星形成ゼミ	
  2016/12/2	
  SFN	
  #286	
  11-­‐15		
  長谷川哲夫（国立天文台）	

built with various distribution functions of the IMF parameters. The synthe
the binary population, stellar evolution, sample incompleteness, and ejecteddistributions of the IMF parameters are required in order to reproduce th
http://arxiv.org/pdf/1609.04858
Galactic clusters. They also do not lend support to the existence of a clu
We propose a probabilistic formulation of the IMF whereby the paramete
Massive stars reveal variations of the stellar initial mass function
the Milky
distributioninfunctions
centeredWayaround γ = 0.91, Γ = 1.37, and Mch = 0.4
stellar clustersσΓ = 0.60, and σMch = 0.27 M" around these values.

Accepted by ApJ

Sami Dib1,2 , Stefan Schmeja3,4 and Sacha Hony5

Accepted by MNRAS

1

1.

2.

Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen,Øster Voldgade 5-7, DKhttp://arxiv.org/pdf/1605.08438
1350, Copenhagen, Denmark.
Parameters	  2 that	  describe	
  the	
  shape	
  of	
  the	
  IMF	
  for	  the	
  Unidad de Astronomı́a, Departamento de Fisica, Universidad de Atacama, Copayapu 485, Copiapo, Chile.
3 of	
  young	  GalacBc	
  clusters:	  	
  populaBon	
  Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, 69120
Heidelberg,• Slopes	
  in	
  the	
  lGermanyow	
  and	
  high	  stellar	
  mass	  regimes,	
  γ	
  and	  Γ,	  4Technische Informationsbibliothek, Welfengarten 1b, 30167 Hannover, Germany
5
respecBvely	
  Institut für Theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Überle-Straße 2,69120 Heidelberg,
Germany.
• CharacterisBc	
  mass,	
  
M .	
  	
  
ch

E-mailThe	
  method	  	
   contact: sami.dib at gmail.com
Weexclusively	
  investigate whether
thestellarinitialmass function(IMF)
is universal, or whether it varies significantly among• relies	  on	
  the	
  
high	
  
mass	
  
content	
  of	
  the	  clusters,	  young stellar clusters in the Milky Way. We propose a method to uncover the range of variation of the parametersbut	
  ithats	
  able	  to	
  yield	
  informaBon	
  on	
  the	  distribuBons	
  of	
  describe the shape of the IMF for the population of young Galactic clusters. These parameters are the slopes
parameters	  escribe	  he	
  IMF	  over	
  γthe	  nBre	
  stellar	
  and the characteristic mass, Mch. The methodin the lowthat	
  
and d
high
stellartmass
regimes,and eΓ,respectively,
reliesexclusively
on
the
high
mass
contentoftheclusters,
but is able to yield information on the distributions ofmass	
  range.	
  	
  parameters that describe the IMF over the entire stellar mass range. This is achieved by comparing the fractions of•
single and lonely massive O stars in a recent catalog of the Milky Way clusters with a library of simulated clusters
built with various distribution functions of the IMF parameters. The synthetic clusters are corrected for the effects ofthe binary population, stellar evolution, sample incompleteness, and ejected O stars. Our findings indicate that broad
distributions of the IMF parameters are required in order to reproduce the fractions of single and lonely O stars in
Galactic clusters. They also do not lend support to the existence of a cluster mass-maximum stellar mass relation.
We propose a probabilistic formulation of the IMF whereby the parameters of the IMF are described by Gaussian
distribution functions centered around γ = 0.91, Γ = 1.37, and Mch = 0.41 M" , and with dispersions of σγ = 0.25,σΓ = 0.60, and σMch = 0.27 M" around these values.
Accepted by MNRAS
http://arxiv.org/pdf/1605.08438

12

12

(fiducial), 20, and 10 M! . Our fiducial value of β is 2 as thisbuilt with various distribution functions of the IMF parameters. The synthe
is in agreement withthe slopethe cluster mass function at
Accepted
byofApJ
the binary population, stellar evolution, sample incompleteness, and ejectedintermediate- to high cluster masses in nearby galaxies (e.g.,
distributions of the IMF parameters are required in order to reproduce th
http://arxiv.org/pdf/1609.04858
Elmegreen & Efremov 1997; Zhang & Fall 1999; Hunter et
Galactic clusters. They also do not lend support to the existence of a clu
al. 2005; de Grijs & Anders 2006; Selman & Melnick 2008;
We propose a probabilistic formulation of the IMF whereby the paramete
Larsen 2009; Chandar et al. 2010; Fall & Chandar 2012) and
Massivestars
revealvariations
ofthestellarinitialmassfunction
the Milky
distributioninfunctions
centeredWayaround γ = 0.91, Γ = 1.37, and Mch = 0.4
with theoretical expectations (Elmegreen 2006; Dib et al.
stellarclustersσΓ = 0.60, and σMch = 0.27 M" around these values.
2011; Dib 2011a,b; Dib et al. 2013). We also consider cases
3,4with β = 2.2 and Sami
β = 1.8.
For1,2eachclusterSchmejawith an assigned
Dib, Stefanand Sacha Hony5
Accepted by MNRAS
Variations of the IMF in the Milky Way 7
mass Mcl , the massesof star-systems (i.e., individual stars
1
Niels
Bohr
Institute&
CentreforStar
andPlanetFormation,
UniversityofCopenhagen,ØsterVoldgade 5-7, DKhttp://arxiv.org/pdf/1605.08438
or binary systems) in the clusters are randomly sampled1350,
Copenhagen,Denmark.
using a tapered power law (TPL) distribution function (deFor	  Marchi
each	
  cet
luster	  w2ith	  an	
  assigned	
  ass	
  MDepartamento,	
  the	  manyasses	
  Unidadde Astronomı́a,de Fisica, Universidad de Atacama, Copayapu 485, Copiapo, Chile.
al. 2010;
Parravanoet al.m2011).
Withoutcl3
Astronomisches
Rechen-Institut,für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, 69120
binary(i.e.,	
  fraction,a stellar s”system”
mass sMcanof	
  sassignedtar-­‐systems	  individual	
  
tars	
  
or	
  bofinary	  ystems)	
  ∗Zentrum
Germany
correspond
toaan
individual
star
or to a binary
system.
The
12in	
  the	  clusters	  re	
  Heidelberg,randomly	  sampled	
  
u
sing	
  
a
	
  
t
apered	  4
TPL function is givenbyTechnische
Informationsbibliothek, Welfengarten 1b, 30167 Hannover, Germany

2/2	

power	
  law	  (TPL)	
  d5istribuBon	  funcBon	  Institut für Theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Überle-Straße 2,!
"$γ+Γ %&
69120
Heidelberg,# Germany.
M∗
dN∗
−Γ
= A∗ × M∗
1 − exp −,(6)
dlogM∗
Mch at gmail.com
E-mail contact: sami.dib••

Figure 1. The figure displays the probability distribution functions of the three parameters that describe the IMF used in thiswork. The acronym δF-GF refers to delta functions of the parametersat thepositionsof the Galactic
field values,
whereasinvestigate
whetherstellarinitial massfunction(IMF)
is universal,
or whether
it varies
significantly among
where dN∗ is theWe
numberof stellar
systemsthewiththe logaδF-OBS
referstodeltafunctionslocatedatthemeanvaluesrithm of their masses
betweenlogM+ dlogM
young
stellarlogM
clustersthe∗ MilkyWay.
We propose a method to uncover the range of variationofof the parameters∗ andin∗,the parameters derived by Dib (2014a) for a sample of 8 youngand A∗ is the normalization
coefficient
which
given
by:for the population of young Galactic clusters. These parameters are the slopesthat describe
the shapeof istheIMF
Galactic stellar clusters. The cases GPD-σobs , GPD-σobs /2, andin the low and high stellar mass regimes, γGPD-σand obs
Γ,/4respectively,
and withthe characteristic
mass,disMch . The method
correspond to cases
a Gaussian probability%& mass content tribution! exclusively" # on $the high' M∗,maxof the IMF
whose
is related
to distributions ofreliesof the clusters,
butparameters
is able toyieldhalf-width
informationon theγ+ΓM∗
1, 0.5, and
0.25massthe valuesof thedispersionof eachbyparameterin the fractions of
Mcl . the entire
A∗ ×M∗−Γ1 − exp that− describe thedM∗ =overparameters
IMF
stellarrange.
Thisis achieved
comparingM
chM∗,minthesampleof Dib(2014a).
FDP-σcorresponds
to massa casewhere in two realizations of the ICLMF. The left panel displays a
Figure5. Theinitial,present-day,andobssingleO-star cluster
functions
single and lonely massive O stars in a recent casecatalogof theMilky Way clusters
withthea IMF
library ofcluster
simulatedclusters
in which thedistribution
set of three parametersdescribe
are each randomly drawn from a GPD-σobs probability
the probability
functionthatof eachparameterofiseachgiven(7) of thebuilt with various distribution functions
IMF
parameters.
The
syntheticclusters
arecorrected
fortheeffectsof describe the IMF is similar to the
distributionfunctionwhereas
the
right
panel
displays
a
case
in
which
the
set
of
three
parametersthatby a boxcar function whose width is given by 2 × σobs . The lower
valuesof the parameters fortheejected
Galactic field
mass function.
All other parameters
set toMcl,min = 50 M! , M∗,min = 0.02 M! ,the binary
population,
evolution,
incompleteness,andOparametersstars.
Ourcorrespondfindings
indicateare
that
broad
and
upper
truncations
for
each
of
the
to
The TPL function
describes
the IMFstellar
with only
three sampleM∗,max = 150 M! , and β = 2. The figure displays the initial cluster mass function (ICLMF) and the present-day cluster mass function
M*,min	  =	
  0.02	
  distributions
Msun	
  
the
lower
andCLMF
upper
limitsof these
derivedby andDib lonely
the regime
IMF parameters
are requiredin Theorder
to isreproduce
thefractionsofsingleObeen
stars
in an age, and has been correctedparameters, the slope
in the lowofmass(γ), the slope(CLMF).
the conversionof parameters
the
ICLMF after
each
individual
cluster has
assigned
M*,max	  =	
  min[Mcl,	
  
150	
  
Msun]	  oTheyr	
  v(Γ),
alues	
  xpected	  (2014a).
for theto
effects
the stellar binary
and mass-maximum
stellar evolution. The numberof clusters that contain single O stars (within the intermediate-to-highmassregimeande
thenotcharGalactic
clusters.
also
dolend support
theof existenceof afraction
clusterstellardistribution
mass relation.

! 15 M! (CLMF-O), peaks at a few tens of stellar masses and most of the clusters in the CLMF-O have masses " 400 M! .
acteristic
massThe
minimumstellar mass,
M∗,min , of theM∗IMF
from	
  
(Mcl	
  
–	
  M(M
*,max)	
  relaBon	  ch ).proposeWea probabilistic
formulation
whereby the parameters of the IMF are described by Gaussianis always taken to be 0.02 M . The maximum stellar mass,

distribution! functions centered around γ = 0.91,= 1.37,atand
0.41
dispersionsof σγ = 0.25,
ch = of" , and witheitherΓlocatedthe MvaluestheMparameters
derivedby
M! which is the mass of the M∗,max , is either given by min[Mcl , 150 M! ] (correspondaverage, at larger distances from the Sun. The normalized
The completeness correction is calculated for each reσ
=
0.60,
and
σ
=
0.27
M
aroundthesevalues.
Γ
M
"
ch
Dib
(2014a),orthe
Galactic
fieldvalues
that
are
given
by
lky Way (e.g., Figer et al.
function fcomp = R2−10 /max(R2−10 ) constitutes the comalization of the cluster mass function with respect to theing to the case of stochastic sampling) or is dictated by at al. 2007; Harayama et al.
Γfsample
0.57,
and Msurvey.
M! (Parpleteness function. A cluster is admitted for the comparison
youngγclusters
the MWSC
In =this0.42
work,
ield =of1.35,
f ield =in
ch,f ield
Acceptedby
MNRAS
clustermass-maximum
stellarmass
relation
(M
−
M
)
∗,max
cl
lore values of Mcl,min = 50
with
the approach
we use Thesein orderfamilies
to accountfor the effectofravanoet al. 2011).
of models
are labeled
δF- the observational data if its completeness probability
by Vanbeveren (1982) and later by Weiducial value of β is 2 as this relation proposedhttp://arxiv.org/pdf/1605.08438
fcomp is larger than a uniform random number drawn becluster
incompletenessis basedon thepopulations ofandlow Galactic
OBS
and
δF-GF
(DeltaFunction
Observations
the cluster mass function at dner & Kroupa (2004). We test models in which the distween 0 and 1. For the families of ICLMFs generated in thismass B stars in the clusters (i.e., stars with masses between
Field,
respectively). We also test flat probability distribuses in nearby galaxies (e.g., tributions of the parameters (Γ, M , γ) are either given
work, typically only about half of the clusters in the ICLMF
2M! # M∗ # 10M! ) whose total number in a cluster ischang & Fall 1999; Hunter ettions(FPD).
These
are describedby boxcar
be- the filter of the completeness function and are used inpassN∗,2−10. For eachrealizationof the ICLMF,
after thefunctions
corby delta function (all clusters have the same value of the6; Selman & Melnick 2008;
tween
(0.4,
1.5)
for
γ,
(0.7,
2.4)
for
Γ,
and
(0.05,
1)
M
forcomparison with the observational data. Additional exrectionsfortheeffectsofthebinarypopulation
andstellar!the; Fall & Chandar 2012) and parameters), Gaussian functions, or boxcar functions. A reof the completeness function for various values of βevolution
been takenfunctions
into account,we computethe of amples
M
distributionoftheparametersthech . The have
Elmegreen 2006; Dib et al. cent study found that the mean values of the parameters
and its effect on the derived values of fO,single and fO,lonely
distributionof 12
low mass
B starsφ(N
6 (top∗,2−10 ). Fig.
IMF
for
all
of
these
modelsaredisplayed
in
Fig.
1.
13). We also consider cases among a relatively small sample of young Galactic stellar
are discussed in App. B.
panel, left) displays an example of the distribution of φFig. 2 displays a few examples of the generated ICLMFs
ch cluster with an assigned clusters are Γ
for one of the ICLMF realizations from the GPD-σobs famobs = 1.37, γobs = 0.91 and Mch,obs = 0.41
tems (i.e., individual stars
withthe expoily ofvarious
models permutations(full black line) of
andthefor Galactic
the young SFR,
clusters
M! with standard deviations of σΓobs = 0.60, σγobs =ers are randomly sampled
nent
of
the
ICLMF
and
the
lower
cutoffin the
MWSC
catalog(β),(purpledashedline) massplottedversusin cluster) distribution function (de 0.25, and σMch,obs = 0.27 M! , respectively (Dib 2014a).
5 aCOMPARISON OF MODELS TO
log(N∗,2−10+ 1). ),
The
unnormalized
ratio ofthethese
two dismasses(Mcl,minandFig. 3 displays
systemIMFs foret al. 2011). Without any When drawing the parameters from Gaussian distributions,tributions(R2−10= φobs/φmodelfrom) is plottedin theFig. realization
6 (middle
few
selectedclusters
drawn
one
of
of
theOBSERVATIONS
r ”system” of mass M∗ can the distributions are always centered on these observed
panel, left). A similar example is shown in the right panel
5.1 Models based on stochastic star formation
ICLMF
in the GPD-σ ICLMF
familyof models (i.e., with varying
or to a binary system. The
for one realization of theobs
from the δf-GF family ofmean values. We test dispersions of the Gaussian distriIMFs).
Additional
technical
detailsonthesamplingofthethis family of models, stellar masses in eachmodels.
Allcompleteness
functions
that
we
have
computedIn
butions of (σΓobs , σγobs , σMch ), (σΓobs , σγobs , σMch ) /2, andICLMF
and of the
IMF cluster
are presented
in App.
§. A.
for the different
synthetic
mass functions
displayacluster are randomly sampled in the mass range" #(σΓobs , σγobs , σMch ) /4, and apply lower and upper cutoffs$γ+Γ %&
similar behavior, namely a peak at LogN∗,2−10 ≈ 1.8 − 2,
[0.02, min(Mcl , 150)]M! for the set of parameters (Γ, Mch ,M∗−,(6) of (0.4, 1.5) for γ, (0.70, 2.4) for Γ, and (0.05, 1) M! forwith a decrease for both increasing and decreasing valuesγ) that are assigned to the cluster. When comparing theMchMch , which correspond to the lower and upper limits deof N∗,2−10
around thepeak.
Weassume a completenessoffractions of single and lonely O stars (fO,single and fO,lonely )4.2
Assigningages
tosimulatedclusters
lar systems with the loga-

HCO+ Detection of Dust-Depleted Gas in the Inner Hole of the LkCa 15 Pre-Transitional
Disk
E. Drabek-Maunder1 , S. Mohanty1 , J. Greaves2 , I. Kamp3 , R. Meijerink4 , M. Spaans3 , W.-F. Thi5 , P.
Woitke61Imperial College London, Blackett Lab., Prince Consort Rd, London SW7 2AZ, UK
School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA
3
Kapteyn Institute, PO Box 800, 9700 AV Groningen, The Netherlands
4
Leiden Observatory, Leiden University, PO Box, 2300 RA Leiden, The Netherlands
5
Max-Planck-Institut für extraterrestrische Physisk, Giessenbachstrasse 1, 85748 Garching, Germany
6
St. Andrews University, School of Physics and Astronomy, St. Andrews KY16 9SS, UK
2E-mail contact: e.drabekmaunder at imperial.ac.uk
LkCa 15 is an extensively studied star in the Taurus region known for its pre-transitional disk with a large inner cavity
in dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes
one or more planets to carve out the inner cavity, while gas continues to flow across the gap from the outer disk onto
the central star. We present spatially unresolved HCO+ J=4–3 observations of the LkCa 15 disk from the JCMTand model the data with the ProDiMo code. We find that: (1) HCO+ line-wings are clearly detected, certifying thepresence of gas in the cavity within <50 AU of the star. (2) Reproducing the observed line-wing flux requires both asignificant suppression of cavity dust (by a factor >104 compared to the ISM) and a substantial increase in the gas
scale-height within the cavity (H0 /R0 ∼ 0.6). An ISM dust-to-gas ratio (d : g = 10−2 ) yields too little line-wing flux
regardless of the scale-height or cavity gas geometry, while a smaller scale-height also under predicts the flux evenwith a reduced d:g. (3) The cavity gas mass is consistent with the surface density profile of the outer disk extended
inwards to the sublimation radius (corresponding to mass Md ∼ 0.03 M" ), and masses lower by a factor >10 appear
to be ruled out.
Accepted by ApJ
http://arxiv.org/pdf/1609.05894

Proper motion survey and kinematic analysis of the Rho Ophiuchi embedded cluster
C. Ducourant1,2 , R. Teixeira2,1 , S. Bontemps1 , D. Despois1 , P. A. B. Galli2 , H. Bouy4 , J.F. Le Campion1 ,M. Rapaport1 and J.C. Cuillandre5
1

Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac,
France2
Instituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão, 1226 - Cidade
Universitária, 05508-900 São Paulo - SP, Brazil
3
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Lab. 8.5.02, Campo Grande, 1749-016,
Lisboa, Portugal
4
Centro de Astrobiologı́a, Dpto de Astrofı́sica, INTA-CSIC, PO BOX 78, E-28691, ESAC Campus, Villanueva de laCañada, Madrid, Spain
5
CEA/IRFU/SAp, Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris Diderot, Observatoire de Paris, PSL
Research University, F-91191 Gif-sur-Yvette Cedex, France
E-mail contact: christine.ducourant at u-bordeaux.fr
The ρ Ophiuchi molecular complex and in particular the Lynds L1688 dark cloud is unique in its proximity (∼130 pc),

and model the data with the ProDiMo code. We find that: (1) HCO+ lin
presence of gas in the cavity within <50 AU of the star. (2) Reproducing
significant suppression of cavity dust (by a factor >104 compared to thescale-height within the cavity (H0 /R0 ∼ 0.6). An ISM dust-to-gas ratio (regardless of the scale-height or cavity gas geometry, while a smaller sca
HCO+ Detection of Dust-Depleted Gas in the Inner Hole of thewith
LkCa
15 Pre-Transitionala reduced
d:g. (3) The cavity gas mass is consistent with the surfac– 30 –
Disk
inwards to the sublimation
radius (corresponding to mass Md ∼ 0.03 M"
1
1
2
3
4 be ruled out. 3
to
E. Drabek-Maunder , S. Mohanty , J. Greaves , I. Kamp , R. Meijerink , M. Spaans , W.-F. Thi5 , P.

Woitke6

Accepted by ApJ

1Imperial College London, Blackett Lab., Prince Consort Rd, London SW7 2AZ, http://arxiv.org/pdf/1609.05894
UK
School of Physics and Astronomy, Cardiff University,
Cardiff CF24 3AA– 28 –
3
Kapteyn Institute, PO Box 800, 9700 AV Groningen, The Netherlands
Proper motion survey and kinematic analysis of the Rh
4
Leiden Observatory, Leiden University, PO Box, 2300 RA Leiden, The Netherlands
1,2
5
Ducourant, R. Teixeira2,1 , S. Bontemps1 , D. Despois1 , P. A. B
Max-Planck-Institut für extraterrestrische Physisk, Giessenbachstrasse 1, 85748 C.
Garching,
Germany
16
M. UK
Rapaport and J.C. Cuillandre5
St. Andrews University, School of Physics and Astronomy, St. Andrews KY16 9SS,
2

– 27 –

1

Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N
France
LkCa 15 is an extensively studied star in the Taurus region known for its pre-transitional
disk with a large inner cavity
2Instituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidadein dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes
Universitária, 05508-900 São Paulo - SP, Brazil
one or more planets to carve out the inner cavity, while gas continues to flow across
3 the gap from the outer disk onto
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C
the central star. We present spatially unresolved HCO+ J=4–3 observations of the LkCa 15 disk from the JCMT
Lisboa,Portugal– 31 –Fig. 4.— Best-fit model to the emission from the disk cavity at radii from 0.1 to 50 AU,
and model the data with the
ProDiMo code. We find that:(1) HCO+ seeline-wings 4are clearly detected,
certifying theSection 4.2.2. Settling parameters are a = 0.01µm and= 0.01, the gas reference scale
Centrode Astrobiologı́a, Dpto de Astrofı́sica, INTA-CSIC, PO BOX 78
heightwithin
is H = 60 AU
and d:g=
10 .of the star. (2) Reproducing the observed line-wing flux requires both apresence of gas in the cavity<50
AU
Fig. 7.— Left:Cañada,
Best-fit modelMadrid,
to both the innercavity and the outer disk (see Section B.3)
Spainsignificant suppression of cavity dust (by a factor >104 compared to the withISM)
a substantial
total anddisk
is 0.10 M . Right:increase
HCO+ J = in
4 !the3 andgas
dust continuum (105 massCEA/IRFU/SAp,
AIM
Paris-Saclay, CNRS/INSU, Universit−2 depths per radius for the Laboratoire
840 µm) opticalbest-fit models. HCO+ remains opticallyscale-height within the cavity (H0 /R0 ∼ 0.6). An ISM dust-to-gas ratio (dand
:
g
=
10
)
yieldstoolittleline-wing
flux
thin ⌧ < 1 atResearchradii r  10 AU.
The 840 µm dust
continuum Gif-sur-Yvetteis optically thin at radii Cedex, France
University,
F-91191
regardless of the scale-height or cavity gas geometry, while a smaller scale-height
under
the
flux dataeven
50 AU< r < 100 also
AU, consistent
withpredicts
the 880 µm dust
continuum
from A11. Similarly
10µm dustE-mailcontinuum contact:is primarily opticallythin at radii r < 50 AU, consistentwithchristine.ducourantat u-bordeaux.fr
with a reduced d:g. (3) The cavity gas mass is consistent with the surfacethe
density
profile
of
the
outer
disk
extended
SED fitting (Espaillat et al. 2008, 2010).
inwards to the sublimation radius (corresponding to mass Md ∼ 0.03 M" ), and masses
by a molecularfactor >10complex
appear and in particular the Lynds L1688 dark
The ρlower
Ophiuchito be ruled out.
in its richness in young stars and protostars, and in its youth (0.5 Myr). It
accessible from the ground to study the early phases of star-formation. Prop
Accepted by ApJ
separating members of clusters from field stars, but very few proper motion
http://arxiv.org/pdf/1609.05894
most of the young sources are deeply embedded in dust and gas. We aim
Fig. 3.— Models are compared to the folded spectrum with 1 RMS. The grey boxes indicate
velocity channels corresponding to the HCO line-wings. Top left: Empty inner cavity modelFig. 5.— Constraining the inner cavity mass by fitting the disk cavity emission, where thestellar objects (YSOs) in the ρ Ophiuchi F core and partially in the E corewith the dust continuum parameters from A11 (see Section 4.1.1). Top right: Determining
standard cavity mass M (0.029 M ) is in green, 0.1 ⇥ M (0.003 M ) is in red and 10 ⇥ M
the characteristic radius R with an empty inner cavity model (see Section 4.1.2). Bottom left:
motion program at the ESO New Technology Telescope (NTT) with the S(0.3 M ) is in blue (see Section 4.2.3).
Propermotionand kinematic analysis of the Rho Ophiuchi
embedded cluster
Empty inner cavity model with R = 250 AU andstandard ISM d:g=
10 (see Section survey
4.1.2).
years in the near-infrared. We complemented these observations with var
We note that models of the outer disk with an empty inner cavity and varying R and R
1,2
2,1
1
1
2
4
1
have not been able to produce the observed C.
HCO Ducouranthigh velocity line-wings. Bottom, R.right:
Teixeira , S. Bontemps , D. Despois , P. A. B.
Gallitime, H.
Bouy, fromJ.F.
Le Campion,fit theof
baseof observations
thetofield
investigation
to 0.5◦ ×0.5◦ . We de
Fig. 8.— Full-disk
modelsgenerated
an innermost anddisk model
inner
disk
Disk without an inner cavity and d:g= 10 (see Section 4.2). Even though
1 there is some
5and
J.C. Cuillandre
described in A11(radii 0.1 toFrom
10 AU; Section
4.1.1)
and aproper
two-component
disk modelwere
to fit derived from SOFI observat
HCO line-wing emission, the filled-cavity M.
models Rapaport
do not fit the high velocity
line-wing
objects.
these,
607
motions
the cavity (10 to 50 AU) and the outermost disk (50 to 400 AU). We show the best-fit cavity
emission present in the HCO spectrum either.
1567heightGeoffroy(60 AU at a reference
radius of 100 AU)
and d:g=
10 , 10 and 10 . Left:
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N,scalealléeSaint-Hilaire,
33615
Pessac,Full-disk SED models with the stellar spectrum (green), innermost disk (blue), disk cavity
France(red) and outer disk (grey). The dashed line depicts the two-disk model with a dust-to-gas
213
in the disk
cavity atRuad:g= 10red), the1226
solid line- isCidadeat d:g= 10 6 (red) and theInstituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidade ratiode SãoPaulo,
do5 (darkMatão,dotted line is at d:g= 10 7 (light red). Right: HCO+ spectra produced from the two-disk
Universitária, 05508-900 São Paulo - SP, Brazil
models using d:g= 10 5 (dark red, dotted line), 10 6 (red, dashed line) and 10 7 (light red,3
solid line).
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C8,
Lab. 8.5.02, Campo Grande, 1749-016,
Lisboa, Portugal
4
Centro de Astrobiologı́a, Dpto de Astrofı́sica, INTA-CSIC, PO BOX 78, E-28691, ESAC Campus, Villanueva de laCañada, Madrid, Spain
5
CEA/IRFU/SAp, Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris Diderot, Observatoire de Paris, PSL
Research University, F-91191 Gif-sur-Yvette Cedex, France

E-mail contact: e.drabekmaunder at imperial.ac.uk

s

s

6

0

+

d

d

d

c

2

c

c

out

+

2

+

+

E-mail contact: christine.ducourant at u-bordeaux.fr
The ρ Ophiuchi molecular complex and in particular the Lynds L1688 dark cloud is unique in its proximity (∼130 pc),

new members are generally fainter than the known ones. We measured a m-24.3)±0.8 mas/yr for the L1688 dark cloud. A supervised classification wa
to allocate a spectral energy distribution (SED) classification to the unclassi
http://arxiv.org/pdf/1609.05894
that the 56 members that were known from previous studies of the ρ Oph
our survey are members of the cluster, and we added 26 new members.
Proper motion survey and kinematic analysis of the Rho Ophiuchi
embedded
unclassified
members of cluster
the cluster. We showed that a large part (23) o
1,2
2,1
1
1
2
4 multiplies the number
dwarfs,which
C. Ducourant , R. Teixeira , S. Bontemps , D. Despois , P. A. B. Galli , H. Bouy , J.F. Le Campion1 , of known substellar objects in the clu
A&A proofs: manuscript no. Ducour
M. Rapaport1 and J.C. Cuillandre5
Accepted by A&A main
1
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy
Saint-Hilaire, 33615 Pessac,
http://arxiv.org/pdf/1609.04963
Francepositions. Th
InstitutodeFAstronomia,
Geofı́sica
YSOs	
  in	
  t2he	  ρ	  Oph	  
	
  and	  parBally	
  E	
   e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão, 1226 - Cidade
thesecatalogd
A photo-evaporative gap in the closest planet
forming
Universitária, 05508-900 São Paulo - SP, Brazil• Near	
  
I
R	
  
p
roper	
  
m
oBon	
  
p
rogram	
  
a
t	
  
t
he	
  
E
SO	
  
N
ew	
  
to
these
data
3
1,2
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Lab.Barbara
8.5.02, CampoGrande,1749-016,P. Rosotti3 , Giovanni Picogna1 , Le
Ercolano, Giovanni( ↵, )= (Technology	
  Telescope	
  (NTT)	
  with	  the	
  Son	  of	
  Lisboa, Portugal
1
Universitäts-Sternwarte München, Scheinerstr. 1, 81679 München,Germ4217) masforCentrode Astrobiologı́a,de9Astrofı́sica,
ESAC Campus, Villanueva de la
2
ISAAC	
  (SOFI)	
  instrument	  Dptoover	  	
  years.	
   INTA-CSIC, PO BOX 78, E-28691,
Excellence Cluster Origin and Structure of the Universe, Boltzmannstr.2
positions. AfCañada, Madrid, Spain
3
Institute of Astronomy, University of Cambridge, Madingley Road, Camb
5
• Public	  image	
  databases	
  to	
  enlarge	  the	
  Bme	  CEA/IRFU/SAp,
Laboratoire
AIM Paris-Saclay,
CNRS/INSU, Université Paris4Diderot, Observatoire de Paris, PSL
catalogue tha
European Southern Observatory, Garching bei München, Germany
Research
University,
Gif-sur-Yvette
France
base	
  
and	
  the	  ﬁeld	
  oF-91191
f	
  invesBgaBon	
  to	
  0Cedex,.5◦	
  ×0.5◦	  5INAF/Osservatorio Astrofisico di Arcetri, Largo E. Fermi 2MASS
5, I-50125posiFireat u-bordeaux.fr
PosiBons	
  E-mailand	
  pcontact:roper	
  christine.ducourant
moBons	  for	  2213	  objects.	
  	
  
and
the
whol
E-mail contact: ercolano at usm.lmu.deTheρ Ophiuchi
complexand in particular
Lynds L1688 dark cloud is unique in its proximity (∼130 pc),
An younga po• 607	
  
from	
  
SOFI	
  (molecular∼1.8	
  mas/yr	
  accuracy)	
  
+	
  13	
  ftherom	
  The dispersal of the circumstellar discs of dust and gas surrounding
in its richness in young stars and protostars, and in its youth (0.5 Myr). It is certainly
one
of
the
best
targets
currently
showedevidr
for the formation of planetary systems. Photo- evaporation from energetic
auxiliary	
  
data	
  
precision	
  ∼3	
  earlymas/yr).	
  	
   star-formation. Proper motionaccessible
from(mean	  the groundto study thephases ofanalysisisavery
efficienttool
for
to drive the dispersal in the majority of discs, by creating amations
gap whichdiwasmembersof clusters
field stars,
in theρ Ophiuchi
region thesinceouter disc from the inside-out, while thFrom	
  the	
  separating
kinemaBc	
  analysis	  we	
  dfromerived;	  	
   but very few proper motions are availableof the discandthen disperses
were
too
num
of the young sources are deeply embedded in dust and gas. We aim at performing
kinematic
censusof young
the star.a In
this Letterwe showthat the disc around TW Hya, thetoclosest• 68	
  mostmembers	
  
and	
  14	
  candidate	
  members,	  excl
stellar objects (YSOs) in the ρ Ophiuchi F core and partially in the E core of thefirst
L1688
dark
cloud.
Werun
a proper gap has been imaged cided
object where a photoevaporativearound the timcomprising	
  
2
6	
  
n
ew	
  
o
bjects	
  
w
ith	
  
a
	
  
h
igh	
  
mean
velocitmotion program at the ESO New Technology Telescope (NTT) with the Son of ISAAC
nineis consistent with the expectations ofdetected(SOFI)
gap ininstrument
the ALMAover
imagesyears in the near-infrared.
with various public
image
databasestoenlargetheThe photoevaporation model
plate-to-plate
membership	
  probability.	
  We
	
   complemented these observations
requiring the presence of a planet.
is also ctime base of observations and the field of investigation to 0.5◦ ×0.5◦ . We derived positions
andpropermotionsfor2213
of the TW Hya system, e.g. accretion rate and the locationbly
of cluster
the gap m
at• mean	  proper	
  
m
oBon	
  
	
  
(
μ
	
  
c
osδ,	
  
μ
)=(-­‐8.2,	
  α
δ were derived from SOFI observations with a ∼1.8 mas/yr accuracy while theobjects. From these, 607 propermotions
central, unresolved 870 µm continuum source might be produced by free f

Accepted by ApJ

1/2	

1.

2.
3.

•

-­‐24.3)±0.8	
  mas/yr	
  for	  the	
  L1688	
  dark	  cloud.	
  	  ρ	  Oph	  F	  cluster	
  
13
• 56	
  previously	
  known	
  members	
  in	
  our	
  survey	
  
area	
  –	
  kinemaBcally	
  conﬁrmed	
  • 26	
  new	
  members	
  added	
  with	  evoluBonary	
  status	  	
  • a	  large	
  part	  (23)	
  of	
  them	  are	
  probably	
  brown	
  dwarfs	
  =>	
  mulBplies	
  the	
  number	  of	
  known	
  substellar	
  objects	
  in	
  the	
  cluster	
  
by	
  a	
  factor	  of	
  3.3.	

We finall
objects sprea
Accepted by MNRAS Lettersarated into tw
http://arxiv.org/pdf/1609.03903
13.80 x 10.80
remaining ob
iliarydata. W
The link between turbulence, magnetic fields,
filaments,
Fig. 1: Areas coveredby the present
catalogue of our proper
tral MolecularZone proper
cloud motion
G0.253+0.016
overlaid on the C.
mapof the 1L1688
cloud 2from
Bontemps
Federrath, J. M.dark
Rathborne, S. N.
Longmore3 , J. The
M. sprea
D. K
1
8
9
10,11,12
et al. (2001). Red
lines
delimitate
the NTT-SOFI
observations
R. M.
Crocker, G. Garay, J. M. Jackson, L. Testimaterial
and
A
prop
and blue lines give
the
total
extensionofthecatalogue
including1
fromthis fig
Research School of Astronomy and Astrophysics, Australian
NationalUnauxiliary data. 2 CSIRO Astronomy and Space Science, P.O. Box 76, Epping
NSW, 1710,
tributionof S
3Astrophysics Research Institute, Liverpool John Moores University,
IC2, L
precise thant
Liverpool L3 5RF, United Kingdom
ple
benefitin
4
Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität H
catalogue thadelberg,
Germany
where the absorptiondue
to dust is much lower and objects are
5
Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, G
detectable in the6 visible
wavelengths. For the vast majority of obCASA, University of Colorado, 389-UCB, Boulder, CO 80309, USA
jects, which are7only
detectablein theinfraredor NIR,
we 9513,
com-NL-2300 RA Leide
LeidenObservatory,
LeidenUniversity,
PO Boxbined the positions from 2MASS with those from the AllWISE
dust inside the gap.

new members are generally fainter than the known ones. We measured a m-24.3)±0.8 mas/yr for the L1688 dark cloud. A supervised classification wa
A&A proofs: manuscript no. Ducourantv2
to allocate a spectral energy distribution(SED) classification to the unclassi
http://arxiv.org/pdf/1609.05894
that
the
56
members
that
were
known
from
of theρ Ophthe kinematic members. We observe that they are mostly located previous
We presentstudies
the distributionof theseH
ourare membersof thecluster, andadded
26 newinthe survey
region of highest
absorption where
star-formationis on- we
known
members(blackmembers.
dotted histog
going.
We alsoembedded
notethat class I objects
globally aligneda (red)that
in Fig. a13large.
Proper motion survey and kinematic analysis of the Rho Ophiuchi
unclassified
membersof cluster
thearecluster.
We on
showedpart (23) onorthwest-southeast axis, mostly located in the most embedded
As expected, most of the new me
1,2
2,1
1
1
2
4 multiplies
1to corresponddwarfs,which
thenumberofknown
substellar
objects
region,which
was
proposed
by
Motte
et
al.
(1998)
withM
rangingfrom5
toin
12.theSinceclu
theC. Ducourant , R. Teixeira , S. Bontemps , D. Despois , P. A. B. Galli , H. Bouy , J.F. Le Campion ,H
totheperpendiculartothedirectionofshock
propagation
by
the
and
BDs
occurs
at
M
⇠5
mag,
that
i
1
5
H
M. Rapaport and J.C. Cuillandre
Acceptedmain
Upper
Scorpiusby
OBA&A
association
onto the core of the ⇢ Oph cloud clusters (e.g., Bara↵e et al. 2015), virtu
ourant C. et al.: Kinematics in ⇢ Ophiuchi
A&A
proofs:manuscriptno.
Ducourantv2
1
fall in the substellar regime. The MH v
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée complex.
Geoffroy
Saint-Hilaire, 33615 Pessac,
http://arxiv.org/pdf/1609.04963
troscopically confirmed BDs in ⇢ Ophiu
FranceFig 13 together with their spectral type.
2
find 23 new substellar members, which
Instituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão, 1226 - Cidade
previously
known BDsformingin the surveyeddAphoto-evaporative
gap
in
the
closestplanetKs bands (cenUniversitária, 05508-900 São Paulo - SP, Brazil
The weakest four new member
3297,0.275) µm)
1,23
BX162727602-24381862,
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Lab.Barbara
8.5.02, CampoGrande,1749-016,P. Rosotti244059.1,
Ercolano, Giovanni, Giovanni
Picogna1 , Leer objects of the244339.5,
and
2MASS-6X
J16265864Ducourant
C.
et
al.:
Kinematics
in⇢OphiuchiLisboa, Portugal
1
the Ks magnimag1,are81679
potentiallyvery low mass
BDs
Universitäts-Sternwarte München, Scheinerstr.
München,Germ
4Centrode Astrobiologı́a, Dpto de Astrofı́sica, INTA-CSIC, PO BOX 78, E-28691,
ESAC Campus, Villanueva de laphotometric data from Table 6. If there
are some contaminants
as cool as L0 (⇠2200K, see discussio2
list in Table 6
Excellence Cluster Origin and Structure of the
Universe,
Boltzmannstr.2
in our kinematic members sample, then they will be incorrectly2015). These cool young BDs are expe
Madrid,Spainin this work for
attributed to one of the three YSO Cañada,classes since we assume
here
3Institute of Astronomy, University of Cambridge,
Road, Cambof onlyMadingley
about 10 MJup (Chabrieret al. 2that each of the 82 members and 5candidates are young stellar
see next section
A&A
proofs:manuscriptno.
Ducourantv2
CEA/IRFU/SAp, Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris4Diderot, Observatoire de Paris, PSL
objects.
We summariseGermany
the evolutionary stat
EuropeanSouthern
Observatory,
Garchingbei
München,Ducourant
C.
et
al.:
Kinematics
in⇢OphiuchiFor
theclassification
we
adoptedasupervised
learning
h the AllWISE
candidates in Table 4. Seven members
Research
University,
F-91191 Gif-sur-Yvette Cedex, France
5
method, whose principle is the following.
The method
considE. Fermi
5, I-50125
Fire
e one hand, it may also be interesting to test any
the classified
kinematic
members. We observe that they are mostly located We present the distribution of these INAF/Osservatorio
H absolute magnitudes forAstrofisico di Arcetri, Largo
are identified
BD (Alvesde Oliveiraet aers the various magnitudes of each previously
memberatalogue for its membership to the F/E cores al(J,H,K s ,w1,w2,w3,w4) and all theirE-mailcolourin
combinations(J-H,ofJ- highest
are BD candidates (Alves de Oliveira echristine.ducourant
u-bordeaux.fr
thecontact:regionabsorption where atstar-formationis on- known members (black dotted histogram) and new members
er motion is not of high accuracy to have a census
K s , J-w1, etc.) and searches for regions in this magnitude-colour
E-mail contact: ercolano at usm.lmu.decomplete as possible. This is why we performedWe
also(red) in Fig. 13 .
hyperspace that are occupied by membersgoing.
of a same
class(I, IInote that class I objects are globally aligned on a
two steps.
Table 4: Summary of evolutionary sta
Thenorthwest-southeast
ρ theseOphiuchicomplexparticular
L1688mostdarkismembers
unique arein itsproximity(∼130 pc),
regions are molecularlected the most reliable proper motions of and
our III). When the parameters characterisingaxis, mostly
located andin theinmostembedded the Lynds
As expected,
of cloudthe newTheweaksources
dispersalof thecircumstellar discs of dust members
and gasandsurroundingyoung
e to derive the kinematic properties of the clus“learned’, the algorithm considers the unclassified members andcandidates.
region,which
was
proposed
by
Motte
et
al.
(1998)
tocorrespondwithMranging
from
5
to
12.
Since
the
transition
betweenstars
inonits
in young stars and protostars, and in its youth H(0.5 Myr). It is certainly
oneformationof the best
targets
currently
field, using objects with at least a time baseattributesofa class to them depending
their richness
localisation in this
for
the
of
planetarysystems.
Photoevaporationfromenergeticr
five years, with a number of observations greater
hyperspace.
to the perpendicular
to the directionof shockby theand BDs occurs at ProperMH ⇠5 mag,that is,M J ⇠6 magyoungth 2mas/yr. From these, we excluded proper
accessible
fromthethe groundto study
thepropagation
early phasesof star-formation.
motionanalysis
isdispersal
afor
very
efficient
tool for of discs, by
StatusMembers
we adopted
than 45 mas/yr, which correspond to foreground Of the various supervised methods available,
to
drive
the
in
the
majoritycreating
a
gap
which
di
Upper
ScorpiusOB
association
onto
the
core
of
the
⇢
Oph
cloud
clusters(e.g.,
Bara↵eetal.
2015),
virtually
all
the
new
members
and successful data classification non-parametric
w1 − w4 [mag]56 known YSOs (CDS)
not belong to the ⇢ Ophiuchi complex. This well-known
left
separating
members of clusters fromfield stars, but veryfall
few
motions
areTheavailable
inoftheρsevenOphiuchiregion thesinceouter disc fromin proper
the substellar
regime.
Mvaluesthe
spec2001; Breiman et al.
ects with highly accurate proper motions. method called random forests (Breimancomplex.
ofH the
disc
and
then
disperses
inside-out, while 4th
ClasstheIership analysis led to the following mean proper2003), complemented by a Monte most
Carlo trialof
to accountfor
erFig.
10:
One
of
the
colourcolourdiagramsforkinematic
memFig. 9: K s are
distributionof known
objects referenced Class II
the young sources are deeply embedded in dusttroscopicallyand gas. confirmed
We aimBDs
at in
performinga In
kinematic
censusofstellar
young⇢ Ophiuchi
also indicatedin young
34
recisions for the cluster derived with 48 memrors in the observable quantities. We adopted the R language im- bers using 2MASS K s and WISE w1,w2, and w4 photometry.
the
star.
this
Letter
we
show
that
the
disc
aroundTW
Hya, the closest= (-7.4 -22.9) ±0.8 mas/yr (hereafter µ stands
atthe AboveCDS
andkinematic
members
or candidates of the Class III
Fig 13 together
withtheir spectraltype.
MH new= 5 mag,
we runplementation of random forests bystellar
Liaw & Wiener(2002), and
13
Objects withclassespreviously
known in the literaturethat andwere partiallyobjects(YSOs)
intheρ
Ophiuchi
F
core
in
the
E
core
of
the
L1688
dark
cloud.
Weaproperd for the field (µ , µ ) = (-3.5, -1.4) ± (0.4,0.3)
first object
where
photoevaporative gap has been
to take all the errors of the available measurements into account, used for the training of the method (train) are shown with filled
nematic values derived for field stars agree reafind 23 new substellar members, cluster.
which
is 3.3 times
moreathan
26 newimaged
YSOs around the tim
wefollowed
a
Monte
Carlo
approach,performing
30000
indemotion program attheandESO
New
Technology(NTT)knownwith BDs
theof ISAAC(SOFI)
instrument
overnine consistentClasssymbols
the objects
we classified
are shown withTelescope
ith predictions from the Besançon Galaxy model
8: Distribution
onempty
the sky ofpreviously
kinematic
members,
candidate
I the expectations of2
inSon
the surveyedarea.
detected
gap inonthe
ALMA
imageswithpendent classifications of the dataset. At each run the following symbols. Squares refer to Fig.
he direction of our field : (µ , µ )= (-2,-2) mas/yr.
class I, circles to class II, and trianFig.
12:
Distribution
the skyof objects
from ouris
proper mowas performed: first the magnitudes
ofin
eachthestar atnear-infrared.
each gles to class III.
d step, we considered all the objects from process
our
years
We
complemented
observations
withpublicimage
databasestoenlarge
the
Class
II
11
members(0.5<P<0.9)theseand field
starsThe
with weakest
indication
ofvarious
the new
local-members
four
(UGCS
J162746.78tions
cataloguethe(greypresencedots) and of ofthe a
82 planet.
kinematic members
andrequiring
The photoevaporation
model is also4c
catalogue that were excluded from previous analfilter are sampled from Gaussian probability distribution func◦◦ Red circles corClass III
isationof ofthe investigation
B, C, E, and F coresof⇢ Ophiuchi.
d those whose data were spread over five or more
244059.1,
UGCS
J162700.96tions with the mean equal to the measured
imputed,thetime (orbaseofseeobservations
and the
field
to
0.5
×0.5BX162727602-24381862,. We derived positions
motions2213
candidates
ofand
theHya⇢proper
Ophiuchicluster(colouredsymbols)
derived1
Fig. 4:main-sequencestars(-6.3±0.3)
kms for(Prato2007;rate
Guentherpochs with a time base of observations
longerDistribution on the sky of objects from our proper motion respond to the kinematic members (P>0.9) derived in this work,
of
the
TW
system,e.g.
accretionandthelocationof the gap at
Fig. 6:below)
Repartition
ofand
membershipprobabilitiesofthe936 ob- (orparagraph
value
the
sigma
equal
to
the
measured
244339.5,
and
2MASS-6X
J16265864-2443281)
with
M
11
in
work.
Red
squares2007;
designateclass al.
I, green
circlesclass IIH
and a precision better than 3.5 mas/yr. We thenjects.
The indication
filled blackcorresponds
tothenknown
objects.
From
these,
607
motions
derived
from
SOFI
observations
with∼1.8unresolved
mas/yraccuracytheet thisal.a 2007;
KurosawaJames2006).
We summarise
computed
basedproperon the angulardistance
the positions
imputed)magnitude
errorhistogramat theof
relevant
all youngthe possicatalogue
withtheirfilter;
magnitude
range.
mbership to the two distributions
and retained
blue
circlesbetween
towerecandidatemembers<0.9).
Filled870µmetwhile
continuum
source might be produced by free fstellar objects (detected by ISO (Bontemps et al. 2001) or Spitzer
mag(0.5<P
are potentiallyvery circles
low mass central,
BDs that reach
spectral types

Accepted by ApJ

2/2	

●

Class

I − Train● II − Train

7.5

III − Train

K − w2 [mag]I − New●● II − New

III − New

5.0

●

●
●●
●
●●
● ● ●● ●● ●● ●●●●● ●● ●●●●● ●●● ● ●●●
●●
● ●
●
●
● ●●
●
●
●
● ●
●
● ● ● ●●●● ●●●●●●●●● ●● ●●●● ●● ● ●●●● ●●●●●●●● ●●
●●
●
●
●●●
●
● ●
● ●●
●
● ●●
●
●
●
●
●
●
●
●
●
●
● ●● ●
●●
●●
●
●●
●
●●
● ●
●
●
●

●

2.5

●

0.0

µ

0.0

⇤
↵

2.5

5.0

7.5

●

●

10.0

⇤
↵

f

⇤
↵

and blue triangles class III. The zones with few grey dots correof each object and the median position of all member objects
in Table 3 the kinematic properties of the ⇢ Ophiuchi (F core).
designateobjects
belongingcatalogue
and triangles(Fig.11). The median projected
radii andthe absolute
median to thespond to themost obscureregions. Crosses indicate the approx- 8. Conclusions
as SOFI
cool asL0 (⇠2200K,
see discussions
in Tottle& Mohanty
deviation for each type of object
shows
that
the
di↵erent
classes
identify known young stellar objects
detectedby ISOor Spitzer.
imative
centresthe E,F, anddotted line indicates2015).
These
cool
young
BDs
are
expected
to beofspatial
very
low
massB cores; thepresent di↵erent preferential projected radii and also di↵erent
Table
3:
Mean
and
propertiesof (1998).
the ⇢ Ophi-With our astrometric observations w
black dots
correspond0 to fieldobjects(P<0.1).
0of clumps and YSOs kinematic
identified byMotte et al.
Ducourant C. et al.: Kinematics in ⇢ Ophiuchi
spread: RI = 5.6 ± 3.1 0 , RTheof onlyabout
10 MJup (Chabrier ettheal.line2000).
II = 8.8 ± 4.5 , RIII = 10.7 ± 5.3 .
uchi
F
core
as
derivedfromthe68
kinematic
members with thepropermotions of 2213 stellar and s
These results indicate that the youngest objects are more concenWesummarisetheevolutionary
statusofthe82
membersand4.1. Comparison to PPMXL and 2MASS catalogues
trated in the central parts of the working zone (cores E and F),
highest membership probability (P>0.9).
Breiman,L., Last,We
M., &perform
Rice, J. 2003
⇢ Ophiuchi cluster
region.
(Springer New York), 243–254
candidates in Table 4. Seven members already known as YSOs
while more evolved objects are more spread towards the exterior.

ble colour combinations between the filters J, H, K, w1, w2, w3
obability greater than 50%.
(Evans et al. 2003)) that are present in our catalogue. For visibiland w4then thea randomclassifierassigns ad up with 82 objects with a membership probaity are
the ycomputed;
axis is truncated;peak thatforests
corresponds
to a probaster higher than 50%. We present the repartition
class bility
to allofthe
objects
with unknownclasses. Finally, after all the⇠0.05
culminates
at 800 objects.
probabilities for the 936 objects analysed hereindependentinruns, the frequency that each object was assigned torve in this figure two clear peaks that correspondeach class is computed and the class with the greatest frequency
ion (P<0.1) and cluster population (P>0.9) andis adopted as the object class.
ermediate probabilities. Sixty-eight objects have
>0.9 and are considered as members, while14 ob- A special approach had to be adopted because some data
embership probability 0.5<P<0.9 and are classipoints were missing in our dataset (e.g., many objects were obte members.
served or detected only in some, but not all, of the 2MASS or
p analyses are very sensitive to outliers (e.g.,
WISE filters). The approach adopted was to perform data imects from the Galaxy with high proper motion)
putation and Monte Carlo sampling of error distributions. The
excluded to derive realistic solutions (see disfirst step is to perform data imputation, but to avoid mixing the
he pruning of the data in Cabrera-Cano & Alfaro⇤
well-known objects with the most uncertain objects, we split
refore excluded objects with µ↵ or µ > 45 mas/yr
objects with proper motions beyond 2.5 of thethe missing data imputation into two phases: first, the data ims of the cluster and of field at the end of step two.
putation was performed using all the objects with previously
st of objects in Table 5 that are considered as outknown classifications; then, the missing data imputation was pereir high membership probability (P>0.9) because
formed considering all objects in our dataset. We adopted a nonotion di↵ers by more than 2.5 from that of thedust inside the gap.

13

Accepted by MNRAS Letters

http://arxiv.org/pdf/1609.03903

ship analysis andCabrera-Cano,derivedJ. a& Alfaro,
list E.ofJ. 1985,
82

Density

Cesarsky, C. J., Abergel, A., Agnese, P
et al. 2012) and 6 new
YSOs
For the optical part of our catalogue, the densest comparison cat- 5.2. New and known membersare identified BD (Alves de OliveiraProperty
Valuecandidate members,
26G., ofthem
are
Chabrier,
Bara↵e,I., Allard,F., &nHhms‘”
Cieza, L., Padgett, D. L., Stapelfeldt, K
are BD candidates (Alves de Oliveiraetal.
2010).
alogue is the PPMXL catalogue (Roeser et al. 2010). We notelishedinareliable
mean
kinD
(↵,
)
(
16
27
22.51
,
24
41
58.5
)
7. Nature of kinematic members and candidates
Cutri,way
R. M. &the
IPAC/WISE
Sciencemembers or candidate members derived in The
Abstracturbulence,magnetic
fields,
L1688 darkcloud tronomical(µfilaments,
cosSociety, µMeeting)=(-8.2
that the present work included some PPMXL propermotions as Of the 82 kinematic(µ↵ coslink, µ ) between( -8.2, -24.3)±
0.8 mas/yr
Class
0.075
ciety↵Meeting Abstracts 219, 401.06
the 82 ofkinematic
members and candidate members in the confirm that the velocity
Tableas4:
Summary
evolutionary
statusthe 82 kinematic
at CDS
young
stellar of
objects,
the Of(l,b)
Cutri, R. M.,of
Skrutskie,F., vanI
this M.
core
isD( 352.9816,16.5540)
starting point of the iterative reduction process but the final cata- this work, 56 are referenced
tral
Molecular
Zone
cloud
G0.253+0.016
Catalog, 2246, 0
weanalysed, we proposeda classificationfor 53 ob- the Upper Scorpius
II
members
and candidates.
26 others are new members
or newcandidates.
Of the known ob- region
association.
Cutri,
R. M., Wright, E. L., Conrow, T
(µ
cos
b,
µ
)
( -23.8,-10.7)±
0.8 mas/yrlblogue should be more or less independent of it. Another difficulty jects, 7 are brown IIIdwarfs (BDs) (Alves de Oliveira et al. 2012), jects. Six objects (2MASS-6X
theAllWISE
Data
Release
Products
J16271965-2441487,
2MASS
0.050
We assigned 3Dawson,
a,SED
class
toD.
the
5a
T. P., etPosition(X, Y, Z) 12MASS-15.6,+37.4) pc 2 ,2MASSC.
Federrath,( 126.9,
J. M.
Rathborne
S. N. Longmore
J.P., Scholz,
M.A., Ray,K
resultsparametricfrom thefact that the 239 objects common to our cata- 1 is a BD candidate (FHTWIR-Oph
J16272661-2440451,
de Zeeuw, P.usingT., Hoogerwerf,R., de Bru
StatusCandidates
80, Alves de Oliveira etMembers
al. J16272439-2441475,
or candidates
a non-pa
missing data imputation method called missForest
1-5.9±0.1, -14.2±0.3,
8 -8.1±0.4) km/s members
9
10,11,12
Velocity
(U,
V,
W)
(
A. 1999, AJ, 117, 354
J16273272-2445004,
2MASS
J16274161-2446447,
and
2MASS
R.
M.
Crocker
,
G.
Garay
,
J.
M.
Jackson
,
L.
Testi
and
A
PPMXL
are mostly
atonthe southern edge (2010)), and 26 were found by the(Stekhoven& Buehlmann2012). Thisconcentrated
method is also based
Do, T.,
Martinez,
G. D., Yelda, S.,et alng meankinematic properties
the cluster andaresupervised methodforclassifying
obje
major spatial
NIR-surveys
permotioncat- of logue
56 known
YSOs (CDS)
Dodson-Robinson, S. E. & Salyk, C. 2
random forests algorithm to predict continuous missing val3. We present the list of the members and canJ16273894-2440206) have been listed by Alves de Oliveira et al. tion of the (J, H, K,
of the aues
field,
which means that the cluster is almost0.025completely ISO (Bontemps et al. 2001) or Spitzer
Ducourant,& Rapaport,
M. 1991,A
w1,C.w2,
w3 andw4
et al. 2003).
1 4 The mean proper
Notes.
motionof the core given here
does
not accountClass(EvansI
0cataloguewhile
s with their astrometricsolution and their memfrom the observed values of all other objects in the dataset
Research
Schoolof
Astronomy
andAstrophysics,
Australian
NationalUn
Ducourant,
C.,
Teixeira,R.,
Chauvin,(2010) as potential brown dwarfs (BDs) based on their position colours. Nine objects are defined as clasG
ility in Table 7. Fig. 7 shows the excluded
vector plot anddi- from
the relation
the object whoseandvalue ismissingand brightest objects
fromthis ofcomparison
only
thethe probable systematic
error (⇠ 2 mas/yr) of our proper motion
Ducourant, C., Teixeira, R., Hambly, N
The kinematic members are mostly
located around the Oph for
Class
II
34
2
logue.
uster and indicates the membership probability,2
ina colour-magnitude diagramand
among
the faintest,
red objects.
Eckart, A., Mužić, K., Yazici, S., et al.
all other objects considering the entire parameter space of theSpace
Science,
P.O. Box76,
Epping
NSW, 1710,
objects
as class
III.
catalogue.
ws the distribution of field stars ofand ourof cluster
Erickson, K. L., Wilking, B. A., Meyecatalogue are concerned. Nevertheless, we performed
the F and E cores, with several new detections
0.000
Class III south to these cores. That
13CSIRO Astronomy
3
dataset.
andidate members across our field.
L. N.new2011, AJ,
142, 140
3 we can kinematically confirm that they are part of the clusWe
discovered
23
BDscandida
0
5
10
15
20
The
results
oftheclassification
performed
here
arerepreSome
previously
known
membersaround
Oph
B
core
are
also
Astrophysics
Research
Institute,
LiverpoolJohn
Moores
University,
Evans,II,
N. J., Allen, L. IC2,
E., Blake, G.L
comparison
of
both
sets
of
propermotions,
and
we
noted
a
sys26 new YSOs
ows that the repartition of the kinematic members
ter indicates that they are probably BDs.
Radius [arcmin]Fritz, T., Gillessen,S., Trippe, S.,sented in one of the many possible colour-colour planes in Fig.
potentially multiplying
the number
ofet al.
kular, as expected. The dispersion of their properWe
comparedthesevalueswiththekinematic
characteristics
classified
askinematic
members.
The
highconcentrationofkineFig.
7:
Vectorplot
diagram.
Red
circlescorrespondtothekineFritz, T. K., Chatzopoulos, S., Gerhard
Class
I
2
3
tematicdi↵erence
(in
the
sense
this
work
minus
PPMXL)
UsingthetypicalIR
excesses
in
J,
H,
and
K
bands
for
class
mas/yr) is larger than expected fromthe astro10 mean
which
shows
that
most
of
the
objects
lackingliterature
clasLiverpool
L3
5RF,
UnitedKingdommatic members (P>0.9) derived in this work,
blue circles
canthemD.mightbeM
Fig.
12: toDistribution
on the sky of objects
fromour propermo- part of the field covered by this of the Upper Scorpius (US) association since the ⇢ Oph clustercluster by 3.3. A few
Furlan,ofE., Watson,
M., McClure,of view (1-2to
mas/yr)and reflects the difficulties
members
centralFig. 11: Radial density plot.matic
The projected
densitiesinof theeach classsificationwere
assigneda<0.9).
classTheII black
status.
Ofcorrespondthe 53 unclassified
down
much
Gallagher, D. B., Irace, W. R., & We
didatemembers(0.5<P
dots
to
field
Class
II
11
5
II
and
class
III
YSOs
and
the
extinctionlawinnear-IR
as
in
4
of
(
µ
cos(
),
µ
)=(-1,+6)
mas/yr.
↵2roper motions in such obscured zones and themembers
re- objects
in the10 M(blacktions
catalogue
dots)
82ofkinematic
members
and of deep SOFI observations.
Jup regime.
Astronomisches
Rechen-Institut,
Zentrum
Astronomie
derUniversitätof YSOs
are andgivenofin thenumberobjects par arcmin
areOpticalInstrumentation EngineersHor(P<0.1).
candidates,
wereassigneda class
III status,
Filled 16
circlesdesignateobjects
belongingto the 32 a(greyFig. 13:
Distributionof (seeabsolute
Hfürmagnitudes
of known
is expected
thederived
Upper theSco
association
Wilking
study
corresponds
to andtheeachzone
uracy.andTwenty-six
members are YSOs that have SOFI catalogue and triangles identify known young stellar obBontemps
ettoal.be(2001),
absolute
J and
H maguereachesClass III
4
1part ofwe
Telescopes and Instruments,
versus cluster
theprojected
distance tosymbols)
the center [ofclassII, and 5 a class
I.origin of thecandidates
We wereconableGirard,
toSpaceestablisha seconda
dotted) and new (solid red) members.
Spectroscopicallyof the displayed⇢di↵erence
Ophiuchi(colouredderivedTomemdetermine
thelarge systematic(esby ISO or Spitzer. Field stars and cluster
T. M., van Altena, W. F., Zacha
1 the
et
al.
(2008)).
We
observethatthevelocity
derivedhere
forWe
present
in
Fig.
9
the
repartition
in
terms
of
K
magnitudes
jects
detectedbyISOor
Spitzer.
delberg,
Germanysclass.
nitudesforthekinematic
members
andcandidates
members.
firmed brown dwarfs by Alves de Oliveiraframe
et al. (2012)
are indiN.,
Yano, T., where
Yamada, Y.,refeted in Fig.7 by a layer of objects with intermediate To analyse how probable it was to find a young stellar obin the
NIRGouda,
inVol.a576,
regionin thiswork.
Redsquaresdesignate ofclass
circlesclass
sentially
inclasses
declination),
the
2MASS
catalogue
catedwetogetherwith theirspectraltype.
The Three-Dimensional
clusterisverysimilar
to
the
one
that
deriveforthesampleject ofI, II, or III at awe
givenconsidered
distancefrom
thecenterobabilities (candidates).
5
theI,56green
known
and 26
newIImembers.
1 Max-Planck Institut für Astronomie, Königstuhl
17,astrometric69117O’Flaherty,
Heidelberg,
G7& M. A. C.can
Perryman,
existing
catalogues
ha
One
new
member(WISE
J162702.05-243938.6)
wasdetected inthe ⇢ Ophiuchi
cluster F core,
weepochbuilt
probability
densitywith
on on the sky of which ofprovides
andbluetriangles
class
III.
The
zones
with
few
grey
dots
correof117
members
of
Upper
Sco
OB2
group
with
Hipparcos
meapositions
for⇠1999.3
errors⇠100
Guenther,E.
W.,
Esposito,M.,
Mundt,The new members appear essentially fainter (down to only
Article number, page 7 of 16
6 one near-IR band therefore we were unable to derive its absolute catalogue will undoubtedly
estimations using kernel density estimators.
The projected radii
This is also visible in Fig.12, which displays the distribution
a valuab
Gutermuth, R.USA
A., beMegeath,S. T., Mye
CASA,(deUniversity
Colorado,
Boulder,
CO 80309,
totheweremostandobscureCrosses
theknown
approxneous, as shown mas andsurements
Zeeuw et al.of
1999)(U,V,W)US389-UCB,= (-5.0 , -14.8,
D. J., Melo, C., Santos, N. C., &Ks=18.1)
thancatalogue
theand were revealed by the magnitudes.
compared
its positions
to
PPMXL
for theobjects classified
as members ofspondeachthe
SED
class
on
theto
skyourof regions.
thecataobjects ofour properindicate
motionand of members
8. Conclusions
ciations
young James,stars,
as2007,
Hipparcos
wS
view of the star-formation processes and toaccess theof
youngest
Kurosawa,
R.
in Multiplicity in7
imative centresof theE, F, and Bofcores;
dottedobservations
line indicates
-6.5
)
±
(0.1,
0.4,
0.2)
km/s.
ected where the logue, each transported to the 2MASS
deeptheNear-IR
performed
in
this
work.
LeidenObservatory,
LeidenUniversity,
PO
Box
9513,
NL-2300
RA
Leideclusters
(<
a
few
Myr),
infrared
astrometriccatalogues
willbeLada, C. J. & Lada,
E. A. 2003,
ARA&
epoch byapplication
Article number, page 9 of 16
the crucial tool, however. The future space infrared astrometric Lawrence, A., Warren, S. J., Almaini, O
With ourastrometricobservations
wenumber,have page
determinedthethe lineofclumpsand
YSOs
identified
by
Motte
et
al.
(1998).
Article
10
of
16
We
note
that
some
well-attributed
membersof⇢Ophiuchie with the clus- its own proper motions. We present
these comparisons in Fig. 5.
mission Jasmine (Gouda et al. 2005) may in this respect be the Liaw, A. & Wiener, M. 2002, R News,Accepted by A&A main
http://arxiv.org/pdf/1609.04963

A photo-evaporative gap in the closest planet forming disc
Barbara Ercolano1,2 , Giovanni P. Rosotti3 , Giovanni Picogna1 , Leonardo Testi2,4,5
1

Universitäts-Sternwarte München, Scheinerstr. 1, 81679 München, Germany
Excellence Cluster Origin and Structure of the Universe, Boltzmannstr.2, 85748 Garching bei München, Germany
3Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, UK
4
European Southern Observatory, Garching bei München, Germany
5
INAF/Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy2E-mail contact: ercolano at usm.lmu.de

The dispersal of the circumstellar discs of dust and gas surrounding r furonsnuseen0.9(d)nscecry
Tf[(T)-0.7(h)0.9(e)hjbctcrchjin d ar0.9(d)hdr snc(n)0.9(a(r)-295.2

velocity PDF typical for turbulence. We measure the total and turbulent velocity dispersion, 8.8 ±0.1 km s−1 , respectively. Using magnetohydrodynamical turbulence simulations, we find that G0.
magnetic field Bturb = 130 ± 50 µG is only <http://arxiv.org/pdf/1609.03903∼1/10 of the ordered field component. Combining
we reconstruct the dominant turbulence driving mode in G0.253+0.016 and find a driving param
indicating solenoidal (divergence-free) driving. We compare this to spiral-arm clouds, which typic
The link between turbulence, magnetic fields,compressive
filaments,and starformation
Cen(curl-free)drivingcomponentin(b the> 0.4).
Motivated by previous reports of strong shtral Molecular Zone cloud G0.253+0.016
CMZ, we speculate that shear causes the solenoidal driving in G0.253+0.016 and show that
rate(SFR) by4,5a, factorof 6.9nearby clouds.
6 compared to typical
C. Federrath1 , J. M. Rathborne2 , S. N. Longmore3 ,formation
J. M. D.
Kruijssen
J. Bally, Y. Contreras7 ,Accepted by MNRAS Letters

R. M. Crocker1 , G. Garay8 , J. M. Jackson9 , L. Testi10,11,12
and
J. Walsh13
Accepted
byA.
ApJ

1.
2.

3.

4.

4

1

http://adsabs.harvard.edu/pdf/2016arXiv160905911F
Research School of Astronomy and Astrophysics, Australian
National
Federrathet al.University, Canberra, ACT 2611, Australia

2
turbulence,	
  magneBc	
  
ﬁeld	
  and
and	
  Spaceﬁlamentary	  structure	
  CSIRO
Astronomy
Science, P.O.
Box 76, Epping NSW, 1710, Australia
3
Astrophysics
Research
Institute,
LiverpoolJohn
Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill,in	
  the	
  central	
  molecular	
  zone	  (CMZ)	
  cloud	  Spitzer Observations of Long Term Infrared Variability Among Young
Liverpool L3 5RF, United Kingdom
inUniversität
Chamaeleon
I Mönchhofstraße 12-14, 69120 Hei4
G0.253+0.016	
  Astronomisches Rechen-Institut, Zentrum für Astronomie derHeidelberg,
1, Lindsay DeMarchi2,8 , James Muzerolle3 , Zoltan Balog4 , W
delberg, mGermany
Dust-­‐conBnuum	
  ap	
  with	  ALMA+Herschel:	
  ﬁlaments	
   Kevin M. Flaherty
5
5ThomasMegeath,Elise
Furlan6 , Robert Gutermuth7
Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
and	
  at	
  least	  6 one	
  dense	
  core	  along	  them	
  1
CASA, University of Colorado, 389-UCB, Boulder, CO 80309,
USA
Van
Vleck Observatory, Astronomy Dept., Wesleyan University, 96 Foss Hill Drive, Middletow
7
2
LeidenObservatory,
University,
RAofLeiden,
Netherlands• ﬁlament	
  width	  Wﬁl	
  =	  0Leiden
.17	
  ±	
  0
.08	
  pc	
   PO Box 9513, NL-2300
Dept.
PhysicstheandAstronomy, Colgate University, 13 Oak Drive, Hamilton, NY 13346, US
3
Space
Telescope
Science
Institute, 3700 San Martin Drive, Baltimore, Maryland, 21218, USA• sonic	
  scale	  of	
  turbulence	
  λsonic	
  =	
  0.15	
  ±	
  0.11	
  pc	
  4
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany(the	
  transiBon	
  scale	  from	  supersonic	
  to	
  subsonic	
  14 5 Ritter Astrophysical Research Center, Dept. of Physics and Astronomy, University of ToledUSA
turbulence)	
  =>	
  	
  Wﬁl	  ≈	
  λsonic	  	
  6Infrared Processing and Analysis Center, California Institute of Technology, 770 S. Wilson Ave,
HNCO	
  intensity-­‐weighted	
  velocity	
  maps	
  obtained	
  USA
7
Department of Astronomy, University of Massachusetts, Amherst, MA 01003, USAwith	
  ALMA+Mopra	
  8Department of Physics, Syracuse University, Syracuse, NY, 13244, USA•
Velocity	
  gradient:	
  large-­‐scale	
  shear	
  E-mail contact: kflaherty at wesleyan.edu•
Turbulence:	
  nearly	
  Gaussian	
  velocity	
  PDF	
  Infrared variability is common among young stellar objects, with surveys finding daily to we•
Velocity	
  dispersion:	
  8.8	  ±	  0.2	
  km/s	  (total),	
  	
  few tenths of a magnitude. Space-based observations can produce highly sampled infrared light
limited to total baselines of about a month due to the orientation of the spacecraft. Here we
3.9	
  ±	
  0.1	
  km/s	  (turbulence)	
  of the Chameleon I cluster whose low declination makes it observable by the Spitzer space tele
Comparison	
  with	  MHD	
  turbulence	
  simulaBons	
  period. We observe 30 young stellar objects with a daily cadence to better sample variability on•
Bturb	  =	  130	
  ±	
  50	
  μG	
  is	
  only	  <∼1/10	
  of	
  the	  We find such variability is common, occurring in ∼80% of the detected cluster members. The
color
over 200 days for many of the sources falls between that expected for extinction and fluctua
ordered	
  ﬁeld	  component	  	
  With our high cadence and long baseline we can derive power spectral density curves covering tw•
Driving	  parameter	
  b	
  =	
  0.22	
  ±	
  0.12	
  indicates	  in frequency and find significant power at low frequencies, up to the boundaries of our 200 dsolenoidal	
  (divergence-­‐free)	
  driving	
  	
  
•
cf.	
  b	
  >	
  0.4	  in	
  spiral-­‐arm	
  clouds:	
  signiﬁcant	  15compressive	
  (curl-­‐free)	
  driving	
  component	  •SpeculaBon:	  	
  shear強い=>	
  solenoidal	
  driving	
  =>	
  SFR低い	  velocity PDF typical for turbulence. We measure the total and turbulent velocity dispersion, 8.8 ±0.1 km s−1 , respectively. Using magnetohydrodynamical turbulence simulations, we find that G0.
magnetic field Bturb = 130 ± 50 µG is only <http://arxiv.org/pdf/1609.03903∼1/10 of the ordered field component. Combining
we reconstruct the dominant turbulence driving mode in G0.253+0.016 and find a driving param
indicating solenoidal (divergence-free) driving. We compare this to spiral-arm clouds, which typic
The link between turbulence, magnetic fields,compressive
filaments,and starformation
Cen(curl-free)drivingcomponentin(b the> 0.4).
Motivated by previous reports of strong shtral Molecular Zone cloud G0.253+0.016
CMZ, we speculate that shear causes the solenoidal driving in G0.253+0.016 and show that
rate(SFR) by4,5a, factorof 6.9nearby clouds.
6 compared to typical
C. Federrath1 , J. M. Rathborne2 , S. N. Longmore3 ,formation
J. M. D.
Kruijssen
J. Bally, Y. Contreras7 ,Accepted by MNRAS Letters

R. M. Crocker1 , G. Garay8 , J. M. Jackson9 , L. Testi10,11,12
and
J. Walsh13
Accepted
byA.
ApJ

Federrath et al.
http://adsabs.harvard.edu/pdf/2016arXiv160905911F
Research School of Astronomy8 and Astrophysics, Australian
National
University, Canberra, ACT 2611, Australia
CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW, 1710, Australia
3
Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill,
Spitzer Observations of Long Term Infrared Variability Among Young
Liverpool L3 5RF, United Kingdom
inUniversität
Chamaeleon
I Mönchhofstraße 12-14, 69120 Hei4
Astronomisches Rechen-Institut, Zentrum für Astronomie derHeidelberg,
Kevin M. Flaherty1 , Lindsay DeMarchi2,8 , James Muzerolle3 , Zoltan Balog4 , W
delberg, Germany
55ThomasMegeath, Elise Furlan6 , Robert Gutermuth7
Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg,
Germany
6
1
CASA, University of Colorado, 389-UCB, Boulder, CO 80309,
USA
Van
Vleck Observatory, Astronomy Dept., Wesleyan University, 96 Foss Hill Drive, Middletow
7
2
Leiden Observatory, Leiden University, PO Box 9513, NL-2300
RAofLeiden,
Netherlands
Dept.
PhysicstheandAstronomy, Colgate University, 13 Oak Drive, Hamilton, NY 13346, US
3Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland, 21218, USA
4
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
14 5 Ritter Astrophysical Research Center, Dept. of Physics and Astronomy, University of Toled
USA
6
Infrared Processing and Analysis Center, California Institute of Technology, 770 S. Wilson Ave,
USA
7
Department of Astronomy, University of Massachusetts, Amherst, MA 01003, USA
8
Department of Physics, Syracuse University, Syracuse, NY, 13244, USA

1
2E-mail contact: kflaherty at wesleyan.edu

Infrared variability is common among young stellar objects, with surveys finding daily to we
few tenths of a magnitude. Space-based observations can produce highly sampled infrared light
limited to total baselines of about a month due to the orientation of the spacecraft. Here weof the Chameleon I cluster whose low declination makes it observable by the Spitzer space tele
period. We observe 30 young stellar objects with a daily cadence to better sample variability on
We find such variability is common, occurring in ∼80% of the detected cluster members. The
color over 200 days for many of the sources falls between that expected for extinction and fluctuaWith our high cadence and long baseline we can derive power spectral density curves covering tw
in frequency and find significant power at low frequencies, up to the boundaries of our 200 d
15