THESTAR

FORMATION

NEWSLETTER

An electronic publication dedicated to early stellar/planetary evolution and molecular clouds
No. 317 — 15 May 2019

Editor: Bo Reipurth (reipurth@ifa.hawaii.edu)

List of Contents
The Star Formation Newsletter
Editor: Bo Reipurthreipurth@ifa.hawaii.edu

Abstracts of Newly Accepted Papers . . . . . . . . . . . 3
Abstracts of Newly Accepted Major Reviews . 31
Dissertation Abstracts . . . . . . . . . . . . . . . . . . . . . . . . 32

Associate Editor: Anna McLeod
anna.mcleod@berkeley.edu

New Jobs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Technical Editor: Hsi-Wei Yen
hwyen@asiaa.sinica.edu.tw

Summary of Upcoming Meetings . . . . . . . . . . . . . 40

Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Editorial Board
Joao Alves
Alan Boss
Jerome Bouvier
Lee Hartmann
Thomas Henning
Paul Ho
Jes Jorgensen
Charles J. Lada
Thijs Kouwenhoven
Michael R. Meyer
Ralph Pudritz
Luis Felipe Rodrı́guez
Ewine van Dishoeck
Hans Zinnecker
The Star Formation Newsletter is a vehicle forfast distribution of information of interest for astronomers working on star and planet formationand molecular clouds. You can submit material
for the following sections: Abstracts of recently
accepted papers (only for papers sent to refereed
journals), Abstracts of recently accepted major reviews (not standard conference contributions), Dissertation Abstracts (presenting abstracts of new
Ph.D dissertations), Meetings (announcing meetings broadly of interest to the star and planet formation and early solar system community), New
Jobs (advertising jobs specifically aimed towards
persons within the areas of the Newsletter), andShort Announcements (where you can inform or request information from the community). Additionally, the Newsletter brings short overview articles
on objects of special interest, physical processes ortheoretical results, the early solar system, as wellas occasional interviews.

Newsletter Archive
www.ifa.hawaii.edu/users/reipurth/newsletter.htm

Cover Picture
The image shows and approximately 3 degree wide
area of the Taurus clouds. The largest, high-opacity
cloud is Barnard 18, which is host to a numberof young stars, including IRAS 04239+2436, which
drives the giant Herbig-Haro flow HH 300. North
is to the right and East is up.
Image courtesy Oliver Czernetz
https://www.astrobin.com/users/OliverCzernetz/

Submitting your abstracts
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Abstracts of recently accepted papers

1

A sensitive λ 3 mm line survey of L483: a broad view of the chemical composition of acore around a Class 0 object
M. Agúndez1 , N. Marcelino1 , J. Cernicharo1 , E. Roueff2 , and M. Tafalla3
1

Instituto de Fı́sica Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain; 2 Sorbonne Université, Observatoirede Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France; 3 Observatorio Astronómico Nacional, C/ Alfonso
XII 3, E-28014 Madrid, Spain
E-mail contact: marcelino.agundez at csic.es
We present an IRAM 30m line survey of the dense core L483 in the λ 3 mm band. We detected 71 molecules (140including different isotopologues), most of which are present in the cold and quiescent ambient cloud. Of particularinterest are the cis isomer of HCOOH, the complex organic molecules HCOOCH3 , CH3 OCH3 , and C2 H5 OH, a wide
variety of carbon chains, nitrogen oxides like N2 O, and saturated molecules like CH3 SH. In general, fractional molecularabundances in L483 are systematically lower than in TMC-1 (especially for carbon chains), tend to be higher than in
L1544 and B1-b, while they are similar to those in L1527. Apart from the overabundance of carbon chains in TMC-1,
we find that L483 does not have a marked chemical differentiation with respect to starless/prestellar cores like TMC-1
and L1544, although it does chemically differentiate from Class 0 hot corino sources like IRAS 16293−2422. This factsuggests that the chemical composition of the ambient cloud of some Class 0 sources could be largely inherited fromthe dark cloud starless/prestellar phase. We also derived isotopic ratios for a variety of molecules, some of which show
isotopic anomalies like an extreme depletion in 13 C for one of the two isotopologues of c-C3 H2 , a drastic enrichment in
18
O for SO and HNCO (SO being also largely enriched in 17 O), and different abundances for the two 13 C substituted
species of C2 H and the two 15 N substituted species of N2 H+ . We quantify for the first time the deuterium fractionationfor HDCCO and c-C3 D. The detailed chemical characterization of the dense core L483 presented here provides a piece,
that together with similar exhaustive characterizations of other low-mass prestellar and protostellar sources, should
allow us to understand which are the main factors that regulate the chemical composition of cores along the process
of formation of low-mass protostars.
Accepted by A&A
https://arxiv.org/pdf/1904.06565.pdf

2

The Origin of [CII] 158um Emission toward the HII Region Complex S235
L.D. Anderson1 , Z. Makai1 , M. Luisi1 , M. Andersen2 , D. Russeil3, M.R. Samal4 , N. Schneider5 , P.
Tremblin6 and A. Zavagno31West Virginia University, USA; 2 Gemini South, Chile; 3 Aix Marseille University, France; 4 Physical ResearchLaboratory, India; 5 Physikalisches Institut der Universitat zu Koln, Germany; 6 CEA Saclay, France
E-mail contact: loren.anderson at mail.wvu.edu

Although the 2 P3/2 −2P1/2 transition of [C II] at λ ≃ 158 µm is known to be an excellent tracer of active star formation,
we still do not have a complete understanding of where within star formation regions the emission originates. Here,
we use SOFIA upGREAT observations of [C II] emission toward the H II region complex Sh2-235 (S235) to better
understand in detail the origin of [C II] emission. We complement these data with a fully-sampled Green Bank
Telescope radio recombination line map tracing the ionized hydrogen gas. About half of the total [C II] emission
associated with S235 is spatially coincident with ionized hydrogen gas, although spectroscopic analysis shows little
evidence that this emission is coming from the ionized hydrogen volume. Velocity-integrated [C II] intensity is strongly
correlated with WISE 12 µm intensity across the entire complex, indicating that both trace ultra-violet radiation fields.
The 22 µm and radio continuum intensities are only correlated with [C II] intensity in the ionized hydrogen portionof the S235 region and the correlations between the [C II] and molecular gas tracers are poor across the region. We
3find similar results for emission averaged over a sample of external galaxies, although the strength of the correlations
is weaker. Therefore, although many tracers are correlated with the strength of [C II] emission, only WISE 12 µm
emission is correlated on small-scales of the individual H II region S235 and also has a decent correlation at the scaleof entire galaxies. Future studies of a larger sample of Galactic H II regions would help to determine whether theseresults are truly representative.
Accepted by ApJ
https://arxiv.org/pdf/1904.12029

3

Physical and chemical fingerprint of protostellar disc formation
E. Artur de la Villarmois1, J. K. Jørgensen1 , L. E. Kristensen1 , E. A. Bergin2 , D. Harsono3 , N. Sakai4 ,E. F. van Dishoeck3,5 and S. Yamamoto6
1

Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5-7, 1350,
Copenhagen K., Denmark; 2 Department of Astronomy, University of Michigan, 311 West Hall, 1085 S. University
Ave, Ann Arbor, MI 48109, USA; 3 Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, theNetherlands; 4 The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako-shi, Saitama 3510198, Japan; 5 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748, Garching bei München,
Germany; 6 Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
E-mail contact: elizabeth.artur at nbi.ku.dk

Context. The structure and composition of emerging planetary systems are likely strongly influenced by their natal
environment within the protoplanetary disc at the time when the star is still gaining mass. It is therefore essential
to identify and study the physical processes at play in the gas and dust close to young protostars and investigate thechemical composition of the material that is inherited from the parental cloud.
Aims. The purpose of this paper is to explore and compare the physical and chemical structure of Class I low-mass
protostellar sources on protoplanetary disc scales.
Methods. We present a study of the dust and gas emission towards a representative sample of 12 Class I protostars
from the Ophiuchus molecular cloud with the Atacama Large Millimeter/submillimeter Array (ALMA). The continuum
at 0.87 mm and molecular transitions from C17 O, C34 S, H13 CO+ , CH3 OH, SO2 , and C2 H were observed at highangular resolution (0.4′′ , ∼60 au diameter) towards each source. The spectrally and spatially resolved maps reveal
the kinematics and the spatial distribution of each species. Moreover, disc and stellar masses are estimated from thecontinuum flux and position-velocity diagrams, respectively.
Results. Six of the sources show disc-like structures in C17 O, C34 S, or H13 CO+ emission. Towards the more luminous
sources, compact emission and large line widths are seen for transitions of SO2 that probe warm gas (Eu ∼200 K). In
contrast, C17 O emission is detected towards the least evolved and less luminous systems. No emission of CH3 OH isdetected towards any of the continuum peaks, indicating an absence of warm CH3 OH gas towards these sources.
Conclusions. A trend of increasing stellar mass is observed as the envelope mass decreases. In addition, a power-law
relation is seen between the stellar mass and the bolometric luminosity, corresponding to a mass accretion rate of (2.4
± 0.6) × 10−7 M⊙ year−1 for the Class I sources, with a minimum and maximum value of 7.5 × 10−8 and 7.6 × 10−7M⊙ year−1 , respectively. This mass accretion rate is lower than the expected value if the accretion is constant in timeand rather points to a scenario of accretion occurring in bursts. The differentiation between C17 O and SO2 suggeststhat they trace different physical components: C17 O traces the densest and colder regions of the disc-envelope system,
while SO2 may be associated with regions of higher temperature, such as accretion shocks. The lack of warm CH3 OH
emission suggests that there is no hot-core-like region around any of the sources and that the CH3 OH column density
averaged over the disc is low. Finally, the combination of bolometric temperature and luminosity may indicate an
evolutionary trend of chemical composition during these early stages.
Accepted by Astronomy & Astrophysics
https://arxiv.org/pdf/1904.13161

4Sub-millimeter non-contaminated detection of the disk around TWA 7 by ALMA
A. Bayo1,2 , J. Olofsson1,2 , L. Matra3 , J. C. Beamin1,2 , J. Gallardo4 , I. de Gregorio-Monsalvo4,2, M.
Booth5 , C. Zamora1,2 , D. Iglesias1,2, Th. Henning6 , M. R. Schreiber1,2 and C. Caceres7,24

1Instituto de Fisica y Astronomia, Facultad de Ciencias, Universidad de Valparaiso, Av. Gran Bretana 1111, Valparaiso, Chile; 2 Nucleo Milenio Formacion Planetaria - NPF, Universidad de Valparaiso, Av. Gran Bretana 1111,
Valparaiso, Chile; 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;
4
Atacama Large Millimeter / Submillimeter Array, Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura
763-0355, Santiago, Chile; 5 Astrophysikalisches Institut und Universitaetssternwar-5.89115(1377(V)87.5

56

Matthew Willson3, Adam L. Kraus4 , Aaron Rizzuto4 , Matthew T. Agnew5 and Sarah T. Maddison51

Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia;
Department of Astronomy, University of Michigan, Ann Arbor, Michigan 48109, USA; 3 University of Exeter,
Astrophysics Group, School of Physics, Stocker Road, Exeter, EX4 4QL, UK; 4 Department of Astronomy, The
University of Texas at Austin, TX 78712, USA; 5 Centre for Astrophysics and Supercomputing, Swinburne Universityof Technology, Hawthorn, Victoria 3122, Australia
2E-mail contact: eloise.birchall at anu.edu.au
This work presents a study of two Herbig Ae transitional discs, Oph IRS 48 and HD 169142; which both have reported
rings in their dust density distributions. We use Keck-II/NIRC2 adaptive optics imaging observations in the L’filter (3.8 µm) to probe the regions of these discs inwards of ∼ 20 au from the star. We introduce our method forinvestigating these transitional discs, which takes a forward modelling approach: making a model of the disc (using
the Monte Carlo radiative transfer code RADMC), convolving it with point-spread functions of calibrator stars, andcomparing the convolved models with the observational data. The disc surface density parameters are explored witha Monte Carlo Markov Chain technique. Our analysis recovers emission from both of the discs interior to the wellknown optically thick walls, modelled as a ring of emission at ∼ 15 au in Oph IRS 48, and ∼ 7 au for HD 169142,
and identifies asymmetries in both discs. Given the brightness of the near-symmetric rings compared to the reported
companion candidates, we suggest that the reported companion candidates can be interpreted as slightly asymmetricdisc emission or illumination.
Accepted by MNRAS
https://arxiv.org/pdf/1904.05990

7

ALMA survey of Class II protoplanetary disks in Corona Australis: a young region withlow disk masses
P. Cazzoletti1 , C.F. Manara2 , Hauyu Baobab Liu2,3 , E.F. van Dishoeck1,4 , S. Facchini2 , J.M. Alcalà5 , M. Ansdell6,7 , L. Testi2 , J.P. Williams8, C. Carrasco-González9 , R. Dong10 , J. Forbrich11,12 ,M. Fukagawa13 , R. Galván-Madrid9 , N. Hirano3 , M. Hogerheijde4,14 , Y. Hasegawa15 , T. Muto16 , P.
Pinilla17 , M. Takami3 , M. Tamura13,18,19 , M. Tazzari20 , and J.P. Wisniewski21
1

Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstr. 1, 85748, Garching, Germany; 2 European
Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany; 3 Academia Sinica Instituteof Astronomy and Astrophysics, Roosevelt Rd, Taipei 10617, Taiwan; 4 Leiden Observatory, Leiden University, Niels
Bohrweg 2, 2333 CA Leiden, The Netherlands; 5 INAF-Osservatorio Astronomico di Capodimonte, via Moiariello16, 80131 Napoli, Italy; 6 Center for Integrative Planetary Science, University of California at Berkeley, Berkeley,
CA 94720, USA; 7 Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720, USA; 8
Institute for Astronomy, University of Hawai’i at Mānoa, Honolulu, HI 96822, USA; 9 Instituto de Radioastronomı́a yAstrofsica (IRyA-UNAM), Universidad Nacional Autónoma de México, Campus Morelia, ApartadoPostal 3-72, 58090
Morelia, Michoacán, Mexico; 10 Department of Physics & Astronomy, University of Victoria, Victoria, BC, V8P 1A1,
Canada; 11 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK; 12
Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138, USA; 13 National Astronomical
Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 Japan; 14 Anton Pannekoek Institute for Astronomy,
University of Amsterdam, PO Box 94249, 1090 GE, Amsterdam, the Netherlands; 15 Jet Propulsion Laboratory,
California Institute of Technology, Pasadena, CA 91109, USA; 16 Division of Liberal Arts, Kogakuin University, 124-2 NishiShinjuku, Shinjuku-ku, Tokyo 163-8677, Japan; 17 Department of Astronomy/Steward Observatory, The
University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA; 18 Department of Astronomy, The Universityof Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; 19 Astrobiology Center of NINS, 2-21-1, Osawa, Mitaka,
Tokyo 181-8588, Japan; 20 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA,
UK; 21 Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street,
Norman, OK 73019, USA
E-mail contact: pcazzoletti at mpe.mpg.de
In recent years, the disk populations in a number of young star-forming regions have been surveyed with ALMA.
Understanding the disk properties and their correlation with those of the central star is critical to understand planet

6formation. In particular, a decrease of the average measured disk dust mass with the age of the region has been
observed. We conducted high-sensitivity continuum ALMA observations of 43 Class II young stellar objects in CrA
at 1.3 mm (230 GHz). The typical spatial resolution is ∼ 0.′′ 3. The continuum fluxes are used to estimate the dust
masses of the disks, and a survival analysis is performed to estimate the average dust mass. We also obtained new
VLT/X-Shooter spectra for 12 of the objects in our sample. 24 disks are detected, and stringent limits have been
put on the average dust mass of the non-detections. Accounting for the upper limits, the average disk mass in CrA
is 6±3 M⊕ , significantly lower than that of disks in other young (1–3 Myr) star forming regions (e.g. Lupus) andappears consistent with the 5–10 Myr old Upper Sco. The position of the stars in our sample on the HR diagram,
however, seems to confirm that that CrA has age similar to Lupus. Neither external photoevaporation nor a lower
than usual stellar mass distribution can explain the low disk masses. On the other hand, a low-mass disk population
could be explained if the disks are small, which could happen if the parent cloud has a low temperature or intrinsic
angular momentum, or if the the angular momentum of the cloud is removed by some physical mechanism such as
magnetic braking. In order to fully explain and understand the dust mass distribution of protoplanetary disks andtheir evolution, it may also be necessary to take into consideration the initial conditions of star and disk formation
process, which may vary from region to region, and affect planet formation.
Accepted by A&A
https://arxiv.org/pdf/1904.02409.pdf

8Molecular Bullets in A High-mass Protostar
Yu Cheng1,2,3 , Keping Qiu1,4 , Qizhou Zhang5 , Friedrich Wyrowski6 , Karl Menten6 and Rolf Güsten6
1

School of Astronomy and Space Science, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China; 2 Dept. of
Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA; 3 Dept. of Astronomy, University of Florida,
Gainesville, Florida 32611, USA; 4 Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University),
Ministry of Education, Nanjing 210023, China; 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street,
Cambridge, MA 02138, U.S.A.; 6 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
E-mail contact: kpqiu at nju.edu.cn
We present Submillimeter Array (SMA) observations in the CO J = 3–2, SiO J = 5–4 and 8–7, and SO 98 –87
lines, as well as Atacama Pathfinder EXperiment (APEX) observations in the CO J = 6–5 line, of an extremely
high-velocity and jet-like outflow in high-mass star-forming region HH 80–81. The outflow is known to contain two
prominent molecular bullets, namely B1 and B2, discovered from our previous SMA CO J = 2–1 observations. While
B1 is detected in all the CO, SiO, and SO lines, B2 is only detected in CO lines. The CO 3–2/2–1 line ratio in
B1 is clearly greater than that in B2. We perform a large velocity gradient analysis of the CO lines and derive atemperature of 70–210 K for B1 and 20–50 K for B2. Taking into account the differences in the velocity, distancefrom the central source, excitation conditions, and chemistry between the two bullets, we suggest that the bullets are
better explained by direct ejections from the innermost vicinity of the central high-mass protostar, and that we are
more likely observing the molecular component of a primary wind rather than entrained or swept-up material fromthe ambient cloud. These findings further support our previous suggestions that the molecular bullets indicate anepisodic, disk-mediated accretion in the high-mass star formation process.
Accepted by ApJ
https://arxiv.org/pdf/1904.01429.pdf

9Oscillatory migration of accreting protoplanets driven by a 3D distortion of the gas flow
O. Chrenko1 and M. Lambrechts2
1

Institute of Astronomy, Charles University in Prague, CZ-18000 Prague 8, Czech Republic; 2 Lund Observatory,
Department of Astronomy and Theoretical Physics, Lund University, Box 43, 22100 Lund, Sweden
E-mail contact: chrenko at sirrah.troja.mff.cuni.cz
Context. The dynamics of a low-mass protoplanet accreting solids is influenced by the heating torque, which was
found to suppress inward migration in protoplanetary disks with constant opacities.
Aims. We investigate the differences of the heating torque between disks with constant and temperature-dependent
7

opacities.
Methods. Interactions of a super-Earth-sized protoplanet with the gas disk are explored using 3D radiation hydrodynamic simulations.
Results. Accretion heating of the protoplanet creates a hot underdense region in the surrounding gas, leading tomisalignment of the local density and pressure gradients. As a result, the 3D gas flow is perturbed and some of thestreamlines form a retrograde spiral rising above the protoplanet. In the constant-opacity disk, the perturbed flow
reaches a steady state and the underdense gas responsible for the heating torque remains distributed in accordancewith previous studies. If the opacity is non-uniform, however, the differences in the disk structure can lead to morevigorous streamline distortion and eventually to a flow instability. The underdense gas develops a one-sided asymmetry
which circulates around the protoplanet in a retrograde fashion. The heating torque thus strongly oscillates in timeand does not on average counteract inward migration.
Conclusions. The torque variations make the radial drift of the protoplanet oscillatory, consisting of short intervalsof alternating rapid inward and outward migration. We speculate that transitions between the positive and oscillatory heating torque may occur in specific disk regions susceptible to vertical convection, resulting in the convergent
migration of multiple planetary embryos.
Accepted by A&A
https://arxiv.org/pdf/1904.12497.pdf

10

Bok globule CB17: Polarization, extinction and distance
G.B. Choudhury1 , A. Barman1 , H.S. Das1 and B.J. Medhi2
1

Department of Physics, Assam University, Silchar 788011, India; 2 Department of Physics, Gauhati University,
Guwahati 781014, India
E-mail contact: hsdas at associates.iucaa.in
In this paper, the results obtained from the polarimetric study of a Bok globule CB17 in both optical and submillimeter wavelength are presented. The optical polarimetric observations in R-band (λ = 630 nm, ∆λ = 120 nm)
were conducted from 1.04-meter Sampurnanand Telescope, ARIES, Nainital, India on 9th March 2016, while, thesub-mm polarimetric data are taken from the SCUPOL data archive which has been reanalyzed. The contours of
Herschel SPIRE 500 µm dust continuum emissions of CB17 (typically a cometary-shaped globule) are overlaid on the
DSS image of CB17 along with polarization vectors (optical and submm). The magnetic field strength at the core of
the globule is estimated to be 99 µG. Using the Near-Infrared photometric technique and Gaia data, the distance toCB17 is found to be 253±43 parsec. A correlation between the various quantities of the globule is also studied. It
is observed that the magnetic field in the cloud core as revealed by polarization measurements at the sub-millimeter
dust emission is found to be almost aligned along the minor axis of the globule which fits the magnetically regulated
star formation model. The misalignment between core-scale magnetic field direction and molecular outflow directionis also found.
Accepted by MNRAS
https://arxiv.org/pdf/1904.12833.pdf

11

TRAO Survey of Nearby Filamentary Molecular clouds, the Universal Nursery of Stars(TRAO FUNS) I. Dynamics and Chemistry of L1478 in the California Molecular Cloud
Eun Jung Chung1 , Chang Won Lee1 , Chang Won Lee2 , Shinyoung Kim1 , Shinyoung Kim2 , Gwanjeong
Kim3 , Paola Caselli4 , Mario Tafalla5 , Philip C. Myers6 , Archana Soam7 , Tie Liu1 , Tie Liu8 , Maheswar
Gopinathan9 , Miryang Kim1 , Kyoung Hee Kim10 , Woojin Kwon1 , Hyunwoo Kang1 and Changhoon
Lee1
1

Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea; 2
University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, Daejeon, Korea; 3 Nobeyama Radio Observatory,
National Astronomical Observatory of Japan, Nagano 384-1305, Japan; 4 Max-Planck-Institut für Extraterrestrische
Physik, D-85748 Garching, Germany; 5 Observatorio Astronómico Nacional (IGN), Alfonso XII 3, 28014 Madrid, Spain;
6
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; 7 SOFIA Science8Centre, USRA, NASA Ames Research Centre, MS N232, Moffett Field, CA 94035, USA; 8 East Asian Observatory,
660 N. Aoho?ku? Place, University Park, Hilo, HI 96720, USA; 9 Indian Institute of Astrophysics, Koramangala,Bangalore 560034, India; 10 Department of Earth Science Education, Kongju National University, 56 Gongjudaehakro, Gongju-si, Chungcheongnam-do 32588, Korea
E-mail contact: rigelej at gmail.com′′

TRAO FUNS′′ is a project to survey Gould Belt’s clouds in molecular lines. This paper presents its first results on
the central region of the California molecular cloud, L1478. We performed On-The-Fly mapping observations using
the Taedeok Radio Astronomy Observatory (TRAO) 14m single dish telescope equipped with a 16 multi-beam arraycovering ∼1.0 square degree area of this region using C18 O(1−0) mainly tracing low density cloud and about 460 squarearcminute area using N2 H+ (1−0) mainly tracing dense cores. CS(2−1) and SO(32 −21 ) were also used simultaneously
to map ∼440 square arcminute area of this region. We identified 10 filaments by applying the dendrogram techniqueto the C18 O data-cube and 8 dense N2 H+ cores by using FellWalker. Basic physical properties of filaments suchas mass, length, width, velocity field, and velocity dispersion are derived. It is found that L1478 consists of several
filaments with slightly different velocities. Especially the filaments which are supercritical are found to contain dense
cores detected in N2 H+ . Comparison of non-thermal velocity dispersions derived from C18 O and N2 H+ for the filaments
and dense cores indicates that some of dense cores share similar kinematics with those of the surrounding filaments
while several dense cores have different kinematics with those of their filaments. This suggests that the formation
mechanism of dense cores and filaments can be different in individual filaments depending on their morphologies andenvironments.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/1904.10594

12

A Preferential Attachment Model for the Stellar Initial Mass Function
Jessi Cisewski-Kehe1, Grant Weller2 , and Chad Schafer3
1

Department of Statistics & Data Science, Yale University, New Haven, CT 06511, USA; 2 United Health Group
Research & Development Minneapolis, MN 55430, USA; 3 Department of Statistics & Data Science, Carnegie Mellon
University, Pittsburgh, PA, 15213, USA
E-mail contact: jessica.cisewski at yale.edu
Accurate specification of a likelihood function is becoming increasingly difficult in many inference problems in astronomy. As sample sizes resulting from astronomical surveys continue to grow, deficiencies in the likelihood function leadto larger biases in key parameter estimates. These deficiencies result from the oversimplification of the physical processes that generated the data, and from the failure to account for observational limitations. Unfortunately, realistic
models often do not yield an analytical form for the likelihood. The estimation of a stellar initial mass function (IMF)
is an important example. The stellar IMF is the mass distribution of stars initially formed in a given cluster of stars, a
population which is not directly observable due to stellar evolution and other disruptions and observational limitationsof the cluster. There are several difficulties with specifying a likelihood in this setting since the physical processes
and observational challenges result in measurable masses that cannot legitimately be considered independent draws
from an IMF. This work improves inference of the IMF by using an approximate Bayesian computation approachthat both accounts for observational and astrophysical effects and incorporates a physically-motivated model for starcluster formation. The methodology is illustrated via a simulation study, demonstrating that the proposed approach
can recover the true posterior in realistic situations, and applied to observations from astrophysical simulation data.
Accepted by Electronic Journal of Statistics
https://arxiv.org/pdf/1904.11306.pdf

13Determining the recurrence timescale of long-lasting YSO outbursts
Carlos Contreras Peña1 , Tim Naylor1 and Sam Morrell1
1School of Physics, Astrophysics Group, University of Exeter, Stocker Road, Exeter EX4 4QL, UK

E-mail contact: c.contreras at exeter.ac.uk

9We have determined the rate of large accretion events in class I and II young stellar objects (YSOs) by comparing
the all-sky digitised photographic plate surveys provided by SuperCOSMOS with the latest data release from Gaia
(DR2). The long mean baseline of 55 years along with a large sample of class II YSOs (≃15,000) allows us to study
approximately 1 million YSO-years. We find 139 objects with ∆R ≥ 1 mag, most of which are found at amplitudes
between 1 and 3 mag. The majority of YSOs in this group show irregular variability or long-lasting fading events, which
is best explained as hot spots due to accretion or by variable extinction. There is a tail of YSOs at ∆R ≥ 3 mag andthey seem to represent a different population. Surprisingly many objects in this group show high-amplitude irregularvariability over timescales shorter than 10 years, in contrast with the view that high-amplitude objects always havelong outbursts. However, we find 6 objects that are consistent with undergoing large, long lasting accretion events, 3of them previously unknown. This yields an outburst recurrence timescale of 112 kyr, with a 68% confidence interval[74 to 180] kyr. This represents the first robust determination of the outburst rate in class II YSOs and shows thatYSOs in their planet-forming stage do in fact undergo large accretion events, and with timescales of ≃100,000 years.
In addition, we find that outbursts in the class II stage are ≃10 times less frequent than during the class I stage.
Accepted by MNRAS
https://arxiv.org/pdf/1904.04068

14

The JCMT BISTRO Survey: The Magnetic Field of the Barnard 1 Star-Forming Region
Simon Coudé1,2 , Pierre Bastien2 , Martin Houde3 , Sarah Sadavoy4 , Rachel Friesen5 , James Di Francesco6,7 ,Doug Johnstone6,7 , Steve Mairs8 , Tetsuo Hasegawa9 , Woojin Kwon10,11 , Shih-Ping Lai12,13 , Keping
Qiu14,15 , Derek Ward-Thompson16 , David Berry8 , Michael Chun-Yuan Chen6 , Jason Fiege17 , Erica
Franzmann17 , Jennifer Hatchell18 , Kevin Lacaille19,20 , Brenda C. Matthews6,7 , Gerald H. MoriartySchieven7 , Andy Pon3 and the B-fields In STar-forming Regions Observations (BISTRO) collaboration8
1

SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, M.S. N232-12,
Moffett Field, CA 94035, USA; 2 Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal,Département de Physique, C.P. 6128 Succ. Centre-ville, Montréal, QC, H3C 3J7, Canada; 3 Department of Physics andAstronomy, The University of Western Ontario, 1151 Richmond Street, London, ON, N6A 3K7, Canada; 4 HarvardSmithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138, USA; 5 National Radio Astronomy
Observatory, 520 Edgemont Rd., Charlottesville, VA, 22903, USA; 6 Department of Physics and Astronomy, Universityof Victoria, Victoria, BC, V8P 1A1, Canada; 7 NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich
Rd, Victoria, BC, V9E 2E7, Canada; 8 East Asian Observatory, 660 N. A‘ohōkū Place, University Park, Hilo, HI
96720, USA; 9 National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Osawa, Mitaka,
Tokyo 181-8588, Japan; 10 Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon
34055, Republic of Korea; 11 Korea University of Science and Technology, 217 Gajang-ro, Yuseong-gu, Daejeon 34113,
Republic of Korea; 12 Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu
30013, Taiwan; 13 Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan;
14
School of Astronomy and Space Science, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China; 15 Key
Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210023,
China; 16 Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, United Kingdom; 17
Department of Physics and Astronomy, The University of Manitoba, Winnipeg, MB, R3T 2N2, Canada; 18 Physics
and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, United Kingdom; 19 Department of Physics andAtmospheric Science, Dalhousie University, Halifax, NS, B3H 4R2, Canada; 20 Department of Physics and Astronomy,
McMaster University, Hamilton, ON, L8S 4M1, Canada
E-mail contact: scoude at usra.edu
We present the POL-2 850 µm linear polarization map of the Barnard 1 clump in the Perseus molecular cloud complex
from the B-fields In STar-forming Region Observations (BISTRO) survey at the James Clerk Maxwell Telescope. We
find a trend of decreasing polarization fraction as a function of total intensity, which we link to depolarization effects
towards higher density regions of the cloud. We then use the polarization data at 850 µm to infer the plane-of-sky
orientation of the large-scale magnetic field in Barnard 1. This magnetic field runs North-South across most of themolecular lines from the Green Bank Ammonia Survey (GAS) to estimate the strength of the plane-of-sky componentof the magnetic field through the Davis-Chandrasekhar-Fermi method. With a plane-of-sky amplitude of 120 ± 60 µG
and a criticality criterion λc = 3.0 ± 1.5, we find that Barnard 1 is a supercritical molecular cloud with a magnetic
field nearly dominated by its turbulent component.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/1904.07221

15

Ultraviolet extinction properties of the 30 Dor Nebula and interpreting observations of
starburst clusters
Guido De Marchi1 and Nino Panagia2
1

European Space Research and Technology Centre, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands; 2 Space
Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
E-mail contact: gdemarchi at esa.int

Recent investigation of the extinction law in 30 Dor and the Tarantula Nebula, at optical and near infrared wavelengths,
has revealed a ratio of total to selective extinction RV = AV /E(B − V ) of about 4.5. This indicates a larger fractionof big grains than in the Galactic diffuse interstellar medium (ISM). Possible origins include coalescence of small
grains, small grain growth, selective destruction of small grains, and fresh injection of big grains. From a studyof the ultraviolet extinction properties of three massive stars in the 30 Dor Nebula (R 139, R 140, R 145), observedwith the International Ultraviolet Explorer, we show that the excess of big grains does not come at the expense ofsmall grains, which are still present and possibly even more abundant. Fresh injection of large grains appears thedominant mechanism. A process able to naturally account for this in environments such as the Tarantula Nebula,where formation of massive stars has been ongoing for over ∼ 20 Myr, is the explosion of massive stars as type-II
supernovae. The ensuing change in the conditions of the ISM is only temporary, lasting less than ∼ 100 Myr, because
shattering and shocks will eventually break and destroy the bigger grains. However, this is the only time when starforming regions are detectable as such in starburst and high-redshift galaxies and we highlight the complexity inherent
in interpreting observations of star-forming regions in these environments. If the extinction characteristics are notknown properly, any attempts to derive quantitative physical parameters are bound to fail.
Accepted by ApJ
https://arxiv.org/pdf/1904.13395

16

Unveiling molecular clouds toward bipolar HII region G8.14+0.23
L. K. Dewangan1 , H. Sano2,3 , R. Enokiya3 , K. Tachihara3 , Y. Fukui2,3 and D. K. Ojha4
1

Physical Research Laboratory, Navrangpura, Ahmedabad - 380 009, India.; 2 Institute for Advanced Research,
Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.; 3 Department of Physics, Nagoya University,
Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.; 4 Department of Astronomy and Astrophysics, Tata Institute ofFundamental Research, Homi Bhabha Road, Mumbai 400 005, India.
E-mail contact: lokeshd at prl.res.in

Most recent numerical simulations suggest that bipolar H ii regions, powered by O-type stars, can be formed at theinterface of two colliding clouds. To observationally understand the birth of O-type stars, we present a detailed multiwavelength analysis of an area of 1 deg x 1 deg hosting G8.14+0.23 H ii region associated with an infrared bipolar
nebula (BPN). Based on the radio continuum map, the H ii region is excited by at least an O-type star, which islocated toward the waist of the BPN. The NANTEN2 13 CO line data reveal the existence of two extended clouds at[9, 14.3] and [15.3, 23.3] km s−1 toward the site G8.14+0.23, which are connected in the position-velocity space througha broad-bridge feature at the intermediate velocity range. A “cavity/intensity-depression” feature is evident in theblueshifted cloud, and is spatially matched by the “elongated redshifted cloud”. The spatial and velocity connectionsof the clouds suggest their interaction in the site G8.14+0.23. The analysis of deep near-infrared photometric data
reveals the presence of clusters of infrared-excess sources, illustrating ongoing star formation activities in both theclouds. The O-type star is part of the embedded cluster seen in the waist of the BPN, which is observed toward thespatial matching zone of the cavity and the redshifted cloud. The observational results appear to be in reasonable11

agreement with the numerical simulations of cloud-cloud collision (CCC), suggesting that the CCC process seems to
be responsible for the birth of the O-type star in G8.14+0.23.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/1904.10708.pdf

17Observational signatures of end-dominated collapse in the S242 filamentary structure
L. K. Dewangan1 , L. E. Pirogov2 , O. L. Ryabukhina2,3 , D. K. Ojha4 and I. Zinchenko2
1

Physical Research Laboratory, Navrangpura, Ahmedabad - 380 009, India; 2 Institute of Applied Physics of theRussian Academy of Sciences, 46 Ulyanov st., Nizhny Novgorod 603950, Russia; 3 Institute of Astronomy of the Russian
Academy of Sciences, 48 Pyatnitskaya st., Moscow 119017, Russia; 4 Department of Astronomy and Astrophysics, Tata
Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
E-mail contact: lokeshd at prl.res.in
We present new CO (13 CO(1–0) and C18 O(1–0)) and CS(2–1) line observations of an elongated filamentary structure(length ∼30 pc) in the star-forming site S242, which were taken with the OSO-20m telescope. One filament’s end hosts
the S242 H ii region, while the other end contains Planck cold clumps. Several sub-regions are identified in the filament,
and are supersonic with Mach number of 2.7–4.0. The study of the dynamical states shows supercritical nature of the
sub-regions (except central part), which could not be supported by a combination of thermal and turbulent motions.
Young stellar objects are seen toward the entire filament, but more concentrated toward its ends. Dense molecularcores are observed mainly toward the filament ends, and are close to virial equilibrium. Position-velocity plots trace
velocity gradients (∼1 km s−1 pc−1 ) toward both the ends. An oscillatory pattern in velocity is also observed toward
the filament, indicating its fragmentation. The collapse timescale of the filament is computed to be ∼3.5 Myr. Using
the 13 CO data, the structure function in velocity of the filament is found to be very similar as seen in the Musca
cloud for lags ∼1–3 pc, and deviates from the Larson’s velocity-size relationship. The observed oscillatory patternin the structure function at higher lags suggests the existence of large-scale and ordered velocity gradients as well as
the fragmentation process through accretion along the filament. Considering all the observed results along with theiruncertainties, the S242 filament is a very good example of the end-dominated collapse.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/1904.07639.pdf

18

Using Multiwavelength Variability to Explore the Connection between X-ray Emission,
the Far-Ultraviolet H2 Bump, and Accretion in T Tauri Stars
C.C. Espaillat1 , C. Robinson1 , S. Grant1 and M. Reynolds2
1
Department of Astronomy & The Institute for Astrophysical Research, Boston University, 725 CommonwealthAvenue, Boston, MA 02215, USA; 2 Department of Astronomy, University of Michigan, 830 Dennison Building, 500
Church Street, Ann Arbor, MI 48109, USA

E-mail contact: cce at bu.edu
The high-energy radiation fields of T Tauri stars (TTS) should affect the surrounding circumstellar disk, having
implications for disk transport and heating. Yet, observational evidence of the effect of high-energy fields on disks
is scarce. Here we investigate the connection between X-ray emission and the innermost gas disk by leveraging thevariability of TTS. We obtained multiple epochs of coordinated data (taken either simultaneously or within a few
hours) of accreting TTS with the Hubble Space Telescope, the Neil Gehrels Swift Observatory, and the Chandra X-ray
Observatory. We measured the far-ultraviolet (FUV) H2 bump feature at 1600 Å, which traces gas < 1 AU fromthe star; the near-ultraviolet (NUV) emission, from which we extract the accretion luminosity; and also the X-ray
luminosity. We do not find a correlation between the FUV H2 bump and X-ray luminosity. Therefore, an observable
tracer of the effect of X-ray ionization in the innermost disk remains elusive. We report a correlation between the FUV
H2 bump and accretion luminosity, linking this feature to the disk surface density. We also see a correlation between
the X-ray luminosity and the accretion column density, implying that flaring activity may influence accretion. These
results stress the importance of coordinated multiwavelength work to understand TTS.

12

Accepted by ApJ
https://arxiv.org/pdf/1904.05458

19

Maser Flare Simulations from Oblate and Prolate Clouds
M. D. Gray1 , J. Baggott1 , J. Westlake1 and S. Etoka1
1

Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, M13 9PL, UK

E-mail contact: Malcolm.Gray at manchester.ac.uk
We investigated, through numerical models, the flaring variability that may arise from the rotation of maser clouds
of approximately spheroidal geometry, ranging from strongly oblate to strongly prolate examples. Inversion solutions
were obtained for each of these examples over a range of saturation levels from unsaturated to highly saturated. Formal
solutions were computed for rotating clouds with many randomly chosen rotation axes, and corresponding averaged
maser light curves plotted with statistical information. The dependence of results on the level of saturation and on
the degree of deformation from the spherical case were investigated in terms of a variability index and duty cycle.
It may be possible to distinguish observationally between flares from oblate and prolate objects. Maser flares fromrotation are limited to long timescales (at least a few years) and modest values of the variability index (≤ 100), andcan be aperiodic or quasi-periodic. Rotation is therefore not a good model for H2 O variability on timescales of weeks
to months, or of truly periodic flares.
Accepted by MNRAS
https://arxiv.org/pdf/1904.10347

20

Proper Motions and Shock Wave Dynamics in the HH 7–11 Stellar Jet
P. Hartigan1 , R. Holcomb1 , and A. Frank2
1
Physics and Astronomy Dept., Rice University, Houston, TX, USA; 2 Physics and Astronomy Dept., University ofRochester, Rochester NY, USA

E-mail contact: hartigan at sparky.rice.edu
We have used the Hubble Space Telescope to acquire new broad-band and narrow-band images of the optical line
emission and red continuum associated with the HH 7–11 stellar jet in the NGC 1333 star formation region. Combining
the new narrow-band images of Hα, [OI] λ6300 and [SII] λ6716 allows us to measure electron densities and excitations
at each point in the outflow with the spatial resolution of HST, while the I-band image traces out the boundary of thecavity evacuated by the outflow. Comparing these images with those taken ∼20 years ago yields high precision propermotions for all the HH objects in the outflow. HH 11 is a bullet-like clump, and emerges from the exciting source SVS
13A towards the Earth at 24 degrees to line of sight. In contrast, HH 8 and HH 10 consist of two rings of shocked gasthat show no bulk proper motions even though the emitting gas is blueshifted. The HH 8 rings are expanding withtime. These shocks mark places where ambient material located along the path of the jet redirects the outflow. HH
7 consists of multiple shells, and emits strongly in H2 in what appears to be a terminal bow shock for the outflow,
implying that the jet has yet to fully break out of its nascent cloud core. The jet largely fragments into clumps by
the time it reaches HH 7. As in the case of HH 110, deflection from ambient material plays a key role in producing
observable shock waves in the HH 7–11 outflow.
Accepted by ApJ
https://arxiv.org/pdf/1904.05983.pdf

21

An initial overview of the extent and structure of recent star formation within the
Serpens Molecular Cloud using Gaia Data Release 2
Gregory J. Herczeg1 , Michael A. Kuhn2 , Xingyu Zhou1,3 , Jennifer Hatchell4 , Carlo Manara5 , Doug
Johnstone6,7 , Michael Dunham8 , Anupam Bhardwaj1 , Jessy Jose9 and Zhen Yuan10
1

KIAA, Peking University; 2 Caltech; 3 Department of Astronomy, Peking University; 4 University of Exeter; 5European Southern Observatory; 6 NRC Herzberg Astronomy and Astrophysics,; 7 University of Victoria; 8 State
13

University of New York at Fredonia; 9 Indian Institute of Science Education and Research Tirupati; 10 Shanghai
Astronomical Observatory
E-mail contact: gherczeg1 at gmail.com
The dense clusters within the Serpens Molecular Cloud are among the most active regions of nearby star formation.
In this paper, we use Gaia DR2 parallaxes and proper motions to statistically measure ∼ 1167 kinematic members of
Serpens, few of which were previously identified, to evaluate the star formation history of the complex. The opticalmembers of Serpens are concentrated in three distinct groups located at 380–480 pc; the densest clusters are still highly
obscured by optically-thick dust and have few optical members. The total population of young stars and protostars
in Serpens is at least 2000 stars, including past surveys that were most sensitive to protostars and disks, and may
be far higher. Distances to dark clouds measured from deficits in star counts are consistent with the distances tothe optical star clusters. The Serpens Molecular Cloud is seen in the foreground of the Aquila Rift, dark clouds
located at 600–700 pc, and behind patchy extinction, here called the Serpens Cirrus, located at ∼ 250 pc. Based on
the lack of a distributed population of older stars, the star formation rate throughout the Serpens Molecular Cloud
increased by at least a factor of 20 within the past ∼ 5 Myr. The optically bright stars in Serpens Northeast are
visible because their natal molecular cloud has been eroded and not because they were flung outwards from a central
factory of star formation. The separation between subclusters of 20–100 pc and the absence of an older population
leads to speculation that an external forcing was needed to trigger the active star formation.
Accepted by ApJ
https://arxiv.org/pdf/1904.04085

22

Driving Conditions of Protostellar Outflows in Different Star-Forming Environments
Koki Higuchi1 , Masahiro N. Machida1 and Hajime Susa2
1

Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan; 2
Department of Physics, Konan University, Okamoto, Kobe, 658-8501, Japan
E-mail contact: higuchi.koki.054 at s.kyushu-u.ac.jp
The evolution of collapsing clouds embedded in different star-forming environments is investigated using threedimensional non-ideal magnetohydrodynamics simulations considering different cloud metallicities (Z/ Z⊙ = 0, 10−5 ,10−4 , 10−3 , 10−2 , 10−1 and 1) and ionisation strengths (Cζ =0, 0.01, 1 and 10, where Cζ is a coefficient controllingthe ionisation intensity and Cζ = 1 corresponds to the ionisation strength of nearby star-forming regions). With all
combinations of these considered values of Z/ Z⊙ and Cζ , 28 different star-forming environments are prepared andsimulated. The cloud evolution in each environment is calculated until the central density reaches n ≈ 1016 cm−3 justbefore protostar formation, and the outflow driving conditions are derived. An outflow appears when the (first) adiabatic core forms in a magnetically active region where the magnetic field is well coupled with the neutral gas. In cases
where outflows are driven, their momentum fluxes are always comparable to the observations of nearby star-forming
regions. Thus, these outflows should control the mass growth of the protostars as in the local universe. Roughly,
an outflow appears when Z/ Z⊙ > 10−4 and Cζ ≥ 0.01. It is expected that the transition of the star formation
mode from massive stars to normal solar-type stars occurs when the cloud metallicity is enhanced to the range of
Z/ Z⊙ ≈ 10−4 –10−3 , above which relatively low-mass stars would preferentially appear as a result of strong massejection.
Accepted by MNRAS
http://arxiv.org/pdf/1904.06078

23

Sulfur Chemistry in L1157-B1
Jonathan Holdship1, Izaskun Jimenez-Serra2 , Serena Viti1 , Claudio Codella3,4 , Milena Benedettini5
Francesco Fontani3 , Mario Tafalla6 , Rafael Bachiller6 and Cecilia Ceccarelli7,81Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT; 2 Centro de
Astrobiologa (CSIC, INTA), Ctra. de Ajalvir, km. 4, Torrejn de Ardoz, E-28850 Madrid, Spain; 3 INAF, Osservatorio
Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy; 4 Univ. Grenoble Alpes, Institut de Plantologie etd’Astrophysique de Grenoble (IPAG), 38401 Grenoble, France; 5 INAF, Istituto di Astrofisica e Planetologia Spaziali,
14via Fosso del Cavaliere 100, I-00133 Roma, Italy; 6 IGN, Observatorio Astronómico Nacional, Calle Alfonso XII,
E-28014 Madrid, Spain; 7 Univ. Grenoble Alpes, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG),
38401 Grenoble, France; 8 CNRS, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), 38401 Grenoble,
FranceE-mail contact: ijimenez at cab.inta-csic.es
The main carrier of sulfur in dense clouds, where it is depleted from the gas phase, remains a mystery. Shock waves inyoung molecular outflows disrupt the ice mantles and allow us to directly probe the material that is ejected into thegas phase. A comprehensive study of sulfur-bearing species towards L1157-B1, a shocked region along a protostellar
outflow, has been carried out as part of the IRAM-30m large program ASAI. The dataset contains over 100 linesof CCS, H2 CS, OCS, SO, SO2 and isotopologues. The results of these observations are presented, complementing
previous studies of sulfur-bearing species in the region. The column densities and fractional abundances of these
species are measured and together these species account for 10% of the cosmic sulfur abundance in the region. The
gas properties derived from the observations are also presented, demonstrating that sulfur bearing species trace a wide
range of different gas conditions in the region.
Accepted by ApJ
https://arxiv.org/pdf/1904.10895.pdf

24Observations of CH3 OH and CH3 CHO in a Sample of Protostellar Outflow Sources
Jonathan Holdship1, Serena Viti1 , Claudio Codella2,3 , Jonathan Rawlings1 and Izaskun Jimenez-Serra4 ,Yenabeb Ayalew5 , Justin Curtis6 , Annur Habib6 , Jamel Lawrence6 , Sumaya Warsame6 and Sarah Horn6
1

Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT; 2 INAF,
Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy; 3 Univ. Grenoble Alpes, Institut dePlantologie et d?Astrophysique de Grenoble (IPAG), 38401 Grenoble, France; 4 Centro de Astrobiologa (CSIC, INTA),
Ctra. de Ajalvir, km. 4, Torrejn de Ardoz, E-28850 Madrid, Spain; 5 Hammersmith Academy, London, UK; 6
Hammersmith Academy, 25 Cathnor Road, London, W12 9JD
E-mail contact: jrh at star.ucl.ac.uk
IRAM 30-m Observations towards eight protostellar outflow sources were taken in the 96–176 GHz range. Transitionsof CH3 OH and CH3 CHO were detected in seven of them. The integrated emission of the transitions of each species
that fell into the observed frequency range were measured and fit using RADEX and LTE models. Column densities
and gas properties inferred from this fitting are presented. The ratio of the A and E-type isomers of CH3 OH indicatethat the methanol observed in these outflows was formed on the grain surface. Both species demonstrate a reductionof terminal velocity in their line profiles in faster outflows, indicating destruction in the post-shock gas phase. This
destruction, and a near constant ratio of the CH3 OH and CH3 CHO column densities imply it is most likely that
CH3 CHO also forms on the grain surface.

Accepted by ApJ
https://arxiv.org/pdf/1904.11360.pdf

25

On the origin of very massive stars around NGC 3603
V.M. Kalari1,2 , J.S. Vink3 , W.J. de Wit4 , N.J. Bastian5 & R.A. Méndez2
1
Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena, Chile; 2 Departamento de
Astronomı́a, Universidad de Chile, Casilla 36-D Santiago, Chile; 3 Armagh Observatory, College Hill, Armagh, BT61
9DG, UK; 4 European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago, Chile; 5 Astrophysics
Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK

E-mail contact: tvkalari at gemini.edu
The formation of the most massive stars in the Universe remains an unsolved problem. Are they able to form in
relative isolation in a manner similar to the formation of solar-type stars, or do they necessarily require a clusteredenvironment? In order to shed light on this important question, we study the origin of two very massive stars(VMS): the O2.5If∗ /WN6 star RFS7 (∼100 M⊙ ), and the O3.5If∗ star RFS8 (∼70 M⊙ ), found within ≈ 53 and15

58 pc respectively from the Galactic massive young cluster NGC 3603, using Gaia data. RFS7 is found to exhibit
motions resembling a runaway star from NGC 3603. This is now the most massive runaway star candidate known in
the Milky Way. Although RFS8 also appears to move away from the cluster core, it has proper-motion values thatappear inconsistent with being a runaway from NGC 3603 at the 3σ level (but with substantial uncertainties due todistance and age). Furthermore, no evidence for a bow-shock or a cluster was found surrounding RFS8 from available
near-infrared photometry. In summary, whilst RFS7 is likely a runaway star from NGC 3603, making it the first
VMS runaway in the Milky Way, RFS8 is an extremely young (∼2 Myr) VMS, which might also be a runaway, but
this would need to be established from future spectroscopic and astrometric observations, as well as precise distances.
If RFS8 were still not meeting the criteria for being a runaway from NGC 3603 from such future data, this would
have important ramifications for current theories of massive star formation, as well as the way the stellar initial massfunction (IMF) is sampled.
Accepted by A&A
https://arxiv.org/pdf/1904.02126.pdf

26

Merged H/H2 and C+/C/CO transitions in the Orion Bar
Maria S. Kirsanova1 and Dmitri S. Wiebe1
1Institute of Astronomy, Russian Academy of Sciences

E-mail contact: kirsanova at inasan.ru
High-resolution ALMA images towards the Orion Bar show no discernible offset between the peak of H2 emission
in the photodissociation region (PDR) and the 13CO(3-2) and HCO+(4-3) emission in the molecular region. Thisimplies that positions of H2 and CO dissociation fronts are indistinguishable in the limit of ALMA resolution. We
use the chemo-dynamical model MARION to show that the ALMA view of the Orion Bar, namely, no appreciableoffset between the 13CO(3-2) and HCO+(4-3) peaks, merged H2 and CO dissociation fronts, and high intensityof HCO+(4-3) emission, can only be explained by the ongoing propagation of the dissociation fronts through themolecular cloud, coupled to the dust motion driven by the stellar radiation pressure, and are not reproduced in themodel where the dissociation fronts are assumed to be stationary. Modelling line intensities, we demonstrate thatafter the fronts have merged, the angular separation of the 13CO(3-2) and HCO+(4-3) peaks is indeed unresolvablewith the ALMA observations. Our model predictions are consistent with the results of the ALMA observations about
the relation of the bright HCO+(4-3) emission to the compressed gas at the border of the PDR in the sense thatthe theoretical HCO+(4-3) peak does correspond to the gas density enhancement, which naturally appears in the
dynamical simulation, and is located near the H2 dissociation front at the illuminated side of the CO dissociation
front.
Accepted by MNRAS
https://arxiv.org/pdf/1904.04423

27

Massive Young Stellar Objects and Outflow in the Infrared-Dark Cloud G79.3+0.3
Anna S.E. Laws1,2 , Joseph L. Hora3 and Qizhou Zhang3
1

Astrophysics Group, University of Exeter, Stocker Road, Exeter, EX4 4QL, U.K.; 2 School of Physics and Astronomy,
University of Southampton, Highfield, Southampton SO17 1BJ, UK; 3 Center for Astrophysics
E-mail contact: al630 at exeter.ac.uk
G79.3+0.3 is an infrared dark cloud in the Cygnus-X complex that is home to massive deeply embedded young stellar
objects (YSOs). We have produced a submillimeter array (SMA) 1.3 mm continuum image and 12 CO line maps ofthe eastern section of G79.3+0.3 in which we detect five separate YSOs. We have estimated physical parameters
for these five YSOs and others in the vicinity of G79.3+0.3 by fitting existing photometry from Spitzer, Herschel,and ground-based telescopes to spectral energy distribution models. Through these model fits we find that the most
massive YSOs seen in the SMA 1.3 mm continuum emission have masses in the 5 − 6 Msun range. One of the SMA
sources was observed to power a massive collimated 12 CO outflow extending at least 0.94 pc in both directions fromthe protostar, with a total mass of 0.83 Msun and a dynamical timescale of 23 kyr.

16

Accepted by ApJ
https://arxiv.org/pdf/1904.12517

28

Development of models for nearby young stellar moving groups: creation, revision, andfinalisation of the models
Jinhee Lee1 and Inseok Song1
1The University of Georgia, Department of Physics and Astronomy, Athens, GA 30605, USA

E-mail contact: jinhee at uga.edu
Lee & Song (2018, Paper 1) developed a tool for calculating Bayesian membership probability for nearby youngstellar moving groups (BAMG: Bayesian Analysis of Moving Groups). The study presented the importance of carefulconstruction of models in moving group membership assessment, using β Pictoris moving group as a test case. In thisstudy, we build models for all major nearby young stellar moving groups (NYMGs hereafter) through 4 stages. A setof prototype models is created using members listed in the discovery paper of each group. For each group, suggested
members after the discovery of the group are used for revising these prototype models. As these additional members
being incorporated, group properties of a NYMG changes, thus membership probabilities change as well. A subsetof stars show consistently large membership probabilities regardless of the details of a chosen method for ingesting
additional members. Utilising these members, the NYMG models are finalised. The finalised models are applied
for evaluating memberships of all claimed candidate members, resulting in a list of bona fide members. The massfunction of bona fide members for the entire set of NYMG members indicates that more late-M type members should
be identified. In addition, some objects showing a large difference in membership probability between BAMG andBANYAN Σ (Gagne et al. 2018b) are presented and discussed. Memberships of some planet host stars are changed,
and it can have a significant influence on the estimated planetary masses.
Accepted by MNRAS
https://arxiv.org/pdf/1904.07157.pdf

29

The First Two Thousand Years of Star Formation
Masahiro N. Machida1 and Shantanu Basu2
1

Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan; 2
Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
E-mail contact: machida.masahiro.018 at m.kyushu-u.ac.jp
Starting from a prestellar core with a size of 1.2 × 104 AU, we calculate the evolution of a gravitationally collapsingcore until ∼ 2000 yr after protostar formation using a three-dimensional resistive magnetohydrodynamic simulation, in
which the protostar is resolved with a spatial resolution of 5.6 × 10−3 AU. Following protostar formation, a rotationally
supported disk is formed. Although the disk size is as small as ∼ 2 − 4 AU, it remains present until the end of thesimulation. Since the magnetic field dissipates and the angular momentum is then not effectively transferred bymagnetic effects, the disk surface density gradually increases and spiral arms develop due to gravitational instability.
The disk angular momentum is then transferred mainly by gravitational torques, which induce an episodic massaccretion onto the central protostar. The episodic accretion causes a highly time-variable mass ejection (the highvelocity jet) near the disk inner edge, where the magnetic field is well coupled with the neutral gas. As the mass ofthe central protostar increases, the jet velocity gradually increases and exceeds ∼ 100 km s−1 . The jet opening angle
widens with time at its base, while the jet keeps a very good collimation on the large scale. In addition, a low-velocity
outflow is driven from the disk outer edge. A cavity-like structure, a bow shock and several knots, all of which areusually observed in star-forming regions, are produced in the outflowing region.
Accepted by ApJ
https://arxiv.org/pdf/1904.04424

17

30

Excitation of Planetary Obliquities Through Planet-Disk Interactions
Sarah Millholland1,3, and Konstantin Batygin2
1

Department of Astronomy, Yale University, New Haven, CT 06511, USA; 2 Division of Geological and Planetary
Sciences, California Institute of Technology, Pasadena, CA 91125, USA
E-mail contact: sarah.millholland at yale.edu
The tilt of a planet’s spin axis off its orbital axis (“obliquity”) is a basic physical characteristic that plays a central
role in determining the planet’s global circulation and energy redistribution. Moreover, recent studies have also
highlighted the importance of obliquities in sculpting not only the physical features of exoplanets but also their orbital
architectures. It is therefore of key importance to identify and characterize the dominant processes of excitation of
non-zero axial tilts. Here we highlight a simple mechanism that operates early on and is likely fundamental for many
extrasolar planets and perhaps even Solar System planets. While planets are still forming in the protoplanetary disk,
the gravitational potential of the disk induces nodal recession of the orbits. The frequency of this recession decreases
as the disk dissipates, and when it crosses the frequency of a planet’s spin axis precession, large planetary obliquities
may be excited through capture into a secular spin-orbit resonance. We study the conditions for encountering thisresonance and calculate the resulting obliquity excitation over a wide range of parameter space. Planets with semimajor axes in the range 0.3 AU <∼a<
∼ 2 AU are the most readily affected, but large-a planets can also be impacted.
We present a case study of Uranus and Neptune and show that this mechanism likely cannot help explain their highobliquities. While it could have played a role if finely tuned and envisioned to operate in isolation, large-scale obliquity
excitation was likely inhibited by gravitational planet-planet perturbations.
Accepted by ApJ
https://arxiv.org/pdf/1904.07338.pdf

31

Evolution of young protoclusters embedded in dense massive clumps. A new grid of
population synthesis SED models and a new set of L/M evolutionary tracks
Sergio Molinari1 , Adriano Baldeschi1 , Thomas P. Robitaille2, Esteban F.E. Morales2,5 , Eugenio Schisano1 ,Alessio Traficante1 , Manuel Merello,1, Marco Molinaro3 , Fabio Vitello4 , Eva Sciacca4 and Scige J. Liu1
1

Istituto Nazionale di Astrofisica - IAPS, Via Fosso del Cavaliere 100, I-00133 Roma, Italy; 2 Max Planck Institutefor Astronomy, Königstuhl 17, D-69117, Heidelberg, Germany; 3 Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Trieste, Via Bazzoni 2, I-34124 Trieste, Italy; 4 Istituto Nazionale di Astrofisica - Osservatorio Astrofisico
di Catania, Via S. Sofia 78, I-95123 Catania, Italy; 5 I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77,
50937, Köln, Germany.
E-mail contact: molinari at iaps.inaf.it
A grid of 20 millions 3–1100 µm SED models is presented for synthetic young clusters embedded in dense clumps.
The models depend on four primary parameters: the clump mass Mclump and dust temperature Tdust , the fraction ofmass fcore locked in dense cores, and the age of the clump tSF . We populate the YSO clusters using the IMF fromKroupa (2001) and the YSOs SED models grid of Robitaille et al. (2006). We conduct extensive testing of SED fitting
using a simulated dataset and we find that Mclump essentially depends on the submillimeter portion of the SED, while
Tdust is mostly determined from the shape of the SED in the 70–350 µm range. Thanks to the large number of models
computed we verify that the combined analysis of L/M , [8 − 24] and [24 − 70] colours removes much of the SEDs
fcore –tSF degeneracy. The L/M values are particularly useful to diagnose fcore . L/M ≤ 1 identifies protoclusters
5
with fcore ≤ 0.1 and tSF <∼ 10 years, while L/M ≥ 10 excludes fcore ≤ 0.1. We characterize lower limits of L/M
where ZAMS stars are not found in models, and we also find models with L/M ≥ 10 and no ZAMS stars, in which[8 − 24] >∼ 0.8 ± 0.1 independently from Mclump, temperature and luminosity. This is the first set of synthesis SED
models suited to model for embedded and unresolved clusters of YSOs. A set of new evolutionary tracks in the L/M
diagram is also presented.
Accepted by MNRAS
https://arxiv.org/pdf/1904.08140.pdf

18

32

The Inner Disk and Accretion Flow of the Close Binary DQ Tau
James Muzerolle1 , Kevin Flaherty2 , Zoltan Balog3 , Tracy Beck1 and Robert Gutermuth4
1

Space Telescope Science Institute, 3700 San Martin Dr., Baltimore MD 21218, USA; 2 Department of Astronomy
and Department of Physics, Williams College, Williamstown, MA 01267, USA; 3 Center for Astronomy, University of
Heidelberg, Heidelberg, Germany; 4 Dept. of Astronomy, University of Massachusetts, Amherst, MA 01003, USA
E-mail contact: muzerol at stsci.edu
We present multi-epoch optical and near-infrared (NIR) photometry and spectroscopy of the spectroscopic binary T
Tauri star DQ Tau. The photometric monitoring, obtained using SMARTS ANDICAM, recovers the previously-seencorrelation between optical flux and the 15.8-day binary orbital period, with blue flux peaks occurring close to mostobserved periastron passages. For the first time, we find an even more consistent correlation between orbital period
and NIR brightness and color. The onset of pulse events in the NIR on average precedes those in the optical by a few
days, with the rise usually starting near apastron orbital phase. We further obtained five epochs of spectroscopy using
IRTF SpeX, with a wavelength range of 0.8 to 5 microns, and derived spectra of the infrared excess emission. The
shape and strength of the excess varies with time, with cooler and weaker characteristic dust emission (T ∼ 1100−1300
K) over most of the binary orbit, and stronger/warmer dust emission (T ∼ 1600 K, indicative of dust sublimation)
just before periastron passage. We suggest our results are broadly consistent with predictions of simulations of disk
structure and accretion flows around close binaries, with the varying dust emission possibly tracing the evolution ofaccretion streams falling inwards through a circumbinary disk cavity and feeding the accretion pulses traced by the
optical photometry and NIR emission lines. However, our results also show more complicated behavior that is not
fully explained by this simple picture, and will require further observations and modeling to fully interpret.
Accepted by ApJ
https://arxiv.org/pdf/1904.06424

33

Rapid destruction of protoplanetary discs due to external photoevaporation in starforming regions
Rhana B. Nicholson1,2 , Richard J. Parker2 , Ross P. Church3 , Melvyn B. Davies3 , Niamh M. Fearon4
and Sam R. J. Walton1
1

Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK; 2
Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH,
UK; 3 Department of Astronomy and Theoretical Physics, Lund Observatory, Box 43, SE-221 00 Lund, Sweden; 4
School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
E-mail contact: R.B.Nicholson at 2011.ljmu.ac.uk

We analyse N -body simulations of star-forming regions to investigate the effects of external far and extreme ultraviolet photoevaporation from massive stars on protoplanetary discs. By varying the initial conditions of simulatedstar-forming regions, such as the spatial distribution, net bulk motion (virial ratio), and density, we investigate whichparameters most affect the rate at which discs are dispersed due to external photoevaporation. We find that discdispersal due to external photoevaporation is faster in highly substructured star-forming regions than in smooth andcentrally concentrated regions. Sub-virial star-forming regions undergoing collapse also show higher rates of discdispersal than regions that are in virial equilibrium or are expanding. In moderately dense (∼100 M⊙ pc−3 ) regions,half of all protoplanetary discs with radii ≥100 AU are photoevaporated within 1 Myr, three times faster than iscurrently suggested by observational studies. Discs in lower-density star-forming regions (∼10 M⊙ pc−3 ) survive forlonger, but half are still dispersed on short timescales (∼2 Myr). This demonstrates that the initial conditions of thestar forming regions will greatly impact the evolution and lifetime of protoplanetary discs. These results also imply
that either gas giant planet formation is extremely rapid and occurs before the gas component of discs is evaporated,or gas giants only form in low-density star-forming regions where no massive stars are present to photoevaporate gas
from protoplanetary discs.
Accepted by MNRAS
http://adsabs.harvard.edu/pdf/2019MNRAS.485.4893N
http://arxiv.org/pdf/1902.11094

19

34

Revealing dust segregation in protoplanetary discs with the help of multi-frequency
spectral index maps
Yaroslav Pavlyuchenkov1 , Vitaly Akimkin1 , Dmitri Wiebe1 and Eduard Vorobyov2,31

Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya str. 48, Moscow, 119017, Russia; 2 Instituteof Physics, Southern Federal University, Rostov-on-Don, 344090, Russia; 3 University of Vienna, Department of
Astrophysics, Vienna, 1180, Austria
E-mail contact: pavyar at inasan.ru
Dust is known to drift and grow in protoplanetary discs, which results in dust segregation over the disc extent. Mapsof the spectral index α are a common tool for studying the dust content in protoplanetary discs. The analysis ofobservationally derived maps reveals significant gradients of the spectral index, confirming that dust evolves in thedisc, but a more detailed information about the dust redistribution is required to make inferences about the earlystages of dust growth. We calculated the spectral index maps based on the results of numerical hydrodynamical
simulations using the FEOSAD code, which allows studying a long-term dynamics of a self-gravitating viscous disc
populated with coagulating, drifting, and fragmenting dust. Here we demonstrate that values of the spectral index
estimated for different wavelength intervals within the far-infrared and radio bands reveal the presence of dust grainsof various sizes. Specifically, we show that the disc regions with the maximal spectral index in a specific wavelengthinterval are the regions with the prevalence of dust grains of a specific size. Thus, a set of spectral index maps derived
using different wavelength intervals can be used to recover the dust size-distribution over the disc extent.
Accepted by MNRAS, 2019https://arxiv.org/pdf/1904.05251

35

The dispersal of protoplanetary discs I: A new generation of X-ray photoevaporation
models
Giovanni Picogna1 , Barbara Ercolano1,2 , James E. Owen3 , Michael L. Weber1
1

Universitäts-Sternwarte, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 München, Germany; 2Excellence Cluster Origin and Structure of the Universe, Boltzmannstr. 2, 85748 Garching bei München, Germany; 3
Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK
E-mail contact: picogna at usm.lmu.de
Photoevaporation of planet forming discs by high energy radiation from the central star is potentially a crucial
mechanism for disc evolution and it may play an important role in the formation and evolution of planetary system.
We present here a new generation of X-ray photoevaporation models for solar-type stars, based on a new set ofhydrodynamical simulations, which account for stellar irradiation via a new, significantly improved, parameterisationof gas temperatures, based on detailed photoionisation and radiation transfer calculations. This is the first of a seriesof papers aiming at providing a library of models which cover the observed parameter space in stellar and disc mass,
metallicity and stellar X-ray properties. We focus here on solar-type stars (0.7 M⊙ ) with relatively low-mass discs(1% of the stellar mass) and explore the dependence of the wind mass loss rates on stellar X-ray luminosity. We model
primordial discs as well as transition discs at various stages of evolution. Our 2D hydrodynamical models are thenused to derive simple recipes for the mass loss rates that are suitable for inclusion in one-dimensional disc evolution
and/or planet formation models typically employed for population synthesis studies. Line profiles from typical winddiagnostics ([OI] 6300 Å and [NeII] 12.8 µm) are also calculated for our models and found to be roughly in agreementwith previous studies. Finally, we perform a population study of transition discs by means of one-dimensional viscous
evolution models including our new photoevaporation prescription and find that roughly a half of observed transition
discs cavities and accretion rates could be reproduced by our models.
Accepted by MNRAS

https://arxiv.org/pdf/1904.02752.pdf

20

36

A tale of two clusters: dynamical history determines disc survival in Tr14 and Tr16 in
the Carina Nebula
Megan Reiter1 and Richard J. Parker2
1

UK Astronomy Technology Centre; 2 University of SheffieldE-mail contact: megan.reiter at stfc.ac.uk
Understanding how the birthplace of stars affects planet-forming discs is important for a comprehensive theory ofplanet formation. Most stars are born in dense star-forming regions where the external influence of other stars,
particularly the most massive stars, will affect the survival and enrichment of their planet-forming discs. Simulations
suggest that stellar dynamics play a central role in regulating how external feedback affects discs, but comparing
models to observations requires an estimate of the initial stellar density in star-forming regions. Structural analyses
constrain the amount of dynamical evolution a star-forming region has experienced; regions that maintain substructureand do not show mass segregation are likely dynamically young, and therefore close to their birth density. In thispaper, we present a structural analysis of two clusters in the Carina Nebula, Tr14 and Tr16. We show that neither
cluster shows evidence for mass segregation or a centrally concentrated morphology, suggesting that both regions are
dynamically young. This allows us to compare to simulations from Nicholson et al. (2019) who predict disc survival
rates in star-forming regions of different initial densities. The surviving disc fractions in Tr14 and Tr16 are consistent
with their predictions (both are ∼ 10%), supporting a growing body of evidence that the star-forming environment
plays an important role in the survival and enrichment of protoplanetary discs.
Accepted by MNRAS
https://arxiv.org/pdf/1904.09902

37

ALMA reveals a pseudo-disc in a proto-brown dwarf
B. Riaz1 , M. N. Machida2 and D. Stamatellos3
1

LMU, Munich; 2 Kyushu University, Japan; 3 University of Central Lancashire, UK

E-mail contact: basriaz at gmail.com
We present the observational evidence of a pseudo-disc around the proto-brown dwarf Mayrit 1701117, the driving
source of the large-scale HH 1165 jet. Our analysis is based on ALMA 12 CO (2-1) line and 1.37 mm continuum
observations at an angular resolution of ∼0.4′′ . The pseudo-disc is a bright feature in the CO position-velocity
diagram (PVD), elongated in a direction perpendicular to the jet axis, with a total (gas+dust) mass of ∼0.02 M⊙ ,size of 165-192 AU, and a velocity spread of ±2 km s−1 . The large velocity gradient is a combination of infalling
and rotational motions, indicating a contribution from a pseudo-disc and an unresolved inner Keplerian disc. Thereis weak emission detected in the H2 CO (3-2) and N2 D+ (3-2) lines. H2 CO emission likely probes the inner Keplerian
disc where CO is expected to be frozen, while N2 D+ possibly originates from an enhanced clump at the outer edge ofthe pseudo-disc. We have considered various models (core collapse, disc fragmentation, circum-binary disc) that can
fit both the observed CO spectrum and the position-velocity offsets. The observed morphology, velocity structure,and the physical dimensions of the pseudo-disc are consistent with the predictions from the core collapse simulations
for brown dwarf formation. From the best model fit, we can constrain the age of the proto-brown dwarf system tobe ∼30,000-40,000 yr. A comparison of the H2 column density derived from the CO line and 1.37 mm continuum
emission indicates that only about 2% of the CO is depleted from the gas phase.
Accepted by MNRAS
http://adsabs.harvard.edu/doi/10.1093/mnras/stz1032
http://arxiv.org/pdf/1904.06418

38

Massive star formation via torus accretion: the effect of photoionization feedback
N.S. Sartorio1 , B. Vandenbroucke2 , D. Falceta-Goncalves1,3 , K. Wood2 and E. Keto4
1
Instituto Nacional de Pesquisas Espaciais - INPE, Divisão de Astrofı́sica, Av. dos Astronautas, 1.758, Jd. Granja,
São José dos Campos, SP CEP 12227-010 Brazil; 2 SUPA, School of Physics & Astronomy, University of St Andrews,
North Haugh, St Andrews, KY16 9SS, United Kingdom; 3 Escola de Artes, Ciências e Humanidades, Universidade de21São Paulo, Rua Arlindo Bettio 1000, São Paulo, SP, 03828-000, Brazil; 4 Harvard-Smithsonian Center for Astrophysics,
160 Garden St, Cambridge, MA 02420, USA
E-mail contact: nina.sartorio at gmail.com
The formation of massive stars is a long standing problem. Although a number of theories of massive star formation
exist, ideas appear to converge to a disk-mediated accretion scenario. Here we present radiative hydrodynamic simulations of a star accreting mass via a disk embedded in a torus. We use a Monte Carlo based radiation hydrodynamics
code to investigate the impact that ionizing radiation has on the torus. Ionized regions in the torus midplane arefound to be either gravitationally trapped or in pressure driven expansion depending on whether or not the size ofthe ionized region exceeds a critical radius. Trapped Hii regions in the torus plane allow accretion to progress, while
expanding Hii regions disrupt the accretion torus preventing the central star from aggregating more mass, thereby
setting the star’s final mass. We obtain constraints for the luminosities and torus densities that lead to both scenarios.
Accepted by MNRAS
https://arxiv.org/pdf/1904.11994.pdf

39

ACRONYM III: Radial Velocities for 336 Candidate Young Low-Mass Stars in the Solar
Neighborhood, Including 78 Newly Confirmed Young Moving Group Members
Adam C. Schneider1 , Evgenya L. Shkolnik1 , Katelyn N. Allers2 , Adam L. Kraus3 , Michael C. Liu4 ,Alycia J. Weinberger5 and Laura Flagg6
1

School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85282, USA; 2 Department of Physics
and Astronomy, Bucknell University, Lewisburg, PA 17837, USA; 3 The University of Texas at Austin, Departmentof Astronomy, Austin, TX 78712, USA; 4 Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA; 5
Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA; 6 Physics &Astronomy Department, Rice University, Houston, TX 77005, USA
E-mail contact: aschneid10 at gmail.com
Young, low-mass stars in the solar neighborhood are vital for completing the mass function for nearby, young coevalgroups, establishing a more complete census for evolutionary studies, and providing targets for direct-imaging exoplanet
and/or disk studies. We present properties derived from high-resolution optical spectra for 336 candidate young
nearby, low-mass stars. These include measurements of radial velocities and age diagnostics such as Hα and Li λ6707
equivalent widths. Combining our radial velocities with astrometry from Gaia DR2, we provide full 3D kinematics forthe entire sample. We combine the measured spectroscopic youth information with additional age diagnostics (e.g.,
X-ray and UV fluxes, CMD positions) and kinematics to evaluate potential membership in nearby, young moving
groups and associations. We identify 78 objects in our sample as bonafide members of 10 different moving groups, 15of which are completely new members or have had their group membership reassigned. We also reject 44 previously
proposed candidate moving group members. Furthermore, we have newly identified or confirmed the youth of numerous
additional stars that do not belong to any currently known group, and find 69 co-moving systems using Gaia DR2
astrometry. We also find evidence that the Carina association is younger than previously thought, with an age similar
to the β Pictoris moving group (∼22 Myr).
Accepted by AJ
https://arxiv.org/pdf/1904.07193.pdf

40

Unlocking CO Depletion in Protoplanetary Disks II. Primordial C/H Predictions Inside
the CO Snowline
Kamber R. Schwarz1,2 , Edwin A. Bergin1 , L. Ilsedore Cleeves3 , Ke Zhang1 , Karin I. Öberg4 , Geoffrey
A. Blake5 and Dana E. Anderson5
1

Department of Astronomy, University of Michigan, 1085 South University Ave., Ann Arbor, MI 48109, USA; 2 Lunarand Planetary Laboratory, University of Arizona, 1629 E. University Blvd, Tucson, AZ 85721, USA; 3 Departmentof Astronomy, University of Virginia, 530 McCormick Rd, Charlottesville, VA 22904; 4 Harvard-Smithsonian Center
for Astrophysics, 60 Garden Street, Cambridge, MA 02138, SA; 5 Division of Geological & Planetary Sciences, MC
150-21, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125
22

E-mail contact: kschwarz at lpl.arizona.edu
CO is thought to be the main reservoir of volatile carbon in protoplanetary disks, and thus the primary initial sourceof carbon in the atmospheres of forming giant planets. However, recent observations of protoplanetary disks point
towards low volatile carbon abundances in many systems, including at radii interior to the CO snowline. One potential
explanation is that gas phase carbon is chemically reprocessed into less volatile species, which are frozen on dust grainsurfaces as ice. This mechanism has the potential to change the primordial C/H ratio in the gas. However, current
observations primarily probe the upper layers of the disk. It is not clear if the low volatile carbon abundances extend tothe midplane, where planets form. We have run a grid of 198 chemical models, exploring how the chemical reprocessingof CO depends on disk mass, dust grain size distribution, temperature, cosmic ray and X-ray ionization rate, and initialwater abundance. Building on our previous work focusing on the warm molecular layer, here we analyze the resultsfor our grid of models in the disk midplane at 12 au. We find that either an ISM level cosmic ray ionization rateor the presence of UV photons due to a low dust surface density are needed to chemically reduce the midplane COgas abundance by at least an order of magnitude within 1 Myr. In the majority of our models CO does not undergo
substantial reprocessing by in situ chemistry and there is little change in the gas phase C/H and C/O ratios over the
lifetime of the typical disk. However, in the small sub-set of disks where the disk midplane is subject to a source ofionization or photolysis, the gas phase C/O ratio increases by up to nearly 9 orders of magnitude due to conversion of
CO into volatile hydrocarbons.
Accepted by ApJ
https://arxiv.org/pdf/1904.10422.pdf

41

Line Ratios Reveal N2 H+ Emission Originates Above the Midplane in TW Hydrae
Kamber R. Schwarz1 , Richard Teague2 and Edwin A. Bergin2
1

Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd, Tucson, AZ 85721, USA; 2
Department of Astronomy, University of Michigan, 1085 South University Ave., Ann Arbor, MI 48109, USA
E-mail contact: kschwarz at lpl.arizona.edu
Line ratios for different transitions of the same molecule have long been used as a probe of gas temperature. Here we
use ALMA observations of the N2 H+ J = 1–0 and J = 4–3 lines in the protoplanetary disk around TW Hya to derive
the temperature at which these lines emit. We find an averaged temperature of 39 K with a one sigma uncertaintyof 2 K for the radial range 0.′′ 8–2′′ , significantly warmer than the expected midplane temperature beyond 0.′′ 5 in thisdisk. We conclude that the N2 H+ emission in TW Hya is not emitting from near the midplane, but rather from higher
in the disk, in a region likely bounded by processes such as photodissociation or chemical reprocessing of CO and N2
rather than freeze out.
Accepted by ApJL
https://arxiv.org/pdf/1904.09303.pdf

42

Virial Ratio: Direct Evaluation from Molecular Cloud Data and the Challenges of
Improving Accuracy
Ayushi Singh1 , Christopher Matzner1 and Peter Jumper2
1

Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario, Canada,
M5S 3H4; 2 10 Jody Lane, Forestdale, MA, 02644
E-mail contact: ayushi.singh at mail.utoronto.ca
The virial ratio between kinetic and gravitational terms provides key insight into the balance of forces that confine amolecular cloud, but the clumpy and filamentary structures of resolved clouds make it difficult to evaluate this ratio
in a consistent way. For clouds with resolved maps of column density as well as a line tracer, we demonstrate thatthe gravitational energy can be estimated directly from observations in a manner similar to the kinetic energy. This
offers improved diagnostic power and consistency. Disentangling a cloud from foreground and background material isa persistent challenge, for which we introduce a strategy based on Abel’s transform. We provide proofs of principle
using simulated clouds.

23Accepted by The Astrophysical Journal
https://arxiv.org/pdf/1905.00024

43

Star-forming regions at the periphery of the supershell surrounding the Cyg OB1 association. II. ISM kinematics and YSOs in the star cluster vdB 130 region
T.G. Sitnik1 , O.V. Egorov1,2 , T.A. Lozinskaya1 , A.V. Moiseev2,1 , A.M. Tatarnikov1 , O.V. Vozyakova1 ,D.S. Wiebe3
1Lomonosov Moscow State University, Sternberg Astronomical Institute, Universitetsky pr. 13, Moscow 119234,
Russia; 2 Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnij Arkhyz 369167, Russia; 3 Instituteof Astronomy (INASAN), Russian Academy of Sciences, Pyatnitskaya str. 48, Moscow 119017, Russia
E-mail contact: tat.sitnik2011 at yandex.ru
We present an observational study of small-scale feedback processes operating in the star-forming region located in thewall of the expanding supershell around the Cyg OB1 association. The interstellar gas and dust content and pre-stellar
populations in the vicinity of the open star cluster vdB 130 are analysed based on new optical and IR observations
performed with the 6-m (3D spectroscopic mapping in the [Sii] doublet) and 2.5-m (optical and NIR images) Russian
telescopes along with the archival data of Spitzer and Herschel space telescopes. Analysing ionized gas kinematics andemission spectra, we discovered a compact region with supersonic motions. These motions may be caused either bystellar wind, or a bipolar outflow from a protostellar disc. Young stellar objects were identified and classified in thearea under study. Two star-forming regions were identified. One of them is a region of ongoing star formation in thehead of the molecular cloud observed there and another one is a burst of star formation in the cloud tail.
Accepted by MNRAS
https://arxiv.org/pdf/1904.01641.pdf

44

Alignment of a circumbinary disc around an eccentric binary with application to KH
15D
Jeremy L. Smallwood1, Stephen H. Lubow2 , Alessia Franchini1 and Rebecca G. Martin1
1
Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas,
NV 89154, USA; 2 Space Telescope Science Institute, Baltimore, MD 21218, USA

E-mail contact: Smallj2 at unlv.nevada.edu
We analyse the evolution of a mildly inclined circumbinary disc that orbits an eccentric orbit binary by means ofsmoother particle hydrodynamic (SPH) simulations and linear theory. We show that the alignment process of an
initially misaligned circumbinary disc around an eccentric orbit binary is significantly different than around a circularorbit binary and involves tilt oscillations. The more eccentric the binary, the larger the tilt oscillations and the longer
it takes to damp these oscillations. A circumbinary disc that is only mildly inclined may increase its inclination by afactor of a few before it moves towards alignment. The results of the SPH simulations agree well with those of linear
theory. We investigate the properties of the circumbinary disc/ring around KH 15D. We determine disc properties
based on the observational constraints imposed by the changing binary brightness. We find that the inclination iscurrently at a local minimum and will increase substantially before setting to coplanarity. In addition, the nodal
precession is currently near its most rapid rate. The recent observations that show a reappearance of Star B impose
constraints on the thickness of the layer of obscuring material. Our results suggest that disc solids have undergone
substantial inward drift and settling towards to disc midplane. For disc masses ∼ 0.001M⊙, our model indicates thatthe level of disc turbulence is low α ≪ 0.001. Another possibility is that the disc/ring contains little gas.
Accepted by MNRAS
https://arxiv.org/pdf/1904.00985.pdf

24

45

Magnetic stability of massive star forming clumps in RCW 106
Shohei Tamaoki1 , Koji Sugitani1 , Quang Nguyen-Luong2 , Fumitaka Nakamura3 , Takayoshi Kusune3 ,Takahiro Nagayama4 , Makoto Watanabe5 , Shogo Nishiyama6 and Motohide Tamura7,8,3
1

Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501, Japan; 2 IBM Canada,
120 Bloor Street East, Toronto, ON, M4Y 1B7, Canada; 3 National Astronomical Observatory of Japan, Mitaka, Tokyo
181-8588, Japan; 4 Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan; 5 Department of Applied
Physics, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan; 6 Miyagi Universityof Education, 149 Aramaki-aza-Aoba, Aobaku, Sendai, Miyagi 980-0845, Japan; 7 Department of Astronomy, The
University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan; 8 Astrobiology Center of NINS, 2-21-1,
Osawa, Mitaka, Tokyo 181-8588, Japan
E-mail contact: s.tamaoki at nsc.nagoya-cu.ac.jp
The RCW 106 molecular cloud complex is an active massive star-forming region where a ministarburst is taking place.
We examined its magnetic structure by near-IR polarimetric observations with the imaging polarimeter SIRPOL on the
IRSF 1.4 m telescope. The global magnetic field is nearly parallel to the direction of the Galactic plane and the cloud
elongation. We derived the magnetic field strength of ∼ 100–1600 µG for 71 clumps with the Davis-ChandrasekharFermi method. We also evaluated the magnetic stability of these clumps and found massive star-forming clumps tend
to be magnetically unstable and gravitationally unstable. Therefore, we propose a new criterion to search for massive
star-forming clumps. These details suggest that the process enhancing the clump density without an increase of themagnetic flux is essential for the formation of massive stars and the necessity for accreting mass along the magnetic
field lines.
Accepted by Astrophysical Journal Letters
https://doi.org/10.3847/2041-8213/ab1346
http://arxiv.org/pdf/1904.06221

46

Is there more than meets the eye? Presence and role of submicron grains in debris discs
Philippe Thebault1 and Quentin Kral1
1

LESIA, Observatoire de Paris, France

E-mail contact: philippe.thebault at obspm.fr
The presence of sub-micron grains has been inferred in several debris discs, usually because of a blue colour of thespectrum in scattered light or a pronounced silicate band around 10µm, even though these particles should be blownout by stellar radiation pressure on very short timescales. So far, no fully satisfying explanation has been found forthis apparent paradox. We investigate the possibility that the observed abundances of sub-micron grains could benaturally produced in bright debris discs, where the high collisional activity produces them at a rate high enoughto partially compensate for their rapid removal. We also investigate to what extent this potential presence of small
grains can affect our understanding of some debris disc characteristics. We used a numerical collisional code to follow
the collisional evolution of a debris disc down to sub-micron grains far below the limiting blow-out size sblow . We
considered compact astrosilicates and explored different configurations: A and G stars, cold and warm discs, brightand very bright systems. We then produced synthetic spectra and spectral energy distributions, where we identified−3
and quantified the signature of unbound sub-micron grains.We find that in bright discs (fractional luminosity >∼10 )around A stars, the number of sub-micron grains is always high enough to leave detectable signatures in scattered light
where the disc colour becomes blue, and also in the mid-IR (10 ≤ λ ≤ 20µm), where they boost the disc luminosity
by at least a factor of 2 and induce a pronounced silicate solid-state band around 10µm. We also show that withthis additional contribution of sub-micron grains, the spectral energy distribution can mimic that of two debris belts
separated by a factor of ∼ 2 in radial distance. For G stars, the effect of s ≤ sblow grains remains limited in the spectra
although they dominate the geometrical cross section of the system. We also find that for all considered cases, thehalo of small (bound and unbound) grains that extends far beyond the main disc contributes to ∼ 50% of the flux up
to λ ∼ 50µm wavelengths.
Accepted by Astronomy and Astrophysics
http://arxiv.org/pdf/1904.05395

25

47

A centrally concentrated sub-solar mass starless core in the Taurus L1495 filamentarycomplex
Kazuki Tokuda1,2 , Kengo Tachihara3 , Kazuya Saigo2 , Phillipe André4 , Yosuke Miyamoto3 , Sarolta
Zahorecz1,2 , Shu-ichiro Inutsuka3 , Tomoaki Matsumoto5 , Tatsuyuki Takashima1 , Masahiro N. Machida6 ,Kengo Tomida7 , Kotomi Taniguchi8 , Yasuo Fukui3 , Akiko Kawamura2 , Kenichi Tatematsu9 , Ryo
Kandori10 and Toshikazu Onishi1
1

Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku,
Sakai, Osaka 599-8531, Japan; 2 National Astronomical Observatory of Japan, National Institutes of Natural Science,
2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 3 Department of Physics, Nagoya University, Chikusa-ku, Nagoya
464-8602, Japan; 4 Laboratoire AIM, CEA/DSM-CNRS-Universit Paris Diderot, IRFU/Service dAstrophysique, C.E.
Saclay, Orme des Merisiers, F-91191, Gif-sur-Yvette, France; 5 Faculty of Sustainability Studies, Hosei University,
Fujimi, Chiyoda-ku, Tokyo 102-8160, Japan; 6 Department of Earth and Planetary Sciences, Faculty of Sciences,
Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan; 7 Department of Earth and Space Science, Osaka University,
Toyonaka, Osaka 560-0043, Japan; 8 Departments of Astronomy and Chemistry, University of Virginia, Charlottesville,
VA 22904, USA; 9 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 10
Astrobiology Center of NINS, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan
E-mail contact: tokuda at p.s.osakafu-u.ac.jp
The formation scenario of brown dwarfs is still unclear because observational studies to investigate its initial condition
are quite limited. Our systematic survey of nearby low-mass star-forming regions using the Atacama Compact Array(aka Morita array) and the IRAM 30 m telescope in 1.2 mm continuum has identified a centrally concentrated starlesscondensation with the central H2 volume density of ∼106 cm−3 , MC5-N, connected to a narrow (width ∼0.03 pc)
filamentary cloud in the Taurus L1495 region. The mass of the core is ∼0.2-0.4 M⊙ , which is an order of magnitude
smaller than typical low-mass prestellar cores. Taking into account a typical core to star formation efficiency forprestellar cores (∼20-40%) in nearby molecular clouds, brown dwarf(s) or very low-mass star(s) may be going to beformed in this core. We have found possible substructures at the high-density portion of the core, although muchhigher angular resolution observation is needed to clearly confirm them. The subsequent N2 H+ and N2 D+ observations
using the Nobeyama 45 m telescope have confirmed the high-deuterium fractionation (∼30%). These dynamicallyand chemically evolved features indicate that this core is on the verge of proto-brown dwarf or very low-mass starformation and an ideal source to investigate the initial conditions of such low-mass objects via gravitational collapse
and/or fragmentation of the filamentary cloud complex.
Accepted by PASJ
http://arxiv.org/pdf/1904.05490

48

On the Mass Function, Multiplicity, and Origins of Wide-Orbit Giant Planets
Kevin Wagner1,2,3 , Dániel Apai1,3,4 , and Kaitlin M. Kratter1
1

Steward Observatory, University of Arizona; 2 National Science Foundation Graduate Research Fellow; 3 NASA
NExSS Earths in Other Solar Systems Team; 4 Lunar and Planetary Laboratory, University of Arizona
E-mail contact: kwagner at as.arizona.edu
A major outstanding question regarding the formation of planetary systems is whether wide-orbit giant planets form
differently than close-in giant planets. We aim to establish constraints on two key parameters that are relevant
for understanding the formation of wide-orbit planets: 1) the relative mass function and 2) the fraction of systems
hosting multiple companions. In this study, we focus on systems with directly imaged substellar companions, andthe detection limits on lower-mass bodies within these systems. First, we uniformly derive the mass probability
distributions of known companions. We then combine the information contained within the detections and detection
limits into a survival analysis statistical framework to estimate the underlying mass function of the parent distribution.
Finally, we calculate the probability that each system may host multiple substellar companions. We find that 1) thecompanion mass distribution is rising steeply toward smaller masses, with a functional form of N ∝ M −1.3±0.3 , andconsequently, 2) many of these systems likely host additional undetected sub-stellar companions. Combined, theseresults strongly support the notion that wide-orbit giant planets are formed predominantly via core accretion, similar
to the better studied close-in giant planets. Finally, given the steep rise in the relative mass function with decreasing

26

mass, these results suggest that future deep observations should unveil a greater number of directly imaged planets.
Accepted by ApJ
https://arxiv.org/pdf/1904.06438.pdf

49

APEX Observations of the CO Envelope around the Young FUor-type Star V883 Ori
J.A. White1 , Á. Kóspál1,2 , C. Rab3 , P. Ábrahám1 , F. Cruz-Sáenz de Miera1 , T. Csengeri4 , O. Fehér1,5 ,R. Güsten4 , T. Henning2 , E. Vorobyov6,7 , M. Audard8 and A. Postel8
1

Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, KonkolyThege Miklós út 15-17, 1121 Budapest, Hungary; 2 Max Planck Institute for Astronomy, Königstuhl 17, 69117
Heidelberg, Germany; 3 Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen,
The Netherlands; 4 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany; 5 IRAM, 300
Rue de la Piscine, 38046 Saint Martin d’Hères, France; 6 University of Vienna, Dept. of Astrophysics, Türkenschanzstr.
17, 1180 Wien, Austria; 7 Research Institute of Physics, Southern Federal University, Stachki 194, Rostov-on-Don,
344090, Russia; 8 Department of Astronomy, University of Geneva, Ch. d’Ecogia 16, 1290 Versoix, Switzerland

E-mail contact: jacob.white at csfk.mta.hu
The accretion-driven outbursts of young FU Orionis-type stars may be a common stage of pre-main sequence evolution
and can have a significant impact on the circumstellar environment as it pertains to the growth of solids and eventuallyplanets. This episodic accretion is thought to be sustained by additional gas in-falling from the circumstellar envelopeand disk. We present APEX observations of the CO gas in the envelope around V883 Orionis, a young outbursting
star. The observations mapped the 12 CO (4–3), 12 CO (3–2), and 13 CO (3–2) lines with the FLASH+ instrument andthe 12 CO (6–5) line with the SEPIA instrument. We detected high signal-to-noise emission extending out to radii>10000 au and calculated integrated fluxes of 1100 Jy km s−1 for 12 CO (6–5), 2400 Jy km s−1 for 12 CO (4–3), 1600
Jy km s−1 for 12 CO (3–2), and 450 Jy km s−1 for 13 CO (3–2). We used the thermo-chemical code PRODIMO totest several models and find the data are best described by an envelope structure with Menv ≈ 0.2–0.4 M⊙ and a
mass-infall rate of Ṁinf = 1–2 × 10−6 M⊙ yr−1 . We infer that the observed envelope and outflow structure aroundV883 Ori could be caused by multiple outbursts, consistent with episodic accretion.
Accepted by ApJ
https://arxiv.org/pdf/1904.07269.pdf

50

The Ophiuchus DIsk Survey Employing ALMA (ODISEA): Disk Dust Mass Distributions across Protostellar Evolutionary Classes
Jonathan Williams1, Lucas Cieza2 , Antonio Hales3 , Megan Ansdell4 , Dary Ruiz-Rodriguez5 , Simon
Casassus6 , Sebastian Perez6 and Alice Zurlo2
1

University of Hawaii, Honolulu, HI, USA; 2 Universidad Diego Portales, Santiago, Chile; 3 Joint ALMA Observatory,
Santiago, Chile; 4 University of California, Berkeley, CA, USA; 5 Rochester Institute of Technology, Rochester, NY,
USA; 6 Universidad de Chile, Santiago, Chile
E-mail contact: jw at hawaii.edu
As protostars evolve from optically-faint/infrared-bright (Class I) sources to optically-bright/infrared-faint (Class II)
the solid material in their surrounding disks accumulates into planetesimals and protoplanets. The nearby, young
Ophiuchus star-forming region contains hundreds of protostars in a range of evolutionary states. Using the Atacama
Large Millimeter Array to observe their millimeter continuum emission, we have measured masses of, or placed strong
upper limits on, the dust content of 279 disks. The masses follow a log-normal distribution with a clear trend of
decreasing mass from less to more evolved protostellar infrared class. The (logarithmic) mean Class I disk mass,M = 3.8 M⊕ , is about 5 times greater than the mean Class II disk mass, but the dispersion in each class is so high,σlog M ≃ 0.8 − 1, that there is a large overlap between the two distributions. The disk mass distribution of flatspectrum protostars lies in between Class I and II. In addition, three Class III sources with little to no infrared excess
are detected with low disk masses, M ≃ 0.3 M⊕.
Despite the clear trend of decreasing disk mass with protostellar evolutionary state in this region, a comparison withsurveys of Class II disks in other regions shows that masses do not decrease monotonically with age. This suggests that27

the cloud-scale environment may determine the initial disk mass scale or that there is substantial dust regeneration
after 1 Myr.
Accepted by Astrophysical Journal Letters
https://arxiv.org/pdf/1904.06471

51

Enlarging habitable zones around binary stars in hostile environments
Bethany A. Wootton1 and Richard J. Parker1
1

52

Department of Physics and Astronomy, The University of Sheffield,

53

G5.89: An Explosive Outflow Powered by a Proto-Stellar Merger?
Luis A. Zapata1 , Paul T. P. Ho2,3 , Estrella Guzmán-Ccolque4 , Manuel Fernández-Lopéz4 , Luis F.
Rodrı́guez1,6 , John Bally5 , Patricio Sanhueza7 , Aina Palau1 , and Masao Saito7
1Instituto de Radioastronomı́a y Astrofı́sica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090,
Morelia, Michoacán, México
2
Academia Sinica Institute of Astronomy and Astrophysics, PO Box 23-141, Taipei, 10617, Taiwan; 3 East Asian
Observatory, 666 N. A’ohoku Place, Hilo, Hawaii 96720, USA; 4 Instituto Argentino de Radioastronomı́a (CCT-La
Plata, CONICET; CICPBA), C.C. No. 5, 1894, Villa Elisa, Buenos Aires, Argentina; 5 Astrophysical and Planetary
Sciences Department University of Colorado, UCB 389 Boulder, Colorado 80309, USA; 6 Mesoamerican Centre for
Theoretical Physics, Universidad Autónoma de Chiapas, Carretera Emiliano Zapata, Real del Bosque, 29050 Tuxtla
Gutiérrez, Chiapas, México; 7 National Astronomical Observatory of Japan, National Institutes of Natural Sciences,
2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
E-mail contact: lzapata@irya.unam.mx
The explosive outflows are a newly-discovered family of molecular outflows associated with high-mass star forming
regions. Such energetic events are possibly powered by the release of gravitational energy related with the formationof a (proto)stellar merger or a close stellar binary. Here, we present sensitive and high angular resolution observations(0.85′′ ) archival CO(J=3-2) observations carried out with the Submillimeter Array (SMA) of the high-mass star
forming region G5.89−0.39 that reveal the possible presence of an explosive outflow. We find six well-defined andnarrow straight filament-like ejections pointing back approximately to the center of an expanding molecular and ionizedshell located at the center of this region. These high velocity (−120 to +100 km s−1 ) filaments follow a Hubble-likevelocity law with the radial velocities increasing with the projected distance. The estimated kinematical age of thefilaments is about of 1000 yrs, a value similar to the dynamical age found for the expanding ionized shell. G5.89 is thethus the third explosive outflow reported in the galaxy (together with Orion BN-KL and DR21) and argues in favorof the idea that this is a frequent phenomenon. In particular, explosive outflows, in conjunction with runaway stars,
demonstrate that dynamical interactions in such groups are a very important ingredient in star formation.
Accepted by MNRAS Letters
https://academic.oup.com/mnrasl/article/486/1/L15/5476504
http://arxiv.org/pdf/1904.04385

54

A transiting exocomet detected in broadband light by TESS in the β Pictoris system
Sebastian Zieba1 , Konstanze Zwintz1 , Matthew Kenworthy2 and Grant M. Kennedy3
1

Universität Innsbruck, Institut für Astro- und Teilchenphysik, Technikerstraße 25, A-6020 Innsbruck, Austria; 2
Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands; 3 Department of Physics,
University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
E-mail contact: konstanze.zwintz at uibk.ac.at

We search for signs of falling evaporating bodies (FEBs, also known as exocomets) in photometric time series obtainedfor β Pictoris after fitting and removing its δ Scuti-type pulsation frequencies. Using photometric data obtained by
the TESS satellite we determined the pulsational properties of the exoplanet host star β Pictoris through frequency
analysis. We then pre-whitened the 54 identified δ Scuti p-modes and investigated the residual photometric time series
for the presence of FEBs. We identify three distinct dipping events in the light curve of β Pictoris over a 105-day
period. These dips have depths from 0.5 to 2 millimagnitudes and durations of up to 2 days for the largest dip.
These dips are asymmetric in nature and are consistent with a model of an evaporating comet with an extended tailcrossing the disc of the star. We present the first broadband detections of exocomets crossing the disc of β Pictoris,
complementing the predictions made 20 years earlier by Lecavelier Des Etangs et al. (1999). No periodic transits areseen in this time series. These observations confirm the spectroscopic detection of exocomets in calcium H and K linesthat have been seen in high resolution spectroscopy
Accepted by A&A
http://arxiv.org/pdf/1903.11071

29

A Large Catalog of Accurate Distances to Local Molecular Clouds: The Gaia DR2

55 Edition

Catherine Zucker1 , Joshua S. Speagle1 , Edward F. Schlafly2 , Gregory M. Green3 , Douglas P. Finkbeiner1 ,Alyssa A. Goodman1,4 and João Alves4,51

Harvard Astronomy, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA; 2
Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA; 3 Kavli Institute for Particle
Astrophysics and Cosmology, Physics and Astrophysics Building, 452 Lomita Mall, Stanford, CA 94305, USA; 4
Radcliffe Institute for Advanced Study, Harvard University, 10 Garden St, Cambridge, MA 02138, USA; 5 Universityof Vienna, Department of Astrophysics, Türkenschanzstraße 17, 1180 Vienna, Austria
E-mail contact: catherine.zucker at cfa.harvard.edu
We present a uniform catalog of accurate distances to local molecular clouds informed by the Gaia DR2 data release.
Our methodology builds on that of Schlafly et al. 2014. First, we infer the distance and extinction to stars alongsightlines towards the clouds using optical and near-infrared photometry. When available, we incorporate knowledgeof the stellar distances obtained from Gaia DR2 parallax measurements. We model these per-star distance-extinction
estimates as being caused by a dust screen with a 2-D morphology derived from Planck at an unknown distance, which
we then fit for using a nested sampling algorithm. We provide updated distances to the Schlafly et al. 2014 sightlines
towards the Dame et al. 2001 and Magnani et al. 1985 clouds, finding good agreement with the earlier work. For asubset of 27 clouds, we construct interactive pixelated distance maps to further study detailed cloud structure, andfind several clouds which display clear distance gradients and/or are comprised of multiple components. We use thesemaps to determine robust average distances to these clouds. The characteristic combined uncertainty on our distancesis ≈ 5 − 6%, though this can be higher for clouds at farther distances, due to the limitations of our single-cloud model.
Accepted by ApJ
https://arxiv.org/pdf/1902.01425

30

Abstracts of recently accepted major reviews

Submillimeter and Far-Infrared Polarimetric Observations of Magnetic Fields in StarForming Regions
Kate Pattle1 and Laura Fissel2
1

National Tsing Hua University, Hsinchu, Taiwan; 2 National Radio Astronomy Observatory, Charlottesville, VI,
United States
E-mail contact: kpattle at gapp.nthu.edu.tw
Observations of star-forming regions by the current and upcoming generation of submillimeter polarimeters will shed
new light on the evolution of magnetic fields over the cloud-to-core size scales involved in the early stages of thestar formation process. Recent wide-area and high-sensitivity polarization observations have drawn attention to thechallenges of modeling magnetic field structure of star forming regions, due to variations in dust polarization properties
in the interstellar medium. However, these observations also for the first time provide sufficient information to begin
to break the degeneracy between polarization efficiency variations and depolarization due to magnetic field sub-beam
structure, and thus to accurately infer magnetic field properties in the star-forming interstellar medium. In thisarticle we discuss submillimeter and far-infrared polarization observations of star-forming regions made with singledish instruments. We summarize past, present and forthcoming single-dish instrumentation, and discuss techniques
which have been developed or proposed to interpret polarization observations, both in order to infer the morphology
and strength of the magnetic field, and in order to determine the environments in which dust polarization observations
reliably trace the magnetic field. We review recent polarimetric observations of molecular clouds, filaments, andstarless and protostellar cores, and discuss how the application of the full range of modern analysis techniques torecent observations will advance our understanding of the role played by the magnetic field in the early stages of starformation.
Accepted by Frontiers in Astronomy and Space Sciences
https://www.frontiersin.org/articles/10.3389/fspas.2019.00015/full
https://arxiv.org/pdf/1904.04826

31

Dissertation Abstracts

The Dynamical State of a Young Stellar Cluster
Timothy Sullivan

University of Missouri-St Louis, USA
2131 Yale Ave Apt 102 Maplewood MO 63143
Electronic mail: tsullivan at umsl.edu
Ph.D dissertation directed by: Bruce Wilking
Ph.D degree awarded: May 2019

The dynamical state of the young star-forming cluster Rho Ophiuchi is considered, with emphasis on the L1688 cloud.
Radial velocities are derived for 32 YSOs, with some being multi-epoch, using Markov-Chain Monte Carlo routines
based upon the package emcee. Sources are chosen based upon their spectral index to focus on the earlier stagesof star formation, in this case, Class I and Flat spectrum objects, and compared with a sample of Class II and III
objects from the same embedded cluster. It is found that the radial velocity dispersion for these younger objects is∆v = 2.8 ± 0.6 km s-1 which is about 2σ higher than the dispersion for Class II and III objects. The implication is that
there are either small number statistics at play, or the cluster’s dispersion is being increased as an inverse functionof the distance from the center of the cluster due to a collapse-and-rebound phase that has been proposed in recent
simulations.
https://www.umsl.edu/~physics/files/pdfs/TimothySullivanDissertation1919.pdf

32

Towards a Complete Study of the Initial Mass Function and Early
Kinematics Evolution of the 25 Orionis Stellar Group
Genaro Suárez

Instituto de Astronomı́a, UNAM sede Ensenada
Instituto de Astronomı́a, Universidad Nacional Autónoma de México, Unidad Académica en Ensenada, Ensenada
BC 22860, México
Electronic mail: gsuarez at astro.unam.mx
Ph.D dissertation directed by: Carlos Román-Zúñiga & Juan José Downes
Ph.D degree awarded: February 2019Young stellar aggregates are the laboratories where we study the process by which almost every star in the Galaxy
has formed. Most of the young stellar groups break up in at most a few tens of Myr and only a few of them survive as
gravitational bound entities to become open clusters. This phenomenon is usually understood as a rapid evolution ofyoung stellar systems when the parental molecular gas is expelled, however, there is also evidence suggesting that theseunbound stellar associations are formed in a structured process. To understand how stars are formed and how youngstellar systems evolve, it is essential to estimate the total mass of the association, which can be achieved through theanalysis of the stellar initial mass function (IMF). Despite many contributions to the study of the IMF, only a few ofthem over the whole cluster mass range, it is still unclear how it depends on environmental conditions and/or time.
Due to its closeness, low extinction, stellar density and evolutionary status, an excellent place to study the IMF, fromplanetary-mass objects to intermediate/high-mass stars, and the early evolution of a young stellar system that justemerged from its embedded phase, is the 25 Orionis stellar group (25 Ori).

Combining new deep optical photometry from DECam with optical and NIR data from the literature, we selected 1687
member candidates of 25 Ori with Ic -band magnitudes between 5 and 23.3 mag in an area of 1.1◦ radius. With thissample we derived the system IMF of 25 Ori from 0.012 to 13.1 M⊙ , which is one of the few IMFs across the entire
mass range of a stellar association. The resultant system IMF is well-described by a two-part power-law fun2Td[(g)-5.8890.9295.88

we estimated that the 25 Ori mean radial velocity is 20.9 ± 2.0 km s−1 . Using these parameters we found that 25 Ori
is a dynamically young group without time enough to be relaxed and confirmed that it is, in fact, a gravitationallyunbound association that will be part of the Galactic Disk population.
Considering the observed and confirmed members as well as those already confirmed in the literature, the spectroscopic
follow-up is ∼75% complete, with most of the remaining candidates to be observed with estimated masses around thesubstellar mass limit. We have ongoing observations to complete the spectroscopic survey of 25 Ori.
https://doi.org/10.5281/zenodo.2598767

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Abstract submission deadline
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submitted after the deadline will appear in the following month’s issue.

34

New Jobs

Two Postdoctoral Positions on Debris Disks
at Friedrich Schiller University, Jena
The Astrophysical Institute and University Observatory (AIU) of the Friedrich Schiller University, Jena, Germany, isseeking two postdoctoral researchers.
The positions are to work in the Research Unit FOR 2285 “Debris Disks in Planetary Systems”, funded by the German
Research Foundation (DFG). The successful candidates will join the theory group at the AIU. The researchers will
benefit from close collaboration with other observational, theory, and laboratory projects of the Research Unit runningin Jena, Braunschweig, and Kiel.
One position is part of the Research Unit’s project P1 “Masses and stirring of debris disks.” The main goal ofthis project is to develop a detailed understanding of the origins of debris disks. The researcher is expected to tackle achallenging “mass problem” identified recently for both debris disks and their protoplanetary disk progenitors. They
will also address a related question of what excites the planetesimals in debris disks and when, activating the dust
production. Both problems should be investigated by means of analytic work and/or numerical simulations, taking
into account a wealth of available observational constraints.
The second position is part of project P3 “Origin of the warm and hot dust and planetary system architecture.” The successful candidate will work to constrain the occurrence rate and parameters of warm and hot dust disks
commonly observed in planetary systems, set up and run simulations for plausible cometary and asteroidal scenariosof dust production, transport and removal, consider implications for the overall architecture of the systems, and makesuggestions for future observational tests.
The positions are for three years and can start at any time in the summer or fall 2019. The salary is standard for
postdoc positions in Germany (TV-L E13/3–E14/2 of the German federal public service scale) and includes a numberof social and family-related benefits. Funding is available for travel, computational resources and relocation expenses.
The applicants should have a strong educational record and hold a doctoral degree or equivalent in physics or astronomy. Previous experience of astronomical research, preferably on debris or protoplanetary disks, exoplanets or planet
formation, is required. Proficiency in English is also required.
Applications as a single document in the PDF format should include a CV, a statement of research interests (4pages max), and the names and contact details of three referees. Please quote “FOR2285/P1” or “FOR2285/P3” inthe subject depending on which project is preferred. All applications received by May 27, 2019 will be given fullconsideration.
The Friedrich Schiller University is an equal opportunity employer and explicitly encourages women to apply. Disabled
persons with equal aptitude, competence and qualification will be given preference.
Applications or enquires about further information should be sent to Prof. Alexander Krivov (krivov@astro.unijena.de).
http://www.astro.uni-jena.de/FOR2285

35

PhD Position on Debris Disks
at Friedrich Schiller University, Jena
The Astrophysical Institute and University Observatory (AIU) of the Friedrich Schiller University, Jena, Germany,
invites applications for a graduate student position.
The position is to work in the Research Unit FOR 2285 “Debris Disks in Planetary Systems”, funded by the German
Research Foundation (DFG). The successful candidate will join the theory group at the AIU and will work for the
Research Unit’s project P2 “Sculpturing of debris disks by planets and companions.” The project aims at
understanding the origin of the observed features in debris disks, such as sharp edges, eccentric offsets, or azimuthal
asymmetries. phenomena. Many of these can be attributed to the gravitational influence of alleged but yet unseen
planets and companions. The graduate student is expected to utilize a model devised earlier in our group to investigate
the disk evolution under the action of secular gravitational perturbations combined with a full collisional cascade anddrag forces. The model should be applied to infer possible dynamical histories of the systems, to explore how theparameter variation affects the predicted structure, and to test the predictions against the structure actually observedin selected disks. The researcher will benefit from close collaboration with other observational, theory, and laboratory
projects of the Research Unit.
The position is for three years and can start at any time in the summer or fall 2019. The salary is standard for doctoral
positions in Germany (1/2 TV-L E13 of the German federal public service scale) and includes a number of social andfamily-related benefits. Travel funding for short-term visits to collaborators or to attend conferences will be provided.
Funding is available for computational resources and the group already has a set of 8 multi-core servers for runningsimulations. Reimbursement of relocation costs is possible.
The applicant should have a strong educational record and hold a Masters’ degree or equivalent in physics or astronomy.
Previous experience with numerics and astronomical research, preferably with debris disks and/or orbital dynamics,
would be a strong advantage. Proficiency in English is required.
Applications as a single PDF document should include a CV, a brief statement of research interests (1 page max), andthe names and contact details of two referees. Please quote “FOR2285/P2” in the subject. All applications received
by June 17, 2019 will be given full consideration.
The Friedrich Schiller University is an equal opportunity employer and explicitly encourages women to apply. Disabled
persons with equal aptitude, competence and qualification will be given preference.
Applications or enquiries for further information should be sent to Dr. Torsten Löhne (tloehne@astro.uni-jena.de).
http://www.astro.uni-jena.de/FOR2285

36

Meetings

First Stars VI in Concepcion, 01-06 March 2020
Dear colleagues,
we are delighted to announce the First Stars VI conference, which will be held in Concepcion, Chile, from 01-06 March2020.
http://www.astro.udec.cl/FirstStarsVI/
Scientific rationale:
During the last decade, significant progress has been made towards probing how the first stars, galaxies and black
holes have actually formed. Particular highlights include the first detections of gravitational waves as a new window
into our Universe, the first detection of a signal from the reionization epoch through the EDGES experiment, as wellas the continuous progress in areas such as stellar archeology or the search for the first galaxies. In addition, significant
further developments will be expected in the coming years due to future missions such as JWST and the SKA.
The conference aims at discussing the current theoretical and observational status of our understanding of stellar
birth throughout cosmic history, the impact of first star and galaxy formation on the subsequent evolution of the
Universe, first supernova explosions and chemical enrichment, cosmic reionization, and formation of supermassive
black holes. Specific focus is given to current and future space-borne and Earth-bound observational campaigns
and their comparison with predictions from state-of-the-art numerical simulations. We will thereby follow up on theprevious First Stars conferences (I-V) that were held in Garching in 1999, in Pennsylvania in 2003, in Santa Fe in 2007,
in Kyoto in 2012 and in Heidelberg in 2016. The current conference is the first in the series to take place in SouthAmerica, and aims particularly at establishing closer connections with the observational community in Chile, hosting
the worlds largest telescopes and providing significant opportunities in its astronomical community. We encourage
especially young researchers and students to attend the conference.
Preliminary program: - Population III stars: formation, IMF, multiplicity and evolution - Transition to secondgeneration star formation - First supernovae and gamma-ray bursts; Pop. III star fates; abundance patterns at highredshift - Gravitational waves as a new probe of the high-z Universe - Stellar archeology as a powerful probe of thehigh-z Universe - From the first galaxies to the epoch of reionization - Dwarf galaxies as a potential probe of the early
Universe - Formation, growth and observational constraints on the first supermassive black holes - Current and future
surveys and observational facilities
Confirmed speakers: - Andrew Bunker, University of Oxford, UK - Elisabetta Caffau,Observatoire de Paris/Meudon,
France - Gen Chiaki, Georgia Tech, USA - Tiziana Di Matteo,Carnegie Mellon University, Pittsburg, USA - Anastasia
Fialkov, Kavli, Cambridge, UK - Tilman Hartwig, University of Tokyo, Japan - Shingo Hirano, Kyushu University,
Kyudai, Japan - Takashi Hosokawa, Kyoto University, Kyoto, Japan - Miho Ishigaki, Tohoku University, Sendai,
Japan - Alexander Ji, Carnegie Observatories, Pasadena, USA - Muhammad Latif, United Arab Emirates University- Karin Lind, MPIA, Heidelberg, Germany - Mattias Magg, ITA, Heidelberg, Germany - Takashi Moriya, National
Astronomical Observatory of Japan, Japan - Laura Pentericci, Osservatorio Astronomico di Roma, Italy - Stefania
Salvadori,University of Florence, Italy - Else Starkenburg, AIP, Postdam, Germany - Ezequiel Treister, Pontificia
Universidad Catolica, Chile - Rosa Valiante, Astronomical Observatory of Rome, Italy - Daniel Whalen, University ofPortsmouth, UK - John Wise, Georgia Tech, USA
Important deadlines: - Pre-registration: 30 June 2019 - Abstract submission: 31 October 2019 - Notification of
speakers: 15 December 2019 - Registration and payment: 01 January 2020 - Begin of conference: 01 March 2020
The venue will be the nice and freely accessible campus of the University of Concepcin close to the city center, including
many nearby bars, restaurants, shops and coffee places. The conference itself will take place in the main auditoriumof the EmpreUdeC building. Students and postdocs will have the possibility to apply for financial support after the
pre-registration. We will provide more information about social events, possible excursions and further activities over37

the next months. We highly encourage participants to also consider a longer stay, for scientific interactions in Chile,
to visit the large observatories or to enjoy the landscapes in Chile, ranging from the big deserts in the North to thebeautiful mountain landscapes and glaciers in the South of Chile, as well as potential visits to the Easter Island before
or after the conference.
Looking forward to seeing you in Concepcion,
Dominik Schleicher on behalf of the LOC/SOC

UNDERSTANDING THE NEARBY STAR FORMING UNIVERSE
WITH JWST
Courmayeur Mont Blanc, Italy - August 26-30 2019
Understanding the way nature assembles matter into stars remains one of the key problems in astrophysics. We knowthat stars mostly form in clustered systems enshrouded by the densest regions of giant molecular clouds. The process
is accompanied by a rich, multi-wavelength phenomenology tracing mass accretion, outflows, radiative energy andmomentum feedback into the parental cloud and nearby young stellar objects. The James Webb Space Telescope,with its complement of infrared instrumentation offering an unparalleled combination of sensitivity and diffraction
limited performance, will open a new window on the process of star formation. The Birth of Stars and Protoplanetary
Systems represents one of the original science drivers of the JWST. Approaching the JWST Call for Proposal for
Cycle 1 observations, we invite the community to discuss the potential impact of JWST on our understanding of starformation, also in light of the recent advances enabled by e.g. ALMA and Gaia, and the prospects enabled by the next
generation of giant telescopes. The meeting will include invited reviews on the Guaranteed Time and Early Release
Science Programs, as well as contributed talks. ESA staff will support a hands-on session on the JWST Exposure
Time Calculator and Proposal Tool. Topics include:• Open Problems in Star Formation• Protostars and Class 0 objects• Accretion, disks• Mass loss, jets and HH objects• Massive stars, feedback and multiplicity• Substellar Objects in the field and as companions• Star formation in the local universe (LMC and beyond)38

Confirmed invited speakers
A. Adamo (U. Stockholm)
J. Bally (U. Colorado)
G. de Marchi (ESA-ESTEC)
L. Hillenbrand (Caltech)
P. Kalas (U. Berkeley)
C. F. Manara (ESO)
M. McCaughrean (ESA-ESTEC)
M. Meixner (STScI)T. Ray (Dublin IAS)
J. Tan (U. Chalmers)

C. Alves de Oliveira (ESA-STScI)P. Clark (U. Cardiff)
T. Greene (NASA-Ames)
K. Hodapp (U. Hawaii)
M. Krumholz (Australian National U.)
A. Maury (CEA-Saclay)
M. MacGregor (Carnegie)
K. Pontoppidan (STScI)K. Stapelfeldt (NASA-JPL)
E. Tognelli (U. Pisa)

Science Organizing Committee: J. Bally (Colorado), C. Beichman (JPL), D. Calzetti (UMass), R. Doyon (ESA),
D. Gouliermis (HD), T. Henning (MPIA), C.Lada (CFA), M. Meixner (STScI), A. Nota (ESA), M. Robberto (STScI& JHU, SOC Chair), E. Sabbi (ESA, SOC Co-Chair), M. Sirianni (ESA, SOC Co-Chair)Conference location
The meeting will be held at the futuristic conference center at Pavillon du Mont-Frety (2173m = 7130ft a.s.l.), locatedat the intermediate station of the newly rebuild SkyWay Monte Bianco. This is the italian leg of the cable car that does
the grand-tranvers of Mont Blanc from Courmayeur (Italy) to Chamonix (France). The location offers breathtaking
views of Mont Blanc and its glaciers. Hotels and accomodations will be in the village of Courmayeur. The registration
fee includes the daily cable-car tickets.
REGISTRATION DEADLINE: June 30, 2019
CONFERENCE WEBSITE: http://www.stsci.edu/institute/conference/unsfjwst201939

Summary of Upcoming Meetings

Exploring the Infrared Universe: The Promise of SPICA
20 - 23 May 2019, Crete, Greece
http://www.spica2019.org
Workshop on Polarization in Protoplanetary Disks and Jets
20 - 24 May 2019, Sant Cugat del Vallès, Catalonia, Spain
http://sites.google.com/view/sant-cugat-forum-astrophysics/next-session
Cloudy Workshop
20 - 24 May 2019, University of Kentucky, USA
http://cloud9.pa.uky.edu/~gary/cloudy/CloudySummerSchool/
Star Clusters: from the Milky Way to the Early Universe
27 - 31 May 2019, Bologna, Italy
http://iausymp351.oas.inaf.it/
Partially Ionised Plasmas in Astrophysics
3 - 7 June 2019, Palma de Mallorca, Spain
http://solar1.uib.es/pipa2019/
Zooming in on Star Formation - A tribute to Åke Nordlund
9 - 14 June 2019, Nafplio, Greece
http://www.nbia.dk/nbia-zoomstarform-2019
From Stars to Planets II: Connecting our Understanding of Star and Planet Formation
17 - 20 June 2019, Gothenburg, Sweden
http://cosmicorigins.space/fstpii
Gaia’s View of Pre-Main Sequence Evolution. Linking the T Tauri and Herbig Ae/Be Stars
18 - 21 June 2019, Leeds, UK
https://starry-project.eu/final-conference
Gordon Conference on Origins of Solar Systems: Meteoritical, Spacecraft and Astrophysical Perspectives on the Assembly and Composition of Planets
23 - 28 June 2019https://www.grc.org/origins-of-solar-systems-conference/2019/
Astrochemistry: From nanometers to megaparsecs - A Symposium in Honour of John H. Black24 - 28 June 2019, Gothenburg, Sweden
https://www.chalmers.se/en/conference/JHBlacksymp2019/
Smoothed Particle Hydrodynamics International Workshop
25 - 27 June 2019, Exeter, UK
http://spheric2019.co.uk/
Great Barriers in Planet Formation
21 - 26 July 2019 Palm Cove, Australia
https://dustbusters.bitbucket.io/great-barriers-2019/
Summer School Protoplanetary Disks and Planet Formation
5 - 9 August 2019 Copenhagen, Denmark
http://nbia.nbi.ku.dk/nbia-school-2019
Orion Uncovered
26 - 30 August 2019 Leiden, The Netherlands
https://sites.google.com/view/OrionLeiden201940

Understanding the Nearby Star-forming Universe with JCMT
26 - 30 Aug 2019 Courmayeur, Italy
http://www.stsci.edu/institute/conference/unsfjwst2019
Celebrating the first 40 Years of Alexander Tielens’ Contribution to Science: The Physics and Chemistry of the ISM
2 - 6 september 2019, Avignon, France https://tielens2019.sciencesconf.org
From Gas to Stars: The Links between Massive Star and Star Cluster Formation
16-20 September 2019 York, UK
https://starformmapper.org/final-conference/
Crete III - Through dark lanes to new stars Celebrating the career of Prof. Charles Lada
23 - 27 September 2019 Crete, Greece
http://crete3.org
The UX Ori type stars and related topics
30 September - 4 October 2019 St. Petersburg, Russia
http://uxors-2019.craocrimea.ru
First Stars VI
1 - 6 March 2020 Concepcion, Chile
http://www.astro.udec.cl/FirstStarsVI/
Linking Dust, Ice, and Gas in Space19 - 24 April 2020, Capri, Italy
http://frcongressi.net/ecla2020.meet
COOL STARS 21: Cambridge Workshop on Cool Stars, Stellar Systems and the Sun
21 -26 June 2020, Toulouse, France
https://coolstars21.github.io/
The Physics of Star Formation: From Stellar Cores to Galactic Scales
29 June - 3 July 2020 Lyon, France https://cral.univ-lyon1.fr

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