeter	
  and	
  its	  successor	
  (C)	  	  	
  12:00-­‐12:20	
  	
  D.	
  Vorobiev	
  –	
  Polarization-­‐sensitive	
  imaging	
  sensors	
  (C)	  12:20-14:00 Lunch
14:00-­‐14:20	
  	
  A.M.	
  Magalhaes	
  –	
  The	
  SouthPol	
  survey	   	
  (C)	  	  	  	
  14:20-­‐14:55	
  	
  F.	
  Snik	  –	
  Polarimetry	
  with	  Extremely	
  Large	  Telescopes	
  (I)	  	
  SESSION II: New Instrumentation, Facilities, and Techniques:
Far-Infrared and Radio
15:00-­‐15:35	
  	
  H.	
  Nagai	
  –	
  ALMA	  polarimetry,	
  current	
  status	
  and	
  cycle	  3	
  capabilities	  (I)	  	  	  	
  15:35-­‐15:55	
  	
  C.D.	
  Dowell	  –	
  SOFIA	  HAWC+:	
  FIR	
  dust	  polarimetry	
  (C)	  	  	  	
  15:55-­‐16:15	
  	
  C.	
  Thum	  –	
  IRAM	  XPOL:	
  capabilities	
  and	  results	
  (C)	
  16:15-17:00 Coffee and Posters
17:00-­‐17:20	
  	
  I.	
  Mizuno	
  –	  Polarimetry	
  at	
  the	
  Nobeyama	
  45m	
  (C)	
  	
  
	
  	
  	
  17:20-­‐17:40	
  	
  A.	
  Ritacco	
  –	
  NIKA:	
  the	  New	
  IRAM	
  KID	
  Arrays	
  (C)	  	  	  	
  17:40-­‐18:00	
  	
  H.	
  Wiesemeyer	
  –	
  Submillimeter	
  polarimetry	
  with	  APEX	
  (C)	
  
	
  

iii

DAY 2 : Tuesday, May 27th
SESSION III : Particle Properties, Laboratory Measurements,and Modelling.
09:00-09:35 O.	
  Muñoz	
  –	
  Light	
  scattering	
  measurements	
  of	
  cosmic	
  dust	  analogs(I)	
  09:35-09:55 D.	
  Guirado	
  –	
  Extrapolation	
  of	
  scattering	
  matrices	
  (C)
09:55-10h15 E.	
  Hadamcik	
  –	
  Observations	  and	
  expérimental	
  simulations	  in	
  optically	
  	
  
thin	
  clouds	
  (C)	  	
  10:15-11:00 Coffee and Posters
11:00-11:35 K.	
  Muinonen	
  –	  Multiple	
  scattering	
  of	
  light	
  by	
  the	
  surfaces	
  of	
  planetary	  	
  objects	  (I)	  	
  	
  11:35-11:55 I.	
  Milic	
  –	
  Scattering	
  line	  polarization	
  in	
  rotating	
  optically	
  thick	  disks	  (C)	  	
  SESSION IV: ISM, Molecular Clouds, Star Formation
11:55-12:25 A.	
  Lazarian	  –	
  Grain	
  alignment:	
  theory	
  (S)12:30-14:00 Lunch
14:00-14:30 B-­G	
  Andersson	
  –	
  Grain	
  alignment:	
  observations	  (S)14:30-14:50 T.	
  Hoang	  –	
  ISM	
  magnetic	
  field	
  measured	
  using	
  UV	
  dust	  	  polarimetry	
  (C)	  	
  	
  14:50-15:10 T.	
  Robishaw	
  –	
  The	
  Zeeman	
  effect	  to	
  study	  ISM	
  magnetic	
  fields	
  (C)	  15:10-15:30 F.	
  Levrier	
  –	
  Polarization	
  of	
  Galactic	
  foreground	
  from	  Planck	
  (C)	  15:30-15:50 J.	
  Vaillancourt	
  –	
  FIR	
  and	  mm	  polarization	
  in	
  galactic	
  clouds	
  (C)	
  15:50-16:10 M.	
  Houde	  –	  Characterization	
  of	
  magnetized	
  turbulence	
  (C)
16:10-16:55

Coffee and Posters

16:55-17:25 C.	
  Hull	  –	
  Multiscale	
  view	
  of	
  magnetized	
  star	  formation(S)
17:25-17:45 J.	
  Davidson	
  –	
  L1527,	
  a	
  cautionary	
  tale	  (C)17:45-18:15 J.	
  Kwon	  –	
  Circular	
  polarization	
  from	  star	  forming	
  regions	
  (S)	  18:15-18:35 F.	
  Alves	  –	
  Multi-­‐wavelength	
  polarimetry	
  of	
  a	
  pre-­‐stellar	
  core	  (C)	
  18h30 - 21:00
Dinner at MINATEC (long period for poster):Wine, and Cheeseiv

Bread,

DAY 3 : Wednesday, May 28th
SESSION V: Circumstellar Matter
09:00-09:30 S.	
  Quanz	
  –	
  Polarimetric	
  imaging	
  of	
  disks	
  (S)09:30-09:50 H.	
  Canovas	
  –	
  NaCo	  imaging	
  polarimetry	
  of	
  HD	
  142527	
  (C)	
  09:50-10:10 H.	
  Avenhaus	
  –	
  Multi-­‐epoch	
  polarisation	
  differential	
  imaging	
  of	
  HD	
  100546	
  (C)
10:10-10:30 M.	
  Millar-­Blanchaer	
  –	
  GPI	
  observations	
  of	
  the	
  debris	
  disk	  of	
  HD	
  61005	
  (C)	  	
  10:30-11:10 Coffee and Posters

11:10-11:30 C.	
  Telesco	
  –	
  Magnetic	
  fields	
  in	
  young	  disks	
  and	  their	  environments	
  	
  
	
  	
  	
  	
  	
  	
  	
  	
  with	
  GTC	
  /CanariCam	
  (C)	
  11:30-11:50 C.	
  Wright	
  –	
  CanariCam	
  imaging	
  and	
  spectro-­‐polarimetry	
  	
  of	
  YSO	
  driving	
  	
  
	
  	
  	
  	
  	
  	
  bipolar	
  jets	  (C)	
  11:50-12:10 J.	
  Vink	  –	
  Spectropolarimetry	
  and	  the	
  circumstellar	
  environments	
  of	
  	
  
young	
  and	
  massive	  stars	
  (C)	  12:10-12:30 P.	
  Kervella	  –	
  Polarized	
  light	
  in	
  the	
  dusty	  nebula	  of	  	
  the	
  cepheid	
  RS	
  Puppis	
  (C)	  12:30-12:50 R.	
  Tylenda	
  –	
  Linear	  polarization	
  of	
  the	
  red	
  nova	  	
  V4332	
  Sgr	
  (C)	
  12:50-13:00
13:00 -

Logistics	
  ,	
  infoFree AfternoonvDAY 4 : Thursday, May 29th
SESSION VI: Solar and Stellar Magnetic Fields
09:00-09:30 M.	
  Faurobert	
  –	
  The	  Solar	
  magnetic	
  field	
  (I)09:30-09:50 R.	
  Kano	  –	
  Magnetic	
  fields	
  in	
  the	  Solar	
  chromosphere	
  with	  Lyman	  alpha	
  	
  
	
  	
  polarimetry	
  (C)	
  09:50-10:25 J.	
  Morin	
  –	
  Magnetic	
  fields	
  of	
  cool	  stars	  (I)10:25-11:15 Coffee and Posters
11:15-11:50 C.	
  Neiner	
  –	  Magnetic	
  fields	
  of	
  hot	
  stars	  (I)11:50-12:10 S.	
  Jeffers	
  –	
  The	
  BCool	
  survey	
  of	
  solar-­‐type	
  stars	  (C)12:10-12:30 S.	
  Boro	  Saikia	
  –	
  Variable	
  magnetic	
  field	
  of	
  the	
  young	
  	
  sun	  HN	  Peg	
  (C)	  12:30-14:00 LunchSESSION VII:

Solar System and Exoplanets

14:00-14:30 S.	
  Wiktorowicz	
  –	
  Status	
  of	
  exoplanet	
  polarimetry	  (I)14:30-14:50 N.M.	
  Kostogryz	  –	
  Polarimetry	
  of	
  the	  transiting	
  exoplanetary	
  system	
  	
  
	
  	
  	
  HD	
  189733	
  (C)	
  
14:50-15:10 A.	
  Bazzon	
  –	
  The	  polarization	
  of	
  Earth	
  (C)	  15:10-15:30 T.	
  Enomoto	  –	
  Monitoring	
  of	
  Venusian	
  clouds	
  with	  HOPS(C)15:30-15:50 S.	
  Bagnulo	
  –	
  Spectro-­‐polarimetry	  to	
  study	  small	
  Solar	
  	
  System	  bodies	
  (C)	
  15:50-16:10 S.	
  Berdyugina	
  –	  Remote	
  detection	
  of	
  biological	
  pigments	
  on	
  Earth-­‐like	
  	
  
	
  	
  planets	
  (C)	  	
  16:10-16:50

Coffee and Posters

SESSION VIII:

Cosmological Microwave Background16:50-17:20 C.D.	
  Dowell	  –	
  Detection	
  of	
  B-­‐mode	
  polarization	
  at	
  degree	  angular	
  scales	  	
  using	
  BICEP	
  2	
  (I)	  17:20-17:50 J.	
  Macias	
  Perez	
  –	
  Polarisation	
  of	
  the	  CMB:	
  first	  results	
  from	  Planck	
  (I)	
  17:50-18:10 V.	
  Guillet	
  –	
  Polarized	
  emission	
  of	
  Galactic	
  dust	  seen	  by	
  Planck	
  (C) 	  18:10-18:30 J.	
  Peloton	
  –The	  Polarbear	
  experiment:	
  first	  results	
  (C)18h40-21h00
DINNER at WTC + long poster session :Ravioles de Roman and Mini Quenelles de Lyon

vi

Local specialties

DAY 5 : Friday, May 30th
SESSION IX:

External Galaxies, Active Galactic Nuclei

09:00-09:35 C.	
  Tadhunter	
  –	
  Optical	
  and	
  near-­‐infrared	
  polarimetry	
  of	
  AGNs(I)09:35-09:55 E.	
  Ramirez	
  –	
  NIR	  polarimetry	
  of	
  narrow-­‐line	  radio	
  galaxies	
  with	  HST	
  (C)	
  09:55-10:15 C.	
  Ramos	  Almeida	
  –	
  VLT/FORS	
  spectropolarimetry	
  of	
  	
  Seyfert	
  galaxies	
  (C)	
  10:15-10:35 C.	
  Packham	
  –	
  Infrared	
  polarimeters	
  and	
  AGNs	  (C)10:35-11:20

Coffee and Posters

11:20-11:40 E.	
  Lopez-­Rodriguez	
  –	
  Polarimetry	
  in	
  AGNs	  (C)11:40-12:00 B.	
  Shahzamanian	  –	
  Near	  infrared	
  polarized	
  light	
  from	  Sgr	  A*	  (C)
12:00-12:20 M.	
  Yoshida	
  –Spectropolarimetry	
  of	
  starburst	
  galaxies(C)12:30-14:00

Lunch

SESSION X:

High Energy Astrophysics, Gamma-Ray Bursts,
Supernovae

14:00-14:20 K.M.G.	
  Silva	
  –	
  Polarimetric	
  observations	  and	  modelling	
  of	
  V393	
  Pav	
  and	
  	
  
	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  other	
  AM	
  Her	
  systems	  	
  (presented	
  by	
  CV	
  Rodrigues)	
  (C)	  14:20-14:40 E.	
  Angelakis	
  –	
  Optical	
  polarization	
  monitoring	
  of	
  gamma-­‐ray-­‐loud	
  Blazars	
  (C)	  
14:40-15:00 P.	
  Moran	  –	
  INTEGRAL/IBIS	  and	
  optical	
  monitoring	
  of	
  the	
  CRAB	
  nebula/pulsar	
  	
  
	
  	
  	
  
	
  
	
  
	
  
	
  	
  	
  	
  	
  	
  polarization	
  (C)	
  15:00-15:20 K.	
  Takaki	
  –	
  Polarization	
  observations	
  of	
  5	
  GRB	
  afterglows	
  (C)	
  
15H20-15H30

LAST WORDS+GOODBYE !

POSTERS :By default all abstracts not selected for talks are expected
to become posters. Posters will be visible all week.
POSTER SIZE : recommended is A0 in Portrait mode.
(or about 90cm wide (horizontal) by 120cm high (vertical))

vii

1

Session I.
New Instrumentation, Facilities & Techniques: OPTICAL /NIRPolarimetry with the Gemini Planet Imager
Marshall D. Perrin1 , James R. Graham 2 , Max Millar-Blanchaer3 , Sloane Wiktorowicz4 ,Gaspard Duchene2 , Michael Fitzgerald5 , Paul Kalas2 , Bruce Macintosh6 , and the Gemini
Planet Imager team
1

Space Telescope Science Institute, 3700 San Martin Ave, Baltimore MD, 21218 USA, mperrin@stsci.edu
2
UC Berkeley, jrg@berkeley.edu
3
University of Toronto, maxmb@utoronto.ca
4
UC Santa Cruz, sloanew@ucolick.org
5
UCLA, mpfitz@ucla.edu 6 Stanford University, bmacintosh@stanford.edu

The Gemini Planet Imager is one of a new generation of specialized adaptive optics instruments, fully
optimized for the detection of planets and circumstellar dust at high contrast and small angular separations.
For studies of circumstellar disks in polarized light, GPI includes an imaging polarimetry mode implemented
via a novel “integral field polarimetry” architecture. GPI achieved first light in November 2013 and iscurrently proceeding through a verification and commissioning phase, including shared-risk community
science time. I will describe the technical advances that enable GPI to achieve contrasts up to a factor of ten
better than previous generation instruments at small separations, discuss the design decisions made in
developing GPI’s polarimetry mode, and present some of our initial results from first light andcommissioning. Starting in 2014B the GPI Exoplanet Survey campaign will carry out a large survey forcircumstellar disks and exoplanets around nearby young stars, while GPI will be available to the community
for investigations ranging from solar system targets to post main sequence stars.

Figure 1: GPI first light polarimetry observations of HR 4796A

1

Polarimetry with the VLT/SPHERE high contrast
imager.
D. Mouillet 1 , J.L. Beuzit 1 , K. Dohlen 2 , Hans-Martin Schmid 3 , and SPHERE consortium
1

UJF-Grenoble, CNRS/IPAG, 38041 Grenoble, France
LAM, Observatoire de Marseille, 38 rue Frederic Joliot-Curie, 13388 Marseille, France
3
ETH Zurich, Institute of Astronomy, Wolfgang-Pauli-Str 27, 8093 Zurich, Switzerland
2

SPHERE is a second generation instrument for the VLT, dedicated to high contrast imaging of bright stars
in the visible and near IR. It is now in commissioning phase.
I will first remind the strong motivation of accurate polarization measurement, both for its intrinsic
astronomical interest to characterize the scattering properties of the circumstellar material, and for its helps
to achieve very high contrast capabilities through differential measurements.
Second, on the instrumental side, I will discuss at high level how this polarimetric capability has been
implemented in the instrument design. The induced polarization effects from the telescope and the
instrument are kept at a relatively low level despite its location at Nasmyth focus, and a complete calibration
scheme has been defined. The discussion will distinguish whether the astronomical purpose of a given
observation requires absolute polarimetric accuracy or differential measurement of a localized polarimetricsignature within a stellar halo. In visible, ZIMPOL is a dedicated polarimetric instrument with a very
specific polarimetric measuring principle, while IRDIS is a very sensitive double beam imager andspectrograph with a quite ”traditional” polarimetric mode for double beam polarimetry with beam exchange.
I will emphasize some specificities raised by the combination of high contrast and high accurary polarimetry
which led to some unprecedented specifications and new challenges for some optical components.
Finally, I will illustrate the high contrast performance that can be obtained with the complete system inpolarimetry. Such polarimetric imaging can be performed both in visible an near IR, by two different
approachs. The combination of near-IR polarimetry and visual polarimetry will provide much enhanced
diagnostic power for the investigation of scattering phenomena.

2

An N -band polarimeter for COMICS
Takuya Fujiyoshi,1 Mitsuhiko Honda,2 and Hideaki Fujiwara3
1,3

Subaru Telescope, National Astronomical Observatory of Japan, National Institutes of Natural Sciences,
650 North A’ohoku Place, Hilo, Hawaii 96720, USA (tak@subaru.naoj.org, hideaki@naoj.org)
2
Department of Mathematics and Physics, Faculty of Science, Kanagawa University, 2946 Tsuchiya,
Hiratsuka, Kanagawa 259-1293, Japan (hondamt@kanagawa-u.ac.jp)

We are in the final stages of the construction of an add-on N -band (8−13 µm) polarimeter for the facility
mid-infrared imaging-spectrometer COMICS for the Japanese 8.2-m Subaru Telescope in Hawaii, USA. In
this presentation, we will outline the design of the polarimetry unit and describe some of its key components.
We would also like to draw attention to the fact that, because COMICS is a facility instrument, afternecessary engineering and commissioning processes, the polarimeter will be available to the wider
astronomical community, including the Japanese community, and the Keck and Gemini communities throughthe time exchange programme with Subaru Telescope.

3

Polarimetric concept and test results for the ZIMPOL
high-contrast imaging polarimeter of the SPHERE
planet finder
Hans-Martin Schmid1 , Ronald Roelfsema2 , Andreas Bazzon1 , Johan Pragt2 , Daniel Gisler3 ,Bernardo Salasnich4 , Alexey Pavlov5 , Andrea Baruffolo4 , Anthony Boccaletti6 Jean-Luc
Beuzit7 , Anne Costille8 , Sebastian Deiries9 , Kjetil Dohlen8 , Carsten Dominik10 , Mark
Downing9 , Eddy Elswijk2 , Markus Feldt5 , Markus Kasper9 , David Mouillet7 , Pascal Puget7 ,Christian Thalmann1 , Francois Wildi111

ETH Zurich, Institute of Astronomy, Wolfgang-Pauli-Str. 27, 8093 Zurich, Switzerland
NOVA Optical-Infrared Group at ASTRON, 7991 PD Dwingeloo, The Netherlands
3
Kiepenheuer-Institut fr Sonnenphysik, Schneckstr. 6, D-79104 Freiburg, Germany
4
INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
5
Max-Planck-Institut fr Astronomie, Knigstuhl 17, 69117 Heidelberg, Germany
6
LEISA, Obs. de Paris, 5 place Jules Janssen, 92195 Meudon, France
7
UJF-Grenoble, Inst. de Plantologie et d’Astrophys. de Grenoble (IPAG), 38041 Grenoble, France
8
LAM, Observatoire de Marseille, 38 rue Frdric Joliot-Curie, 13388 Marseille, France
9
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
10
Astronomical Institute Anton Pannekoek, 1098 SJ Amsterdam, The Netherlands
11
Observatoire Astronomique de lUniversit de Genve, 1290 Sauverny, Switzerland
2

ZIMPOL is as subsystem of the upcoming SPHERE VLT planet finder which will provide high contrast andhigh resolution imaging polarimetry. ZIMPOL works in the wavelength range 500–900 nm and is optimized
for the search and characterization of scattered and therefore polarized light from faint sources around brightstars using differential polarimetry for speckle noise suppression.
ZIMPOL is very innovative polarimeter which includes several polarimetric concepts which are implemented
for the first time for night-time telescopes:• fast modulation / demodulation imaging polarimetry with a frequency of about 1 kHz for the efficiency
suppression of the speckle noise,• broad-band compensation of the telescope polarization at the Nasmyth focus fo an alt-azimuth
telescope,• combination of polarimetry with image derotation,• and a three stage polarimetric calibration strategy.
All these polarimetric functions are realized, together with complex AO and coronagraph control functions,in a user-friendly telescope instrument. We promote this instrument with test results, which demonstratethat a guest observer, who does not need to be an instrument expert, can obtain with this system easy to
reduce, well calibrated data.
SPHERE-ZIMPOL should become in the near future “our best” instrument for very high sensitivity linear
polarization measurements with unprecedented spatial resolution and contrast for the visual range. This
opens up many new research opportunities like the search for scattered light from extra-solar planets, thecharacterization of circumstellar material such as disks and shells, and the polarimetric mapping of solar
system objects and very extended red giant stars.

4The Extreme Polarimeter and its successor, thePolarimetric IFU: Design, results & lessons learned
M. Rodenhuis 1 , H. Canovas 2 , S. V. Jeffers 3,1 , M. Min 4,1 , J. de Boer 1,5 , C. U. Keller 1
1

Leiden Observatory, Niels Bohrweg 2, NL-2333CA Leiden, The Netherlands. e-mail:rodenhuis@strw.leidenuniv.nl
2
Departemento de Fı́sica y Astronomia, Universidad de Valparaiso, Chile.
3
Institut für Astrophysik, Georg-August-Universität, Göttingen, Germany.
4
Sterrekundig Instituut Anton Pannekoek, Universitieit van Amsterdam, Amsterdam, The Netherlands.
5
European Southern Observatory, Santiago, Chile.

At the previous AstroPol conference, the design and first laboratory results of the Extreme Polarimeter(ExPo), an imaging polarimeter developed for high-contrast observations of starlight scattered bycircumstellar material, were presented. In the intervening period, the successful observations with this
instrument have demonstrated both the contrast enhancing and the diagnostic power of imaging polarimetry.
The results include:• Imaging of sub-arcsecond structures in protoplanetary disks• Observation of localized dust clouds emitted by the evolved variable star R CrB• Constraining the three-dimensional morphology of dust clouds around both young and evolved stars• Characterization of circumstellar dust grain size distribution• Imaging of intriguing polarized features in the atmospheres of Venus and Saturn.
Here we present a compilation of these results and the lessons learned during the development and operationof ExPo.
One key lesson learned is that wavelength information greatly increases the diagnostic capabilities of imaging
polarimetry, in particular for characterizing circumstellar dust. Future ELT exoplanet direct imaging
instruments will require wavelength resolution to go beyond mere exoplanet detection. Based on our
experiences with ExPo, we have developed the Polarimetric Integral Field Unit (pIFU). This instrument
offers the imaging polarimetry capabilities of ExPo with simultaneous imaging in 20 contiguous wavelength
bands in the visible part of the spectrum. It relies on several innovative technologies such as a polarization
grating and polychromatic polarization modulation. We present the design of this new instrument and theresults from recently obtained first-light observations.

5Polarization-sensitive imaging sensors for astronomy
Dmitry Vorobiev 1 , Zoran Ninkov 1
1

Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester NY, USA 14623
vorobiev.dm@gmail.com

Recent advancements in microfabrication techniques have facilitated the development of micropolarizer
arrays. These devices consist of pixel-sized polarizers (or retarders), which can be used with conventional
imaging sensors (in the optical and infrared regimes) to creative polarization-sensitive detectors. This
technique is analogous to the use of color filter arrays to create color-sensitive detectors. Although RGB
imagers are of limited use to astronomers (who are often interested in specific parts of the spectrum), thisdivision-of-focal plane technique efficiently samples the electric field and allows the determination of the
Stokes parameters using a single exposure (Figure 2).
Polarimeters based on micropolarizer arrays are attractive due to their compactness, small weight, lack ofmoving parts, large field of view, broad spectral response and ”snapshot” capability. At RIT, we areinvestigating the potential utility of these novel devices in astronomy using high resolution 3D simulations, aswell as our first prototype, the RIT Polarization Imaging Camera (RITPIC). We report our initial findings,
describe useful calibration techniques and outline our goals for future work.

Figure 2: Micropolarizer arrays can be used to add polarization sensitivity to conventional imaging sensors.
These hybrid devices are capable of ”snapshot” acquisition of Stokes parameters across a broad spectral range.
The compactness and mechanical robustness of these devices makes them ideally suited for deployment on
space-based and airborne platforms.

6

SOUTH POL: Revealing the Polarized Southern Sky
A.M. Magalhães 1 , E. Ramirez 1 , N.L. Ribeiro 1 , M. Rubinho 1 , D.B. Seriacopi 1 , T. Ferrari
1, J. Felix 1 , A.J.F.B. Barbosa 1
1

IAG, Universidade de São Paulo, Rua do Matão 1226, São Paulo, SP 05508-090, Brazil,
antonio.mario@iag.usp.br

SOUTH POL will be a survey of the Southern sky in optical polarized light. It will use a newly designed
polarimeter for an 80cm Robotic Telescope. Telescope and polarimeter will be installed at CTIO, Chile,during 2014. The initial goal is to cover the sky south of declination −15◦ , aiming at a polarimetric accuracy≤ 0.1% down to V=15, with a camera covering a field of about 2.0 square degrees.
SOUTH POL will impact areas such as Cosmology, Extragalactic Astronomy, Interstellar Medium of the
Galaxy and Magellanic Clouds, Star Formation, Stellar Envelopes, Stellar Explosions and Solar System,
among others.
The polarimeter, with its optics and control electronics, has just been built. We will describe the Survey, theinstrument and the data reduction pipeline.
This project is supported by FAPESP. AMM is also supported by CNPq.

7

INVITED: Polarimetry with Extremely Large
Telescopes
Frans Snik1
1

Leiden Observatory, Leiden University
Postbus 9513, 2300 RA Leiden, the Netherlands
snik@strw.leidenuniv.nl

The upcoming generation of 30–40-m optical telescopes (the “extremely large telescopes”) will truly
revolutionize astronomy. Many exciting scientific discoveries will be enabled by the optimal implementationof polarimetric instrumentation at these telescopes. Their aperture sizes furnish the large photon collection
rates that highly sensitive polarimetric measurements require, and they can deliver an unprecedented spatial
resolving power that will unveil currently undetectable polarization signals.
To maximize the science potential of polarimetric instrumentation, they demand an integrated design at
systems level. I will provide an overview of polarimetric modulation concepts that limit the influence ofsystematic effects (e.g. seeing and differential abberations) to the polarimetric sensitivity. In general, thepolarimetric accuracy will be limited by the instrumental polarization of the telescope mirrors. I introduce
modulation, calibration and mitigation strategies to constrain the overall polarimetric error budget within
the stringent requirements for several proposed instruments. Moreover, I will present modeling results of thepolarization structure in the PSF due to a segmented primary mirror, taking into account the effects ofmultiple missing segments and limited adaptive optics performance.
We apply these concepts to the EPICS instrument for the 39-m European Extremely Large Telescope, which
will be capable to provide the first images of habitable-zone rocky exoplanets owing to its combination ofsensitive imaging polarimetry with other high-contrast imaging techniques.

82Session II.
New Instrumentation, Facilities & Techniques: FIR / RadioINVITED: ALMA Polarimetry: Current Status andCycle 3 Capability
Hiroshi Nagai 1, * , Kouichiro Nakanishi 2, 1 , Ed Fomalont 2, 3 , George Moellenbrock 4 , and
ALMA Polarization Commissioning Team
1

National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
2
Joint ALMA Observatory, Alonso de Cordova 3107 Vitacura, Santiago, Chile
3
National Radio Astronomy Observatory Headquarters, 520 Edgemont Road Charlottesville, VA 22903-2475,
USA
4
National Radio Astronomy Observatory Array Operation Center, P.O. Box O 1003 Lopezville Road
Socorro, NM 87801-0387, USA*email: hiroshi.nagai@nao.ac.jp

The Atacama Large Millimeter/submillimeter Array (ALMA), an international partnership of Europe, North
America and East Asia in cooperation with the Republic of Chile, is the largest astronomical project inexistence. ALMA will be a single telescope of revolutionary design, composed of 66 high precision antennas
located on the Chajnantor plateau, 5000 meters altitude in northern Chile. Thanks to the unprecedented
sensitivity and high angular resolution, ALMA is a promising telescope to open a new window for exploring
the astrophysics in connection with the magnetic field in millimeter and sub-millimeter regimes.
The polarization commissioning team has been working on the verification of instrumental polarization(D-term), which is a key part of polarization sensitivity, and development of the calibration plan. Recent
results suggest that
1. mean on-axis D-term of 12m antenna is few percent in bands 3/6/7,
2. considerable frequency dependence of D-term (peak-to-peak amplitude ∼ ±3% at most) is seen inbands 3/6 but is less apparent in band 7,
3. the peak-to-peak amplitude of frequency structure becomes larger with increasing the distance fromthe on-axis up to half-power beam width, but mean D-term level at each off-axis field is not muchdifferent from that at on-axis field.
We confirmed that the on-axis D-term was successfully calibrated at a level of 0.1% with continuum
observation mode (low frequency resolution / time-domain mode). Based on these results, ALMA
Observatory offers the polarization observation capability at 3 mm (band 3), 1.3 mm (band 6), and 0.85 mm(band 7) for compact and continuum sources in Early Science Cycle 2. We are now testing the polarization
characteristics in higher frequency resolution (frequency domain mode) and wider field of view for both 12m
and 7m antennas. In this presentation, we will introduce (i) ALMA polarization observation system, (ii)calibration strategy, (iii) summary of Cycle 2 capability, and (iv) prospects for Cycle 3 capability.

9

SOFIA/HAWC+: Upcoming Capability for Mapping
Interstellar Magnetic Fields through Far-Infrared Dust
Polarimetry
C. Darren Dowell1 , for the HAWC+ Instrument and Science Teams1

Jet Propulsion Laboratory, MS 169-237, 4800 Oak Grove Drive, Pasadena, CA 91109, U.S.A.;
Charles.D.Dowell@jpl.nasa.gov

Prior work with airborne, ground-based, balloon-borne, and space missions has established the utility of
infrared polarimetry of dust emission in establishing and understanding the magnetic field structure of dense
molecular clouds. Furthermore, the discovery of unexpected trends in the wavelength dependence of
far-infrared/submillimeter polarization has given clues to, and important constraints on, the alignment of thedust grains producing the polarization. Current facilities for far-IR/submm polarimetry have limitations insensitivity, angular resolution, wavelength coverage, and/or availability to a wide community. Here, we
describe HAWC+, a facility far-IR polarimetric imager for SOFIA. It is currently under construction, with
first flights expected in 2015. HAWC+ will have state-of-the-art thousand-element detector arrays from
NASA/GSFC, allowing operation with high quantum efficiency at the photon noise limit over a broad
wavelength range, initially fielded as five continuum bands at 53, 62, 89, 155, and 216 µm. The angularresolution of SOFIA/HAWC+ is 500 at 53 µm, scaling with wavelength, and the flight altitude of SOFIA
provides the sensitivity to map to the edges of molecular clouds and over scales of many arcminutes. Initial
targets for HAWC+ include 1) the Galactic Center, where the interaction of magnetic fields, dense gas,rotation, and tidal forces will be explored on scales from 1 to 100 pc; 2) circumstellar environments ofprotostars, where HAWC+ will have sensitivity to both disks and envelopes; 3) diffuse molecular gas in avariety of environments, where we will test theories of grain alignment and apply Chandrasekhar-Fermi
techniques to estimate magnetic field strengths. HAWC+ will be offered to the community as a SOFIA
facility, likely in Observing Cycle 4.

10

XPOL - capabilities and results
C. Thum 1 , I. Agudo 2 , C. Casadio 3 , S. N. Molina 4 , D. Morris 5 , G. Paubert 6 , H.
Wiesemeyer 7 ,1

IRAM, Avd. Divina Pastora No.7, Nucleo Central, 18012 Granada, Spain; thum@iram.es
2
JIVE, iagudo@jive.nl
3
Instituto de Astrofı́sica de Andalucı́a, CSIC
4
Instituto de Astrofı́sica de Andalucı́a, CSIC
5
IRAM, morris@iram.fr
6IRAM, paubert@iram.es
7
MPIfR, hwiese@mpifr-bonn.mpg.de

As soon as the IRAM 30m telescope was equipped with dual polarization receivers, a procedure designated
XPOL was developped for making efficient polarization observations. The procedure measures all Stokes
parameters and handles both spectral lines and continuum. We describe XPOL and demonstrate its mainstrengths and limitations. The intricate correction for polarized sidelobes, necessary in observations ofextended sources, is illustrated by our observations of the Crab Nebula where we derived an upper limit of
its circular polarization of 0.2% (Wiesemeyer et al. 2010).
We further describe and present first results from a monitoring program of the polarization of the brightest
AGN which we started in 2006. Originally intended to monitor the instrumental polarization properties of
the then somewhat unstable receiver configuration, we obtain reliable results for the linear and circularpolarization of more than 200 AGN. A subset of 40 sources (Fig. 3 shows an example) was observed morethan 50 times until end of 2013. The database is being prepared for consultation through the web.

Figure 3: Polarization parameters of the QSO
2251+158 (z = 0.859) observed with XPOL at
the IRAM 30m telescope as part of a program tomonitor mm–loud QSO (I. Agudo et al., to be
published).

11New full Stokes polarization observing system inNobeyama 45m radio telescope
Izumi Mizuno 1 , Seiji Kameno 2 , Fumitaka Nakamura 3 , Nario Kuno 4 , Hideo Ogawa 5 ,Kazuhito Dobashi 6 , Yoshinori Yonekura7 , Hiroko Shinnaga 81

Department of Physics Graduate School of Science and Engineering Kagoshima University / Nobeyama
Radio Observatory, 462-2 Minamimaki, Minamisaku, Nagano 384-1805 Japan, k7330312@kadai.jp
2
Joint ALMA Observatory, seiji.kameno@nao.ac.jp
3
National Astronomical Observatory of Japan, fumitaka.nakamura@nao.ac.jpl
4Nobeyama Radio Observatory, nario.kuno@nao.ac.jp
5Department of Physical Science, Graduate School of Science, Osaka Prefecture University,
ogawa@p.s.osakafu-u.ac.jp
6Department of Astronomy and Earth Sciences, Tokyo Gakugei University, dobashi@u-gakugei.ac.jp
7
Center for Astronomy Ibaraki University, y.yone@mx.ibaraki.ac.jp
8
National Astronomical Observatory of Japan, hiroko.shinnaga@nao.ac.jp

We have developed a full Stokes observing system at 45 GHz on the Nobeyama 45-m telescope to measuremagnetic fields in star-forming cores through the Zeeman shift of the CCS molecular line. The new recever,Z45, performs TRX ∼ 50 K for dual linear polarizations (X and Y ) in 43 – 46 GHz band. The newsoftware-based polarization spectrometer, PolariS, is capable to caluculate power spectra (hXX ∗ i andhY Y ∗ i) and cross power spectra (hXY ∗ i) to output full Stokes spectra of I, Q, U, and V with a highspectral resolution of 61 Hz. We also developed polarization calibration method for that system., in terms ofdiffecences in complex gain between two polarizations and cross talk also known as the D-term. Phase
difference between two polarizations is determined by using artifitial linearly polarization signal thtough awire grid. Gains and D-terms can be estimated by observations toward unpolarized sources like planets andlinearly polarized sources like the limb of the moon. We will present the performance of the polarization
observing system, accuracy in the calibration scheme, and the initial results of full-Stokes spectra of SiO
masers and CCS molecular emission.

12

First polarization measurements with the New IRAM
KID Arrays (NIKA)
Alessia Ritacco 1 , Andrea Catalano 2 , Nicolas Ponthieu 3 and the NIKA Core Team1

LPSC Grenoble (alessia.ritacco@lpsc.in2p3.fr) 2 LPSC Grenoble 3 Institut de Plantologie etdAstrophysique de Grenoble (IPAG)

The New IRAM KID Array (NIKA) is a dual-band camera operating with 315 frequency multiplexed
Lumped Element Kinetic Inductance Detectors (LEKID) cooled at 100 mK. It is designed to observe theintensity and polarization of the sky at 1.25 and 2.05 mm from the IRAM 30 m telescope. NIKA is atest-bench for the final NIKA2 camera that will be made of about 1000 detectors at 2.14 mm and 2 x 2000
detectors with polarization capability at 1.25 mm. NIKA2’s field of view will be circular with a 6.5 arcmin
diameter and will be commissioned at the end of 2015. To modulate the incoming polarization, we
continuously rotate a warm half-wave-plate (HWP) in front of an analyzer. In this way, a linearly polarized
signal is modulated by the combined action of an ”ideal” HWP and subsequent analyzer at four times themechanical rotation frequency. It can hence be extracted with a lock-in procedure by isolating the amplitudeof the mechanical rotation’s fourth harmonic. The accuracy of this strategy lies in the calibration of the
HWP: the correct amplitude of the Fourier components is required in order to decouple unwanted
instrumental contaminations from the desired signal. This specificity was tested during NIKA’s last technical
run in January 2014. This contribution aims at presenting the performances of this system together with thefirst results obtained on some extended and point sources.

13Submillimeter Polarimetry with the APEX: Filling the
Gap between Planck and ALMA
H. Wiesemeyer 1* , E. Kreysa 1 , T. Hezareh 1 , R. Güsten 1 , S. Heyminck 1 , K.M. Menten 1 , A.
Weiss1 , G. Siringo 2 , F. Schuller 2 , A. Kovacs 3
1

Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, 53121 Bonn, Germany
2
European Southern Observatory, Santiago, Chile
3
University of Minnesota, Minneapolis, MN 55405*
hwiese@mpifr.de

The Planck all-sky survey of polarized dust emission at 353 GHz, with a spatial resolution of 4.08, will become
a valuable tool to study large-scale correlations between the topology of Galactic magnetic field components
and the dust emission from diffuse gas and molecular cloud complexes. ALMA, on the other hand, willobserve the polarization of protostellar condensations, accretion disks and their associated outflows. Theintermediate scales define the boundary conditions for gravitational instabilities, and are observed by(sub-)millimeter cameras with an instantaneous field of view of typically 100 .
In order to fill this gap, and motivated by the 345 GHz ATLASGAL survey of the Galactic plane, we
equipped the Large Bolometer Camera of the APEX telescope with PolKa, a reflection-type polarimeter (seeFigure below). This contribution will present the commissioning of the instrument and first polarization
maps with 2000 resolution, along with algorithms for the data reduction and the correction of the instrumental
polarization. An outlook will be given on the next-generation polarimeter for the A-MKID dual-color camera.

Figure 4: Design drawing of PolKa. The tunable gridmirror unit (azure and bright blue) is mounted on topof an air bearing (the two hemispheres shown in paleorange).

14

3

Session III. Particle properties, Lab Measurements, modelling

INVITED: Light scattering measurements of cosmic
dust analogs at visible wavelengths. The IAA Cosmic
Dust Laboratory.
Olga Muñoz 1 , Fernando Moreno 1 , Dominika D. Dabrowska 1 , Coralie Brasse 2 , Patrice Coll2
, Francois Raulin 2
1

Instituto de Astrofı́sica de Andalucı́a, CSIC, Glorieta de la Astronomnı́a sn, Granada 18008, Spain,
olga@iaa.es
2
Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA), 61 avenue du General de Gaulle,
94010 Creteil Cedex, France

Small irregular dust particles are present in a wide variety of astronomical environments. By analyzing thelight scattered by those particles we can retrieve valuable information about their physical properties (shape,size, and composition) as well as their location within a certain atmosphere. The main goal of this talk is toshow how experimental data of intensity and polarization of the scattered light of different cosmic dust
analogs can be used to shed some light on the nature of dust particles. In particular, we will focus on
samples relevant for the study of the atmospheres of planets, satellites, and comets in the Solar System. The
measurements have been performed at the IAA COsmic DUst LABoratory (IAA-CODULAB) (Muñoz et al.
2011). The experimental data are freely available in digital form in the Amsterdam-Granada Light scattering
Database at www.iaa.es/scattering (Muñoz et al., 2012). The database consists of two branches, one withexperimental data from the Amsterdam Light scattering setup (Hovenier, 2000) and the other one withexperimental data from the IAA-CODULAB.

References[1] J.W. Hovenier. Measuring scattering matrices of small particles at optical wavelengths. In: Light
scattering by nonspherical particles, edited by M. I. Mishchenko, J. W. Hovenier, and L. D. Travis,
Academic, San Diego, CA, 2000:355-365.
[2] Muñoz, O.; Moreno, F.; Guirado, D.; Ramos, J.L.; Volten, H.; Hovenier, J.W. The IAA Cosmic Dust
Laboratory: experimental scattering matrices of clay particles. Icarus, vol. 211, pp. 894-900, 2011.
[3] Muñoz, O.; Moreno, F.; Guirado, D.; Dabrowska, D.D.; Volten, H.; Hovenier, J.W. The
Amsterdam-Granada Light Scattering Database. JQSRT, vol. 113(7), pp. 565-574, 2012.

15

Extrapolation of scattering matrices
D. Guirado 1,2 , O. Muñoz 1
1Instituto de Astrofı́sica de Andalucı́a2
dani@iaa.es

Based on the modulation of the polarization state of light scattered by dust aerosols, all elements of thescattering matrices of such dust samples are measured as functions of the scattering angle at the COsmic
DUst LABoratory (CODULAB) [1]. Due to physical restrictions, only a limited range of scattering angles
can be measured: the laser beam hits the frame of the detector when this is located close to the forward or
backward direction. Typically, this limited range is [3,177] deg. for CODULAB. But we need to know the
scattering matrix in [0,180] deg. for several purposes, as the calculation of the polarimetric color of a sample
or the utilization of a measured scattering matrix as an input for a Monte Carlo simulation of radiativetransfer of polarized light. Several extrapolation methods have been proposed [2]. These methods takeadvantage of some physical conditions that must be fulfilled at 0 and 180 deg. for some of the elements ofthe scattering matrix, but not for all. Recently, a new paper has been published that reveals that derivatives
must be zero at the strict forward and backward directions [3] for all elements of a scattering matrix. A newtechnique which compiles the method given in [2] and the condition unveiled by [3] has been implemented.
Important differences for Monte Carlo simulations of radiative transfer of polarized light will be shown, as
well as the application of this method to polarimetric measurements by another setup: FIGIFIGO [4].

References[1] O. Muñoz, F. Moreno, D. Guirado, J.L. Ramos, H. Volten, J.W. Hovenier. The IAA cosmic dust
laboratory: Experimental scattering matrices of clay particles. Icarus 2011; 211: 894-900.
[2] L. Liu, M.I. Mishchenko, J.W. Hovenier, H. Volten, O. Muñoz. Scattering matrix of quartz aerosols:
comparison and synthesis of laboratory and Lorenz-Mie results. Journal of Quantitative Spectroscopy
and Radiative Transfer 2003; 79/80: 911-920.
[3] J.W. Hovenier, D. Guirado. Zero slopes of the scattering function and scattering matrix for strict forward
and backward scattering by mirror symmetric collections of randomly oriented particles. Journal of
Quantitative Spectroscopy and Radiative Transfer 2014; 113: 596-602.
[4] J. Peltoniemi; T. Hakala; J. Suomalainen; E. Puttonen. Polarised bidirectional reflectance factor
measurements from soil, stones, and snow. Journal of Quantitative Spectroscopy and Radiative Transfer
2009; 110: 1940-1953.

16

Polarimetric observations and experimental simulationsin optically thin clouds: case of cometary andinterplanetary dust
Hadamcik E. 1,2 , Lasue J. 3 , Levasseur-Regourd A.C. 1,4 , Renard J.-B. 5
1

Sorbonne Universites, UPMC Univ. Paris 06; CNRS/INSU, LATMOS-IPSL; Universite Versailles
St-Quentin; 2 11 bld dAlembert , 78280 Guyancourt, France; edith.hadamcik@latmos.ipsl.fr
3
IRAP, Univ. Toulouse, France; jlasue@irap.omp.eu
4
4 place jussieu, 75005 Paris, France; Chantal.Levasseur@aerov.jussieu.fr
5
LPC2E-CNRS/Universite d’Orleans, jbrenard@cnrs-orleans.Fr

Remote polarimetric observations are used to tentatively infer the physical properties of the dust particles incometary and interplanetary environments. The scattered light is partially linearly polarized with apolarization degree depending on the physical properties of the dust and on the geometry (phase angle) andwavelength of observations. To interpret the observations numerical and experimental simulations arenecessary. Light scattering measurements on levitating particles with the PROGRA2 experiment -in
dedicated microgravity flights or in the laboratory for low-density particles- provide relevant simulations of
the scattering properties of real particles, which can present large size distributions and a large variety ofstructures and materials (Hadamcik et al., 2009). Previous systematic experiments, together with numericalmodels and laboratory analysis of cosmic particles (e.g. Stardust samples) allow to optimize dust particles
properties -such as their structures, sizes, size distributions, and silicate to organics ratios.
Intensity and polarization images of cometary comae provide evidence for changes in the polarization
properties in the internal regions of the coma (Hadamcik et al., 2003), linked to the variation of particles
properties with nucleus distance and/or rotation phase (Hadamcik et al., 2013). Associated experimental
simulations help us to interpret how particles evolve within different coma regions and at different solar
distances. We expect in situ confirmation of our results during the Rosetta mission to comet
67P/Churyumov-Gerasimenko in 2014-2015 (Hadamcik et al., 2010).
Analyses of observations of the zodiacal light scattered by the interplanetary dust cloud particles have shown
local polarisation changes with the solar distance (Levasseur-Regourd et al., 2001). Such changes areinterpreted through numerical models to be related to variations in the composition and physical propertiesof the particles through various processes including thermal degradation (Lasue et al., 2007;
Levasseur-Regourd et al., 2007). This interpretation is now validated on real mixtures of particles
corresponding to the zodiacal dust composition at different solar distances.

17

INVITED: Multiple Scattering of light by the surfacesof atmosphereless planetary objects
Karri Muinonen 1 , Antti Penttilä 2 , Gorden Videen 3
1

Department of Physics, Gustaf Hällströmin katu 2a, P.O. Box 64, FI-00014 University of Helsinki, Finland&
Finnish Geodetic Institute, Geodeetinrinne 2, P.O. Box 15, FI-02431 Masala, Finland,
karri.muinonen@helsinki.fi
2
Department of Physics, University of Helsinki, Finland, antti.i.penttila@helsinki.fi
3Army Research Laboratory, Adelphi, Maryland, U.S.A. &Space Science Institute, Boulder, Colorado, U.S.A., gorden.videen@gmail.com

Scattering of electromagnetic waves in a macroscopic particulate medium composed of microscopic particles
constitutes an open computational problem in planetary astrophysics. This problem manifests itself in theabsence of inverse methods to address fundamental astronomical observations of atmosphereless planetary
objects. There are two ubiquitous phenomena observed at small solar phase angles (the Sun-Object-Observer
angle) from, for example, asteroids, the Moon, Saturn’s Rings, and transneptunian objects. First, a nonlinear
increase of brightness is observed toward the zero phase angle in the magnitude scale that is commonly called
the opposition effect. Second, the scattered light is observed to be partially linearly polarized parallel to the
Sun-Object-Observer plane that is commonly called the negative polarization surge.
The aforedescribed polarimetric and photometric observations of atmosphereless planetary objects areinterpreted using a radiative-transfer coherent-backscattering model (RT-CB) that makes use of a so-called
phenomenological fundamental single scatterer (Muinonen and Videen 2012). For the validity of RT-CB, see
Muinonen et al. (2012). The modeling allows us to constrain the single-scattering albedo, phase function,and polarization characteristics as well as the mean free path length between successive scatterings. With thehelp of laboratory experiments and exact theoretical methods, it further allows us to put constraints on thesize, shape, and refractive index of the fundamental scatterers.
Acknowledgments: The research has been partially funded by the ERC Advanced Grant No 320773
entitled Scattering and Absorption of Electromagnetic Waves in Particulate Media (SAEMPL), by the
Academy of Finland (contract 257966), NASA Outer Planets Research Program (contract NNX10AP93G),
and NASA Lunar Advanced Science and Exploration Research Program (contract NNX11AB25G).
References: Muinonen, K., and Videen, G. (2012). A phenomenological single scatterer for studies ofcomplex particulate media. JQSRT 113, 2385.
Muinonen, K., Mishchenko, M. I., Dlugach, J. M., Zubko, E., Penttilä, A., and Videen, G. (2012). Coherent
backscattering numerically verified for a finite volume of spherical particles. ApJ 760, 118.

18

Scattering Line Polarization in Rotating Optically Thick
Disks
Ivan Milić 1 ,Marianne Faurobert 212

Astronomical Observatory, Volgina 7, 11 000 Belgrade, Serbia, milic@aob.rs
Laboratoire Lagrange, Observatoire de la Côte d’Azur, Nice, France, marianne.faurobert@oca.eu

In this contribution we study polarized line formation in optically thick disks which are either self-emitting
or illuminated by a host star. Disks are rotating obeying Keplerian law with typical velocities of up to ten
Doppler velocities of the line. We study a prototype line in the framework of a two-level atom model andemploy fully-consistent NLTE numerical radiative transfer techniques for the transfer of polarized radiation
on cylindrical axisymmetric grids where physical parameters depend only on z and r coordinates. We findthat presence of rotation of the disk severely influences emergent polarization. Especially interesting are themodels where the rotating disks are illuminated from the inside by the host star. In such models we findsignificant Stokes U (i.e. the rotation of the polarization plane). A specific shape of the dependence of therotation angle on the wavelength could prove to be useful diagnostics tool for diagnostics of disk geometry
and rotation velocity.

Figure 5: Intensity and polarization line profiles for an internally illuminated rotating disk with radial andvertical optical thickness’ equal to 1000 and 10, respectively. Note significant Stokes U , which does not exist
in the absence of rotation. Different line styles correspond to different inclinations of the system with respect
to the observer.

19

4

Session IV. Results: ISM , Molecular Clouds, Star Formation

Grain Alignment: Current State of Theory
Alexandre Lazarian 1
1Univ. of Wisconsin, Madison, USA

Dust is known to be aligned in interstellar medium and the arising polarization is extensively used to trace
magnetic fields. What process aligns dust grains was one of the most long-standing problems of astrophysics
in spite of the persistent efforts to solve it. For years the Davis-Greenstein paramagnetic alignment was theprimary candidate for explaining grain alignment. However, the situation is different now and the mostpromising mechanism is associated with radiative torques (RATs) acting on irregular grains. I shall present
the analytical theory of RAT alignment, discuss the observational tests that support this theory. I shall also
discuss in what situations we expect to see the dominance of paramagnetic alignment.

20

Observational tests of grain alignment mechanisms
B-G Andersson 1
1

SOFIA-USRA, Moffett Field, CA, USA

Dust induced interstellar polarization in the optical and infrared is a potentially powerful method for probing
the magnetic field strength and structure. Its use for these purposes has however been hampered by theuncertain nature of the physical alignment mechanisms for the dust grains. Over the last decade observations
have now shown - at least for the ”large” dust grains - that the classical paramagnetic relaxation alignment
is likely not viable. In contrast, a number of observational tests, both at optical/NIR and FIR wavelengths,
have been carried out which all support the Radiative Alignment Torque (RAT) mechanism. I will review
these observations and show that a quantitatively established grain alignment theory will not only allow
better probes of the ISM magnetic field, but also provide new probes of the dust characteristics and the ISM
environment.

21

A novel method for measuring interstellar magnetic
fields using UV dust polarimetry
Thiem Hoang 1,2 , A. Lazarian 3 , Peter G. Martin 2
1

Ruhr-Universität Bochum, 44780 Bochum, Germany, hoang@cita.utoronto.ca
2
Canadian Institute for Theoretical Astrophysics, Canada
3
University of Wisconsin-Madison, USA

We present a novel method to measure the strength of interstellar magnetic fields based on ultraviolet (UV)polarization of starlight, which is in part produced by weakly aligned, small interstellar grains. We begin
with calculating degrees of paramagnetic alignment of small (size a ∼ 0.01µm) and very small (a ∼ 0.001µm )grains in the interstellar magnetic field by the Davis-Greenstein relaxation and resonance relaxation. We
compute the degrees of paramagnetic alignment with the ambient magnetic field B using Langevin equations.
In this paper, we take into account various processes essential for the dynamics of small grains, including
infrared (IR) emission, electric dipole emission, plasma drag and collisions with ionized species. We find thatweak alignment of small grains is required to reproduce the observed polarization in the UV, although thepolarization arising from these small grains is negligible at the optical and IR wavelengths. Based on fitting
theoretical models to observed extinction and polarization curves, we find that the best-fit model requires ahigher degree of alignment of small grains for the case with the peak wavelength of polarization
λmax < 0.55µm, which exhibits an excess UV polarization relative to the Serkowski law, compared to thetypical case λmax = 0.55µm. We interpret the correlation between the systematic increase of the UV
polarization relative to maximum polarization (i.e. of p(6µm−1 )/pmax ) with λ−1
max by appealing to the higher
degree of the alignment of small grains. We identify paramagnetic relaxation as the cause of the alignment ofsmall grains and utilize the dependence of the degree of alignment on the strength of magnetic fields B tosuggest a new way to measure the strength of magnetic fields using the observable parameters λmax andp(6µm−1 )/pmax . Applying our new technique to the available observational data, we estimate the upper
limit of interstellar magnetic field B ∼ 10 − 15µG for the typical sightline (λmax = 0.55µm), which isconsistent with the strength obtained from other available techniques.

22

The Zeeman Effect As a Tool to Study Magnetic Fields
in the Interstellar Medium
Timothy Robishaw 1
1

National Research Council Canada, Herzberg Astronomy and Astrophysics Programs, Dominion Radio
Astrophysical Observatory, PO Box 248, Penticton, BC V2A 8J3, Canada;tim.robishaw@nrc-cnrc.gc.ca

The Zeeman effect is the only observational tool that allows us to directly measure the magnetic fieldstrength and direction in the interstellar medium. We provide an overview of ongoing projects in which weare using the Zeeman splitting of the 21-cm line and the 18-cm hydroxyl (OH) transitions in order to probe
astrophysical magnetic fields. We will also discuss previous measurements of the Zeeman effect in Galactic
21-cm radio emission, some of the instrumental challenges involved in such measurements, and theambiguities that circular polarization conventions have introduced in their interpretation. We will present
highlights that include the first detection of extragalactic Zeeman splitting in the OH megamaser emission
from starburst galaxies and results from a southern hemisphere survey of Zeeman splitting in OH masers in
our Milky Way’s spiral arms that suggest field reversals relative to the field directions probed by Faraday
rotation. Finally, we discuss plans for and preliminary results from a large-scale 21-cm emission Zeeman
survey underway on the 64-m Parkes Telescope and the 26-m John A. Galt Telescope at the Dominion Radio
Astrophysical Observatory.

23

Polarized thermal dust emission from Planck
F. Levrier 1 on behalf of the Planck Collaboration
1

LERMA / LRA - Ecole Normale Supérieure de Paris et Observatoire de Paris, 24 rue Lhomond 75231 Paris
Cedex 05, francois.levrier@ens.fr

The Planck satellite has mapped the polarized microwave and submillimetre sky (from 30 GHz to 353 GHz)
with unprecedented sensitivity and angular resolution. This wealth of data sheds new light on thepolarization of Galactic foregrounds, especially that of thermal emission from aligned aspherical dust grains,which dominates the polarized cosmic microwave background (CMB) at the high end of the Planck frequency
range. I will present the first results from the current analysis of Planck polarization data related to thermal
dust emission. The Planck polarization data is scheduled to be made publically available in the fall of 2014.

24

Observations of Far-infrared and Millimeter Polarizationin Galactic Clouds
John E. Vaillancourt1
1

SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, Moffett
Field, CA, USA; jvaillancourt@sofia.usra.edu

Polarized radiation at far-infrared (FIR) through millimeter (MM) wavelengths (λ ∼ 50–2000 µm) arises
from thermally emitting dust grains whose axes exhibit a net alignment with the local magnetic field. As aresult of this mechanism, FIR/MM polarization observations have been used successfully for decades tomeasure magnetic field strength and structure in the densest molecular clouds in the Galaxy. Most recently
the advent of more sensitive single-dish instruments and interferometers have extended such observations to
individual proto-stars and clusters, thus allowing more definitive tests of magnetically-regulated andturbulence-regulated star formation. Additionally, more advanced physical models of grain alignment
mechanisms have been proposed, models that lend themselves to tests with multi-wavelength FIR/MM
observations. In the absence of a well-understood alignment model, the aforementioned magnetic fieldmeasurements would all be suspect. The FIR/MM spectra require models with multiple domains of grain
temperature, alignment efficiency, and possibly composition. Extension of Galactic cloud observations to
MM wavelengths, extension of FIR observations to low-density clouds, and complementary opticalpolarization observations will provide improved tests of alignment models covering a wide range ofastrophysical/environmental conditions (e.g., density, temperature, radiation field, composition).

W3

NIR
60 µm
100 µm
850 µmFigure 6: Left: Multi-wavelength polarization measurements in the molecular cloud W3. Right: Medianpolarization at multiple wavelengths in five different clouds.

25Characterizing Magnetized Turbulence with
Polarization Maps
Martin Houde 1 , John E. Vaillancourt 2 , Roger H. Hildebrand 3
12

University of Western Ontario, London, Ontario, N6A 3K7, Canada, mhoude2@uwo.ca
Stratospheric Observatory for Infrared Astronomy, Universities Space Research Association, NASA Ames
Research Center, USA, jvaillancourt@sofia.usra.edu
3
University of Chicago, USA, roger@oddjob.uchicago.edu

I will discuss how an analysis in the angular dispersion of polarization vectors can be used to characterizefundamental parameters pertaining to magnetic fields and turbulence in the interstellar medium. I will use
different sets of data, ranging from lower resolution single-dish to high-resolution interferometry polarization
maps (or a combination of both), to describe how, for example, magnetic field strengths, correlation lengthscales, and the anisotropy of turbulence leave their imprint on the data and can be accurately measured inmolecular clouds (e.g., Orion KL and DR 21(OH)) and galaxies (M51). I will also show how the inertial anddissipation ranges of the turbulent power spectrum can be parameterized when the data were obtained withhigh-enough resolution.

26

INVITED: From clouds to cores to envelopes to disks:a multi-scale view of magnetized star formation
Charles L. H. Hull1 , Richard L. Plambeck2 , & the TADPOL collaboration3
1

Radio Astronomy Laboratory, University of California, Berkeley. 601 Campbell Hall, Berkeley, CA 94720,
USA — EMAIL: chat@astro.berkeley.edu
2Radio Astronomy Laboratory, UC Berkeley — EMAIL: plambeck@astro.berkeley.edu
3
http://tadpol.astro.illnois.edu

Magnetic fields have long been thought to play an important role in the formation of stars. However,that importance has been called into question by previous observations showing that bipolar outflows andmagnetic fields (B-fields) are misaligned in young protostars, and that B-field morphology in these objects
can change near the ∼ 1000 AU scales of the protostellar envelope. To investigate these inconsistencies, weused the 1.3 mm full-Stokes polarimeter at CARMA to map dust polarization toward 30 star-forming coresas part of the TADPOL survey (see Figure 7 for sample maps). We find that a subset of the sources haveconsistent B-field orientations between large (∼ 10,000 AU) scales and the small (∼ 1000 AU) scales measured
by CARMA, and that those same sources also tend to have high fractional polarization. This suggests that in
at least some cases B-fields play a role in regulating the infall of material all the way down to the protostellar
envelope scale. We also find that outflows appear to be randomly aligned with B-fields; although, in sources
with low polarization fractions, there is a hint that outflows are preferentially perpendicular to small-scale
B-fields, which suggests that in these sources the fields have been wrapped up by envelope rotation.

L1157

Ser-emb 8, 8(N)1000 AU

1000 AU

Figure 7: Sample maps of low-mass protostellar cores from the TADPOL survey. The line segments show the inferred magnetic

field orientations; they have been rotated by 90◦ relative to the polarization orientations. The segment lengths are proportional
to the square root of polarized intensity, not fractional polarization. The grayscale is proportional to the total intensity (Stokes
I) dust emission. The blue and red contours are the blue- and redshifted spectral line wings [L1157: CO(J = 2 → 1); Ser-emb 8:
SiO(J = 5 → 4)].

27

The magnetic field structure of L1527:
A Cautionary TaleDavidson, J.A. 1 , Li, Z-Y. 2 , Chapman, N. 3 , Crutcher, R. 4 , Hull, C.5 , Kwon, W. 6 , Looney, L. 4 , Matthews,
B. 7 , Novak, G. 3 , Plambeck, R. 5 , Stephens, I., 4, 8 and Tobin, J.9
1

Univ. of Western Australia, M013, School of Physics, 35 Stirling HWY, Crawley, WA 6009, Australia;
jackie.davidson@uwa.edu.au
2
Univ. of Virginia; 3 Northwestern U.; 4 U. of Illinois; 5 U.C. Berkeley; 6 SRON; 7 U. of Victoria & NRCC; 8 Boston
U.; 9 NRAO

Many studies average the orientation of magnetic field vectors (as inferred from polarisation) over an observed
region of a cloud core to estimate the initial uniform magnetic field orientation for that core. We have used
global core collapse models with orthogonal and aligned initial magnetic fields with respect to the rotation
axis of the core (inferred by a core’s bipolar outflow) to see if these spatial averages of the magnetic fieldorientations give misleading results in regards to the initial field orientation. We also compared these models
to the 131 polarisation vectors measured for a well-studied, nearby, cloud core containing a Class 0 embedded
protostar, L1527. The models were integrated along the line-of-sight coincident with the observed vectors,
with optical depth and beam effects included. Our results show that for weak magnetic field strengths,
global core collapse models retain very little of their initial magnetic field orientation and have very similar
evolved morphologies; only for strong fields do the aligned and orthogonal models evolve significantly different
morphologies. Our results also show that spatial averages of field orientation angles depend strongly on theregions sampled in the cloud core for the averages and so these averages can be very misleading in regards tothe initial field orientation.

Figure 8: Magnetic field orientations in L1527: red vectors are based on SCUPOL, SHARP and CARMA observations; blackand cyan vectors are based on the models. Vector lengths are proportional to polarisation fractions. Model (A) represents an
initial weak field aligned with the outflow; Model (B) represents an initial weak field orthogonal to the outflow. Green arrows
represent the outflow axis for L1527. The greyscale shows the model integrated intensities.

28

INVITED: Circular polarization from star forming
regions
Jungmi Kwon 1 , Motohide Tamura 2 , SIRPOL team 3
1

National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan, email:jungmi.kwon@nao.ac.jp
2
Dept. of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo
113-0033, Japan, email: motohide.tamura@nao.ac.jp

The star and planet formation is one of the foremost issues in Astronomy. However, the history of star andplanet formation still remains a mystery, even though for a single star and its parent cloud including amolecular cloud core there are many studies in recent years. Near-infrared polarimetry is powerful techniqueto study the dust scattering and magnetic fields in star forming regions that is heavily obscured by dense
clouds of gas and dust. Linear imaging polarimetry has been extensively explored so far, while circularimaging polarimetrh has much less utilized, especially at infrared wavelengths. In this presentation, we
present the first near-infrared circular and linear polarimetry survey of famous star forming regions observedin the near-infrared bands with the unique polarimeter SIRPOL on the InfraRed Survey Facility (IRSF)
1.4m telescope that is placed in South African Astronomical Observatory (SAAO). It is the only instrumentthat can make polarimetric imaging with a wide fields (7.70 × 7.70 ) in three bands (J, H, Ks ),simultaneously. The results of circular polarimetry are also compared with that of linear polarimetry. Ourdata is covering covering from high-mass to low-mass young stellar objects, and it means we can performstatistical discussions for the first time. Our results show not only the magnetic field orientation of aroundyoung stellar objects, but also the structure of circumstellar matter such as outflow regions and their parent
molecular cloud along the line-of-sight. In addition, we tried to understand the origins of circularpolarization, especially for the high circular polarization that was not well explained with the present
scattering mechanisms and ever verified by both observations and models. Our survey results may support
the circular polarization in star forming regions as an origin of the biological homochirality on Earth, as
proposed for the Orion nebular.

29

Multi-wavelength polarimetry toward a magnetizedprestellar core
Felipe Alves 1 , Pau Frau 2 , Fábio P. Santos 3 , Helmut Wiesemeyer 4 , Josep M. Girart 5 ,Gabriel Franco 6 , Carmen Juárez 5 , Aina Palau7
1

Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121 Bonn, Germany falves@astro.uni-bonn.de2
Observatorio Astronómico Nacional, Alfonso XII 3, E-28014 Madrid, Spain, p.frau@oan.es
3
Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208,
USA, fabiops@northwestern.edu
4Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany,hwiese@mpifr-bonn.mpg.de
5
Institut de Ciències de l’Espai (CSIC-IEEC), Campus UAB, Facultat de Ciències, C5 par 2a , E-08193,
Bellaterra, Catalunya, Spain, girart@ice.cat
6
Departamento de Fı́sica – ICEx – UFMG, Caixa Postal 702, 30.123-970 Belo Horizonte, Brazil,
franco@fisica.ufmg.br
7
Centro de Radioastronomı́a y Astrofı́sica, Universidad Nacional Autonoma de México, P.O. Box 3-72,
58090 Morelia, Michoacán, Mexico, a.palau@crya.unam.mx

Magnetic fields are thought to prevent or delay the formation of new stars within a molecular cloud, but how
this process occurs during the earliest stages of star formation is still unclear. Our team presents newpolarization data toward one of the starless cores found in the magnetized and sub-Alfvénic Pipe nebula.
The new data reveal a strong submillimeter (submm) polarization flux toward Core 109, a textbook case of aprestellar core on the verge of collapse. This object is embedded in a very magnetized gas, as revealed by
optical and near-infrared polarization data. In this talk, I will show how the submm polarization compareswith the shorter wavelengths. An intriguing magnetic field configuration from the core envelope to the center
is observed. The magnetic field in the core has field lines which are very ordered but slightly misaligned withthe envelope B-field, in disagreement with theoretical predictions. I will discuss the possible scenarios
associated to the dynamical evolution of this object by comparing our polarization maps to molecular data.

30

5

Session V. Results: Circumstellar matter

INVITED: A VLT/NACO program to study the inner
regions of protoplanetary disks
Sascha P. Quanz1 , Henning Avenhaus2 , Antonio Garufi2 , Hans Martin Schmid2 , Esther
Buenzli3 , Michael R. Meyer2 , Carsten Dominik4 , and Sebastian Wolf51

ETH Zurich; Institute for Astronomy; Wolfgang-Pauli-Strasse 27, Building HIT-J, CH-8093 Zurich,
Switzerland; sascha.quanz@astro.phys.ethz.ch
2
ETH Zurich; Institute for Astronomy
3
Max Planck Institute for Astronomy
4
University of Amsterdam, Astronomical Institute Anton Pannekoek
5
University of Kiel, Institute of Theoretical Physics and Astrophysics

In the past few years, we have used the adaptive optics assisted high-resolution near-infrared camera NACO
at the Very Large Telescope to study the protoplanetary disks around 8 young intermediate mass Herbig
Ae/Be stars. All disks were observed in polarimetric differential imaging mode providing unprecedented
sensitivity and resolution at separations down to 0.100 (∼10 AU from the central stars). Our images reveal avariety of previously unseen sub-structures in most of the disks. This talk will summarize the key resultsfrom this program and compare them with complementary datasets to address to what extent ongoing planet
formation within the observed disks is the result – or the cause – of the detected structures. Outstanding
questions will be discussed and an outlook will be provided what can be expected from the next generationof high-contrast imagers now coming online at the VLT and Gemini Observatory.

Figure 9: Exemplary results from our NACO/PDI program: The disks around SAO206462, HD169142, andHD142527 (Garufi et al. (2013, A&A 560, 105); Quanz et al. (2013, ApJL 766, 2); Avenhaus et al. (2014,
ApJ 781, 87)). Possible signs of (forming) planets (e.g, spiral arms, cavities and gaps) are commonly observedin the inner 10-100 AU.

31

Imaging polarimetry of the potentially planet-forming
circumstellar disk HD 142527. The NaCo view.
Cánovas, H. 1,8 , Ménard, F. 2,8 , Hales, A.3,8 , A. Jordán4,8 , M. R. Schreiber1,8 , S. Casassus5,8 ,T. M. Gledhill6 , C. Pinte7,81

Departamento de Fisica y Astronomı́a, Universidad de Valparaı́so, Gran Bretaña 1111, Valparaı́so, Chile.
Email: hector.canovas@uv.cl
2
UMI-FCA, CNRS / INSU France (UMI 3386). Email: francois.menard@obs.ujf-grenoble.fr
3
Atacama Large Millimeter/Submillimeter Array, Joint ALMA Observatory. Email: ahales@alma.cl
4
Instituto de Astrofı́sica, Pontificia Universidad Católica de Chile. Email: ajordan@astro.puc.cl
5
Departamento de Astronomı́a, Universidad de Chile. Email: simon@das.uchile.cl6
Science and Technology Research Institute, University of Hertfordshire. Email: t.gledhill@herts.ac.uk
7
UJF-Grenoble 1 / CNRS-INSU, Institut de Plantologie et d’Astrophysique de Grenoble (IPAG). Email:christophe.pinte@obs.ujf-grenoble.fr
8
Millenium Nucleus “Protoplanetary Disks in ALMA Early Science”

HD 142527 is a unique system in terms of planet formation. Its high accretion rate combined with its hugeinner gap and short age make of it an ideal candidate for harboring forming planets. ALMA cycle-0
observations revealed gap crossing gas streams and showed that the millimeter-sized dust particles are
distributed in a horse-shoe shape. Here I present our recent NIR imaging polarimetry results of HD 142527
obtained with NaCo/VLT. By means of polarimetry, we remove most of the stellar light, directly imaging the
disk’s inner regions. Our observations allow us to constrain the dust properties (size, composition andporosity) on the surface of the the outer disk. We also detect two regions of the disk with low emission(“nulls”) both in polarized and unpolarized light. Intriguingly, one of these nulls is azimuthally coincident
with the maximum of the horse-shoe shape detected by ALMA. We discuss the possible link between thesetwo (different?) features.

Figure 10: Left: Polarized intensity images of HD 152427 at H-band (adapted from Canovas et al. 2013).
Right: Continuum ALMA Band-7 image (345 GHz, 0.87 mm), adapted from Casassus et al. 2013). The
maximum emission at the continuum is roughly coincident with the gap observed in polarized intensity in the
H-band at top position.

32

Multi-epoch Polarimetric Differential Imaging ofHD100546
Henning Avenhaus 1 , Sascha P. Quanz 2 , Michael R. Meyer 2 , Sean D. Brittain 3 , John S.
Carr 4 , Joan R. Najita 5
1

ETH Zurich; Institute for Astronomy; Wolfgang-Pauli-Strasse 27, Building HIT-J, CH-8093 Zurich,
Switzerland; h.avenhaus@phys.ethz.ch
2
ETH Zurich; Institute for Astronomy
3
Clemson University; Department of Physics & Astronomy
4
Naval Research Laboratory, Washington DC
5
National Optical Astronomy Observatory, Tuscon

The transition disk of HD100546 has been imaged in both thermal and scattered light. Recently, it got
further attention by the detection of two companion candidates: One within the inner gap of the disk, which
has a radius of ∼15 AU, and a second one further out in the disk at ∼68 AU. This makes HD100546 anespecially interesting object, because we may be observing the formation of planets and their interaction
with the surrounding gas-rich disk directly. In 2013, we obtained second-epoch Polarimetric Differential
Imaging (PDI) data, which I will present here along with a re-reduction of data taken in 2006 using a new,improved pipeline. We also, for the first time ever, were able to image the scattered light of a circumstellar
disk using PDI in the L0 band. We achieve an inner working angle of ∼0.1”, and clearly reveal the disk andits gap at high signal-to-noise ratio. In my talk, I will summarize our key results for this interestingtransitional disk and discuss possible connections between the disk and the two proposed companions.

Distance (AU)Distance (arcsec)
−1"
100

−0.5"

0"

0.5"

1"

−100
1"

1"

0

r

100
100

se

m
ax imais jo0m
ax imi
is n

−0.5"

−1"
−1"

−0.5"

−100
−0.5"

0"
0.5"
Distance (arcsec)

1"

−100
−100

0
Distance (AU)

−1"
100

spiral
arm

0

la

ne

0"

−0.5"

rk

0"

−1"
−1"

da

0

Distance (arcsec)

0Distance (AU)

0"

0.5"

back side

Distance (arcsec)

0.5"

se

or

0.5"

100
100

Distance (AU)Distance (AU)−100
1"front side
−0.5"

0"
0.5"
Distance (arcsec)

−100
1"

Figure 11: PDI results for HD100546. Left: P⊥ for the Ks filter. Positive values in orange, negative values (not seen) inblue. Middle: Pk , which contains essentially noise on the same level, for comparison. We achieve a high S/N ratio. Right:
Features marked in the disk. The green points are the approximate positions of the two companion candidates (see Avenhaus etal. submitted for further information).

33

Polarimetry with the Gemini Planet Imager: Speckle
Suppression and the HD61005 Debris Disk
Max Millar-Blanchaer1 , Marshall D. Perrin2 , James R. Graham3 , Sloane Wiktorowicz4 ,Bruce Macintosh5 , Michael P. Fitzgerald6 , Fredrik Rantakyro7 , Pascale Hibon8 and theGemini Planet Imager Team
1

University of Toronto, Department of Astronomy and Astrophysics, 50 St. George St., Toronto, Ontario,
Canada, M5S 3H4, maxmb@astro.utoronto.ca
2Space Telescope Science Institute, mperrin@stsci.edu
3University of California, Berkeley, jrg@berkeley.edu
4
University of California, Santa Cruz, sloanew@ucolick.org
5
Stanford University, bmacintosh@stanford.edu
6
University of California, Los Angeles, mpfitz@ucla.edu
7Gemini Observatory, frantaky@gemini.edu
8Gemini Observatory, phibon@gemini.edu

The Gemini Planet Imager (GPI), currently undergoing commissioning at the 8-m Gemini South Telescope,
is equipped with a dual-channel polarimetry mode designed for the detection of scattered, polarized lightfrom circumstellar disks around nearby stars. GPI has been on-sky since November 2013 and the polarimetrymode has been operational since December 2013. We provide results from the ongoing characterization of the
instrument. Observations of the twilight sky, strongly polarized due to Rayleigh scattering in the upper
atmosphere, provide a simple first order test of GPI’s ability to measure the position angle of polarized light.
We successfully recover the expected position angle of the polarized twilight sky, at 1.1, 1.6, and 2 microns.
Coronagraphic observations of unpolarized stars demonstrate GPI’s ability to suppress unpolarized light byover a factor 150 at working angles as small as 0.3 arcseconds, from 1.1 to 2 microns. In addition, we present
H-band images of the circumstellar environment of HD61005, where we resolve ”The Moth” debris disk inboth total intensity and polarized intensity at smaller angular separations down to 0.3 arcseconds.

34

Exploring Magnetic Fields in Young Circumstellar Disks
and their Environments with CanariCam Polarimetry at
the GTC
C. M. Telesco 1 , D. Li 1 , C. M. Wright 2 , C. Alvarez 3,4 , P. J. Barnes 1 , S. Fernández 3 , J. H.
Hough 5 , N. Mariñas 1 , C. Packham 6 , H. Zhang 1
1

Department of Astronomy, University of Florida, Gainesville, FL 32611 USA, telesco@astro.ufl.edu,
d.li@ufl.edu, pjb@astro.ufl.edu, marinas@astro.ufl.edu, hanzh0420@ufl.edu
2
University of New South Wales, C.Wright@adfa.edu.au
3
Instituto de Astrofisica de Canarias, carlos.alvarez@gtc.iac.es, sergio.fernandez@gtc.iac.es
4
Universidad de La Laguna
5
University of Hertfordshire, jhh@star.herts.ac.uk
6
University of Texas at San Antonio, Chris.Packham@utsa.edu

Astronomers are well aware that magnetic fields (B-fields) play a critical role in the formation of stars andplanets. Numerous theoretical studies have demonstrated that B-fields alter, and in many regimes, control,
the dynamics and lifetimes of cloud collapse and subsequent protostellar evolution. The resultant young
circumstellar disks are likely threaded by B-fields that are first pulled inward as part of the collapse, thentwisted into the disk plane by Keplerian rotation. Magnetic coupling of gas at different orbital radii, alongwith the Keplerian shear, must give rise to turbulence and a highly irregular B-field structure in the disk.
The turbulence and resultant viscosity are thought to have a dramatic effect on planet-formation timescales.
However, few, if any, observations exist that constrain B-field strengths and morphologies in planet-forming
disks, which has been a major obstacle to progress in planet-formation studies. With the start of its
commissioning and science operations in 2012, the facility multi-mode mid-IR camera CanariCam at theGran Telescopio CANARIAS (GTC) on La Palma, has emerged as a promising and powerful tool in the
exploration of B-fields in these and other environments. In particular, CanariCam’s 8-13 micrometerpolarimetric mode offers the potential for astronomers to determine B-field structure with approximately 0.3
arcsec resolution and unprecedented sensitivities in young disks and their environments. After a brief
overview of CanariCam’s polarimetric mode, we will present recent results from our GTC program to explore
B-fields in young disks and their environments, results that demonstrate CanariCams capabilities. Amongthese results are: (1) the mapping of the B-field variations both across, and potentially along the line of sightwithin, the disk and environment of the YSO K3-50; (2) tentative evidence for detection of the B-field within
the environment of the Herbig Ae star AB Aur. The GTC is a joint initiative of Spain, the University of
Florida, and Mexico.

35

CanariCam imaging- and spectro-polarimetry of
embedded Young Stellar Objects driving bipolar outflow
Christopher M. Wright 1 , Charles M. Telesco 2 , Dan Li 2 , Patrick F. Roche 3 , James H.
Hough 4 , Carlos Alvarez 5,6 , Sergio Fernandez Acosta 5 , Chris Packham 7
1

School of Physical, Environmental and Mathematical Sciences, UNSW Canberra, PO Box 7916, Canberra
BC 2610, Australia, c.wright@adfa.edu.au2
University of Florida, telesco@astro.ufl.edu, d.li@ufl.edu
3
University of Oxford, P.Roche1@physics.ox.ac.uk
4
University of Hertfordshire, j.h.hough@herts.ac.uk
5Instituto de Astrofisica de Canarias, carlos.alvarez@gtc.iac.es, sergio.fernandez@gtc.iac.es
6
Universidad de La Laguna
7
University of Texas at San Antonio, Chris.Packham@utsa.edu

Some of the key questions behind our origins can be probed via thermal (or mid-) infrared polarimetricobservations. These include the influence of magnetic fields during the early evolution of young stars, andthe compositional and mineralogical evolution of cosmic dust.
Conservation of angular momentum dictates that as a forming star gravitationally contracts it would spin up
to a break-up point unless some mechanism exists to prevent it. A cosmic magnetic field is the main suspect,
whereby it acts in concert with rotation to tap the gravitational potential well of a star+disk system to ejectmaterial along the poles. The ejected material carries away angular momentum, allowing infall and accretion
to proceed. An ability to map the magnetic field in the near environs of a young star is an ideal way to study
this and related processes.
Cosmic dust grains are the raw material for the formation of rocky planets. But the process(es) by which
multi-trillions sub-micron sized pieces of grit are transformed into a planet are poorly understood. Yet theseprocesses must surely have some influence on the dust itself, inducing chemical, physical and/or
morphological changes. An ability to constrain and/or determine dust properties in the envelopes and disks
around young stars is crucial to better understand these processes.
Polarimetry in the mid-infrared is an especially powerful technique to address the issues outlined above. The
polarization is due to emission from, or absorption by, a medium of dust grains whose short axes have been
preferentially aligned with the ambient magnetic field. Thus, the polarization position angle observed fromsuch a medium is related to the magnetic field direction projected onto the plane of the sky. Further, thecross sections for absorption of radiation along the major and minor axes of a spheroidal dust grain peak at
different wavelengths, and the polarization is formed by a difference between these cross sections. They aresensitively dependent on the grain dielectric function, a unique identifier of the responsible material, as wellas grain shape and presence of a mantle.
Since mid-2012 we have been using the world’s newest and most advanced mid-IR instrument, CanariCam,on the world’s largest single-aperture optical/IR telescope, the 10.4 m Gran Telescopio CANARIAS (GTC),
to observe the polarization from a sample of embedded Young Stellar Objects. We will present a selection of
results from multi-filter imaging polarimetry across the 10 µm silicate band, which has allowed theseparation of magnetic field components within both emitting and absorbing regions near the source. We will
also present some early spectropolarimetric observations, which have revealed in unprecedented detail theunusual dust mineralogy toward several young stars.

36

Linear line spectro-polarimetry and the circumstellar
medium around young and massive stars
Jorick S. Vink1
1

Armagh Observatory, College Hill, BT61 9DG Armagh, Northern Ireland (jsv@arm.ac.uk)

Linear line spectro-polarimetry is a powerful tool to probe circumstellar structures on spatial scales thatcannot yet be achieved through direct imaging or interferometry. I discuss the role that emission-line
polarimetry can play in constraining both geometrical and physical properties of a wide range ofcircumstellar environments, varying from the accretion disks around pre-main sequence (PMS) T Tauri and
Herbig Ae/Be stars, to the issue of stellar wind clumping, and the aspherical outflows from the massive starprogenitors of supernovae (SNe) and long gamma-ray bursts (GRBs).

37

Play of polarized light in the dusty nebula of the long
period Cepheid RS Puppis
P. Kervella1 , H. E. Bond2 , M. Cracraft2 , J. Breitfelder1,3 , L. Szabados4 , A. Mérand2 , W. B.
Sparks2 , A. Gallenne5 , D. Bersier6 , P. Fouqué7 ,and R. J. Havlen8
1

LESIA, Observatoire de Paris, Meudon, France, pierre.kervella@obspm.fr
2
Space Telescope Science Institute, Baltimore, MD, USA
3
European Southern Observatory, Santiago, Chile
4
Konkoly Observatory, Budapest, Hungary
5
Universidad de Concepción, Chile
6
Astrophysics Research Institute, Liverpool John Moores University, UK
7
IRAP, Toulouse, France 8 Albuquerque, NM, USA

The long-period Cepheid RS Pup is one of the most luminous Cepheids in the Milky Way (P = 41.4 days). It
is surrounded by a large circumstellar dusty nebula reflecting the light from the central star. The origin andphysical properties of the nebula are however uncertain: was it created through mass loss from the star, or isit a pre-existing interstellar cloud ? To address this question, we used the VLT/FORS instrument to map the
degree of linear polarization pL in the nebula. Using a simple polarization model, the scattering angle can berecovered from pL , and therefore give access to the 3D dust distribution. We derive a total dust mass of
Mdust = 2.9 ± 0.9 M within 1.80 of the Cepheid. This very high mass excludes that it was created by thestar itself. Due to the changing luminosity of the central source, light echoes propagate into the nebula. This
remarkable phenomenon can yield a reliable geometric distance to RS Pup, provided we achieve a sufficientaccuracy on the 3D structure of the dust distribution. Such a distance is highly valuable e.g. to calibrate theLeavitt law, as well as the Cepheid’s projection factor p used in Baade-Wesselink distance estimates. We
obtained 7 epochs of polarimetric imaging with HST/ACS, from which we derive a distance d ≈ 2 kpc, and ap-factor around 1.3 (work in progress).

Figure 12: Three-color composite view of the nebula of RS Pup (HST/ACS).

38

Strong linear polarization of the optical continuum of
the red nova V4332 Sagittarii
Romuald Tylenda 1 , Tomasz Kamiński 2
1

2

N. Copernicus Astronomical Centre, Toruń, Poland, tylenda@ncac.torun.pl
Max-Planck Institut fuer Radioastronomie, Bonn, Germany, kaminski@mpifr.de

Pol. degree (%)

Pol. angle (degr.)

V4332 Sgr is a red nova (also named as red transient or V838-Mon-type object), which erupted in 1994. Red
novae, contrary to classical novae, evolve during the eruption to progressively lower effective temperature anddecline as late M-type (super)giants. We now know that the red novae result from stellar mergers.
V4332 Sgr did not atract any interest from observers until the V838 Mon eruption in 2002, whenastrophysicits realised that both objects belong to the same class and are very intriguing. Spectroscopic
observations of V4332 Sgr done in 2003 revealed an unusual spectrum as for stellar objects: strong emission
lines of neutral atoms and molecules superimposed on a weak, early M-type continuum.
In previous studies we have shown that the main object in V4332 Sgr is not visible for us as it is now
embedded in a dusty disc: the observed stellar-like continuum in the optical most probably arises fromscattering of the main object spectrum on dust grains, while the emission features are produced by atoms
and molecules in the outflowing matter in the process of resonant scattering. Consequently the continuum
should be considerably polarized but not the emission features. Our recent spectropolarimetric observations(as presented in the figure) show that this is indeed largely the case although not entirely.

180
160
140
120
100
80
60
40
20
0
25

PA = 114º.6

PL = 16.6 %

20
15
10
5

atm O2

5900

6000

6100

6200

6300

6900

7000

TiO a (2ï2)

TiO a (1ï1)

TiO a (0ï0)
atm O26800

TiO a (0ï0) sat.

CrO BïX (1ï3)

6500 6600 6700
Wavelength (Å)

TiO a (2ï1) + CrO

CrO BïX (1ï2)

6400

CaI

TiO a (1ï0)

CrO BïX (0ï1)

NaI

TiO a’ (0ï0)

ScO AïX (0ï0)

8
7
6
5
4
3
2
1
0

YO AïX (0ï0)

Stokes I0

atm H2O

7100

7200

7300

Figure 13: Spectropolarimetry of V4332 Sgr. Bottom: spectrum, middle: polarization degree, top: polarization
angle.

39

6

Session VI. Results: Solar & Stellar Magnetic Fields

Invited: Solar magnetic fields
M. Faurobert 1
1

University of Nice-Sophia Antipolis, Lagrange Laboratory UMR7293, Parc Valrose, 06108 Nice cedex 2.
France. marianne.faurobert@unice.fr

The Sun is the first astrophysical object where magnetic fields have been detected and measured. As ourclosest star it offers the possibility of studying a case of stellar magnetism with great details. Its complex
magnetic structuring has been explored with increasing spatial and temporal resolution, in particular
recently from space born instruments such as SOT on the Hinode satellite, HMI on SDO or IMAX on
SUNRISE . I will present some of the new results obtained with these instruments and give some directions
for future developments.

40

Exploration of Magnetic Fields in Solar Chromosphereby High-Precision Lyman-Alpha PolarimetryKano, R. 1 , CLASP team1

National Astronomical Observatry of Japan; 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan;
ryouhei.kano@nao.ac.jp

Above the solar surface (photosphere) with temperature of ∼6000 K, hotter plasma occupies the outer solar
atmosphere: the chromosphere is ∼10,000 K and the corona is over 1 million K. The heating mechanism ofthese high-temperature layers is one of the longstanding mysteries of solar physics. Magnetic fields generated
in the solar interior and emerging through the photosphere must play an important role in the heating
mechanism. This topic has been investigated by using photospheric magnetic fields derived by the Zeeman
effect from spectro-polarimetric observations as well as chromospheric/coronal activities taken by
EUV-spectroscopic or X-ray-imaging observations. However, observations by the Japanese solar satellite“Hinode” discovered a variety of dynamic events in the chromosphere such as jets and waves, indicating thatthese events may be responsible for heating the chromosphere and corona. Such discoveries imply that thenext frontier in solar physics lies in simultaneous observations between the dynamics and magnetic structuresin the chromosphere and transition region, where the gas-dominant photosphere changes to themagnetic-dominant corona.
In the chromosphere or above it, the polarization by the Zeeman effect is not applicable to derive magnetic
fields, because of the weaker magnetic fields than the photosphere’s. However, the recent model calculations
suggest that the Hanle effect can make small but observable amount of polarization in the hydrogen
Lyman-alpha line (121.6 nm) even in the chromosphere and transition region. Now, a sounding-rocket
experiment called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is under development tomeasure the linear polarization profiles caused by scattering processes and the Hanle effect in the
Lyman-alpha line with high accuracy (0.1%), and then to infer the magnetic fields in the chromosphere. The
Lyman-alpha is the brightest line among the chromospheric lines in vacuum ultra-violet wavelengths, andbright anywhere on the solar disk. Therefore, the high-precision polarimetric observation in the Lyman-alphais a good start-point to explore weak magnetic fields in the outer solar atmosphere.

41

Review: Exploring the magnetic Hertzsprung-Russell
diagram with spectropolarimetry
Julien MORIN 1
1

LUPM - Univ. Montpellier 2

During the past few years, magnetic fields have been detected and studied on stars throughout the
Hertzsprung-Russell diagram, and spectropolarimetric techniques have played a key role in this exploration.
In this review I will briefly summarize the theoretical puzzles we want to address in the field of stellar
magnetism, discuss issues specific to stellar spectropolarimetry, and present a selection of recent results
obtained with spectropolarimetry alone or coupled to other techniques. Finally, I will present how future
instruments operating in the near infrared will contribute to the next advances in the field.

42

Review: spectropolarimetry of massive stars
C. Neiner 1
1

LESIA, Paris-Meudon Observatory

I will review the low- and high-resolution spectropolarimetric techniques used for the study of magnetism inmassive stars, the results obtained for those objects in particular by the MiMeS and BinaMIcS collaborations
on the occurrence of magnetic fields, their origin, and their impact on the star and its environment, as well
as future projects in this domain.

43

The Bcool magnetic snapshot survey of solar-type stars
S.V. Jeffers 1 , P. Petit 2 , S.C.Marsden 3 and the BCool collaboration
1

IAG Goettingen, Germany
IRAP, Toulouse, France
3
University of Southern Queensland, Australia
2

Stellar magnetic field measurements obtained from spectropolarimetry offer key data for activity anddynamo studies, and we present the results of a major high-resolution spectropolarimetric Bcool projectmagnetic snapshot survey of nearly 200 solar-type stars from observations with the Telescope Bernard Lyot
and the Canada-France-Hawaii Telescope. Surface magnetic fields were detected for one third of our sample,
including surprising detections on a few subgiant stars. In this talk we will show how the magnetic fieldstrength (longitudinal field) is correlated with basic stellar parameters such as rotation rate, age,chromospheric activity indicators as well as with spectral type. This survey constitutes the most extensive
spectropolarimetric survey of cool stars undertaken to date, and suggests that it is feasible to pursue
magnetic mapping of a wide range of moderately active solar-type stars to improve understanding of theirsurface fields and dynamos.

44

Variable magnetic field of the young sun HN Peg
S. Boro Saikia 1 , S. V. Jeffers 1 , Pascal. Petit 2 , S. Marsden 3 , J. Morin 1,4 , C. Folsom 3
1

Institut für Astrophysik, Universität Göttingen, Friedrich Hund Platz 1, 37077 Göttingen, Germany,sudeshna@astro.physik.uni-goettingen.de, jeffers@astro.physik.uni-goettingen.de2
CNRS, Institut de Recherche en Astrophysique et Planétologie, 14 Avenue Edouard Belin, F-31400
Toulouse, France, pascalpetit08@gmail.com, cfolsom@irap.omp.eu
3Computational Egineering and Science Research Centre, University of Southern Queensland, Toowoomba
4350, Australia, Stephen.Marsden@usq.edu.au
4
LUPM-UMR 5299,CNRS & Université Montpellier, Place Eugéne Bataillon, 34095 Montpellier Cedex
05,France, julien.morin@univ-montp2.fr

We investigate the variability of the large-scale surface magnetic field and chromospheric activity of theyoung G0 dwarf HN Peg. The large-scale magnetic field geometry is reconstructed using Zeeman Doppler
Imaging at six epochs over seven years of observations. The chromospheric variations were also measured
using three chromospheric lines: Ca II H&K,Hα and Ca II Infrared Triplet. The magnetic field topology of
HN Peg exhibits a variable and complex geometry. While the poloidal component exhibits a stable magnetic
geometry at each observational epoch, the toroidal component is strongly variable in strength, where a positive
polarity toroidal band at equatorial latitudes undergoes significant variations through out the observationaltimespan. HN Peg exhibits a weak longitudinal magnetic field over the epochs of this analysis, with nosignicant long term trend. The chromospheric activity indicators exhibit long-term variations over our timespan of observations, where the variability in Ca II H&K and Hα proxies exhibit a long-term correlation.

45

7

Session VII. Results: Solar System & Exoplanets

INVITED: Status of Exoplanet Polarimetry
Sloane J. Wiktorowicz 1
1

NASA Sagan Fellow, University of California Santa Cruz
1156 High Street, Santa Cruz, CA 95064, USA
sloanew@ucolick.org

The last decade has witnessed an explosion in the atmospheric characterization of spatially unresolved
exoplanets using transmission and emission spectra, but understanding is hampered by degeneracies
resolvable by optical scattered light observations. In particular, transmission spectra of many exoplanets areequally consistent with atmospheres dominated by clouds or by water vapor. While several recent studies
provide compelling evidence for the presence of clouds on exoplanets, cloud particle composition is as yet
unknown. In the early 1970s, ground-based polarimetry of Venus enabled the discovery of sulfuric acid cloudparticles by drawing on the sensitivity of Rayleigh/Mie scattering to the size distribution, shape, andchemical composition of cloud particles, and also to scattering optical depth. Thus, the presence of clouds on
exoplanets, and their chemical composition, is an extremely important issue in exoplanet characterizationthat may require polarimetry to identify. The technical challenges inherent in separating scatteredexoplanetary light from direct illumination by the host star are severe: 1) high contrast imaging is required
to spatially resolve long-period exoplanets, and 2) highly stable, accurate polarimeters are required tomeasure the small, periodic change in system polarization due to short-period exoplanets. However,complementary instrumentation now exists to suppress stellar flux and isolate exoplanetary scattered light at
both period regimes. As with all high-sensitivity observations, measurement and control of systematic effects
is the key to accurate study of exoplanets in polarized, scattered light. I will report on the current status of
the detection and study of exoplanets with polarimetry. This work is supported by a NASA Sagan
Fellowship, a NASA Origins of Solar Systems grant, and UCO/Lick Observatory.

46

Polarimetry of transiting exoplanetary system HD
189733
N.M.Kostogryz 1, 3 , S.V.Berdyugina 1, 2 , T.M.Yakobchuk 3
1

Kiepenheuer-Institut fr Sonnenphysik, Schneckstr.6, 79104 Freiburg, Germany
kostogryz@kis.uni-freiburg.de, sveta@kis.uni-freiburg.de
2
Main Astronomical Observatory of NAS of Ukraine, Zabolotnoho str. 27, 03680 Kyiv, Ukraine.
3
NASA Astrobiology Institute, University of Hawaii, USA

We present and discuss a polarimetric effect caused by a planet transiting the stellar disk and, therefore,
breaking its symmetry and resulting in linear polarization of a partially eclipsed star. Estimates of this effectfor transiting planets were made only recently. In particular, we demonstrated that the maximum
polarization for one of the brightest transiting planets HD189733b strongly depends on the centre-to-limb
variation of linear polarization for the host star. However, observational and theoretical studies of the limb
polarization have been largely concentrated on the Sun. As was shown in our previous study, we expect toobserve a larger centre-to-limb linear polarization for cooler stars. Here we solve the radiative transfer
problem for polarized light and simulate the centre-to-limb polarization for stars of different spectral classes
taking into account various opacities.

47

The polarization of Earth
Earthshine polarimetry in the B, V , R, and I band asfunction of phase
Andreas Bazzon1 , Hans Martin Schmid2 , Daniel Gisler3
1

ETH Zurich, Institute for Astronomy, Wolfgang-Pauli-Str. 27, 8093 Zurich, Switzerland,bazzon@astro.phys.ethz.ch
2
ETH Zurich, Institute for Astronomy, schmid@astro.phys.ethz.ch
3
Kiepenheuer Institut für Sonnenphysik, gisler@kis.uni-freiburg.de

Earth-like extrasolar planets may soon become observable with upcoming high-contrast polarimeters.
Therefore, the characterization of the polarimetric properties of planet Earth is important for theinterpretation of expected observations and the planning of future instruments.
We present benchmark values for the polarization signal of integrated light from planet Earth in broad band
filters B, V , R, and I, derived from our polarimetric observations of the earthshine backscattered from the
Moon’s dark side for Earth-phase angles α between 30◦ and 110◦ .
The observations were carried out with a new, specially designed wide field polarimeter at a 21 cm
Dall-Kirkham Cassegrain telescope. Depending on wavelength λ and lunar surface albedo a the polarizationof the back-scattered earthshine is strongly reduced. To determine the polarization of Earth, we correct ourearthshine measurements by a polarization efficiency function (λ, a) for the lunar surface derived frommeasurements of Apollo lunar soil samples from the literature.
The fractional polarization for Earth is decreasing with wavelength and at quadrature phase we find values
24.6 % for the B band, 19.1 % for the V band, 13.5 % for the R band, and 8.3 % for the I band. Together
with literature values for the spectral reflectivity we obtain a contrast between the polarized flux of Earthand the (total) flux of the Sun with an uncertainty of less than 20 %, and we find that the best phase todetect an Earth twin is around α = 65◦ . Our results are in qualitative agreement with polarimetric models ofEarth-like planets and they can now be used to guide more detailed computations.

48

Monitoring of Venusian clouds and hazes with animaging–polarimetry system “HOPS”
Takayuki Enomoto 1 , Takehiko Satoh 2 , Yoshikazu Nakatani 3 , Takao M. Sato 2 Takashi
Nakakushi 4 , Mayu Hosouchi 5
1

SOKENDAI, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan, enomoto@ac.jaxa.jp
2
Institute of Space and Astronautical Science/JAXA, satoh@stp.isas.jaxa.jp
3
Kyoto University, nakatani@kwasan.kyoto-u.ac.jp
4
Wakayama University, kushio@center.wakayama-u.ac.jp
5Tokyo University, mayu@eps.s.u-tokyo.ac.jp

Linear polarization of reflected sunlight from the optically-thick Venusian clouds carry a wealth of
information about the atmosphere and aerosols. Hansen and Hovenier [1974] analyzed the ground-based(disk-integrated) polarimetric data of 1960’s and found the Venusian clouds are composed of sulfuric aciddroplets (1 µm in radius). Kawabata et al. [1980] analyzed “spatially-resolved” polarization maps from
Pioneer Venus Orbiter (PVO) and discovered for the first time that there were abundant sub-micrometer
sized particles “hazes” mostly on polar regions, which obviously were not present in 1960’s.
To monitor Venusian upper hazes, we performed observations in 2012 and 2013 by attaching a two-beamimaging polarimeter HOPS (details in another paper) to the 65cm refracting telescope at Hida observatory of
Kyoto University. Polarimetric data of Venus were acquired at solar phase angles around 39◦ , 56◦ , 58◦ , 85◦
and 129◦ in 4 bands from blue (438nm) to IR (930nm). The reference planes of polarization were calibrated
by observations of polarized standard stars (BS6353 and oSco). We averaged observed degree of linear
polarization (DOLP) over the polar regions (latitudes higher than 60◦ ). Obtained DOLP at IR and phaseangle 85◦ are, for example, 4.6 % and 1.5 % for northern and southern polar regions. Though PVO while inorbit measured polarization of Venus from a variety of latitudes, the initial-phase data were so compiled thatthey can conveniently be compared with ground-based observations [Kawabata et al., 1980]. Comparison
with our IR data exhibits a major difference in the neutral point (the phase angle of null polarization). It isaround 75◦ in our data in contrast with around 40◦ in the PVO initial-phase data. As the PVO initial-phaseis known for optically thick hazes in polar regions, difference in the neutral point may be a result of different
condition of hazes in 2012 - 2013.
We performed radiative-transfer analysis and searched for the best combination of the particle radius ofhazes (reff ) and optical thickness of haze layer (τh ). The resultant parameters for northern and southern
polar region are reff = 0.22 µm, 0.20 µm, τh = 0.09, 0.05 at IR, respectively. The optical thickness iscomparable with those observed during the declining phase during PVO mission period [Sato et al., 1996].
The mechanism of such a variation is not understood, so polarimetry is useful tool to monitor the
microphysical parameters of Venusian cloud and hazes.

49Spectro-polarimetry as a new diagnostic tool for thephysical characterisation of small
Solar System bodies
S. Bagnulo 1 , A. Cellino 2 , M. Sterzik 3
1

Armagh Observatory, College Hill, Armagh, BT61 9DG, UK. email: sba@arm.ac.uk
2
INAF - Osservatorio Astrofisico di Torino, via Osservatorio 20,
I-10025 Pino Torinese, Italy
3
European Southern Observatory, Karl-Schwarzschild-Str. 2,
D-85748 Garching bei Muenchen Germany

Most investigations in the field of polarimetry of the small bodies of the Solar System have been traditionallyfocused on measurements of the variation of linear polarisation in the V band as a function of thephase-angle (the angle between the directions to the Sun and to the observer as seen from the target
asteroid). The so-called phase-polarisation curves obtained from observations have been used to derive thegeometric albedo of the objects, and, in case of asteroids, Centaurs, and trans-Neptunian objects, some
information on the typical sizes of regolith particles covering asteroid surfaces.
Something that has been poorly studied until now is the dependence of polarisation upon wavelength.
Earlier studies, essentially based on limited sets of measurements in different colours, suggested that at large
phase-angles the linear polarisation of moderate-albedo asteroids decreases wtih wavelength, whereas at
smaller phase angles, in the so-called negative polarisation branch, polarisation increases with wavelength.
Interestingly, low-albedo objects were found to exhibit an opposite behaviour. If this is true, one single
spectro-polarimetric measurement obtained at a suitable phase angle might be sufficient to distinguishbetween bodies belonging to different albedo classes.
To test this hypothesis, we have performed what is to our best knowledge the first spectro-polarimetricsurvey of small bodies of our solar system. We have discovered that asteroids exhibit a large variety ofspectro-polarimetric behaviours, that may be used to obtain a substantial improvement of their classificationand characterisation. In this talk we will present some preliminary results of our survey. We will also compare
our new data with our laboratory spectra of organic material and with Earthshine spectro-polarimetric data,
and discuss the use of spectro-polarimetric techniques for the search of extra-terrestrial life.

50

Remote detection of biological pigments on Earth-likeplanets with spectropolarimetry
S.V. Berdyugina 1,4 , T. Santl-Temkiv 2 , K. Finster 2 D.M. Harrington 3 J.R. Kuhn 3
1

Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany, sveta@kis.uni-freiburg.de
Aarhus University, Aarhus, Denmark, temkiv@phys.au.dk, kai.finster@biology.au.dk
3
Institute for Astronomy, University of Hawaii, USA, dmh@if.hawaii.edu, kuhn@ifa.hawaii.edu
4NASA Astrobiology Institute, University of Hawaii, USA
2

Recently, it was demonstrated that polarized reflected light can be detected from exoplanetary atmospheres(Berdyugina et al. 2008, 2011). Here we focus on identifying biosignatures resulting from biologicalpolarization, e.g., selective light absorption or scattering by biogenic molecules.
The terrestrial biosphere dominates both the planetary surface and the atmosphere, which is used as a majordispersal route by many organisms. In fact, there is a substantial amount of bioaerosols in the atmosphere.
Both surface biosphere and bioaerosols are directly in contact with Sun’s radiation. Many of these organisms
evolved a potential to produce pigments, i.e., molecules that selectively absorb certain wavelengths of light,
in order to harvest energy or protect the organisms. We aim at identifying unique spectro-polarimetricsignatures of pigmented organisms found either on planetary surfaces or in their atmospheres, which can be
employed for remote sensing of life forms on the Earth and extraterrestrial environments.
We have carried out a laboratory spectro-polarimetric study of light reflected by various bacterial types andterrestrial plants, which contained different photosynthetic and non-photosynthetic pigments. Measurements
on non-biological samples (e.g., rocks and sands) were also performed in order to avoid false positives. These
measured reflection spectra were then used to synthesize polarized spectra of Earth-like planets with various
contributions from the land, photosynthetic organisms, ocean, atmosphere, and clouds. We estimate therequired photometric and polarimetric sensitivity to detect such planets in habitable zones of nearby stars.
We show that spectro-polarimetry provides a great advantage for high-contrast remote detection of biologicalphotosynthetic organisms as compared to spectroscopy.

51

8

Session VIII. Results: Cosmological Microwave Background

INVITED: Detection of microwave B-mode polarization
at degree angular scales using BICEP2
C. Darren Dowell1 , for the BICEP2 collaboration1

Jet Propulsion Laboratory, MS 169-237, 4800 Oak Grove Drive, Pasadena, CA 91109, U.S.A.;
Charles.D.Dowell@jpl.nasa.gov

We report results from the BICEP2 experiment, a Cosmic Microwave Background (CMB) polarimeter
specifically designed to search for the signal of inflationary gravitational waves in the B-mode power
spectrum at degree scales. The receiver was comprised of a 26 cm aperture all-cold refracting telescope
equipped with a focal plane of 512 antenna-coupled 150 GHz bolometers. A low-foreground region of sky
with an effective area of 380 square degrees was observed from the South Pole to a depth of 87 nK-degrees in
Stokes Q and U. We find an excess of B-mode power over the base lensed-LCDM expectation in the range
30 < ` < 150, inconsistent with the null hypothesis at a significance of > 5σ. Through jackknife tests andsimulations based on detailed calibration measurements we show that systematic contamination is muchsmaller than the observed excess. We also estimate potential foreground signals and find that available
models predict these to be considerably smaller than the observed signal. These foreground models possessno significant cross-correlation with our maps. Additionally, cross-correlating BICEP2 against 100 GHz maps
from the BICEP1 experiment, the excess signal is confirmed with 3σ significance and its spectral index isfound to be consistent with that of the CMB, disfavoring synchrotron or dust at 2.3σ and 2.2σ, respectively.
The observed B-mode power spectrum is well-fit by a lensed-LCDM + tensor theoretical model withtensor/scalar ratio r = 0.20 + 0.07 − 0.05.

52

CMB polarisation observations with the plancksatellite
Juan Francisco Macias-Perez 1
1

LPSC, Grenoble, France

CMB temperature and polarisation anisotropies have become a key cosmological probe to both measurecosmological parameters and study the early universe. The Planck satellite has measured with unprecedented
accuracy the CMB temperature and polarisation anisotropies over the full sky using 9 frequency bands from30 to 857 GHz. We will present in this talk the first Planck polarisation results. These will include a review
of polarised foreground emission including synchrotron and thermal dust emission. We finally discuss thecapabilities of Planck to measure the CMB polarisation and discuss recent results.

53

Polarized emission of Galactic dust as seen by Planck :new constraints for dust models.
Vincent Guillet1 , on behalf of the Planck collaboration
1

Institut d’Astrophysique Spatiale, Université Paris-Sud, Bât. 121, 91405 Orsay,
vincent.guillet@ias.u-psud.fr

The HFI instrument onboard the Planck satellite is providing a full-sky coverage of the dust submillimeterpolarized emission, with an unprecedented view onto the diffuse ISM. This diffuse dust polarized emission isimportant both for Galactic physics (dust polarization traces the Galactic magnetic field) and for cosmology(dust is the a dominant foreground to the CMB polarization at high frequencies). In this talk, I will present
the derived dust thermal SED, from 353GHz down to 70GHz, in total and polarized intensity. I will also
show that the dust polarized emission observed at 353GHz correlates very well with starlight polarization
measures, allowing us to define new dust physical quantities, the submm-to-optical polarization ratios, which
are found to be rather uniform in the diffuse ISM. These new observational constraints will be comparedwith existing dust models.

54

Polarbear experiment: Results from the firstobservational campaign and systematic instrumental
effects characterization
Julien Peloton 1 for the Polarbear collaboration
1

AstroParticule et Cosmologie, Univ Paris Diderot, CNRS/IN2P3, CEA/Irfu, Obs de Paris, Sorbonne Paris
Cité, France
julien.peloton@apc.univ-paris7.fr

Recent measurements of the B-mode polarization power spectrum in the cosmic microwave background(CMB) have started opening up a new window onto cosmology. While the bicep-2 experiment has reported a
detection of the B-mode polarization at the largest angular scales, a complementary observation conductedby the Polarbear experiment located on the Atacama Desert in Chile has recently provided tightconstraints on the small scales.
The characterization and the control of systematic instrumental effects on B-mode polarization data areparticularly demanding for such efforts. In this talk, I will describe the Polarbear results focusing on theanalysis techniques developed to characterize and control the spurious effects of the Polarbear data set. In
particular I will present an end-to-end simulation pipeline used to determine their impact on the final CMB’s
B-mode angular power spectrum.

Figure 14: Photograph of the Huan Tran Telescope deployed at the James Ax Observatory in the Atacama
Desert in Northern Chile.

55

9Session IX. Results: External Galaxies, Active Galactic Nuclei

INVITED: Optical and near-IR polarimetry of active
galactic nuclei
Clive Tadhunter 1
1

University of Sheffield, Department of Physics & Astronomy, University of Sheffield, Sheffield S6 3TG, UK;
c.tadhunter@sheffield.ac.uk

I will review the application of optical and near-IR polarimetry techniques to the study of Active Galactic
Nuclei (AGN), highlighting the key importance of polarimetry for investigating the geometries of theunresolved nuclear regions of AGN, testing the unified schemes that attempt to understand the relationships
between the various types of active galaxies, and investigating the evolution of the AGN host galaxies.
Following an historical introduction, I will describe the latest results from the Hubble Space Telscope andvarious ground-based 4 and 8m class telescopes, before assessing the prospects for future progress in this field.

56

Near-infrared polarimetry of a complete sample ofnarrow-line radio galaxies with Hubble Space Telescope
E. A. Ramı́rez 1 , C. N. Tadhunter 2 , D. Axon 3 , D. Batcheldor 5 , C. Packham 6 , E.
Lopez-Rodriguez 6 , W. Sparks 7 , S. Young 8
1

Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária, São Paulo 05508-900, Brazil.
E-mail:e.ramirez@usp.br2
Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK.
3
Physics Department, Rochester Institute of Technology, Rochester, NY 14623, USA.
4
School of Mathematical and Physical Sciences, University of Sussex, Brighton BN1 9QH, UK.
5
Department of Physics and Space Sciences, Florida Institute of Technology, FL 32901, USA.
6
Department of Physics & Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio,
TX 78249, USA.
7
SpaceTelescope Science Institute, 3700 San Martin Drive, Baltimore, MD21218, USA.
8
Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire,
Hatfield AL10 9AB, UK.

We present the analysis of 2.05 µm Hubble Space Telescope (HST) polarimetric data for a sample of 13
narrow-line radio galaxies (NLRG) Fanaroff and Riley type II (FRII) powerful radio galaxies at
0.03 < z < 0.11. We found that the NLRG in our sample are intrinsically highly polarised (6–60 per cent),
with the electronic-vector (E-vector) perpendicular to the radio axis in 54 per cent of the sources. We
analyse the mechanisms that could be producing the measured degree of nuclear polarisation: i) dichroic
extinction, ii) synchrotron radiation, and iii) scattering. We found that the extinction required to produce
such high levels of near-infrared polarisation based on the dichroic mechanism, is similar to that estimated in
the basis of four different techniques reported in Ramirez et al. (2014), provided that the dichroic mechanism
has its maximum efficiency. This consistency suggests that the nuclear polarisation may be due to dichroic
extinction, the product of elongated dust grains aligned in a toroidal magnetic field in the torus. However,additional polarimetry observations at other near- or mid-IR wavelengths are needed to distinguish between
the dichroic or scattering polarisation mechanism.

57

VLT/FORS2 spectropolarimetry of Seyfert galaxies
Cristina Ramos Almeida 1,2 , Marı́a Jesús Martı́nez González 1,2 , Andrés Asensio Ramos 1,2 ,José Antonio Acosta-Pulido 1,21Instituto de Astrofı́sica de Canarias, Calle Vı́a Láctea, s/n, E-38205, La Laguna, Tenerife, Spain. cra@iac.es2
Departamento de Astrofı́sica, Universidad de La Laguna, E-38205, Tenerife, Spain

The origin of the unification scheme for Seyfert galaxies (Antonucci & Miller 1985) was the detection ofpolarized broad lines in the nucleus of the Seyfert 2 galaxy NGC 1068. Although very successful and widelyused, this simplistic geometrical model is unable to explain several observational properties of Seyfert
galaxies. For example, only 30-50% of nearby Seyfert 2 galaxies show a type 1 polarized spectrum (Tran
2001). This might imply that either 1) not all Seyferts harbour a hidden BLR (e.g. Tran 2001, 2003; Gu &Huang 2002) or 2) the distribution of dust within the torus and its inclination are not as simple as predictedby the unified model. In Ramos Almeida et al. (2009, 2011) we reproduced high spatial resolution spectralenergy distributions (SEDs) of a sample of nearby Seyfert galaxies with clumpy torus models and found thatthe torus properties of the individual Seyfert 2s are different among them. In some cases we reproduced theinfrared SEDs with edge-on, large covering factor tori (as predicted by the unified model), but others
required small covering factor tori with intermediate inclinations. These results could explain the lack ofpolarized broad lines in 50-70% of nearby Seyfert 2 galaxies. I will present preliminary results ofspectropolarimetric observations obtained with the instrument FORS2 on the 8 m VLT. These observations
constitute a homogeneous dataset of polarized optical spectra for a representative flux-limited sample of
Seyfert galaxies for which we have constraints on their torus properties.

Figure 15: Different clumpy tori for different Seyfert 2 galaxies. Left panel shows an example of low covering factor torus(narrow clouds distribution and low number of clumps) and right panel shows a larger covering factor torus, Figure adaptedfrom Ramos Almeida et al. (2014).

58

IR Polarimeters & AGN
C. Packham1 , E. Lopez Rodriguez1 , T. J. Jones2 , C. M. Telesco3 , D. Shenoy2 , A.
Alonso-Herrero4 , C. Alvarez5 , S. Fernandez6 , L. Fuller1 , O. Gonzalez Martin5 , J. H. Hough7 ,K. Ichikawa8 , N. A. Levenson9 , R. E. Mason9 , L. McMaster1 , E. Perlman10 , E. Ramirez11 , C.
Ramos Almeida5 , P. Roche12 , J. M. Rodriguez-Espinosa5 , C. N. Tadhunter13 , Y. Ueda 8 , C.
Warner3 ,1

University of Texas at San Antonio, Dept. of Physics & Astronomy, 1 UTSA Circle, Texas, 78249, USAchris.packham@utsa.edu
2
University of Minnesota
3
University of Florida
4
Instituto de Fisica de Cantabria
5Instituto de Astrofsica de Canarias
6
Gran Telescopio Canarias
7
University of Hertfordshire
8
Kyoto University
9
Gemini Observatory
10
Florida Institute of Technology
11
Universidade de Sao Paulo
12
University of Oxford
13
University of Sheffield

Observations of AGN (active galactic nuclei) using polarimetry have been key to understanding their central
engines. Early observations used optical polarimeters in natural seeing conditions, but suffered from the dual
effects of obscuration in the nuclear regions of the AGN and relatively poor spatial resolution leading to a
low degree of measured polarization. Near-infrared (IR) polarimeters afforded a clearer view through the
obscuring dust, and the advent of adaptive optics (AO) offers diffraction-limited resolution, and mostrecently mid-IR (MIR) polarimetry has been offered on the 10m Gran Telescopio Canarias. We briefly
discuss these instruments and present some of the early results from observations of AGN in polarimetricmode as well as from surveys of hidden/non-hidden broad-line AGN.

59

Polarimetry in Active Galactic Nuclei
Lopez-Rodriguez, E.1 , Packham, C.1 , McMaster, L.1 , Jones, T.2 , Young, S.3 , Elitzur, M.4 ,Tadhunter C.5 , Mason R.6 , Perlman E.7 , Alonso-Herrero A.8 , Ramos Almeida C.9 , Ichikawa
K.10 , Levenson N. A.11 , Rodrı́guez-Espinosa J. M.9 , Shenoy, D.2 , Álvarez C.12 , Ramı́rez
E. A.13 , Telesco C. M.14
1

Department of Physics & Astronomy, University of Texas, One UTSA Circle, San Antonio, TX 78249, USA.
enrique.lopezrodriguez@utsa.edu.
2Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN
55455, USA. 3 Centre for Astrophysics Research, Science & Technology Research Institute, University of
Hertfordshire, Hatfield, AL10 9AB, UK. 4 Department of Physics and Astronomy, University of Kentucky,
Lexington, KY 40506, USA. 5 Department of Physics & Astronomy, University of Sheffield, Sheffield S3 7RH.
6
Gemini Observatory, Northern Operations Center, 670 N. A’ohoku Place, Hilo, HI 96720, USA.
7
Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901.
8
Instituto de Fı́sica de Cantabria, CSIC-UC, 39005 Cantabria, Spain. 9 Instituto de Astrofı́sica de Canarias,
Calle Vı́a Lactea s/n, 38205, Tenerife, Spain. 10 Department of Astronomy, Graduate School of Science,
Kyoto University, Kitashirakawa-Oiwake cho, Kyoto 606-8502, Japan. 11 Gemini Observatory, Casilla 603, La
Serena, Chile. 12 GTC Project, Instituto de Astrofı́sica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain.
13
Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária, São Paulo 05508-900, Brazil.
14
Department of Astronomy, University of Florida, 211 Bryant Space Science Center, P.O. Box 11205,
Gainesville, FL 32611-2055, USA.

Magnetohydrodynamical theories consider the torus of Active Galactic Nuclei (AGN) to be part of an
outflow wind moving away from the central engine. In this framework, the torus is a particular region of thewind, where dusty and optically thick clouds are formed. The outflows are strongly related to the accretion
rate and magnetic field strength, which play an important role in the creation, morphology and evolution of
the torus. Through high-angular (∼0.100 -0.600 ) infrared (IR, 1-13 µm) polarimetry observations, this work (1)explores the role and strength of magnetic field in the torus; (2) studies the AGN/Host galaxy connection;and (3) investigates the nucleus of radio-loud AGN. Although several models have been made to account forthe outflowing dusty winds from the central engine, the magnetic field strength at the position of the torus
remains poorly characterized. Through a novel study using near-IR polarimetry, the magnetic field strength
within the clumpy torus of AGN are estimated. For the archetypical radio-loud AGN, Cygnus A, mid-IR
imaging polarimetry using CanariCam (8-13 µm) on the 10.4-m Gran Telescopio Canarias revealed a highpolarized, 11±3% and 12±3% (at 8.7 µm and 11.6 µm respectively) unresolved nucleus. Polarimetricmodeling suggests that the MIR polarization arises from a synchrotron component. This result represents
the most compelling MIR polarization detection of synchrotron radiation in Cygnus A.

60

NIR polarized light from
Sagittarius A*
Banafsheh Shahzamanian 1,2 , Andreas Eckart 1,2 ,Mohammad Zamaninasab 2 , Gunther Witzel 3 , et al.
1

I.Physikalisches Institut, Universität zu Köln, Zülpicher Str.77, 50937 Köln, Germany,shahzaman@ph1.uni-koeln.de
2
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
3
Department of Physics and Astronomy, University of California, Los Angeles,
CA 90095, USA

We present an overview of polarized near-infrared (NIR) observations of Sagittarius A* (SgrA*) which is
associated with the super massive black hole at the center of the Milky Way. The observations have been
carried out using NACO adaptive optics instrument at the VLT(ESO) (from 2004 to 2012). We will present
several polarized flares that have been observed during these observations and will present the statisticalproperties of NIR K-band polarization of SgrA*. Information about linear polarization at 2.2 micron and its
variations can help us to constrain the physical conditions of the accretion process around this SMBH.

61

Spectropolarimetry of Nearby Starburst Galaxies:
Kinematics of the Dust Wind
Michitoshi Yoshida 1 , Koji Kawabata 2 , Youichi Ohyama 3
1

Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima,739-8526 Japan. yoshidam@hiroshima-u.ac.jp
2
Hiroshima Astrophysical Science Center. kawabtkj@hiroshima-u.ac.jp
3
Academia Sinica, Institute of Astronomy and Astrophysics, Taiwan. ohyama@asiaa.sinica.edu.tw

We report the results of spectropolarimetry of nearby starburst galaxies, M82 and NGC 2146, and discuss
the kinematics of the large scale dust outflow from the nuclear star-forming regions.
It has been evident that significant amount of dust is associated with superwinds in starburst galaxies.
However, the fate of this dust has been uncertain yet because of the lack of kinematic information of thedust. Optical spectropolarimetry is one of the promising ways to probe the dust motion. Outflowing dust
grains scatter and polarize continuum and emission lines emanated from the nuclear light, so that radial
velocities of the polarized emission lines reflect the dust motion with respect to the nucleus. We made optical
spectropolarimetric observations of nearby starbust galaxies with Subaru/FOCAS in order to reveal the
kinematics of the large scale dust outflow. The target galaxies were M82 and NGC 2146.
In M82, the polarized light is substantially redshifted with respect to the unpolarized light. We found thatthe dust flow is much slower than the ionized gas flow and even slower than the molecular gas, and that
there is a decreasing tendency of the dust outflow velocity from the central region to the outer. These results
indicate that the dust outflow in M82 is kinematically decoupled from the other outflowing materials and themost of the dust would fall back to the disk. On the other hand, the polarized light in NGC 2146 showed aclear double-peak profile near the nucleus and an asymmetric profile — a blue peak and red wing structure —at ∼ 0.6 kpc from the nucleus. The polarization angles (Pol-A) of the blue component (BC) and redcomponent (RC) are quite different; the Pol-A of the BC ∼ 90◦ , whereas that of the RC ∼ 170◦ near the
nucleus. The Pol-As of both components are gradually changed as going further from the nucleus. These
results are consistent with the idea that the infalling dust (BC) and outflowing dust (RC) scatter spatiallydifferent light sources, starburst clusters, in the vicinity of the nucleus.
Our work first unveiled the kinematics of the dust flows and the circumnuclear structures of the nearby
starburst galaxies.

62

10

Session X. Results: High Energy Astrophysics,
Gamma-Ray Bursts, Supernovea

Polarimetric observations and modelling of V393 Pav
and other AM Her systems
K. M. G. Silva1 , C. V. Rodrigues2 , D. Cieslinski2 , A. S. Oliveira1 , J. E. R. Costa2 , L. A.
Almeida3,4 V. S. Magalhes
1

2

IP&D/Universidade do Vale do Paraı́ba – Brazil
Divisão de Astrofı́sica/Instituto Nacional de Pesquisas Espaciais – Brazil – claudia.rodrigues@inpe.br
3
Department of Physics & Astronomy/Johns Hopkins University - USA
4
IAG/Univ. de São Paulo - Brazil

AM Her systems, also called polars, are magnetic cataclysmic variables: a binary system composed by ahighly magnetized white-dwarf, B larger than around 5 106 G, and a Roche lobe-filling low-mass dwarf star.
In polars, the accretion occurs along a magnetic accretion column and the rotation of both stars aresynchronized with the orbital period. In optical and infrared wavelengths, the accretion column emits
cyclotron radiation, which is highly anisotropic and polarized. AM Her stars are the strongest sources ofcircular polarization, up to 50% in V band. The total flux and polarization observed are modulated along
the orbital cycle due to the variation of the viewing angle. This characteristic allows to map the accretion
column location and to estimate many of its geometric and physical parameters by modeling. To perform
such modeling, our group has developed the Cyclops code. This code calculates the cyclotron andbremsstrahlung emission of a 3D magnetic accretion column and considers the white-dwarf occultation andthe absorption caused by the column itself. Optical depth effects are taken into account in the radiativetransfer. Applications were previously made for V834 Cen and CP Tuc. Multiband observations areimportant to constrain the physical properties of polars, but few systems have such kind of data. To fill thisgap, we are carrying out an observational follow-up of polars. In this study, we present recent results of thiseffort. We also present the CYCLOPS modelling of VRI photometry and polarimetry of V393 Pav in brightstate. V393 Pav is a polar presenting an active secondary star.

63

The RoboPol optical polarisation monitoring of anunbiased subset of gamma-ray-loud blazars
E. Angelakis 1 , V. Pavlidou 2,3 , I. Myserlis 1 , D. Blinov 2 , O. G. King 4(on behalf of the Robopol collaboration)
1

Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany, eangelakis@mpifr.de2
Foundation for Research and Technology - Hellas, Voutes, 7110 Heraklion, Greece
3
Department of Physics and Institute for Plasma Physics, University of Crete, 71003, Heraklion, Greece
4
California Institute of Technology, 1200 E California Blvd, Pasadena CA, 91125, USA

The extreme phenomenology exhibited by blazars (FSRQs and BL Lacs) as well as their importance in the
study of extragalactic plasma jet physics arise from the close alignment of the their jets to the line of sight.
Being the beamed and boosted subset of Active Galactic Nuclei associates them with extremely intense
variability which happens fast, very broad-band emission reaching up to GeV and TeV energies, as well ascomplex relativity-induced effects. Their emission - attributed to incoherent synchrotron processes involving
relativistic electrons - appears highly polarised especially in the optical bands. The specific conditions
required for the emergence of polarisation, the emission and radiative transfer processes subsequently makethe polarisation parameters and their dynamics, unique probes of the microphysics of the emitting plasma as
well as the conditions at the emission site. The recent discovery of rotations of the polarisation angle seen
associated with high energy flares observed in the GeV energy bands, opened up a new field dealing with thenature of the emission and variability mechanisms, the configuration of the magnetic field and high energy
emission site etc.
The degree of difficulty involved, has limited the polarisation studies - and especially monitoring - tohand-picked cases rather than unbiased samples forbidding systematic population studies. In order to lay theground for systematic and extensive polarimetric studies we have conceived, designed, constructed anovel-design optical polarimeter that has already been commissioned at the Skinakas telescope in Crete. The
program aims at monitoring the linear polarisation for a sample of almost 100 gamma-ray loud sources thatcomprise an unbiased set and 15 gamma-ray quiet ”comparison sample sources” with a duty cycle of close to
3 days for non active sources and for a fraction of a night for cases in active state. The achieved precision in
the polarisation degree reaches a fraction of the percentage for sources of 18-th magnitude. Here we present:(a) the scientific motivation, (b) the design of the instrument, (c) the sample selection and (d) the resultsfrom the first season of operation. We show that while the fractional polarisation for both gamma-ray–loudand gamma-ray–quiet sources are well-described by exponential distributions, the two classes have different
optical polarisation properties. This is the first time this statistical difference is demonstrated in optical
wavelengths.

64

INTEGRAL/IBIS and optical monitoring of the Crabnebula/pulsar polarisation
Paul Moran 1 , Andy Shearer 2 , Christian Gouiffès 3,4 , Philippe Laurent 3,5
1

Centre for Astronomy, National University of Ireland, Galway, Ireland. p.moran4@nuigalway.ie
Centre for Astronomy, National University of Ireland, Galway, Ireland. andy.shearer@nuigalway.ie
3
CEA, IRFU, Service d’Astrophysique, 91191 Gif-sur-Yvette, France.
4AIM, CEA/CNRS/Université Paris Diderot, SAp, Saclay, 91191 Gif-sur-Yvette, France.
christian.gouiffes@cea.fr
5APC, 10 rue Alice Domont et Leonie Duquet, 75205 Paris Cedex 13, France. philippe.laurent@cea.fr
2

Neutron stars power bright synchrotron nebulae consisting of relativistic charged particles, and the emission
from such systems is strongly polarised. Polarimetry provides an unique insight into the geometry of pulsar
emission regions and therefore observational constraints on the models proposed to describe their emission
mechanisms. Previous INTEGRAL/IBIS observations have shown that the gamma-ray radiation of the Crab
Nebula is highly polarised and remarkably aligned along the axis of rotation of the pulsar (Forot et al. 2008).
Their study was based on the first four years of operation of the satellite. Here we present an analysis based
upon data from over ten years of operation. This new analysis allows a better characterisation of thepolarisation fraction and position angle, a measure of spectral energy distribution of the polarised
component, and in particular, to search for any variability in the polarisation of the system in this energy
regime (250-800 keV). These results are then compared to the known optical polarisation of the pulsar andnearby synchrotron knot. In the future we shall compare the gamma-ray polarisation with the phase-resolved
optical polarisation using instruments such as GASP (Kyne et al. 2010).

65

Polarization observations of
5 GRBs afterglow
Katsutoshi Takaki 1 , Koji. S. Kawabata 2 , Ryosuke Itoh 3 , Kenji Toma 4 , Ryo Yamazaki 5 ,Michitoshi Yoshida 6
1

Hiroshima Univ., 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan,
takaki@hep01.hepl.hiroshima-u.ac.jp
2
Hiroshima Univ. Japan, kawabtkj@hiroshima-u.ac.jp
3
Hiroshima Univ. Japan, itoh@hep01.hepl.hiroshima-u.ac.jp
4
Tohoku Univ. Japan, toma@astr.tohoku.ac.jp
5
Aoyama-Gakuinn Univ. Japan, ryo@phys.aoyama.ac.jp
6
Hiroshima Univ. Japan, yoshidam@hiroshima-u.ac.jp

Gamma-ray Burst (GRB) is the most energetic explosions, which releases enormous energy such ∼ 1052 erg
within a very short time scale. It is known that the afterglows acompany substantial amount of GRBs, which
are seen over wide range of wavelength; from radio to X-ray. Synchrotron radiation is most likely the
responsible radiation mechanism, suggesting that GRB can be polarized to some extent. From thepolarization of the GRB afterglow, we can estimate the structure of magnetic field and geometric structurearound emission region. However, the GRBs and their afterglows are relatively short-lasting events and it is
not easy to perform polarimetry. To date we have only a few polerimetric samples obtained for early opticalafterglow. HOWPol (Hiroshima One-shot Wide-field Polarimeter) attached to 1.5-m “Kanata” telescope isdedicated for such prompt observation of early optical afterglow of GRB.
Since the beginning of HOWPol observation in 2009, we have sucsessfully obtained polarimetric data of five
GRBs; GRB 091208B, GRB 111228A, GRB 121011A, GRB 130427A, and GRB 130505A. (i) The afterglow
of GRB 091208B showed ∼ 10% polarization degree (PD) at ∼150–700 s after GRB trigger (Uehara et al.
2012). (ii) In case of GRB 111228A, we extensively observed over ∼160–19000 s. It showed also large PD(>∼ 10%) and its position angle (PA) rotated approximately by 90◦ with time. Although such a rotation of
PA has been expected across jet break time, we have little evidence of jet break during our observation
period. (iii) The afterglow of GRB 121011A showed only small PD (< 2.5%) at ∼90-1100 s. (iv,v) The
afterglow of GRB 130427A and GRB 130505A were observed at somewhat later phases (∼ 2-4 hr) and theyboth showed only small PD (< 2% and < 3.5%, respectively).
These results suggested that (1) the polarization of the earliest afterglows (at < 1000 s) is likely devided into
two groups: larger polarization (>∼ 10%) population and smaller (< 0.5%) one, which is consistent with thecompilation figure (Fig.3) in Mundell et al. (Nature, 2013 Dec 5), and (2) GRB 111228A showed a quite
unique polarization evolution that has not been observed. We discuss the origin of the magnetic field and thesite of emission region (e.g., forward/backward shock region) for the afterglows of these GRBs.

66

11

POSTERS

Optical and Near-infrared Simultaneous Polarimeter
HONIR
Hiroshi Akitaya1 , Yuki Moritani1 , Takahiro Ui2 , Ryosuke Itoh2 , Takeshi Urano2 , Koji
Kawabata1 , Takashi Ohsugi2,1 , Michitoshi Yoshida1 , Takuya Yamashita3
1

Hiroshima Astrophysical Science Center, Hiroshima University, Kagamiyama 1-2-1, Higashi-hiroshima
739-8526 JAPAN; akitaya@hiroshima-u.ac.jp (HA);
2
Department of Physical Science, Hiroshima University, Kagamiyama 1-2-1, Higashi-hiroshima 739-8526
JAPAN;
3
TMT Project Office, National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka Tokyo 181-8588
JAPAN

We are developing an optical and near-infrared (NIR) instrument HONIR (Fig. 16(a)) for the 1.5-m Kanata
telescope at Higashi-hiroshima Observatory of Hiroshima University. HONIR is capable of imaging or
spetcroscopy simultaneously at two bands: optical (0.5-1.0 µm) and NIR (1.1-2.4 µm) wavelengths. In early
2014, we installed polarimetric optics (an YLF Wollaston prism, Pancharatnam type half-wave plate, andappropriate focal masks) into the instrument, which enables us to perform optical and NIR simultaneous
imaging-polarimetry and spectro-polarimetry. An evaluation of its polarimetric performance is now inprogress. Instrumental polarization is at very low level (< 0.05% at V–J-band, and < 0.10 − 0.15% at
H–K-band). We have successfully measured the linear polarization spectra of interstellar polarization over
the whole wavelengths in good agreement with the previous measurement from the literature (Fig. 16(b)).

Figure 16: (a) HONIR on the Kanata telescope. (b) Spectro-polarimetry of a star HD29835 (interstellar
polarization). The previous measurement (Whittet et al. 1992) is also plotted.

67

Polarimetric measures of Low-Mass X-ray
Binaries
M. C. Baglio 1,2 , P. D’Avanzo 1 , S. Campana 1 , S. Covino 1
1

INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Lc), Italy. e-mail:cristina.baglio@brera.inaf.it
2
Università dell’Insubria, Dipartimento di Fisica, Via Valleggio 11, I-22100 Como, Italy

We present a polarimetric study of two low mass X-ray binaries with the aim of detecting the possible
emission of relativistic particles jets. We selected the brightest transient LMXB in quiescence known, Cen
X-4, in order to perform the first polarimetric analysis of a quiescent LMXB and the ultracompact persistentsystem 4U0614+091.
Cen X-4 does not possess a significant polarisation in the optical (BVRI, from ESO/3.6m data) and infrared(J-band, from TNG data). In particular, we are able to obtain very constraining 3 sigma upper limits to thepolarisation degree, e.g., in the I-band, we have P < 0.52%. We estimate an upper limit of ∼ 10% to thecontribution of the possible emitted jet radiation to the total infrared flux (Baglio et al. 2014, A&A
submitted).
The persistent system 4U0614+091 has been found to emit a relativistic particle jet from the analysis of its
infrared Spectral Eenergy Distribution (Migliari et al. 2010). We performed a polarimetric analysis of
R-band data obtained with both the TNG and the NOT polarimeters, observing a non-modulated
polarisation degree of a several %, consistently with the jet emission (Baglio et al. 2014 in preparation).

Figure 17: Left panel : 3σ upper limits on the polarization degree trend of the LMXB Cen X-4 in quiescencewith respect to the wavelength of the four optical BV RI filters (Baglio et al. 2014, A&A submitted). Rightpanel : R-band polarization degree represented as a function of time for the persistent system 4U 0614+091.
Superimposed, the fit with a constant function which yielded a ∼ 3% polarization degree measured for thesource (Baglio et al. 2014 in preparation).

68

Status and Commissioning of POL-2: Update
Pierre Bastien 1 , Antonio Chrysostomou 2 , David S. Berry 3 ,Doug Johnstone 3 , Per Friberg 3 , Giorgio Savini 4 , Simon Coudé 1 ,Martin Houde 5 , and Jane Greaves 6
1

Département de physique & Centre de recherche en astrophysique du Québec, Université de Montréal, C.P.
6128, Succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada, bastien@astro.umontreal.ca,
coude@astro.umontreal.ca
2Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10
9AB, UK; a.chrysostomou@herts.ac.uk
3
Joint Astronomy Center, 666 N A’ohoku Place, University Park, Hilo, HI 96720, USAd.berry@jach.hawaii.edu, d.johnstone@jach.hawaii.edu, p.friberg@jach.hawaii.edu
4
Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT,
UK; g.savini@ucl.ac.uk;
5
Department of Physics and Astronomy, University of Western Ontario, London,
ON N6A 3K7, Canada; mhoude2@uwo.ca
6
SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16
9SS, UK; jsg5@st-andrews.ac.uk

POL-2 is a polarimeter built for use at the JCMT with the detector SCUBA-2. The instrument waspresented at the last two ASTROPOL conferences (Bastien et al. 2005; 2011). Commissioning data wereobtained in September 2012 and on request on various dates between October 2012 and December 2013.
There was a strong concerted effort by this “commissioning team”, in particular during the period
May-September 2013. Unfortunately, POL-2 could not be commissioned on time, at the end of September
2013, so that it could have been offered to general observation by the astronomical community during thecurrent management period of the telescope, before the end of September 2014.
In this contribution, we will discuss the various issues involved, presenting the work that was done and what
the remaining issues are. However, POL-2 remains a very attractive instrument for future users of thetelescope, with some additional work necessary to solve the remaining problems.

69

Polarimetric detection and characterization of hot
Jupiters
A.V. Berdyugin 1 , S.V. Berdyugina 2,3 , V. Piirola 1
1

2

FINCA, Turku University, Turku, Finland, andber@utu.fi, piirola@utu.fi
Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany, sveta@kis.uni-freiburg.de
3
NASA Astrobiology Institute, University of Hawaii, USA

The light scattered in the planetary atmosphere is linearly polarized perpendicular to the scattering plane.
In general, when the planet rotates around the parent star, the scattering angle changes and the Stokes
parameters Q and U of linear polarization vary. If the orbit is close to circular, two peaks per orbital period
are observed. The observed polarization variability exhibits therefore the orbital period of the planet andreveals the inclination, eccentricity, and orientation of the orbit. Due to their proximity to the star, hot giant
planets with short orbital periods (Hot Jupiters) may develop extended peculiar atmospheres and halos
which effectively scatter the light in the blue spectral region. This can give rise to a degree of polarization
detectable with the currently existing modern polarimeters. Parameters of this polarization, e.g., wavelength
dependence, are defined by physical conditions in upper layers of the planetary atmoshpere. Thus,
polarimetry of hot Jupiters in combination with other methods of observations may be used to draw
conclusions on properties of their atmospheres.
Recently, we have demonstrated that polarized reflected light can be detected from exoplanetaryatmospheres (Berdyugina et al. 2008, 2011). We have determined for the first time the geometrical albedo indifferent colors and concluded that the high reflectivity of the hot Jupiter HD189733b in the blue due toRayleigh scattering determines its blue appearance. This was confirmed with secondary eclipse
spectro-photometry in the near UV (Evans et al. 2013).
Here we present new polarimetric observations of several hot Jupiters, both transiting and non-transiting, inthree bands: blue (UB), green (V), and red (RI). These data were obtained with our new Double Imaging
Polarimeter (DIPol-2) at the 60cm KVA telescope on La Palma, routinely providing polarimetric accuracy of
10−5 . We analyse these data using our model calculations and infer planet orbit parameters and atmospherereflectivity. We compare our results with measurements of the secondary eclipses of hot Jupiters.

70

Characterisation of the polarimetric mode of the
FoReRo2 instrument of the BNAO – Rozhen: problems
and solutions.1
Galin Borisov 1 , Stefano Bagnulo 2 , Plamen Nikolov 1 , Tanyu Bonev 1
1

Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, 72,
Tsarigradsko Chaussee Blvd., BG-1784 Sofia, Bulgaria,
E-mail: gborisov@astro.bas.bg
2
Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, UK

The 2-Channel Focal Reducer (FoReRo2) is multipurpose instrument attached at the 2 m
Ritchey-Chrétien-Coudé (RCC) telescope of Bulgarian National Astronomical Observatory (BNAO) –Rozhen. In its polarimetric mode it uses a Wollaston prism, placed before a dichroic that splits the signals
into two different channels, but unfortunately does not include a modulator. A Wollaston prism splits thecollimated light into two mutually-orthogonal polarised beams. Given the lack of a modulator, theinstrument suffers from comparatively high instrumental polarization (up to ∼ 2 %), that has been proved
difficult to calibrate. Therefore, we decided to implement a beam swapping technique based on simple
instrument rotation. We observed a number of unpolarised and high polarized standard stars setting the
instrument position angle to 0, 45, 90, . . . , 315 deg, then we combined the observations obtained with the
instrument position angle 90 deg apart. Thanks to this technique, instrumental effects cancel out, and the
instrumental polarisation drops to ∼ 0.05 %. To investigate the spatial instrumental effects, we also observe
all standard stars in different position in the instrument field of view. Here we report the results of ourinvestigations, which prove that FoReRo2 is an instrument capable of delivery high precision imaging andspectro-polarimetric measurements. However, rotating the instrument limit the capabilities to observe
extended objects, and is also unpractical. As a result of a collaboration between Armagh Observatory andthe Rozhen Observatory, a λ/2 retarder waveplate has been acquired, which will allow us to apply the beam
swapping technique without physically rotating the instrument. The commissioning of a modified version of
FoReRo2 will happen during summer 2014.
Acknowledgements: Authors gratefully acknowledge observing grant support from the Institute of
Astronomy and Rozhen National Astronomical Observatory, Bulgarian Academy of Sciences. Part of thiswork was supported by the COST Action MP1104 ”Polarization as a tool to study the Solar System andbeyond”. In particular, we gratefully acknowledge funding for a Short Term Scientific Mission (STSM) at the
Armagh Observatory.

1 Based on data collected with 2m RCC telescope at Rozhen National Astronomical Observatory.

71

Polarimetry with the Southern African Large Telescope
D.A.H. Buckley 1 , K.H. Nordsieck 2 , S.B. Potter 3 , J. Brink 1
1

Southern African Large Telescope, PO Box 9, Observatory 7935, South Africa
Space Astronomy Laboratory, University of Wisconsin, Madison, WI 53706, USA
3South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa
2

We discuss the polarimetric modes of the Robert Stobie Spectrograph (RSS) on the Southern African Large
Telescope, for which commissioning began in late 2011, but was curtailed due to technical issues with thepolarizing beamsplitter. From the beginning, RSS was designed with polarimetry in mind, and thecapabilities include linear, circular or all-Stokes modes, for both imaging and spectropolarimetry. We discussthese capabities and some of the unique modes of operation and their science drivers. Initial commissioning
results are presented, specifically the instrumental calibrations. Modification to the beamsplitter design was
subsequnetly required, due to problems of fluid coupling the eighteen calcite Wollaston prisms comprising thebeamsplitter mosaic. This is due for completion in 2014, restoring full polarimetry capability with SALT andallowing completion of the commissioning and the initiation of polarmetric science programs.

72

A catalogue of High DoLP Astronomical
Sources Outside the Solar System
Capobianco Gerardo1 , Fineschi Silvano2 , Andretta Vincenzo3 ,Focardi Mauro4 ,1

INAF-Astrophysical Observatory of Torino, Via Osservatorio, 20 - 10025 Pino T.se (TO) - Italy,
capobianco@oato.inaf.it
2
INAF-Astrophysical Observatory of Torino (Italy), fineschi@oato.inaf.it
3
INAF-Astrophysical Observatory of Capodimonte (Italy), andretta@oacn.inaf.it
4
University of Florence (Italy), mauro@arcetri.astro.it

In the framework of the ESA-Solar Orbiter mission, a catalogue of strongly linearly polarized astronomical
objects with a DoLP greater than 0.1, outside the solar system (Hi DoLPASOSS) has been compiled for thedetection of linearly polarized targets for the in-flight calibration of the polarimetric visible light channel ofthe METIS instrument.
Only a weak subset of the identified objets represents a good target for the purpose of this investigation, due
to the calibration requirements. Here we shows the full catalogue, compilated starting by several availables
catalogues. This catalogue includes objects presenting strong linear polarization at different wavelengths(mainly in visible or infrared)and absolute magnitude less then 20. Stable and instable objects are includedin the catalogue.
The main purpose of the catalogue is to give a reference to all the people interested in astronomical
poalrization. Some objects (a few percent of the total) should be considered as calibrators. Statistics about
these objects and the whole catalogue are presented.

73

POLARIMETRIC BEHAVIOUR OF BLAZAR OJ 248
M. I. Carnerero 1 , C. M. Raiteri 2 , M. Villata 3 , J. A. Acosta-Pulido 4 , F. D’Ammando 5 for
the GASP-WEBT collaboration
1

INAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese, Italy,
maribel@oato.inaf.it
2
INAF, Osservatorio Astrofisico di Torino(Italy), raiteri@oato.inaf.it
3
INAF, Osservatorio Astrofisico di Torino(Italy), villata@oato.inaf.it
4
Instituto de Astrofisica de Canarias (Spain), Departamento de Astrofisica, Universidad de La Laguna(Spain), jap@iac.es
5Dip. di Fisica, Universit degli Studi di Perugia, Perugia (Italy), INAF, Istituto di Radioastronomia,
Bologna (Italy), dammando@ira.inaf.it

We present an analysis of optical photometric, spectroscopic, and polarimetric data of the blazar OJ 248,
obtained by different observatories participating to the GLAST-AGILE Support Program (GASP) of theWhole Earth Blazar Telescope (WEBT; http://www.oato.inaf.it/blazars/webt/). The WEBT was born in1997 as a network of optical, near-infrared, and radio observers who in concert have the capability to obtain
continuous, high-temporal-density monitoring of blazars. This is extremely useful for understanding thebroad-band continuum emission of these sources, especially when the study is performed in conjunction withobservation at higher frequencies (ultraviolet, X and gamma-rays) by satellites and ground-based TeV
telescopes. In the framework of the WEBT one can also get continuous polarimetric monitoring of blazars in
the optical (and recently near-infrared) bands. The polarimetric studies give us information on the magnetic
field in the jet and on the interplay between the polarised synchrotron radiation from the jet and the thermal
emission from the accretion disc. The behaviour of the polarisation degree and angle can be compared tothat of the source flux at various wavelengths to shed light on the variability mechanisms (e.g. Shocks
propagating downstream the jet) and on the geometrical structure of the jet (e.g. Helical morphology).
We present an analysis of the multiwavelength behaviour of the quasar-like blazar OJ 248 at redshift z=0.939
in the period 2006-2013. We use low-energy data (radio, optical and near-infrared) obtained by 15
observatories, as well as high-energy data from the Swift (UV and X-rays) and Fermi (gamma-ray) satellites,
to study flux, spectral, and polarimetric variability and correlations among emission in different bands.
The study focuses mainly on the major flare that occurred at the end of 2012, lasting until the beginning of
2013, which was detected at all frequencies. This event is compared to the previous optical outburst,
occurred in 2006-2007, and radio outburst observed in 2010-2011.

74

A statistical study of the quiet sun polarization
M. Faurobert 1 , G. Ricort 2
1

University of Nice-Sophia Antipolis, Lagrange Laboratory UMR7293, Parc Valrose, 06108 Nice cedex 2.
France. marianne.faurobert@unice.fr
2
University of Nice-Sophia Antipolis. gilbert.ricort@unice.fr

In the quiet solar photosphere the coupling of the turbulent plasma with the magnetic field gives rise to acomplex magnetic structuring which is still partly unknown. In particular, the magnetic energy contained in
weak ”turbulent” magnetic features is a key issue which has been debated for many years. Here we propose
to investigate the magnetic structuring of the quiet photosphere of the Sun on a statistical point of view byusing high quality images of the circular and linear polarization of magnetic sensitive lines.
The SOT/SP instrument onboard the Hinode satellite provides us with high resolution images of the circularand linear polarization in the FeI 630 nm solar lines. We consider the polarization patterns as tracers of themagnetic field structures.

6

Log@EHkLD

5
4
3
2
-1.5

-1.0

0.0

-0.5

0.5

-1

LogH2ΠkLHarcsec L
Figure 18: Power spectrum of the FeI 630.15 nm (red curve) and 630.25 nm lines (green curve) circularpolarization fluctuations recorded at the center of the solar disk. The light-blue curve gives an estimate of
the noise level.
The Fourier spectra, as shown in Fig. 18, allows us to investigate the structures of the images from thesupergranulation scale (40 arcsec) down to subgranular scales on the order of 0.3 arcsec. We shall commenton the properties of these spectra and show how they bring new insight on the magnetic structure of thequiet Sun.

75

CorMag - Coronal Magnetograph
Fineschi Silvano1 , Capobianco Gerardo2 , Massone Giuseppe3 , Jan Rybak4 , Jaroslav
Ambroz5 , Matus Kozak6 , Ales Kucera7
1

INAF-Astrophysical Observatory of Torino, Via Osservatorio, 20 - 10025 Pino T.se (TO) - Italy,fineschi@oato.inaf.it
2
INAF-Astrophysical Observatory of Torino (Italy), capobianco@oato.inaf.it
3
INAF-Astrophysical Observatory of Torino (Italy), massone@oato.inaf.it
4
Astronomical Institute, Slovak Academy of Sciences,(Slovakia), choc@astro.sk
5
Astronomical Institute, Slovak Academy of Sciences,(Slovakia), jaro@astro.sk
6
Astronomical Institute, Slovak Academy of Sciences,(Slovakia), kozak@astro.sk
7
Astronomical Institute, Slovak Academy of Sciences,(Slovakia), akucera@astro.sk

The Turin Astrophysical Observatory, Italy, has developed a liquid crystal Lyot filter for spectro-polarimetricobservations of the coronal green-line emission (FeXIV, 530.3 nm). The science goal of the planned
observations is the study of the coronal magnetic fields that drive the dynamics of the solar wind. The Turincoronal magnetograph (CorMag) has been integrated, as focal-plane instrumentation, to the Zeiss-200/300
coronagraph of the Lomnicky Peak Observatory, Slovakia. The Turin coronal magnetograph (CorMag) is afour-stage Lyot filter with an electro-optically tunable bandpass. The full width at half maximum of thefilter is 0.15 nm. The center wavelength of the bandpass is tuned by using nematic liquid crystal variable
retarders (LCVRs). A separate LCVR, in tandem with the filter, is used for the polarimetric measurements.
The INAF-Turin team has successfully operated the CorMag during the 2010 eclipse, acquiring coronal
images of the green line emission.
This presentation will illustrate the CorMag and Zeiss-200/300 coronagraph, and will describe thepreliminary results from the first-light observations. The presentation will discuss the future observing plansfrom this new coronagraphic facility. These observations would provide the unique opportunity to start
reviving ground-based coronagraphy in Europe by combining first-class, classical telescope technology (theZeiss coronagraph at Lomnicky Observatory) with modern, cutting-edge electro-optical technology (the LC
Lyot filter of the Turin Observatory) originally developed for space applications.

76

Polarized radiative transfer equation: curvilinear
coordinates and refraction
Juris Freimanis 1
1

Engineering Research Institute ”Ventspils International Radio Astronomy Centre” of Ventspils University
College, Inzenieru iela 101, Ventspils, LV-3600, Latvia; email jurisf@venta.lv

Apart from situations where general relativity is essential (accretion disks around and jets from black holes
and neutron stars), radiative transfer equation in general, and polarized radiative transfer equation (PRTE)
in particular, most often is considered assuming plane-parallel symmetry and Cartesian coordinate system.
Sometimes it is written and solved in spherical coordinate system, and quite seldom - in circular cylindricalcoordinate system. But nonrelativistic astronomical objects (Solar prominences, other features and outflows
from the Sun and stars, Be stars, planetary and protoplanetary nebulae, circumstellar dust envelopes etc.)
have many other types of symmetry as well.
In this contribution, the results of systematic derivation of PRTE in different coordinate systems arereviewed. The medium is assumed to be polydisperse; the statistical ensemble of small particles is dispersedin some continuous host medium e.g. vacuum. It is assumed that birefringence in the effective medium is
negligible but refraction due to smooth (spatially differentiable) inhomogeneity of the statistical properties ofpolydisperse medium maybe exists. Differential operator of PRTE is just that part of PRTE dependent on
the spatial coordinate system; the rest terms of PRTE (those describing extinction, scattering and primarysources) are independent of coordinate system. For polarized radiation, seeming rotation of the linear
polarization plane often takes place, and Rytov’s law is satisfied if the medium is inhomogeneous andrefraction exists.
Until this moment, triaxial ellipsoidal system with either x or z axis being the longest, oblate and prolate
spheroidal, elliptic conical, elliptic cylindrical, classical toroidal and simple elliptic (oblate and prolate)toroidal coordinate systems have been considered. For most of these coordinate systems, two alternative
choices of the polar axis for the description of propagation direction of radiation ϑ = 0 were made; forclassical and each of simple toroidal systems only single choice of polar axis was assumed. These results canbe regarded not only as basic for the development of new algorithms for numerical solution of PRTE fullyreflecting the symmetry of the physical problem, but also as the starting point for analytic research revealing
the analytic properties, asymptotics and maybe some exact benchmark solutions of PRTE in different
curvilinear coordinate systems.
These results demonstrate the effectiveness of the general method based on use of covariant derivatives anddescribed in papers by Freimanis (2011,2013). One more paper, with lengthy but clear final expressions, issubmitted to ”Journal of Quantitative Spectroscopy & Radiative Transfer”.

77

Photometric, polarimetric and spectroscopic
investigation of the new polar USNO-A2.0
0825-18396733
Gabdeev M.1 , Borisov N.1 , Afanasiev V.1 , Kolbin A.2
1

Special Astrophysical Observatory RAS, Nizhnij Arkhyz 369167, Karachai-Cherkessian Republic,
Zelenchukskiy region, Russian Federation, gamak@sao.ru
2
Kazan Federal University, 18 Kremlyovskaya St., Kazan 420008, Republic of Tatarstan, Russian Federation,
kolbinalexander@mail.ru

We report the photometric, polarimetric and spectroscopic observations of a new variable star USNO-A2.0
0825-18396733. The photometric data allowed us to refine the orbital period of the system, P=0.d 084841(2)(2.036h). A strong variability of circular polarization led us to the conclusion that this object is a polar (anAM Her type star). Circular polarization reached maximum value of -30%±3. The obtained spectra of theobject reveal red continuum and strong emission lines of hydrogen and helium. Moreover, the spectra show a
CIII-NIII emission blend and lines of other elements. Using the emission lines of Hβ and HeII 4686Åwecomputed the radial velocity curves. After analysis of obtained data we estimate mass of the white dwarf
M1 =0.71-0.78Mo . The Doppler mapping has revealed two emission regions near the inner Lagrange point.
Circular polarization data was analyzed with spatial distribution of cyclotron emission model.

78Spectropolarimetry and modeling of Galactic
Wolf-Rayet star WR156
Maryeva O.1 , Gabdeev M.1
1

Special Astrophysical Observatory RAS, Nizhnij Arkhyz 369167, Karachai-Cherkessian Republic,
Zelenchukskiy region, Russian Federation, olga.maryeva@gmail.com

For the first time spectropolarimetric observations of Wolf-Rayet star WR156 were conducted. Medium
resolution spectropolarimetric data in the range of 3500−7200 Åwere obtained at 6-m telescope of Special
Astrophysical Observatory. These data show that the light from the star is significantly polarized, with thedegree of polarization P = 1.38 ± 0.06%, and the position angle Θ = 77.4o ± 1.2o . This polarization is, mostprobably, has an interstellar origin, as its magnitude and orientation are similar to the ones of field stars.
Also, we present results of numerical modeling of WR156 atmosphere performed using CMFGEN code.
According to it, WR156 is the richest hydrogen WR star of WN8 type in the Galaxy.

79

Shadows and cavities in protoplanetary disks:
HD163296, HD141569A, and HD150193A in polarizedlight
A. Garufi 1 , S.P. Quanz 2 , H. Avenhaus 3 , H.M. Schmid 4 , E. Buenzli 5 , M.R. Meyer 6 , C.
Dominik 7 , S. Wolf 8
1

Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland,antonio.garufi@phys.ethz.ch
2
ETH Zurich, quanz@astro.phys.ethz.ch
3
ETH Zurich, havenhaus@phys.ethz.ch
4
ETH Zurich, schmid@astro.phys.ethz.ch
5
Max-Planck Institute for Astronomy, Heidelberg, buenzli@mpia.de
6
ETH Zurich, mmeyer@phys.ethz.ch
7
Sterrenkundig Instituut Anton Pannekoek, Amsterdam, c.dominik@uva.nl
8
University of Kiel, wolf@astrophysik.uni-kiel.de

The morphological evolution of dusty disks around young stars is pivotal to better understand planet
formation. Since both dust grains and global disk geometry evolve on short timescale, high-resolution imaging
of a sample of objects may provide important hints towards such an evolution. We enlarge the sample ofprotoplanetary disks imaged with high-resolution (less than 0.200 ) by observing HD163296, HD141569A, andHD150193A in polarimetric differential imaging. We integrate our data with previous datasets to paint alarger picture on their morphology. In particular, we report a marginal detection of the disk around
HD163296 in both H and KS band. The disk is resolved as a broken ring structure with a significant light
drop inward of 0.600 . No sign of extended emission is resolved around HD141569A and HD150193A. We
propose that the absence of scattered light in the inner 0.600 around HD163296 and the non-detection of thedisk around HD150193A may be due to similar geometric factors. On the other hand, the non-detection of
HD141569A is consistent with previous datasets revealing the presence of a huge cavity in the dusty disk.

80Modeling the polarization in complex environments withthe 3D radiative transfer code STOKES
R.W. Goosmann 1 , F. Marin 2 , F. Tamborra 3
1

2

Observatoire astronomique de Strasbourg, France
Astronomical Institute, Academy of Sciences, Prague, Czech Republic
3
Observatoire astronomique de Strasbourg, France

We present the 3D radiative transfer code STOKES designed to model time-dependent spectropolarimetry
and polarization imaging in complex reprocessing environments across the optical, ultraviolet and X-ray
domain. Based on the Monte Carlo method, the code includes various relevant processes (de-)polarizing
radiation: electron scattering, dust extinction, photo-absorption and recombination. Emission and scatteringgeometries can be constructed based on elementary or sophisticated geometrical shapes and the escaping
radiating is evaluated at all possible viewing angles. Time-dependent effects can be included to produce
series of polarization spectra and/or images. The code was originally written to model the polarization of
Active Galactic Nuclei but can be applied to a whole range of astrophysical objects in which reprocessing is
an important source of polarization.

81Modeling linear and circular polarization due toradiatively aligned grains in special astrophysicalenvironments
Thiem Hoang 1,2 , A. Lazarian 3
1

Ruhr-Universität Bochum, 44780 Bochum, Germany, hoang@cita.utoronto.ca
2
Canadian Institute for Theoretical Astrophysics, Canada
3
University of Wisconsin-Madison, USA

Grain alignment by radiative torques (RATs) has been extensively studied for various environment
conditions, including interstellar medium, dense molecular clouds, and accretion disks, thanks to significant
progress in observational, theoretical and numerical studies. In this paper, we explore the alignment by
RATs and provide quantitative predictions of dust polarization for a set of astrophysical environments thatcan be tested observationally. We first consider the alignment of grains in the local interstellar medium andcompare predictions for linear polarization by aligned grains with recent observational data for nearby stars.
We then revisit the problem of grain alignment in accretions disks by taking into account the dependence of
RAT alignment efficiency on the anisotropic direction of radiation fields relative to magnetic fields. Moreover,
we study the grain alignment in interplanetary medium, including diffuse Zodiacal cloud and cometary
comae, and calculate the degree of circular polarization (CP) of scattered light arising from single scatteringby aligned grains. We also discuss a new type of grain alignment, namely the alignment with respect to theambient electric field instead of the alignment with the magnetic field. We show that this type of alignment
can allow us to reproduce the systematic features of CP observed across a cometary coma. Our findings
suggest that polarized Zodiacal dust emission may be an important polarized foreground component, whichshould be treated carefully in B-mode polarization cosmic microwave background experiments.

82Non-Zeeman Circular Polarization of Molecular Spectral
Lines in the ISM
Martin Houde 1 and Talayeh Hezareh 2
1
2

University of Western Ontario, London, Ontario, N6A 3K7, Canada, mhoude2@uwo.ca
Max-Planck-Institut für Radioastronomie, Bonn, Germany, thezareh@mpifr-bonn.mpg.de

I will discuss the recent discovery of circular polarization signals in the rotational line profiles of moleculesthat are negligibly sensitive to the Zeeman effect. Initial findings obtained for CO in the Orion KL
star-forming region with the Caltech Submillimeter Observatory were recently followed with similar
detections for two transitions of CO in an exhaustive study of the supernova remnant IC 443 (G), led at the
MPIfR with the IRAM 30m and APEX telescopes. These new results have clearly established that circularpolarization arises, as predicted, from the conversion of linear polarization signals incident on the molecules
responsible for the detected radiation. I will further show how the anisotropic resonant scattering model
developed to explain these observations also provides a viable mechanism to explain the polarization
characteristics of SiO maser lines in the circumstellar envelope of evolved stars. As this scattering model
directly involves the ambient magnetic field, these results suggest the possibility of starting a whole new
subfield of more incisive studies of magnetic fields in the interstellar medium.

83

High Resolution Imaging Polarimetry of Hypergiants
with MMTPol
Terry Jay Jones 1 , Dinesh Shenoy 1 , Chris Packham 2 , Enrique Lopez-Rodriguez 2
1

2

University of Minnesota, 116 Church St SE, Minneapolis, MN 55455
University of Texas at San Antonio, 1 UTSA Circle San Antonio, Texas 78249

We present imaging polarimetry at J (1.25 µm), K (2.2 µm) and Ls (3.1 µm) of the warm hypergiant IRC+10420 and the red supergiant VY CMa made with MMTPol. These observations reveal polarization
features in the light scattered from dust around these stars at 0.1800 spatial resolution. These observations
are combined with broad band imaging at K, L0 (3.8 µm) and M (5 µm) using LMIRCam on the LBT toinvestigate the geometry and nature of the dust in close to these rare, unusual stars. For IRC +10420, we
find the dust is distributed mostly in the plane of the sky showing high polarization with scattering opticaldepths ranging from optically thin to partially optically thick. This geometry is consistent with IRC +10420
having an equatorial ’skirt’ that is part of a bipolar outflow viewed nearly pole-on. For VY CMa, we find avery optically thick clump with a mass greater than 5 Jupiters about 0.900 from the star that is relatively
highly polarized, indicating a low albedo for the dust. This clump was ejected from the star about 250 years
ago in a single, very energetic event. The underlying cause of these mass-loss events are not understood.

84

SGMAP: An Optical Polarimetric Survey Project inHiroshima
K. S. Kawabata 1 , M. Yoshida 1 , M. Uemura 1 , H. Akitaya 1 , Y. Utsumi 1 , Y. Moritani 1 , S.
Miyama 1 , T. Ohsugi 1 , Y. Tanaka 1 , and SGMAP collaboration team1

Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima,
Hiroshima, 739-8526, JapanWe are promoting SGMAP (Search for the Galactic Magnetic-field by All-sky Polarimetry survey) project.
The goal of this project is to produce a homogeneous polarimetric catalog of all astronomical objects brighter
than 13-14 magnitudes at optical three bands in northern hemisphere (δ > −25◦ ), which will be obtained by
non-biased observations with a specially-designed wide-field three-channel imaging polarimeter attached to amodified 2-m MAGNUM telescope (Univ. of Tokyo). The number of the sample objects will reach more thanseveral millions, which is more than hundred times as large as the sample number of the currently-existing
compilation of optical polarimetry (e.g., Heiles 2000). It is still in a fund-raising phase. If this project isrealized, the produced catalog will contribute to many fields of astronomy, e.g., Galactic magnetic field (withhelps of future Gaia/nano-JASMINE astrometry, radio survey with SKA and so on), interstellar media,
mass-losing stars, etc, together with ongoing survey projects as SOUTH POL (Magalhaes et al. 2012) andGPIPS (Galactic Plane Infrared Polarization Survey; Clemens et al. 2012), etc. The polarization map will
also be useful to correct foreground polarization components in extragalactic targets like CMB or AGNs.

85

Discriminating stochastic from deterministic EVPA
swing mechanisms in AGN jets
S. Kiehlmann 1a , T. Savolainen 1 , S.G. Jorstad 2,3 , K.V. Sokolovsky 4,5 , F. Schinzel 6 ,I. Agudo 7,2,8 ,1

Max-Planck-Institut für Radioastronomie, Auf dem Hügel, 69, D-53121, Bonn, Germany askiehlmann@mpifr-bonn.mpg.de2
Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215,
USA
3
Astronomical Institute, St. Petersburg State University, Universitetskij Pr. 28, Petrodvorets, 198504 St.
Petersburg, Russia
4
Astro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, 117997, Moscow, Russia
5
Sternberg Astronomical Institute, M.V.Lomonosov Moscow State University, Universiteskij prosp. 13,
Moscow 119991, Russia
6
Department of Physics and Astronomy, University of New Mexico, Albuquerque NM, 87131, USA
6
Instituto de Astrofı́sica de Andalucı́a, CSIC, Apartado 3004, 18080, Granada, Spain
6
Joint Institute for VLBI in Europe, Postbus 2, 7990 AA, Dwingeloo, the Netherlands

Jets in active galacti nuclei emit synchrotron radiation from radio to optical or x-rays. At optical
wavelengths these sources show linear polarization up to 45structure in the corresponding emission region.
Blazars, active galactic nuclei with a jet closely aligned with the line of sight, exhibit strong variation of thepolarization degree and the electric vector position angle (EVPA). Optical EVPA rotations up to 720 degrees
and changing rotation directions have been reported as well as correlations between optical EVPA rotations
and flares in optical and gamma-rays. Models explaining EVPA swings range from stochastic processes in aturbulent magnetic field to deterministic processes in a large-scale helical magnetic field. The jet magnetic
field structure is one of the major open questions in blazar research.
Applied to a unprecedented data set of optical polarization for the archetypical blazar 3C279 we present a
method to discriminate between stochastic and deterministic EVPA swing mechanisms. Duringlow-brightness states 3C279 resembles stochastic polarization variation, but is dominated by a deterministic
process during flaring states. Moreover we present a toy model capable of producing large EVPA rotations
with changing rotation directions based on an emission feature on a helical trajectory in a helical magnetic
field configuration.

86

Near-Infrared Imaging Polarimetry toward a
Bright-Rimmed Cloud
T. Kusune 1 , K. Sugitani 2 , The SIRPOL team1

Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501, Japan,t kusune@nsc.nagoya-cu.ac.jp
2
Graduate School of Natural Sciences, Nagoya City University, sugitani@nsc.nagoya-cu.ac.jp

Bright-rimmed clouds, which are located at the periphery of HII regions, are considered to be potential sites
for induced star formation by UV radiation from nearby massive stars. We have carried out near-infrared(JHKs ) imaging polarimetry with the imaging polarimeter SIRPOL toward a blight-rimmed cloud (SFO 74)
in order to reveal a magnetic field structure of SFO 74. The SIRPOL, which is polarimetry mode of the
SIRIUS camera, is mounted on the IRSF 1.4 m telescope at the South Africa Astronomical Observatory. The
SIRIUS camera is equipped with three 1024 × 1024 HgCdTe (HAWAII) arrays, JHKs filters, and dichroic
mirrors, which enable simultaneous JHKs observations with the field of view at each band ∼ 70 .7 × 70 .7. The
polarization vector maps obtained by the observation clearly show that the magnetic field in the layer justbehind the bright rim is running along the shape of rim, which is quite different from the ambient magnetic
field. The direction of the magnetic field just behind the tip rim is perpendicular to that of the incident UV
radiation, and the magnetic field configuration appears to be symmetric as a whole with respect to the cloud
symmetric axis, which runs along the UV direction. In addition, we also derived the magnetic field strength
in the two regions (just inside and far inside the tip rim), applying the Chandrasekhar-Fermi method. The
estimated magnetic field strength just inside the tip rim, ∼100 µG, is stronger than that far inside, ∼40 µG,
suggesting that the magnetic field strength just inside the tip rim is more enhanced by the UV radiation.
The shock induced by the UV radiation increases the density within the top layer gas around the tip rim,
and thus increases the magnetic field strength. The magnetic and turbulent pressures is likely to becomparable just inside the tip rim, implying a significant contribution of the magnetic field to the totalinternal pressure. The estimated mass-to-flux ratio is close to the critical value just inside the tip rim,
indicating an importance of the magnetic field in cloud dynamics.

87

On the consistency of magnetic field measurements of
Ap stars: lessons learned from the FORS1 archive
J.D. Landstreet 1 , S. Bagnulo 1 , L. Fossati 2
1

Armagh Observatory, College Hill, Armagh, BT61 9DG, UK.
email: jls@arm.ac.uk and sba@arm.ac.uk
2
Argelander Institut für Astronomie, Auf dem Hügel 71, Bonn, Germany.
email: lfossati@astro.uni-bonn.de

For a decade, the FORS1 spectropolarimeter was a workhorse instrument for the measurement of stellar
magnetic fields. We have revised all its archive data to evaluate the quality and consistency of fieldmeasurements obtained with FORS1, and by extension with its successor FORS2 and other similar
instruments.
Almost all of the unambiguous magnetic field detections obtained with FORS1 have been in magnetic Ap or
Bp stars. We have compared FORS1 field measurements of such stars externally with what is previously
known about specific stars, and internally for consistency with the known behaviour of Ap stars, in order toassess the overall quality of FORS1 magnetic measurements.
In general, FORS1 magnetic measurements are consistent with other field measurements of individual stars,
and the internal consistency of measurements is also excellent. However, it is important to recognise thateach choice of grism and wavelength window constitutes a separate instrumental system, and measurementswith various instrumental systems of a single star at one time can vary from one another by 10 or 20 %.
Furthermore, it is found that measurements made using only hydrogen lines yield results that aremeaningfully different from measurements with metal lines only for stars with effective temperatures above
about 9000 K. Finally, it is necessary to be aware of a problem of occasional outliers in the data.
Magnetic measurements made with FORS1 are generally of excellent quality when appropriate care is taken
in data reduction. This instrument has provided an excellent worked example from which important lessons
applicable to other Cassegrain spectropolarimeters have been learned.

88Evaluation of the Mueller Matrix for Ellipsoidal Grains
with Spline Interpolation
Masafumi Matsumura 1 , Julien Vandeportal 2,3 , Pierre Bastien 2 , and Jean-Charles Augereau
3
1

Faculty of Education, Kagawa University, Takamatsu 760-8522, Japan matsu@ed.kagawa-u.ac.jp
Département de physique & Centre de rechereche en astrophysique du Québec, Université de Montréal,
C.P.6128, Succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada vandeportal@astro.umontreal.ca,
bastien@astro.umontreal.ca
3Institut de Planétologie, Université Joseph Fourier, CNRS 414, Rue de la Piscine, Domaine Universitaire,
BP 53, 38041, Grenoble Cedex 9, France augereau@obs.ujf-grenoble.fr
2,3This paper discusses a method for evaluation of the Mueller matrix for the transformation of polarization
status, i.e. the Stokes parameters (I,Q,U,V), when light is scattered by a dust grain. This matrix isnecessary to calculate polarization in radiative transfer models.
Large linear and circular polarization is observed in/around many young stellar objects (YSOs) in dense
clouds. In those dense clouds, multiple light scattering should occur, since the dust density is high. The dust
grains in those regions are expected to grow and should be larger than in diffuse space. In addition, it issuggested that those grains are nonspherical and aligned in a particular direction. These lines of evidence>
require a multiple light scattering model with large aligned grains, e.g. ∼1µm, to understand the observed
polarization and other properties of YSOs (Vandeportal et al. in preparation).
However, evaluation of the Mueller matrix for large nonspherical grains is not an easy task. Since thescattering properties depend on incidence and scattered directions, the matrix is a function with four angles,
i.e. two for incidence and other two for scattering, measured in the grain’s reference frame. If the grain size
is smaller than wavelength, the Rayleigh approximation is valid and it is relatively simple. However, this is
not the case for larger grains. We thus evaluate the matrix in arbitrary directions using a spline interpolation
method, on the basis of numerical tables obtained with the Fredholm integral equation method (Matsumura
and Seki 1996; Matsumura and Bastien 2009). This paper studies the accuracy and efficiency of this method.

89

ALMA Polarization: Commissioning and Verification
StatusK.Nakanishi 1 , H.Nagai 2 , E.Fomalont, S.Corder 3 , R.Hills 4 ,G.Moellenbrock 5 , Y-W.Tang 6
1

Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile, knakanis@alma.cl
2
National Astronomical Observatory of Japan, hiroshi.nagai@nao.ac.jp
3
Joint ALMA Observatory, efomalon@alma.cl, scorder@alma.cl
4
University of Cambridge, richard@ast.cam.ac.uk
5
National Radio Astronomy Observatory, gmoellen@nrao.edu
6
Academia Sinica Institute of Astronomy and Astrophysics, ywtang@asiaa.sinica.edu.tw

Atacama Large Millimeter/Submillimeter Array (ALMA) can receive two orthogonal linear polarization
simultaneously, and we can obtain the four Stokes parameters and measure polarization of emission fromastronomical sources. The polarization commissioning team has been working on the system and science
verification of polarization observation. ALMA offers polarization observations from the Early Science Cycle
2, although there are some limitations. Commissioning activities to improve and expand the polarization
observation capability is going on.
We report current status of the commissioning activities and also report our future commissioning plan. We
have been focusing on verification of continuum polarization observation. Instrumental polarization
properties (frequency dependencies, stability, and changes in a field of view), which directly affectpolarization sensitivity and development of calibration plan, have been investigated intensively. We find thatthe instrumental polarization is very small and stable, and ALMA can observe polarized flux of ∼ 0.3% of
the total flux for spatially compact objects. Recently, we get started commissioning and verification ofspectral line polarization observation to try to offer it in the near future. This is just the beginning of theactivity, and we are finding that the instrumental polarization of the spectral line mode is likely to have
similar properties to that of the continuum mode.

90

Imaging polarimetry of the dust-rich comet
C/2011 L4 after perihelion
P. Nikolov 1 , G. Borisov 1 , and T. Bonev 1
1

Institute of Astronomy and National Astronomical Observatory, 72, Tsarigradsko Chaussee Blvd., 1784,
Sofia, Bulgaria, e-mail: pnikolov@astro.bas.bg

We present preliminary results based on CCD imaging polarimetry of comet C/2011 L4 (PanSTARRS),
observed during two nights, April 30 and May 30, 2013, at phase angles 41 deg and 32 deg, respectively. The
observations were obtained with the 2-meter telescope of the National Astronomical Observatory (NAO),
equipped with two-channel focal reducer, FoReRo2 (Jockers et al. 2000). Narrow-band filters centered at
443 nm and 684 nm (blue and red channel, respectively) were used for cometary continuum observations. In
the RC-focal plane, in front of the focal reducer, a rectangular mask was mounted with a projected FOV on
the sky of 430×50 arcsec2 . The entire focal reducer was rotated at the position angle of the comet. A
Wollaston prism splits the collimated light into two mutually-orthogonal polarised beams, aligned paralleland perpendicular to the scattering plane. In this configuration the linear polarization is derived by merely
using the relation (F⊥ − Fk )/(F⊥ + Fk ). A second advantage of this configuration is that it allows theconstruction of polarization maps of the cometary dust distribution in solar and anti-solar directions.
Both sets of observations consist of 5 exposures per filter, with a duration of 300 s each. In order to derive
the level of instrumental polarization, the unpolarized nearby standard star HD154345 (Gehrels, 1974) was
observed immediately before the comet. We constructed maps of the linear polarization by integration offluxes in different apertures around the photometric center. The phase-angle dependence of the linear
polarization was derived for the circumnuclear region. A comparison between the data obtained in the red
and in the blue channel was used to derive the spectral dependence of the linear polarization. Indications arefound that the degree of linear polarization is greater close to the nucleus and gradually decreases withincreasing cometocentric distance.
The results concerning the spatial distribution, the phase-angle and spectral dependence of the linear
polarization of comet C/2011 L4 are discussed by comparing them with the data published by Kiselev etal.(2006).

References
T. Gehrels (ed.) 1974, ”Planets, Stars & Nebulae studied with Photopolarimetry ”, University of Arizona Press, Tuscon, pp.
168-169
K. Jockers, T. Credner, T. Bonev et al. 2000, Kinematika i Fizika Nebesnykh Tel, 3, 13-18
Kiselev, N., Velichko, S., Jockers, K., Rosenbush, V., and Kikuchi, S., Eds., Database of Comet Polarimetry. EAR-C-COMPIL5-COMET-POLARIMETRY-V1.0. NASA Planetary Data System, 2006.

91

Anisotropic orientations of polarisations from quasars
ligth:a new statistical method and analysis
V. Pelgrims 1 , J.R. Cudell 2
1

IFPA, AGO dept., University of Liège, B4000 Liège, Belgium, pelgrims@astro.ulg.ac.be
2
IFPA, AGO dept., University of Liège, jr.cudell@ulg.ac.be

We recently built a new statistical method dedicated to the study of the dispersion of polarisation vector directions coming fromsparse cosmic sources. We will basically review the content of the paper (Pelgrims and Cudell, 2014)2 ; namely, we will present
the basis of the new method and we will discuss the results of its application to the sample of quasar polarisation measurements
in optical wavelength compiled in (Hutsemékers et al., 2005)3 . Using the new method, we found that the probability that thelarge-scale alignments of polarisation vectors are due to chance is as low as 0.003%.

2 Pelgrims, V. and Cudell, J.R., 2014, in press [arxiv:1402.4313]
3 Hutsemékers, D., Cabanac, R., Lamy, H., Sluse, D., 2005, A&A, 332, 410

92

Measuring the continuum linear polarization with
ESPaDOnS
Antonio Pereyra 1 , Claudia V. Rodrigues 2 , Eder Martioli 3
1

2Inst. Geofı́sico del Perú, Área Astronomı́a, Calle Badajoz 169, Lima, Perú, apereyra@igp.gob.pe
Inst. Nacional de Pesquisas Espaciais/MCTI, Av. dos Astronautas 1758, São José dos Campos, SP, Brazil,
claudia.rodrigues@inpe.br
3
Lab. Nacional de Astrofı́sica/MCTI, Rua Estados Unidos, 154, Itajubá, MG, Brazil

Our goal is to test the feasibility to obtain accurate measurements of the continuum linear polarization from high-resolution
spectra using the spectropolarimetric mode of ESPaDOnS at the Canada-France-Hawaii telescope. We used the new pipeline
OPERA to reduce recent and archived ESPaDOnS data. A couple of standard polarization stars and several science objects
were tested (an example is shown in Fig. 19, left). Synthetic broad-band polarization was computed from the ESPaDOnS
continuum linear polarization spectra and compared with published values to quantify the accuracy of the instrument. The
continuum linear polarization measured by ESPaDOnS is consistent with the broad-band polarimetry measurements available in
the literature (Fig. 19, right). The polarization degree accuracy is better than 0.2% considering the full sample. The accuracy inpolarization position angle using the most polarized objects is better than 5◦ . Our results suggest that measurements of thecontinuum linear polarization using ESPaDOnS are viable.

(a)

(c)

(b)

(d)

Figure 19: (Left) Linear continuum polarization of the polarized standard star HD19820 from ESPaDOnS data.
(Right) Comparison of synthetic V broad-band polarization from ESPaDOnS and literature values. Polarization level(a) and position angle (c) with residuals (b and d). The gray zone indicates a 1-sigma dispersion around the meanvalue.

93

Magnetic field components analysis of the
SCUPOL 850 microns polarization datacatalogFrédérick Poidevin 1, Diego Falceta-Gonçalves 2 , Grzegorz Kowal 3 ,Elisabete de Gouveia Dal Pino 4 , Antonio-Mário Magalhães. 5
1

Instituto de Astrofsica de Canarias (IAC), C/Va Lctea, s/n, E-38200, La Laguna,Tenerife, Spain. 00349226005200, fpoidevin@iac.es
2
SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St
Andrews, Fife KY16 9SS, UK and Universidade de São Paulo,- Escola de Artes, Ciências e
Humanidades Rua Arlindo Béttio, no. 1000 - Ermelino Matarazzo - São Paulo - SP
03828-000 , Brazil, dfalceta@usp.br3
Universidade de São Paulo,- Escola de Artes, Ciências e Humanidades Rua ArlindoBéttio, no. 1000 - Ermelino Matarazzo - São Paulo - SP 03828-000 , Brazil,
kowal@astro.iag.usp.br4
Universidade de São Paulo, Instituto de Astronomia, Geofı́sica e Cı̂enças Atmosféricas,
Rua do Matão 1226, Butantã, São Paulo, SP 05508-900, Brazil, dalpino@astro.iag.usp.br5
Universidade de São Paulo, Instituto de Astronomia, Geofı́sica e Cı̂enças Atmosféricas,
Rua do Matão 1226, Butantã, São Paulo, SP 05508-900, Brazil, mario@astro.iag.usp.br

We present an extensive analysis of the 850 microns (353 GHz) polarization maps of the
SCUBA Polarimeter Legacy (SCUPOL) Catalogue produced by Matthews et al.. A
description of the several methods used for the analysis of the polarization maps of asample of molecular clouds and star-forming regions is given. We discuss another method
used for describing the turbulent regimes of the four well sampled regions, S106, OMC-2/3,
W49, and DR21 in term of sonic and Alfven Mach numbers. We shown how this method
can be used in order to constrain the values of the inclination angle of the mean magnetic
field with respect to the line of sight. Our estimates of the sonic and Alfven Mach numbers
as well as our calculations of the inclination angle of the mean magnetic field are consistent
with results obtained from independent observation data analysis by other authors. Our
conclusion is that simple, ideal, isothermal, and non-self-gravitating MHD simulations may
be sufficient in order to describe the large-scale observed physical properties of somemolecular cloud envelopes.

94

Low-Frequency Galactic Polarization Foregrounds Probewith QUIJOTE
Frédérick Poidevin1 on behalf of the QUIJOTE team.
1

Instituto de Astrofı́sica de Canarias (IAC), C/Va láctea, s/n, E-38200, La Laguna, Tenerife, Spain,
00349226005200, fpoidevin@iac.es

QUIJOTE is a new CMB polarimetry experiment aimed at characterizing the low-frequency polarized foregrounds and to detect
the primordial B-mode signature. The first QUIJOTE telescope and its first instrument the multi-frequency instrument (MFI)
are operative since november 2012 from the Teide observatory (Tenerife, Spain). I will present the MFI capabilities at central
frequencies of 11, 13, 17 and 19 GHz and the on going observation campaign with this instrument. I will summarize additional
developments of the experiment including commissioning of new instruments and a second telescope. I will discuss preliminary
results regarding anomalous microwave emission (AME) and diffuse synchrotron emission obtained with the MFI.

95

Polarimetry at the South African Astronomical
Observatory
S. B. Potter 1
1

South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa, sbp@saao.ac.za

I discuss the suite of optical and IR polarimeters of the South African Astronomical Observatory. This includes the High speed
Photo-POlarimeter (HIPPO) of the 1.9m telescope, the Infrared simultaneous JHK polarimeter of the 1.4m telescope and thesoon to be installed MASTER 2*0.4cm telescopes.

96

The potential of multi-wavelength continuum
polarimetry to constrain the magnetic field morphology
in the ISM
S. Reissl 1 , S. Wolf 1 , D. Seifried 2
1

Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße
15, 24098 Kiel, Germany
sreissl@astrophysik.uni-kiel.de, wolf@astrophysik.uni-kiel.de2
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
dseifried@hs.uni-hamburg.de

Motivation: Magnetic fields are crucial to many astrophysical phenomena in the interstellar medium (ISM), such as collapsing
giant molecular clouds, accretion of matter, and subsequently star and planet formation. In addition, dust grains also play acentral role in the ISM from thermodynamics to the polarization effects of light by dust grains aligned with the direction of themagnetic field. As a result, previously unpolarized light will gain polarization perpendicular and parallel, respectively, to themagnetic field lines. Although the polarization of light by interstellar dust was discovered half a century ago, its potential totrace the magnetic field in the ISM is still far from being exhausted. In particular, circular polarization provides important
information making multi-wavelength polarization measurements on multiple scales a promising tool to complete our picture of
the fundamental physics of the star formation process.
Goal: We evaluate the potential of multi-wavelength continuum polarization measurements on multiple scales to constrain theimpact of magnetic fields on star formation. For this purpose we post-process complex magnetic field, temperature, and density
distributions as well as velocity fields resulting from MHD simulations of collapsing molecular clouds and cloud cores to create
synthetic polarization maps. Dependent on the local conditions in the ISM dust grains are partially misaligned. Therefore, theanalysis and interpretation of polarization measurements depends also on a detailed understanding of the dominating grainalignment mechanisms inside the ISM. Revealing the underlying magnetic field morphology with the help of polarization
measurements requires dust radiative transfer calculations in arbitrary 3D geometries.
Our approach: To test the role of magnetic fields during star formation we developed an extended, adaptive grid version of the
3D Monte-Carlo radiation transfer code MC3D (Wolf et al., 1999, 2003) suitable for multi-wavelength polarization simulations.
The code solves the radiative transfer problem combined with the polarization effects of dichroic extinction, thermal reemission,and scattering acting on stellar light and background radiation using an algorithm similar to the one described in Whitney &Wolff (2002).
The optical properties of the dust grains are calculated on the basis of laboratory data for the complex refraction indices ofastrosilicate and graphite, applying the Discrete Dipole Approximation (DDA). The idea behind this method is to approximate
the shape of the dust grains with a distinct number of dipoles and material constants as it is implemented in the well tested
program DDSCAT 7.2 (Draine & Flatau 2012).
Existing theories of grain alignment agree that rotating non spherical dust grains align with their shorter axis parallel to themagnetic field direction (Voshchinnikov 2012). However, the dominant alignment mechanism is still a matter of debate. To
make predictions about the impact of imperfectly aligned dust grains on polarization measurements we go beyond previous
approaches in this field. We combine radiative transfer and polarization algorithms with state of the art dust grain alignment
theories. Here, we implement the classical imperfect Davis-Greenstein (IDG) alignment due to paramagnetic relaxation (Davisand Greenstein 1951; Voshchinnikov 2010), the radiative torque alignment (RAT) because of radiation-dust interaction(Lazarian 2007) and considered the effects of mechanical alignment (Gold 1951; Lazarian 1996) as a result of gas streams.
Results: We demonstrate the potential of multi-wavelength polarization measurements and predict unique patterns in linear
and circular polarization maps for different density distributions and magnetic field morphologies for test setups andsophisticated MHD collapse simulations. Various dust grain parameter and advanced multi-scale MHD scenarios are considered
to offer maps for a broad variety of ISM configurations.
Here, we conclude that:• Measurements of linear polarization at a distinct wavelength alone are insufficient to identify the underlying magnetic
field morphology.
• Possible ambiguities in the interpretation of observational data can be resolved by including additional measurements ofcircular polarization in future observations.
• An additional source of ambiguity is inherent in the dichroic polarization mechanism itself. We identify two wavelength
dependent effects of rotation in the orientation angles of the vectors of linear polarization projected on the plane sky.
• Different alignment mechanisms acting on dust grains significantly influence the pattern of linear and circularpolarization in an unique way allowing to identify the dominant alignment mechanism.

97• The main factors limiting an accurate interpretation of continuum polarization measurements are the current uncertainty
of different physical parameter concerning alignment theory and dust composition.
The result of this study provides a more sophisticated insight in the effects of grain alignment on polarization measurements andconstraints for the accuracy, spectral coverage and spatial resolution of polarization measurements required to constrain themagnetic field morphology in molecular clouds .

98

4.36e-3

-0.1

-0.05

0.0

[pc]

0.05

0.1

-0.05

0.0

[pc]

0.05

0.1

2.33e-4
0.15

0.05

[pc]

0.0

0.1

-3.13e-5

-0.1

-0.05

0.0

[pc]

0.05

0.1

1.12e-3

0.1
0.05
0.0
-0.05
-0.1

0.0

0.05

0.0

0.05

0.0

0.05

[pc]

0.1

-5.46e-6
1.77e-5

0.0

0.05

0.1

-0.05

[pc]

-0.05
-0.1

-0.1

0.1

0.0
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0.1

-1.12e-5
3.13e-5

-0.1

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-0.05

[pc]

[pc]

0.1

-1.77e-5
3.52e-5

0.05

0.05

8.81e-4
0.082

0.0

0.1

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0.1
0.05
0.0
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0.05

-0.05

0.1
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[pc]

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[pc]

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0.0
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[pc]

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[pc]

5.46e-6

circular polarization Pc

0.0

[pc]

-0.1

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linear polarization Pl-0.05-5.28e-7
1.12e-5

circular polarization Pc

linear polarization Pl

-0.1

0.1

5.47e-4
0.15

0.1

0.05

0.0
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[pc]

circular polarization Pc

0.0

[pc]

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[pc]

0.11

linear polarization Pl

-0.05

[pc]

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[pc]

circular polarization Pc

linear polarization Pl

-0.1

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0.0

3.57e-6
0.086

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0.0
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[pc]

circular polarization Pc

0.0

[pc]

5.28e-7linear polarization Pl

-0.05

[pc]

[pc]

circular polarization Pc

linear polarization Pl

-0.1

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0.069

0.05

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[pc]

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[pc]

0.1

-3.52e-5

Figure 20: Illustration of the potential of circular polarization measurements: The figure shows maps oflinear polarization and circular polarization at a wavelength of 811 µm of a Bonnor-Ebert sphere with acharacteristic radius Rc = 1100 AU and a density n0 = 1013 m−3 in the center. The inclination angles
are 3◦ (top), 45◦ (middle) and 87◦ (bottom). We modeled a 3D magnetic hourglass morphology (left) and
quadrupole morphology (right) with analytical functions. The temperature distribution is adjusted to keep
the gas temperature and dust temperature in a range of 10 K − 25 K and 5 K − 15 K, respectively. The
dust particles are imperfectly aligned according to the IDG mechanism and the vectors of linear polarization
have an offset angle of 90◦ to match the projected magnetic field. With increasing inclination angle theunderlying hourglass morphology (left) and quadrupole morphology (right), respectively, becomes apparent.
However, for low inclination angles the vector fields of linear polarization shows a similar radial symmetricpattern in both configurations. The underlying magnetic field morphologies would be indistinguishable bymeasurements of linear polarization alone. In contrast to the ambiguities in the pattern of linear polarization,
the maps of circular polarization remain unique for each field morphology independent of inclination angle.
[from Reissl et al., A&A accepted]

99

0

AU

1692

0

0.053

0
-1692

-1692

AU

linear polarization Pl

linear polarization Pl

-1692

1692

0.10

0

1692

AU

-1692

0

AU

1692

0

Figure 21: Illustration of the impact of different alignment mechanisms on polarization measurements: The
figure shows the resulting maps of the degree of linear polarization for a post-processed MHD simulation
with an accretion disc in the center and outflows in the surrounding ISM. We took a snapshot of a run with amass of 100 M after a simulation time of 5000 yr. The radiative transfer and polarization simulation was
performed at a wavelength of 23 µm. We compare the impact of the of different aliment mechanisms on the
resulting pattern of linear polarization. The map of linear polarization with the IDG alignment mechanism ison the left hand side and the RAT alignment mechanism is on the right hand side. We demonstrate thatsynthetic polarization maps resulting from radiative transfer simulations with different alignment mechanisms
provide the possibility to identify the dominant alignment mechanism in the ISM by its influence on thepattern of linear polarization.

100

SPARC4
Simultaneous Polarimeter And Rapid Camera in 4
bands
Claudia V. Rodrigues1 , A. M. Magalhães2 , A. Pereyra3 , D. Jones4 , E. Martioli 5 , F. J.
Jablonski 1 , K. Taylor 6 , L. A. Reitano1 , L. Fraga5 , M. Assafin7 , R. Dominguez 8 , R. Laporte
1, T. Dominici 9 , A. Carciofi2 , A. de C. Milone1 , A. Kanaan10 , C. Strauss1 , D. Cieslinski1 , G.
Franco11 , J. E. R. Costa1 , K. M. G. Silva1 , L. A. Almeida1
1Instituto Nacional de Pesquisas Espaciais – Brazil – claudia.rodrigues@inpe.br
2
IAG/Univ. de São Paulo - Brazil
3
Instituto Geofı́sico del Perú - Peru
4
Prime Optics - Australia
5
Laboratório Nacional de Astrofı́sica - Brazil
6
Instruments4 - USA
7
Observatório do Valongo/UFRJ - Brazil
8
University of Arizona - USA
9Museu de Astronomia e Ciências Afins - Brazil
10
Univ. Federal de Santa Catarina - Brazil
11
Univ. Federal de Minas Gerais - Brazil

We present the status of the development of SPARC4 - Simultaneous Polarimeter And Rapid Camera in 4 bands. The camera
will obtain simultaneously four images in the SSDS griz bands. Each image will have a field-of-view of 5.6 × 5.6 arcmin. The
instrument will obtain linear and circular polarimetry and photometry of point sources with subsecond temporal resolution. It
will be installed at the 1.6-m telescope of the Observatório do Pico dos Dias, in Brazil. While a versatile instrument, which may
be used for several astrophysical purposes, the primary scientific applications will be those related to fast time variability ofstellar sources. The instrument interface will be done using a friendly GUI. We plan to deliver a reduction pipeline and a suiteof quicklook routines. The project will now proceed to the Critical Review Phase.

101Retrieval of Venus cloud layers parameterswith polarimetric data from SPICAV/VEx
Loı̈c Rossi1,* , Emmanuel Marcq1 , Franck Montmessin2 , Anna Fedorova3,4 ,Daphne Stam5 , Jean-Loup Bertaux2 , Oleg Korablev3,4
1

UVSQ/LATMOS-IPSL, 11 boulevard d’Alembert 78280 Guyancourt, France.
2
CNRS/LATMOS-IPSL, Guyancourt, France
3
Space Research Institute (IKI), Moscow, Russia
4
Moscow Institute of Physics and Technology (MIPT), Dolgoprudny, Russia
5
Faculty of Aerospace Engineering, Delft University of Technology, Delft, the Netherlands*
Author contact : loic.rossi@latmos.ispl.fr, http://rossi.page.latmos.ipsl.fr

The study of Venus’s cloud layers is important in order to understand the structure,radiative balance and dynamics of the Venusian atmosphere. Polarization measurements
have given important constraints for the determination of the constituents of the clouds. In
1974, Hansen & Hovenier used ground-based observations to establish that the main cloudparticles are micrometric droplets of a concentrated sulfuric acid solution. The overlying
haze has been identified as r ∼ 0.25 µm particles by Kawabata et al. (1980) using Pioneer
Venus OCPP measurements. Temporal and spatial variability of the haze has also been
observed.
Our study uses the polarimetric data from the SPICAV-IR spectrometer onboard ESA’s
Venus Express spacecraft. The degree of linear polarization of the light scattered at cloud
top is measured in the 0.65 –1.7 µm range, with a global coverage of the northernhemisphere of Venus. The polarization observed is consistent with previous ground-based
observations and with Pioneer Venus OCPP polarimetric measurements, yielding anegative polarization degree at all phase angles, corresponding to the micrometric, sulfuric
acid, cloud particles. The polarization reaches strong positive values at high latitudes,
indicating an increased contribution of the submicron haze. A polarization glory isobserved on several orbits, and is used to put constraints on the refractive index, size andvariance of the cloud particle distribution.
We present here results of the modeling using the Doubling-adding method on the glory tocharacterize the cloud particles, and at higher latitudes to investigate the variation of thehaze layer optical depth. We confirm that the clouds are made of ∼ 1 µm sulfuric aciddroplets, and we observe an increase of the haze optical thickness with increasing latitude.

102

Hida Optical Polarimetry System (HOPS)
Takehiko Satoh 1,5 , Kiyoshi Kawabata 2 , Takashi Nakakushi 3 , Yoshikazu Nakatani 4 ,Takayuki Enomoto 5
1

Institute of Space and Astronautical Sciences, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 252-5210 Japan,
satoh@stp.isas.jaxa.jp
2
Tokyo University of Science, kawabata-k@u01.gate01.com
3
Wakayama University, kushio@center.wakayama-u.ac.jp
4
Kyoto University, nakatani@kwasan.kyoto-u.ac.jp
5
SOKENDAI, enomoto@ac.jaxa.jp

We have developed a “two-beam type” imaging polarimeter, HOPS, designed for use with the 65-cm refracting telescope at the
Hida Observatory, Kyoto University. The name HOPS is an acronym of “Hida Optical Polarimetry System”. The mission of
HOPS is to map the linear polarization of reflected sunlight in visible wavelengths from major planets (Venus, Mars, Jupiter,and Saturn). The original model of HOPS was built in 2000, called HOPS2000, and had its first-light took place in 2001 (Satohet al., in Proceedings of the 34th ISAS Lunar and Planetary Symposium, 2001).
The basic design of HOPS is straightforward. The first element is a collimator lens, for which we use a Nikon zoom lens(f = 80 − 200 mm). After the entrance beam is collimated, a super-achromatic half-wave retarder plate (Pancharatnam type) ona motor-driven rotating stage alters the polar angle of polarized beam. The beam then enters a calcite Wallaston prism which
separates the ordinary ray and extraordinary ray with a separation angle of 5o . These two beams are focused onto a CCD with
an imaging lens.
In HOPS2000, the CCD detector chip was Kodak KAF-1600 (1552 × 1032 pixels with 9-µm pixel pitch). The imaging lens,
Nikon f = 85 mm, yielded an appropriate pixel separation (∼ 800 pixels) of two beams on the CCD. This CCD was no longer
operational, when we started the monitoring program of Venus in 2012, so we had to use an alternative CCD and to modify the
optics accordingly. The new HOPS uses the SBIG STL-1001E camera, of which CCD is Kodak KAF-1001E (1024 × 1024 pixels
with 24-µm pitch). To somewhat compensate for the effect of larger pixel pitch, we replaced the imaging lens with a Nikon
f = 135 mm lens. This yields the separation of two pixels about half a pixel number of HOPS2000 (∼ 400 pixels), acceptable forobservation of planets by considering the typical seeing at the Hida Observatory. On the internal filter wheel of STL-1001E
camera, 4 narrow-band filters: 438 nm, 546 nm, 650 nm, and 930 nm, are installed.
At the workshop, we discuss details of the new HOPS and its performance with some example linear polarization measurements
for major planets. Preliminary results of Venus monitoring program are reported in another paper (Enomoto et al.).

103

Magnetic Field in The Isolated Massive Dense
Clump IRAS 20126+4104 II. A Study AcrossHigh Spatial Dynamic Range
Hiroko Shinnaga 1 , Josep M. Girart 2 , Akimasa Kataoka 3 , Masahiro N.
Machida 4 , Kohji Tomisaka 1,3 , John E. Vaillancourt 5 , Giles Novak 6 , C.
Darren Dowell 7 , T.K. Sridharan 8 , and Thomas G. Phillips 9
1

NAOJ 2-21-1 Osawa Mitaka Tokyo 181-8588 Japan; hiroko.shinnaga@nao.ac.jp
Institut de Ciéncies de l’Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre
C-5p, 08193 Bellaterra, Catalunya, Spain
3
Department of Astronomical Science, School of Physical Sciences, Graduate University
for Advanced Studies (SOKENDAI), Mitaka, Tokyo 181-8588, Japan
4
Department of Earth and Planetary Science, Kyushu University, Higashi-ku, Fukuoka
812-8581, Japan
5
SOFIA Science Center, USRA, NASA Ames Research Center, Moﬀet Field, CA 94035,
USA
6
Department of Physics and Astronomy, Northwestern University, 633 Clark Street
Evanston, IL 60208, USA
7
JPL/Caltech, MS 169-506, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
8Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138,
USA
9
Division of Physics, Mathematics and Astronomy, California Institute of Technology, MC
320-47, Pasadena, CA 91125 USA
2

We report on a study of the magnetic ﬁeld structures of IRAS 20126+4104, a massive
dense clump in which the rotation axis and the magnetic ﬁeld axis are misaligned. In
addition to the SHARP/CSO data that we reported in 2012 (Shinnaga et al. 2012), we
analyzed polarization data sets that were taken with the SMA along withSCUPOL/JCMT, both at 850µm. Comparing with the recent VLBI measurements ofspectropolarimetric observations of this object (Surcis et al. 2014), these four independent
data sets allow us to investigate the magnetic ﬁeld structures across a high spatial dynamic
range, between 20 AU scale and 1 pc scale of the massive dense clump – massive (∼ 10M )(proto)star system. The magnetic ﬁeld vectors measured in these four diﬀerent spacialscales are consistent. At the scale observed with SMA the magnetic ﬁeld appears to berather perpendicular to warm bipolar outﬂow direction. We carried out detailed theoreticalsimulations for this object based on the study by Kataoka et al. 2012. By comparing theobservational results with the theoretical simulations, we ﬁnd that the magnetic ﬁeld playsa critical role during the course of the gravitational collapse of the massive dense clump.

104

Monte Carlo radiative transfer modeling of polarizationby scattering in AGN
Marko Stalevski1,2,3 , Maarten Baes2 , Peter Camps2 , Luka Č. Popović3
1

Departamento de Astronomia, Universidad de Chile, Camino El Observatorio 1515, Santiago, Chile;
mstalevski@das.uchile.cl
2
Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281-S9, Gent, 9000, Belgium
3
Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia

The central engine of active galactic nuclei (AGN) is surrounded by optically and geometrically thick, roughly toroidal structureof dust. This structure, dubbed “the dusty torus”, is absorbing the incoming radiation, re-emitting it at infrared, and scattering
mostly at optical/UV wavelengths. Scattered light is polarized and the angle of polarization depends on the direction of the lastscattering, so it is is expected to be related to the structure of different emitting and scattering regions. As the radiation of
AGNs is polarized over a broad wavelength range, the polarization can be exploited to constrain their structure and geometry.
Previously we have studied infrared emission of the dusty torus, using SKIRT, an efficient 3D continuum radiative transfer code
based on the Monte Carlo algorithm. The code offers full treatment of absorption and multiple anisotropic scattering by dust,
the thermal re-emission of dust, and the emission from very small grains and polycyclic aromatic hydrocarbon molecules. In thiscontribution we will discuss recent efforts to implement treatment of polarization by scattering in SKIRT and present
preliminary results of application in the case of AGN dusty torus.

Figure 22: Face-on (left) and edge-on (right) scattered flux images of the dusty torus obtained with SKIRT.

105

Near-Infrared Imaging Polarimetry of the Serpens South
Cloud in Aquila.
K. Sugitani 1 , F. Nakamutra2 , SIRPOL Team1

Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501, Japan;
sugitani@nsc.nagoya-cu.ac.jp
2
National Astronomical Observatory of Japan; fumitaka.nakamura@nao.ac.jp

We have conducted JHKs polarimetric observations of the the Serpens South cloud and its northward extension region, which
are consist of multi filaments (André et al. 2010). This study is the further work of our previous observation (Sugitani et al.
2011) toward the Serpens South protocluster, which is associated with the hub region of infrared dark cloud filaments and isbelieved to be in the very early stage of star cluster formation (Gutermuth et al. 2008). The imaging polarimeter SIRPOL(polarimetry mode of the SIRIUS camera) mounted on the IRSF 1.4-m telescope at SAAO was used, and the most part of theseregions was covered with 30 FOVs of SIRPOL. Here we present results of our extensive polarization observations, including theprevious polarimetric data around the protocluster, by comparing with the column density map made with the Herschel Gould
Belt survey data. Our linear polarization measurements of near-infrared point sources indicate an ordered global magnetic fieldthat is nearly perpendicular to the main filaments in the observed area, implying that the magnetic field is likely to be relatively
strong. On the other hand, the sub filaments, which are less dense than the main filaments, tend to run along the magnetic field.

106Differential Heating of Magnetically Aligned Dust
GrainsJohn E. Vaillancourt1 & B-G Andersson1
1

SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, Moffett
Field, CA, USA; jvaillancourt@sofia.usra.edu

We use far-infrared photometric maps from IRAS and Herschel to search for the differential heating of asymmetric dust grainsaligned with respect to an interstellar magnetic field and heated by a single star. The grains are known to be asymmetric andhave a net alignment of their axes from observations of background starlight polarization. Modern grain alignment theory
predicts a relation between the alignment efficiency and the angle between the magnetic field and the direction to the aligningradiation source. Along with the observed polarization, such a geometry also has consequences for the distribution of grain
heating. For example, asymmetric grains whose largest cross sections are normal to the incident stellar radiation will reach
warmer equilibrium temperatures compared to grains whose largest cross-section is parallel to that direction. This should beobserved as an azimuthal dependence of the dust color temperature. We present evidence of such a dependence using IRAS data
at 60 and 100 µm. We expect this effect to be stronger using longer wavelength (i.e., 160 µm) data better coupled to the“big-grain” dust population, grains that are also more efficiently aligned with the local magnetic field. Here we also present theresults of our on-going work to search for this signal using Herschel maps towards three candidate stars.

J
"

J
"

!

#

^

J

Figure 23: Left: Geometry of grain heating showing the relative orientations of stellar photons, magnetic
field lines (B), and dust grain axes (rectangular boxes with angular momentum J). Right: Intensity ratio(60-to-100 µm) centered on the star HD 23777 as a function of azimuth (Ψ) at a distance of ∼ 0.5◦ from thestar.

107