THESTAR

FORMATION

NEWSLETTER

An electronic publication dedicated to early stellar/planetary evolution and molecular clouds
No. 332 — 15 August 2020

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

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

Interview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Abstracts of Newly Accepted Papers . . . . . . . . . . . 5
Dissertation Abstracts . . . . . . . . . . . . . . . . . . . . . . . . 46

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

New Jobs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

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

Summary of Upcoming Meetings . . . . . . . . . . . . . . 52

Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

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 Rodríguez
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 large bow shock HH 216 in M16 is seen here
in an HST image. The shock is driven by a source
embedded at the tip of one of the many elephanttrunks in this region.
Image courtesy STScI.

Submitting your abstracts
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In a typical year we were awarded enough observing time
to support two or three series of flights in different seasons
to be able to observe most parts of the Milky Way, including eventually, the southern parts. Flying on the KAO
was an interesting combination of excitement and stress.
We worked with a large number of great people, but thestress came from using state-of-the-art equipment that did
not always choose to function when we needed it to. If
something went wrong in flight with either our equipment
or the observatory’s, there were 20 people in the air andanother 20-40 on the ground "watching over our shoulders". The KAO, though, provided a unique platform toobtain routine observations with, for that era, high spatial resolution. It enabled us to spatially resolve individual
proto-stars and map dust density gradients through simultaneous multi-color photometry.

Paul Harvey
in conversation with Bo Reipurth

Q: In the late 1970s you and your collaborators publisheda series of papers on high spatial resolution far-infraredobservations of a number of star forming regions. What
were your overall conclusions?

Q: Your PhD from 1974 dealt with infrared and microwave
variability of infrared stars. How did you choose that subA: To put this into perspective, you will have to rememject?
ber that this was in the pre-IRAS days, and even when
A: Like so many things in life, it was pretty much an ac- IRAS flew, its spatial resolution at 60 and 100 microns wascident. As an undergrad at Wesleyan University, I had ex- pretty low! So I think our observations were important toperimented with making telescope mirrors from a stretched establish the total luminosity of the obscured young stars,
mylar film with a vacuum behind it. My advisor suggested and compare it to the UV luminosity as inferred from theI get in touch with Bob Leighton when I arrived at Caltech radio continuum emission. With the spatial resolution offor grad school, and Bob said something to the effect of, the KAO we were able to see far-ir emission from dust
“Well, I’m not experimenting with spinning epoxy mirrors associated directly with ionized gas as well as dust thatanymore, but Gerry Neugebauer is using one to make an was heated by objects too young or too low in luminosity
infrared survey of the sky”. So I went to talk to Gerry, and to ionize significant amounts of gas. The spatial resoluhe said something to the effect of, “Well, our sky survey is tion also allowed us to infer the presence of circumstellar
done and we have found all these red giant stars that are disks around two young stars, in NGC 2264 and in theassociated with OH masers. A good project would be to Rosette Nebula, from a comparison of the far-ir opticalsee if there is a correlation between the infrared variabil- depth relative to that in the near-ir.
ity and the OH maser variability”. This was the era of theVietnam War, and I needed Caltech to write a letter to my Q: In the mid-1980s you wrote several papers on the NGC
6334 region. What is special about this particular star
draft board saying that I was doing important research!
forming region?
Q: You then built a far-infrared photometer for the Kuiper
A: Well, to be blunt, it was bright, so it was easy to map,
Airborne Observatory.
and for the KAO it was important to have a collection
A: In between, I also built some instrumentation for my of objects around the sky to piece together a flight-plan
PhD thesis because Neugebauer said, “You can’t get a PhD that would get you home after 7 1/2 hours, while observin physics without building some instrumentation”. So I ing detectable objects most of the time! I also got somemade the first photometer at Caltech for 1.4mm photome- observing time at the IRTF for 1-20 micron observations
try, using the Palomar 200-inch in twilight. When I grad- to follow up after our KAO 50-100 micron observing. We
uated and went to the University of Arizona as a postdoc, were able to spatially resolve a number of structures in theBill Hoffmann was in the process of moving there from three most luminous OB star-forming clusters here. We
Goddard in NYC, and had gotten a small grant to build a found several infrared bipolar nebulae. We interpreted thephotometer for the KAO. He asked if I’d be interested in near-infrared nebulae as reflection nebulae and the far-ir
working on that as well as helping with upgrading his bal- emission as cool dust, both consistent with structure inloon gondola and that sounded great. After that, we ended dicative of circumstellar disks close to the exciting stars.
up creating new, improved versions of the instrument every three years or so until the KAO was retired in 1995. Q: About 10 years ago you carried out a series of studies3

of the Serpens star forming region at mid- and far-infrared Herschel’s big increase in angular resolution. I submitwavelengths with Spitzer.
ted an open-time Key Project proposal to perform a fairly
A: This was a part of the Spitzer “From Cores to Planet- large survey of known BD’s in star-forming regions, but
Forming Disks” Legacy Project (c2d) led by Neal Evans at that was turned down. So I took a large chunk of my guarUT. This was yet another “accident” in my career. Early in anteed time (as a Mission Scientist) together with a big
the planning we talked about who wanted to be in charge contribution from Thomas Henning’s guaranteed time onof which region to be observed. Since I had already sug- the PACS team to observe a subset of the original planned
gested that I would handle the software and processing for set of BD’s. I think our paper was the first large study
source extraction, I thought it would make some sense to of far-infrared emission from young BD’s. Since most of
test it on a region as close to the Galactic Plane as possible the mass in circumstellar disks is in the outer, coolest,
and toward the center of the Galaxy to see what the prob- parts of the disks, these observations and the accompanylems would be with a high density of sources. Serpens fit ing modeling allowed much more accurate estimates of thethat requirement perfectly, as well as being a region where total disk masses, as well as placed limits on the structure
I had made a few observations with the KAO. This was my of the disks. This added to the growing understanding
first experience with relatively large-scale infrared imag- that even sub-stellar objects were formed with surrounding in multiple, simultaneous colors, and it was great fun ing disks, presumably by the same processes that moreproducing the various false-color images that were possible massive, hydrogen-burning stars were formed. Althoughfrom our observations. We were able to successfully iden- there is a very wide range of disk masses seen aroundtify 235 YSOs out of more than 200,000 sources detected, young stars, the evidence suggested that there is a roughand to study their energy distributions, luminosities, and proportionality between the mass of a disk and the massof the central star.
spatial distribution.
Q: You have also used FORCAST onboard SOFIA. What
are the strengths of that instrument and what did you
learn?

Q: In a recent study you used Herschel to study circumstellar disks in the R CrA surroundings. What were theresults?

A: For me the value of FORCAST is that the longest
wavelength filter around 37 microns is long enough that
one is beginning to look at the same dust as that emittingstrongly at 50-100 microns, but with much better angularresolution than possible with Spitzer or the KAO. My first
proposal was to work with the team on some star-forming
region where that resolution would be useful in separating closely spaced sources. In the end we chose Sharpless
140, a region that I had observed many times with the
KAO. The combination of our SOFIA data with high resolution ground-based data from ESO made it possible todetermine the luminosities of the individual young stars
much more reliably. I had also hoped to continue using
FORCAST to attempt observing some lunar occultationsin the mid-infrared. I made some preliminary test observations of the dark limb of the Moon to see how feasible
the project was, but the pointing stability at the time was
not sufficiently good to enable the required sensitivity.

A: This proposal was a small, open-time program that
was aimed at enlarging our data set on very low luminosity stars and BD’s. The proposal had a larger set of objects
than just these in R CrA, but the remaining objects were
not observed before Herschel’s cryogens were depleted. We
did manage to detect all 5 observed objects with S/N of
4-20 at 70 microns, and used radiative transfer modelingto estimate the dust and gas masses in the disks aroundthe stars/BD’s. Our analysis of their spectral energy distributions supported the conclusions of our previous study
that the star-disk mass ratio for brown dwarfs extends the
T Tauri relation to much lower masses.
Q: You led a team in a Herschel and CSO study of the
Auriga-California dark cloud which, despite being comparable in size and mass to the Orion GMC, has a muchsmaller population of young stars. What do you think werethe most important conclusions from that study?

A: The Auriga-California molecular cloud is an interesting
Q: You were involved in the Herschel mission and among contrast to the Orion Molecular Cloud. They both haveother topics studied cold dust in the disks of brown dwarfs. similar masses, but very different star formation rates, esA: I became interested in this area when I realized that pecially for massive stars. We suggested that the main
we were detecting very low luminosity young stars in our observable difference in the clouds is that the amount of
Spitzer c2d observations. That led to a Spitzer PI pro- gas mass in higher density clumps is significantly higher inposal to try to go very deep in a few areas to try to find the OMC than in the AMC. This, of course, just pushes
very young brown dwarfs. In many areas our sensitiv- the question back one step to what has created this differity was limited by Spitzer’s modest angular resolution to- ence?
gether with the presence of diffuse background emission.
So I hoped to improve on these kinds of observations with4

Abstracts of recently accepted papers

1.

Search for Alignment of Disk Orientations in Nearby Star-Forming Regions: Lupus,
Taurus, Upper Scorpius, ρ Ophiuchi, and Orion
Masataka Aizawa1,2 , Yasushi Suto1,3 , Yoko Oya1,3 , Shiro Ikeda4,5,6 , and Takeshi Nakazato6
Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan; 2 College of Science, Ibaraki University,
Bunkyo 2-1-1, Mito, Ibaraki, 310-8512, Japan; 3 Research Center for the Early Universe, School of Science, The
University of Tokyo, Tokyo 113-0033, Japan; 4 The Institute of Statistical Mathematics, 10-3 Midori-cho, Tachikawa,Tokyo 190-8562, Japan; 5 Department of Statistical Science, Graduate University for Advanced Studies, 10-3 Midoricho, Tachikawa, Tokyo 190-8562, Japan; 6 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo
181-8588, Japan1

E-mail contact: masataka.aizawa.mk at vc.ibaraki.ac.jp
Spatial correlations among proto-planetary disk orientations carry unique information on physics of multiple starformation processes. We select five nearby star-forming regions that comprise a number of proto-planetary disks withspatially-resolved images with ALMA and HST, and search for the mutual alignment of the disk axes. Specifically, weapply the Kuiper test to examine the statistical uniformity of the position angle (PA: the angle of the major axis of the
projected disk ellipse measured counter-clockwise from the north) distribution. The disks located in the star-forming
regions, except the Lupus clouds, do not show any signature of the alignment, supporting the random orientation.
Rotational axes of 16 disks with spectroscopic measurement of PA in the Lupus III cloud, a sub-region of the Lupus
field, however, exhibit a weak and possible departure from the random distribution at a 2σ level, and the inclination
angles of the 16 disks are not uniform as well. Furthermore, the mean direction of the disk PAs in the Lupus III cloudis parallel to the direction of its filament structure, and approximately perpendicular to the magnetic field direction.
We also confirm the robustness of the estimated PAs in the Lupus clouds by comparing the different observations andestimators based on three different methods including sparse modeling. The absence of the significant alignment of
the disk orientation is consistent with the turbulent origin of the disk angular momentum. Further observations are
required to confirm/falsify the possible disk alignment in the Lupus III cloud.
Accepted by ApJ
http://arxiv.org/pdf/2007.03393

2. Studying star-forming processes at core and clump scales: the case of the young stellar

object G29.862−0.0044

M.B. Areal1 , S. Paron1 , C. Fariña2,3 , M.E. Ortega1 , M. Celis Peña1 , and M. Rubio4
CONICET - Universidad de Buenos Aires. Instituto de Astronomía y Física del Espacio CC 67, Suc. 28, 1428
Buenos Aires, Argentina; 2 Isaac Newton Group of Telescopes, E38700, La Palma, Spain; 3 Instituto de Astrofísica deCanarias (IAC) and Universidad de La Laguna, Dpto. Astrofísica, Spain; 4 Departamento de Astronomía, Universidad
de Chile, Casilla 36-D, Santiago, Chile
1

E-mail contact: sparon at iafe.uba.ar
Massive molecular clumps fragment into cores where star formation takes place, hence star-forming studies should bedone at different spatial scales. Using near-IR data obtained with Gemini, data of CH3 OCHO and CH3 CN from the
ALMA database, observations of HCN, HNC, HCO+ , and C2 H carried out with ASTE, and CO data from public
surveys, we perform a deep study of the YSO G29.86−0.004 at core and clump spatial scales. The near-IR emission
shows two nebulosities separated by a dark lane, suggesting a typical disk-jets system, but highly asymmetric. They
are likely produced by scattered light in cavities carved out by jets on an infalling envelope of material, which alsopresent line emission of H2 and [FeII]. The presence of the complex molecular species observed with ALMA confirmsthat we are mapping a hot molecular core. The CH3 CN emission concentrates at the position of the dark lane and it
5

appears slightly elongated from southwest to northeast in agreement with the inclination of the system as observedat near-IR. The morphology of the CH3 OCHO emission is more complex and extends along some filaments andconcentrates in knots and clumps, mainly southwards the dark-lane, suggesting that the southern jet is encounteringa dense region. The northern jet flows more freely, generating more extended features. This is in agreement withthe red-shifted molecular outflow traced by the 12 CO J=3–2 line extending towards the northwest and the lack of ablue-shifted outflow. This configuration can be explained by considering that the YSO is located at the furthest edgeof the molecular clump along the line of sight, which is consistent with the position of the source in the cloud mappedin the C18 O J=3–2 line. The detection of HCN, HNC, HCO+ , and C2 H allowed us to characterize the dense gas atclump scales, yielding results that are in agreement with the presence of a high-mass protostellar object.
Accepted by A&A
http://arxiv.org/pdf/2007.07852

3.

A Machine Learning model to infer planet masses from gaps observed in protoplanetarydisks
Sayantan Auddy1 and Min-Kai Lin1
1

Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan

E-mail contact: sauddy at asiaa.sinica.edu.tw
Observations of bright protoplanetary disks often show annular gaps in their dust emission. One interpretation ofthese gaps is disk-planet interaction. If so, fitting models of planetary gaps to observed protoplanetary disk gaps canreveal the presence of hidden planets. However, future surveys are expected to produce an ever-increasing numberof protoplanetary disks with gaps. In this case, performing a customized fitting for each target becomes impracticalowing to the complexity of disk-planet interaction. To this end, we introduce DPNNet (Disk Planet Neural Network),
an efficient model of planetary gaps by exploiting the power of machine learning. We train a deep neural network witha large number of dusty disk-planet hydrodynamic simulations across a range of planet masses, disk temperatures,
disk viscosities, disk surface density profiles, particle Stokes numbers, and dust abundances. The network can then be
deployed to extract the planet mass for a given gap morphology. In this work, first in a series, we focus on the basic
concepts of our machine learning framework. We demonstrate its utility by applying it to the dust gaps observed in
the protoplanetary disk around HL Tau at 10 au, 30 au, and 80 au. Our network predict planet masses of 80 MEarth ,63 MEarth, and 70 MEarth , respectively, which are comparable to other studies based on specialized simulations. We
discuss the key advantages of our DPNNet in its flexibility to incorporate new physics, any number of parameters andpredictions, and its potential to ultimately replace hydrodynamical simulations for disk observers and modelers.
Accepted by ApJ
http://arxiv.org/pdf/2007.13779

4.

LEGO II: A 3 mm molecular line study covering 100 pc of one of the most actively
star-forming portions within the Milky Way Disc
A.T. Barnes1 , J. Kauﬀmann2 , F. Bigiel1, N. Brinkmann3 , D. Colombo3, A.E Guzman4 , W.J. Kim5 , L.
Szűcs6 , V. Wakelam7 , S. Aalto8 , T. Albertsson3 , N.J. Evans II9 , S.C.O. Glover10 , P.F. Goldsmith11,
C. Kramer12 , K. Menten4 , Y. Nishimura13,14 , S. Viti15 , Y. Watanabe16 , A. Weiss3, M. Wienen3,17 , H.
Wiesemeyer3 and F. Wyrowski4
Argelander-Institut für Astronomie (AIfA), Universität Bonn, Auf dem Hügel 71, 53121, Bonn, Germany; 2 HaystackObservatory, Massachusetts Institute of Technology, Westford, MA 01886, USA; 3 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany; 4 National Astronomical Observatory of Japan, National
Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 5 Instituto de Radioastronomía Milimétrica (IRAM), Granada, Spain; 6 Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstr. 1,
D-85748 Garching, Germany; 7 Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France; 8 Department of Space, Earth and Environment, Chalmers University ofTechnology, Onsala Observatory, 439 92 Onsala, Sweden; 9 Department of Astronomy The University of Texas atAustin 2515 Speedway, Stop C1400 Austin, Texas 78712-1205, USA; 10 nstitut für Theoretische Astrophysik, Zentrum
16

für Astronomie der Universität Heidelberg, Albert-Ueberle-Strasse 2, 69120 Heidelberg, Germany; 11 Jet Propulsion
Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena CA 91109, USA; 12 Institut deRadioastronomie Millimetrique, 300 rue de la Piscine, Domaine Universitaire 38406 Saint Martin d’Heres, France;
13
Institute of Astronomy, The University of Tokyo, 2-21-1, Osawa, Mitaka, Tokyo 181-0015, Japan; 14 National
Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan; 15 Department of Physics andAstronomy, UCL, Gower St., London WC1E 6BT, UK; 16 Materials Science and Engineering, College of Engineering,
Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan; 17 University of Exeter, Stocker
Road, Exeter EX4 4QL, UK
E-mail contact: ashleybarnes.astro at gmail.com
The current generation of (sub)mm-telescopes has allowed molecular line emission to become a major tool for studying
the physical, kinematic, and chemical properties of extragalactic systems, yet exploiting these observations requires adetailed understanding of where emission lines originate within the Milky Way. In this paper, we present 60 arcsec(∼ 3 pc) resolution observations of many 3mm-band molecular lines across a large map of the W49 massive starforming region (∼ 100 × 100 pc at 11 kpc), which were taken as part of the “LEGO” IRAM-30m large project. We
find that the spatial extent or brightness of the molecular line transitions are not well correlated with their criticaldensities, highlighting abundance and optical depth must be considered when estimating line emission characteristics.
We explore how the total emission and emission efficiency (i.e. line brightness per H2 column density) of the line
emission vary as a function of molecular hydrogen column density and dust temperature. We find that there is nota single region of this parameter space responsible for the brightest and most efficiently emitting gas for all species.
For example, we find that the HCN transition shows high emission efficiency at high column density (1022 cm−2 )and moderate temperatures (35 K), whilst e.g. N2 H+ emits most efficiently towards lower temperatures (1022 cm−2 ;<20 K). We determine XCO(1−0) ∼ 0.3 × 1020 cm−2 (K km s−1 )−1 , and αHCN(1−0) ∼ 30 M⊙ (K km s−1 pc2 )−1 , which
both differ significantly from the commonly adopted values. In all, these results suggest caution should be taken wheninterpreting molecular line emission.
Accepted by MNRAS
https://arxiv.org/pdf/2007.11005.pdf

5.

High Resolution Infrared Spectroscopy of Hot Molecular Gas in AFGL 2591 and AFGL
2136: Accretion in the Inner Regions of Disks Around Massive Young Stellar Objects
Andrew G. Barr1 , Adwin Boogert2 , Curtis N. DeWitt3 , Edward Montiel3 , Matthew J. Richter4 , John
H. Lacy5 , David A. Neufeld6 , Nick Indriolo7 , Yvonne Pendleton8 , Jean Chiar9 and Alexander G. G.
M. Tielens1
Leiden University Niels Bohrweg 2, 2333 CA Leiden, The Netherlands; 2 Institute for Astronomy University of
Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA; 3 USRA, SOFIA, NASA Ames Research Center, MS 23211, Moffett Field, CA 94035, USA; 4 University of California, Davis, Phys 539, Davis, CA 95616, USA; 5 Department of
Astronomy, The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712, USA; 6 Johns Hopkins
University, Baltimore, MD 21218, USA; 7 ALMA Project, National Astronomical Observatory of Japan, National
Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 8 NASA Ames Research Center, Moffett
Field, CA 94035, USA; 9 Diablo Valley College, 321 Golf Club Rd, Pleasant Hill, CA 94523, USA
1E-mail contact: barr at strw.leidenuniv.nl
We have performed a high resolution 4-13 µm spectral survey of the hot molecular gas associated with the massive protostars AFGL 2591 and AFGL 2136, utilising the Echelon-Cross-Echelle-Spectrograph (EXES) on-board theStratospheric Observatory for Infrared Astronomy (SOFIA), and the iSHELL instrument and Texas Echelon Cross
Echelle Spectrograph (TEXES) on the NASA Infrared Telescope Facility (IRTF). Here we present results of this survey with analysis of CO, HCN, C2 H2 , NH3 and CS, deriving the physical conditions for each species. Also from theIRTF, iSHELL data at 3 µm for AFGL 2591 are presented that show HCN and C2 H2 in emission. In the EXES andTEXES data, all species are detected in absorption, and temperatures and abundances are found to be high (600 K
and 10−6 , respectively). Differences of up to an order of magnitude in the abundances of transitions that trace thesame ground state level are measured for HCN and C2 H2 . The mid-infrared continuum is known to originate in a
disk, hence we attribute the infrared absorption to arise in the photosphere of the disk. As absorption lines require an
outwardly decreasing temperature gradient, we conclude that the disk is heated in the mid-plane by viscous heating
7

due to accretion. We attribute the near-IR emission lines to scattering by molecules in the upper layers of the disk
photosphere. The absorption lines trace the disk properties at 50 AU where a high temperature gas-phase chemistry
is taking place. Abundances are consistent with chemical models of the inner disk of Herbig disks.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/2007.11266.pdf

6.

CMZoom: Survey Overview and First Data Release
Cara Battersby1,2 , Eric Keto2 , Daniel Walker3,4 , Ashley Barnes5 , Daniel Callanan6,2 , Adam Ginsburg7 ,H Perry Hatchﬁeld1 , Jonathan Henshaw8 , Jens Kauﬀmann9 , J. M. Diederik Kruijssen10 , Steven N.
Longmore6 , Xing Lu4 , Elisabeth A. C. Mills11, Thushara Pillai12 , Qizhou Zhang2 , John Bally13 , Natalie
Butterﬁeld14 , Yanett A. Contreras15 , Luis C. Ho16,17 , Juergen Ott18 , Nimesh Patel2 and Volker Tolls2
University of Connecticut, Department of Physics, 196 Auditorium Road, Unit 3046, Storrs, CT 06269 USA; 2 Center
for Astrophysics ; 3 Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138 USA; 4 Joint ALMA Observatory,
Alonso de Córdova 3107, Vitacura, Santiago, Chile; 5 National Astronomical Observatory of Japan, 2-21-1 Osawa,
Mitaka, Tokyo, 181-8588, Japan; 6 Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121,
Bonn, Germany; 7 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool
L3 5RF, UK; 8 University of Florida Department of Astronomy, Bryant Space Science Center, Gainesville, FL, 32611,
USA; 9 Max-Planck-Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg, Germany; 10 Haystack Observatory,
Massachusetts Institute of Technology, 99 Millstone Road, Westford, MA 01886, USA; 11 Astronomisches RechenInstitut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, D-69120 Heidelberg, Germany;
12
Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045,
USA; 13 Boston University Astronomy Department, 725 Commonwealth Avenue, Boston, MA 02215, USA; 14 CASA,
University of Colorado, 389-UCB, Boulder, CO 80309; 15 Green Bank Observatory, 155 Observatory Rd, PO Box
2, Green Bank, WV 24944, USA; 16 Leiden Observatory, Leiden University, PO Box 9513, NL 2300 RA Leiden,
the Netherlands; 17 Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China; 18
Department of Astronomy, School of Physics, Peking University, Beijing 100871, China
1E-mail contact: cara.battersby at uconn.edu
We present an overview of the CMZoom survey and its first data release. CMZoom is the first blind, high-resolution
survey of the Central Molecular Zone (CMZ; the inner 500 pc of the Milky Way) at wavelengths sensitive to the precursors of high-mass stars. CMZoom is a 550-hour Large Program on the Submillimeter Array (SMA) that mapped at
1.3 mm all of the gas and dust in the CMZ above a molecular hydrogen column density of 1023 cm−2 at a resolution of∼3′′ (0.1 pc). In this paper, we focus on the 1.3 mm dust continuum and its data release, but also describe CMZoom
spectral line data which will be released in a forthcoming publication. While CMZoom detected many regions with richand complex substructure, its key result is an overall deficit in compact substructures on 0.1 - 2 pc scales (the compact
dense gas fraction: CDGF). In comparison with clouds in the Galactic disk, the CDGF in the CMZ is substantiallylower, despite having much higher average column densities. CMZ clouds with high CDGFs are well-known sites ofactive star formation. The inability of most gas in the CMZ to form compact substructures is likely responsible forthe dearth of star formation in the CMZ, surprising considering its high density. The factors responsible for the low
CDGF are not yet understood but are plausibly due to the extreme environment of the CMZ, having far-reachingramifications for our understanding of the star formation process across the cosmos.
Accepted by ApJS
https://arxiv.org/pdf/2007.05023

7.

Birth of convective low-mass to high-mass second Larson cores
Asmita Bhandare1 , Rolf Kuiper2,1 , Thomas Henning1 , Christian Fendt1 , Mario Flock1 and GabrielDominique Marleau2,3,1
Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany; 2 Institut für Astronomie undAstrophysik, Universität Tübingen, Auf der Morgenstelle 10, D-72076 Tübingen, Germany; 3 Physikalisches Institut,
Universität Bern, Gesellschaftsstr. 6, CH-3012 Bern, Switzerland

18E-mail contact: bhandare at mpia.de
Stars form as an end product of the gravitational collapse of cold, dense gas in magnetized molecular clouds. This
fundamentally multi-scale scenario occurs via the formation of two quasi-hydrostatic Larson cores and involves complex
physical processes, which require a robust, self-consistent numerical treatment. The primary aim of this study is tounderstand the formation and evolution of the second hydrostatic Larson core and the dependence of its properties
on the initial cloud core mass. We used the PLUTO code to perform high-resolution, one- and two-dimensionalradiation hydrodynamic (RHD) core collapse simulations. We include self-gravity and use a grey flux-limited diffusion
approximation for the radiative transfer. Additionally, we use for the gas equation of state density- and temperaturedependent thermodynamic quantities (heat capacity, mean molecular weight, etc.) to account for effects such as
dissociation of molecular hydrogen, ionisation of atomic hydrogen and helium, and molecular vibrations and rotations.
Properties of the second core are investigated using one-dimensional studies spanning a wide range of initial cloud coremasses from 0.5 M⊙ to 100 M⊙ . Furthermore, we expand to two-dimensional (2D) collapse simulations for a selected
few cases of 1 M⊙ , 5 M⊙ , 10 M⊙ , and 20 M⊙ . We follow the evolution of the second core for ≥ 100 years after its
formation, for each of these non-rotating cases. Our results indicate a dependence of several second core properties on
the initial cloud core mass. Molecular cloud cores with a higher initial mass collapse faster to form bigger and more
massive second cores. The high-mass second cores can accrete at a much faster rate of ≈ 10−2 M⊙ yr−1 compared to
the low-mass second cores, which have accretion rates as low as 10−5 M⊙ yr−1 . For the first time, owing to a resolutionthat has not been achieved before, our 2D non-rotating collapse studies indicate that convection is generated in theouter layers of the second core, which is formed due to the gravitational collapse of a 1 M⊙ cloud core. Additionally,
we find large-scale oscillations of the second accretion shock front triggered by the standing accretion shock instability(SASI), which has not been seen before in early evolutionary stages of stars. We predict that the physics within thesecond core would not be significantly influenced by the effects of magnetic fields or an initial cloud rotation. In our
2D RHD simulations, we find convection being driven from the accretion shock towards the interior of the second
Larson core. This supports an interesting possibility that dynamo-driven magnetic fields may be generated during thevery early phases of low-mass star formation.
Accepted by Astronomy and Astrophysics
https://www.aanda.org/articles/aa/pdf/2020/06/aa37029-19.pdf

8.

FAUST I. The hot corino at the heart of the prototypical Class I protostar L1551 IRS5
E. Bianchi1 , C. J. Chandler2 , C. Ceccarelli1 , C. Codella3,1, N. Sakai4 , A. Lopez-Sepulcre1,5 , L. T.
Maud6 , G. Moellenbrock2 , B. Svoboda2 , Y. Watanabe7 , T. Sakai8 , F. Ménard1 , Y. Aikawa9 , F. Alves10 ,N. Balucani11 , M. Bouvier1 , P. Caselli12 , E. Caux13 , S. Charnley14 , S. Choudhury10 , M. De Simone1 ,F. Dulieu15 , A. Duran16 , L. Evans13,3 , C. Favre1 , D. Fedele3 , S. Feng17,18,19 , F. Fontani3 , L. Francis20,21 ,T. Hama22,23 , T. Hanawa24 , E. Herbst25 , T. Hirota18 , M. Imai26 , A. Isella27 , I. Jimenez-Serra28 , D.
Johnstone20,21 , C. Kahane1 , B. Leﬂoch1 , L. Loinard16,29 , M. J. Maureira10 , S. Mercimek3,30 , A. Miotello6,
S. Mori9 , R. Nakatani4 , H. Nomura31 , Y. Oba33 , S. Ohashi4 , Y. Okoda4 , J. Ospina-Zamudio1 , Y. Oya26 ,J. Pineda10 , L. Podio3 , A. Rimola33, D. Segura Cox12 , Y. Shirley34 , V. Taquet3 , L. Testi6 , C. Vastel13 ,S. Viti35 , N. Watanabe32 , A. Witzel1 , C. Xue25 , Y. Zhang4 , B. Zhao10 and S. Yamamoto26
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France; 2 National Radio Astronomy Observatory, PO Box
O, Socorro, NM 87801, USA; 3 INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125, Firenze, Italy;
4
RIKEN Cluster for Pioneering Research, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan; 5 Institut de Radioastronomie Millimetrique, 38406 Saint-Martin d’Heres, France; 6 European Southern Observatory, Karl-Schwarzschild
Str. 2, 85748 Garching bei München, Germany; 7 Materials Science and Engineering, College of Engineering, Shibaura
Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan; 8 Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan; 9 Dept of Astronomy, The
University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; 10 Max-Planck-Institut für extraterrestrische
Physik (MPE), Giessenbachstr. 1, D-85741 Garching, Germany; 11 Dept of Chemistry, Biology, and Biotechnology,
The University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy}; 12 Center for Astrochemical Studies, Max-PlanckInstitut für extraterrestrische Physik (MPE), Giessenbachstr. 1, D-85741 Garching, Germany; 13 IRAP, Universite
de Toulouse, CNRS, CNES, UPS, Toulouse, France; 14 Astrochemistry Laboratory, Code 691, NASA Goddard Space
Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA; 15 CY Cergy Paris Universite, Sorbonne Universite,
Observatoire de Paris, PSL University, CNRS, LERMA, F-95000, Cergy, France; 16 nstituto de Radioastronomia y19Astrofisica , Universidad Nacional Autonoma de Mexico, A.P. 3-72 (Xangari), 8701, Morelia, Mexico; 17 CAS Key
Laboratory of FAST, National Astronomical Observatory of China, Datun Road 20, Chaoyang, Beijing, 100012, P. R.
China; 18 National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka,
Tokyo 181-8588, Japan; 19 Academia Sinica Institute of Astronomy and Astrophysics, No.1, Sec. 4, Roosevelt Rd,
Taipei 10617, Taiwan, Republic of China; 20 Dept of Physics and Astronomy, University of Victoria, 3800 Finnerty
Road, Elliot Building Victoria, BC, V8P 5C2, Canada; 21 NRC Herzberg Astronomy and Astrophysics 5071 West
Saanich Road, Victoria, BC, V9E 2E7, Canada; 22 Komaba Institute for Science, Univ. of Tokyo, 3-8-1 Komaba,
Meguro, Tokyo 153-8902, Japan; 23 Dept of Basic Science, Univ. of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902,
Japan; 24 Center for Frontier Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan; 25 Dept ofChemistry, Univ. of Virginia, McCormick Road, PO Box 400319, Charlottesville, VA 22904, USA; 26 Dept of Physics,
Univ. of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; 27 Dept of Physics and Astronomy, Rice University,
6100 Main Street, MS-108, Houston, TX 77005, USA; 28 Centro de Astrobiologia (CSIC-INTA), Ctra. de Torrejona Ajalvir, km 4, 28850, Torrejon de Ardoz, Spain; 29 Instituto de Astronomia, Universidad Nacional Autonoma de
Mexico, Ciudad Universitaria, A.P. 70-264, Cuidad de Mexico 04510, Mexico; 30 Universita degli Studi di Firenze,
Dipartimento di Fisica e Astronomia, via G. Sansone 1, 50019 Sesto Fiorentino, Italy; 31 Division of Science, National
Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 32 Institute of Low Temperature
Science, Hokkaido University, N19W8, Kita-ku, Sapporo, Hokkaido 060-0819, Japan; 33 Dept de Quimica, Universitat
Autonoma de Barcelona, 08193 Bellaterra, Spain; 34 Steward Observatory, 933 N Cherry Ave., Tucson, AZ 85721
USA; 35 Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
E-mail contact: eleonora.bianchi at univ-grenoble-alpes.fr
The study of hot corinos in Solar-like protostars has been so far mostly limited to the Class 0 phase, hampering ourunderstanding of their origin and evolution. In addition, recent evidence suggests that planet formation starts alreadyduring Class I phase, which, therefore, represents a crucial step in the future planetary system chemical composition.
Hence, the study of hot corinos in Class I protostars has become of paramount importance. Here we report thediscovery of a hot corino towards the prototypical Class I protostar L1551 IRS5, obtained within the ALMA Large
Program FAUST. We detected several lines from methanol and its isopotologues (13 CH3 OH and CH2 DOH), methyl
formate and ethanol. Lines are bright toward the north component of the IRS5 binary system, and a possible second
hot corino may be associated with the south component. The methanol lines non-LTE analysis constrains the gas
temperature (∼100 K), density (≥1.5×108 cm−3 ), and emitting size (∼10 au in radius). All CH3 OH and 13 CH3 OH
lines are optically thick, preventing a reliable measure of the deuteration. The methyl formate and ethanol relative
abundances are compatible with those measured in Class 0 hot corinos. Thus, based on the present work, little
chemical evolution from Class 0 to I hot corinos occurs.
Accepted by MNRAS Letters
https://arxiv.org/pdf/2007.10275

9. Estimation of the Gould Belt scale height from T Tauri type stars in the Gaia DR2

catalogue

V.V. Bobylev1 and A.T. Bajkova1
1

Central (Pulkovo) Astronomical Observatory, Russian Academy of Sciences, St.-Petersburg, 196140 Russia

E-mail contact: vbobylev at gaoran.ru
We analyze the spatial and kinematic properties of a large sample of young T Tauri type stars in a 500 pc radius solar
neighborhood, closely related to the Gould belt. The following parameters of the exponential density distribution
have been determined: the average (zG )⊙ = −25 ± 5 pc and scale height hG = 56 ± 6 pc. We propose a method of
excluding background stars from the samples, which are located at large heights with respect to the symmetry planeof the Gould belt. We discovered that the expansion effect for the entire star system, KG = 6 ± 1 km s−1 kpc−1 , isdetermined mainly by the dynamics of the Scorpius-Centaurus association. We show that the angular velocity of theresidual intrinsic rotation of the Gould belt can reach ΩG = 6.9 ± 0.2 km s−1 kpc−1 and that this rotation is opposite
to the galactic rotation.
Accepted by Astrophysical Bulletin
http://arxiv.org/pdf/2007.05268
1010. Self-scattering in protoplanetary disks with dust settling
R. Brunngräber 1 and S. Wolf1
Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstr. 15, 24118
Kiel, Germany
1E-mail contact: rbrunngraeber at astrophysik.uni-kiel.de
Scattering of re-emitted flux is considered to be at least partially responsible for the observed polarisation in the(sub-)millimetre wavelength range of several protoplanetary disks. Although the degree of polarisation produced byscattering is highly dependent on the dust model, early studies investigating this mechanism relied on the assumptionof single grain sizes and simple density distribution of the dust. However, in the dense inner regions where thismechanism is usually most efficient, the existence of dust grains with sizes ranging from nanometres to millimetres has
been confirmed. Additionally, the presence of gas forces larger grains to migrate vertically towards the disk midplane,
introducing a dust segregation in the vertical direction. Using polarisation radiative transfer simulations, we analyse
the dependence of the resulting scattered light polarisation at 350 micron, 850 micron, 1.3 mm, and 2 mm on various
parameters describing protoplanetary disks, including the effect of dust grain settling. We find that the different disk
parameters change the degree of polarisation mostly by affecting the anisotropy of the radiation field, the opticaldepth, or both. It is therefore very challenging to deduce certain disk parameter values directly from polarisation
measurements alone. However, assuming a high dust albedo, it is possible to trace the transition from optically thickto optically thin disk regions. The degree of polarisation in most of the considered disk configurations is lower thanwhat is found observationally, implying the necessity to revisit models that describe the dust properties and disk
structure.
Accepted by A&A
https://arxiv.org/pdf/2007.05715

11. The dichotomy of atmospheric escape in AU Mic b
S. Carolan1 , A. A. Vidotto1 , P. Plavchan2 , C. Villarreal D’Angelo3,1 and G. Hazra1
School of Physics, Trinity College Dublin, the University of Dublin, Dublin-2, Ireland; 2 Department of Physics andAstronomy, George Mason University, Fairfax, VA, 22030, USA; 3 Observatorio Astronomico de Cordoba - Universidad
Nacional de Cordoba. Laprida 854, X5000BGR, Cordoba, Argentina
1E-mail contact: carolast at tcd.ie
Here, we study the dichotomy of the escaping atmosphere of the newly discovered close-in exoplanet AU Mic b. On
one hand, the high EUV stellar flux is expected to cause a strong atmospheric escape in AU Mic b. On the other hand,
the wind of this young star is believed to be very strong, which could reduce or even inhibit the planet’s atmosphericescape. AU Mic is thought to have a wind mass-loss rate that is up to 1000 times larger than the solar wind mass-loss
rate (Ṁ⊙ ). To investigate this dichotomy, we perform 3D hydrodynamics simulations of the stellar wind–planetaryatmosphere interactions in the AU Mic system and predict the synthetic Ly-α transits of AU Mic b. We systematicallyvary the stellar wind mass-loss rate from a ‘no wind’ scenario to up to a stellar wind with a mass-loss rate of 1000 Ṁ⊙ .
We find that, as the stellar wind becomes stronger, the planetary evaporation rate decreases from 6.5 × 1010 g/s tohalf this value. With a stronger stellar wind, the atmosphere is forced to occupy a smaller volume, affecting transit
signatures. Our predicted Ly-α absorption drops from ∼ 20%, in the case of ‘no wind’ to barely any Ly-α absorption in
the extreme stellar wind scenario. Future Ly-α transits could therefore place constraints not only on the evaporation
rate of AU Mic b, but also on the mass-loss rate of its host star.
Accepted by MNRAS
https://arxiv.org/pdf/2006.13606

1112. Ubiquitous NH3 supersonic component in L1688 coherent cores
Spandan Choudhury1 , Jaime E. Pineda1 , Paola Caselli1 , Adam Ginsburg2 , Stella S.R. Oﬀner3 et al.
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching, Germany; 2 Departmentof Astronomy, University of Florida, PO Box 112055, USA; 3 Department of Astronomy, The University of Texas atAustin, Austin, TX 78712, USA
1E-mail contact: spandan at mpe.mpg.deContext. Star formation takes place in cold dense cores in molecular clouds. Earlier observations have found that
dense cores exhibit subsonic non-thermal velocity dispersions. In contrast, CO observations show that the ambient
large-scale cloud is warmer and has supersonic velocity dispersions.
Aims. We aim to study the ammonia (NH3 ) molecular line profiles with exquisite sensitivity towards the coherent
cores in L1688 in order to study their kinematical properties in unprecedented detail.
Methods. We used NH3 (1,1) and (2,2) data from the first data release (DR1) in the Green Bank Ammonia Survey(GAS). We first smoothed the data to a larger beam of 1′ to obtain substantially more extended maps of velocity
dispersion and kinetic temperature, compared to the DR1 maps. We then identified the coherent cores in the cloud
and analysed the averaged line profiles towards the cores.
Results. For the first time, we detected a faint (mean NH3 (1,1) peak brightness <0.25 K in TMB ), supersoniccomponent towards all the coherent cores in L1688. We fitted two components, one broad and one narrow, andderived the kinetic temperature and velocity dispersion of each component. The broad components towards all cores
have supersonic linewidths (MS ≥ 1). This component biases the estimate of the narrow dense core component’s
velocity dispersion by ≈28% and the kinetic temperature by ≈10%, on average, as compared to the results fromsingle-component fits.
Conclusions. Neglecting this ubiquitous presence of a broad component towards all coherent cores causes the typicalsingle-component fit to overestimate the temperature and velocity dispersion. This affects the derived detailed physicalstructure and stability of the cores estimated from NH3 observations.
Accepted by A&A
http://arxiv.org/pdf/2007.07149

13. The hierarchical fragmentation of filaments and the role of sub-filaments
S. D. Clarke1 , G. M. Williams2 and S. Walch1,3
I. Physikalisches Institut, University of Cologne, Zuelpicher Str. 77, 50937, Cologne, Germany; 2 Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield,
AL10 9AB, UK; 3 Cologne Centre for Data and Simulation Science, University of Cologne, Cologne, Germany
1E-mail contact: clarke at ph1.uni-koeln.de
Recent observations have revealed the presence of small fibres or sub-filaments within larger filaments. We present
a numerical fragmentation study of fibrous filaments investigating the link between cores and sub-filaments usinghydrodynamical simulations performed with the moving-mesh code Arepo. Our study suggests that cores form in
two environments: (i) as isolated cores, or small chains of cores, on a single sub-filament, or (ii) as an ensemble of cores
located at the junction of sub-filaments. We term these isolated and hub cores respectively. We show that these core
populations are statistically different from each other. Hub cores have a greater mean mass than isolated cores, and themass distribution of hub cores is significantly wider than isolated cores. This fragmentation is reminiscent of parsecscale hub-filament systems, showing that the combination of turbulence and gravity leads to similar fragmentation
signatures on multiple scales, even within filaments. Moreover, the fact that fragmentation proceeds through subfilaments suggests that there exists no characteristic fragmentation length-scale between cores. This is in opposition
to earlier theoretical works studying fibre-less filaments which suggest a strong tendency towards the formation ofquasi-periodically spaced cores, but in better agreement with observations. We also show tentative signs that global
collapse of filaments preferentially form cores at both filament ends, which are more massive and dense than othercores.
Accepted by MNRAS
https://arxiv.org/pdf/2007.15358

12

14.

Anomalous Extinction toward NGC 1938
Guido De Marchi1 , Nino Panagia2,3 and Antonino P. Milone4,5
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; 3 Supernova Limited, OYV #131,
Northsound Road, Virgin Gorda, British Virgin Islands, United Kingdom; 4 Dipartimento di Fisica e Astronomia, Univ.
di Padova, Vicolo dell’Osservatorio 3, Padova I-35122, Italy; 5 Istituto Nazionale di Astrofisica, Osserv. Astronomico
di Padova, Vicolo dell’Osservatorio 5, Padova I-35122, Italy
1E-mail contact: gdemarchi at esa.int
Intrigued by the extended red giant clump (RC) stretching across the colour-magnitude diagram of the stars in a 50×50
pc2 region of the Large Magellanic Cloud (LMC) containing the clusters NGC 1938 and NGC 1939, we have studied
the stellar populations to learn about the properties of the interstellar medium (ISM) in this area. The extended RC iscaused by a large and uneven amount of extinction across the field. Its slope reveals anomalous extinction properties,
with AV /E(B − V ) ≃ 4.3, indicating the presence of an additional grey component in the optical contributing about
30% of the total extinction in the field and requiring big grains to be about twice as abundant as in the diffuse ISM.
This appears to be consistent with the amount of big grains injected into the surrounding ISM by the about 70 SN II
explosions estimated to have occurred during the lifetime of the ∼ 120 Myr old NGC 1938. Although this cluster
appears today relatively small and would be hard to detect beyond the distance of M 31, with an estimated initial
mass of ∼ 4800 M⊙ NGC 1938 appears to have seriously altered the extinction properties in a wide area. This has
important implications for the interpretation of luminosities and masses of star-forming galaxies, both nearby and in
the early universe.
Accepted by The Astrophysical Journal
http://arxiv.org/pdf/2007.11577

15.

RW Aur B: a modest UX Ori type companion of the famous primary
A. Dodin1 , S. Lamzin1 , P. Petrov2 , B. Safonov1 , M. Takami3 and A. Tatarnikov1
Sternberg Astronomical Institute, Moscow M.V. Lomonosov State University, Universitetskij pr., 13, Moscow, 119992,
Russia; 2 Crimean Astrophysical Observatory, Russian Academy of Sciences, 298409, Nauchny, Crimea; 3 Instituteof Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU, No.1, Sec. 4,
Roosevelt Rd., Taipei 10617, Taiwan, R.O.C.
1

E-mail contact: lamzin at sai.msu.ru
The secondary of the famous young binary RW Aur is much less studied than the primary. To compensate thisshortcoming, we present here the results of U BV RIJHK photometric, V RI polarimetric and optical spectral observations of RW Aur B. The star demonstrates chaotic brightness variations in the optical band with irregular short(∼ 1 day) dimmings with an amplitude ∆V up to 1.3m . The dimmings are accompanied with an increase in the linear
polarization (up to 3 per cent in the I band), presumably due to the scattering of the stellar radiation by dust in
the circumstellar disc that means that RW Aur B can be classified as a UX Ori type star. We concluded that theobserved excess emission at λ <∼ 0.45 µm and longward ≈ 2 µm as well as a variability of fluxes and profiles of H I,
He I and Na I D emission lines are due to the accretion process. At the same time, emission components of Ca IIlines indicate that RW Aur B has a powerful chromosphere. Assuming the solar elemental abundances, we found thefollowing parameters of the star: Teff = 4100 − 4200 K, AV = 0.6 ± 0.1 (out of the dimming events), L∗ ≈ 0.6 L⊙ ,R∗ ∼ 1.5 R⊙ , M ∼ 0.85 M⊙ , Ṁacc < 5 × 10−9 M⊙ yr−1 . Finally, we discuss possible reasons for the different levelsof the accretion activity of RW Aur binary components and present arguments in favour of the fact that they are
gravitationally bound.
Accepted by MNRAS
https://arxiv.org/pdf/2007.12559

16. Hunting for Runaways from the Orion Nebula Cluster
Juan P. Farias1 , Jonathan C. Tan1,2 and Laurent Eyer3
1

Dept. of Space, Earth & Environment, Chalmers University of Technology, Gothenburg, Sweden; 2 Dept. of Astron13

omy, University of Virginia, Charlottesville, VA 22904, USA; 3 Geneva Observatory, University of Geneva, Chemindes Maillettes 51, CH-1290, Versoix, Switzerland
E-mail contact: juan.farias at chalmers.se
We use Gaia DR2 to hunt for runaway stars from the Orion Nebula Cluster (ONC). We search a region extending45◦ around the ONC and out to 1 kpc to find sources that overlapped in angular position with the cluster in thelast ∼10 Myr. We find ∼ 17, 000 runaway/walkaway candidates satisfy this 2D traceback condition. Most of theseare expected to be contaminants, e.g., caused by Galactic streaming motions of stars at different distances. We thus
examine six further tests to help identify real runaways, namely: (1) possessing young stellar object (YSO) colors andmagnitudes based on Gaia optical photometry; (2) having IR excess consistent with YSOs based on 2MASS and WISE
photometry; (3) having a high degree of optical variability; (4) having closest approach distances well constrained towithin the cluster half-mass radius; (5) having ejection directions that avoid the main Galactic streaming contamination
zone; and (6) having a required radial velocity (RV) for 3D overlap of reasonable magnitude (or, for the 7% of candidates
with measured RVs, satisfying 3D traceback). Thirteen sources, not previously noted as Orion members, pass all thesetests, while another twelve are similarly promising, except they are in the main Galactic streaming contamination
zone. Among these 25 ejection candidates, ten with measured RVs pass the most restrictive 3D traceback condition.
We present full lists of runaway/walkaway candidates, estimate the high-velocity population ejected from the ONC
and discuss its implications for cluster formation theories via comparison with numerical simulations.
Accepted by ApJ
https://arxiv.org/pdf/2005.04762

17. ACRONYM IV: Three New, Young, Low-mass Spectroscopic Binaries
Laura Flagg1,2,3 , Evgenya L. Shkolnik4 , Alycia Weinberger5 , Brendan P. Bowler6 , Brian Skiﬀ3 et al.
Department of Physics and Astronomy, Rice University, 6100 Main St. MS-108, Houston, TX 77005, USA; 2
Department of Physics and Astronomy, Northern Arizona University, Box 6010, Flagstaff, AZ 86011, USA; 3 LowellObservatory, 1400 W Mars Hill Road, Flagstaff, AZ 86001, USA; 4 School of Earth and Space Exploration, ArizonaState University, 781 S Terrace Road, Tempe, AZ 85281, USA; 5 Department of Terrestrial Magnetism, Carnegie
Institution for Science, 5241 Broad Branch Road, NW, Washington, DC 20015, USA; 6 McDonald Observatory andthe Department of Astronomy, The University of Texas at Austin, Austin, TX 78712, USA
1E-mail contact: laura.flagg at rice.edu
As part of our search for new low-mass members of nearby young moving groups (YMG), we discovered three low-mass,
spectroscopic binaries, two of which are not kinematically associated with any known YMG. Using high-resolution
optical spectroscopy, we measure the component and systemic radial velocities of the systems, as well as their lithium
absorption and Hα emission, both spectroscopic indicators of youth. One system (2MASS J02543316−5108313,
M2.0+M3.0) we confirm as a member of the 40 Myr old Tuc-Hor moving group, but whose binarity was previously
undetected. The second young binary (2MASS J08355977−3042306, K5.5+M1.5) is not a kinematic match to any
known YMG, but each component exhibits lithium absorption and strong and wide Hα emission indicative of active
accretion, setting an upper age limit of 15 Myr. The third system (2MASS J10260210−4105537, M1.0+M3.0) has
been hypothesized in the literature to be a member of the 10 Myr old TW Hya Association (TWA), but with ourmeasured systemic velocity, shows the binary is in fact not part of any known YMG. This last system also has lithium
absorption in each component, and has strong and variable Hα emission, setting an upper age limit of 15 Myr basedon the lithium detection.
Accepted by ApJ
http://arxiv.org/pdf/2007.15799

A survey for variable young stars with small telescopes: III – Warm spots on the active

18. star V1598Cyg

Dirk Froebrich1 , Aleks Scholz2 , Jochen Eislöﬀel3, Bringfried Stecklum3
Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury CT2
7NH, UK; 2 SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16
9SS, UK; 3 Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany
114E-mail contact: df at star.kent.ac.uk
Magnetic spots on low-mass stars can be traced and characterised using multi-band photometric light curves. Here
we analyse an extensive data set for one active star, V1598Cyg, a known variable K dwarf which is either pre-main
sequence and/or in a close binary system. Our light curve contains 2854 photometric data points, mostly in V, Rc ,Ic , but also in U, B and Hα, with a total baseline of about 4yr, obtained with small telescopes as part of the HOYS
project. We find that V1598Cyg is a very fast rotator with a period of 0.8246 days and varying amplitudes in all
filters, best explained as a signature of strong magnetic activity and spots. We fit the photometric amplitudes in V,
Rc , Ic and use them to estimate spot properties, using a grid-based method that is also propagating uncertainties.
We verify the method on a partial data set with high cadence and all five broad-band filters. The method yields
spot temperatures and fractional spot coverage with typical uncertainties of 100 K and 3–4%, respectively. V1598Cyg
consistently exhibits spots that are a few hundred degrees warmer than the photosphere, most likely indicating thatthe light curve is dominated by chromospheric plage. The spot activity varies over our observing baseline, with atypical time scale of 0.5–1yr, which we interpret as the typical spot lifetime. Combining our light curve with archival
data, we find a six year cycle in the average brightness, that is probably a sign of a magnetic activity cycle.
Accepted by MNRAS
http://arxiv.org/pdf/2007.14969

19. Aluminum-26 Enrichment in the Surface of Protostellar Disks Due to Protostellar Cos-

mic Rays

Brandt A.L. Gaches1,2 , Stefanie Walch1,3 , Stella S.R. Oﬀner4,2 and Carsten Münker5
I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937, Köln, Germany; 2 Center of Planetary
Systems Habitability, The University of Texas at Austin, USA; 3 Center for Data and Simulation Science, Universität
zu Köln, Köln, Germany; 4 Department of Astronomy, The University of Texas at Austin, 2515 Speedway, Austin,
Texas, 78712, USA; 5 Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Straße 49b, 50674, Köln,
Germany
1E-mail contact: gaches at ph1.uni-koeln.de
The radioactive decay of aluminum-26 (26 Al) is an important heating source in early planet formation. Since its
discovery, there have been several mechanisms proposed to introduce 26 Al into protoplanetary disks, primarily throughcontamination by external sources. We propose a local mechanism to enrich protostellar disks with 26 Al throughirradiation of the protostellar disk surface by cosmic rays accelerated in the protostellar accretion shock. We calculate
the 26 Al enrichment, [26 Al/27 Al], at the surface of the protostellar disk in the inner AU throughout the evolution of
low-mass stars, from M-dwarfs to proto-Suns. Assuming constant mass accretion rates, ṁ, we find that irradiation by
MeV cosmic rays can provide significant enrichment on the disk surface if the cosmic rays are not completely coupled
to the gas in the accretion flow. Importantly, we find that low accretion rates, ṁ < 10−7 M⊙ yr−1 , are able to produce
canonical amounts of 26 Al, [26 Al/27 Al] ≈ 5 × 10−5 . These accretion rates are experienced at the transition from ClassI- to Class II-type protostars, when it is assumed that calcium-aluminum-rich inclusions condense in the inner disk.
We conclude that irradiation of the inner disk surface by cosmic ray protons accelerated in accretion shocks at the
protostellar surface may be an important mechanism to produce 26 Al. Our models show protostellar cosmic rays may
be a viable model to explain the enrichment of 26 Al found in the Solar System.
Accepted by ApJ
http://arxiv.org/pdf/2007.12707

20. Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): A close

low mass companion to ET Cha

C. Ginski1,2 , F. Ménard3 , Ch. Rab4 , E.E. Mamajek5,6 , R.G. van Holstein2,7 et al.
Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The
Netherlands; 2 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands; 3 Univ.
Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France; 4 Kapteyn Astronomical Institute, University of Groningen,
P.O. Box 800, 9700 AV Groningen, The Netherlands; 5 Jet Propulsion Laboratory, California Institute of Technology,
115

M/S 321-100, 4800 Oak Grove Drive, Pasadena, CA 91109, USA; 6 Department of Physics & Astronomy, Universityof Rochester, 500 Wilson Blvd., Rochester, NY 14627, USA; 7 European Southern Observatory (ESO), Alonso deCórdova 3107, Vitacura, Casilla 19001, Santiago de Chile, Chile
E-mail contact: c.ginski at uva.nl
To understand the formation of planetary systems, one needs to understand the initial conditions of planet formation,i.e. the young gas-rich planet forming disks. Spatially resolved high-contrast observations are of particular interest,since substructures in disks, linked to planet formation, can be detected and close companions or even planets information embedded in the disk can be revealed. In this study we present the first result of the DESTINYS survey(Disk Evolution Study Through Imaging of Nearby Young Stars). DESTINYS is an ESO/SPHERE large program thataims at studying disk evolution in scattered light, mainly focusing on a sample of low-mass stars (<1 M⊙ ) in nearby(∼200 pc) star-forming regions. In this particular study we present the observations of the ET Cha (RECX 15) system,a nearby ’old’ classical T Tauri star (5–8 Myr, ∼100 pc), which is still strongly accreting. We use SPHERE/IRDIS in
H-band polarimetric imaging mode to obtain high contrast images of the ET Cha system to search for scattered lightfrom the circumstellar disk as well as thermal emission from close companions. We additionally employ VLT/NACO
total intensity archival data taken in 2003. We report here the discovery of a low-mass (sub)stellar companion withSPHERE/IRDIS to ET Cha. We are estimating the mass of this new companion based on photometry. Depending on
the system age it is a 5 Myr, 50 MJup brown dwarf or an 8 Myr, 0.10 M⊙ M-type pre-main-sequence star. We explore
possible orbital solutions and discuss the recent dynamic history of the system. Independent of the precise companion
mass we find that the presence of the companion likely explains the small size of the disk around ET Cha. The small
separation of the binary pair indicates that the disk around the primary component is likely clearing from the outsidein, explaining the high accretion rate of the system.
Accepted by A&A
http://arxiv.org/pdf/2007.05274

21. CS Cha B: A disc-obscured M-type star mimicking a polarised planetary companion
S.Y. Haﬀert1 , R.G. van Holstein2,3, C. Ginski4 , J. Brinchmann5 , I.A.G. Snellen2 , J. Milli6 et al.
Steward Observatory, Unversity of Arizona, 933 North Cherry Avenue, Tucson, Arizona; 2 Leiden Observatory, Leiden University, PO Box 9513, Niels Bohrweg 2, 2300 RA Leiden, The Netherlands; 3 European Southern Observatory,
Alonso de Córdova 3107, Casilla 19001, Vitacura, Santiago, Chile; 4 Astronomical Institute Anton Pannekoek, University of Amsterdam, PO Box 94249, 1090 GE Amsterdam, The Netherlands; 5 Instituto de Astrofísica e Ciências doEspaço, Universidade do Porto, CAUP, Rua das Estrelas, PT4150-762 Porto, Portugal; 6 Université Grenoble Alpes,
CNRS, IPAG, 38000 Grenoble, France
1

E-mail contact: shaffert at arizona.edu
Context. Direct imaging provides a steady flow of newly discovered giant planets and brown dwarf companions. These
multi-object systems can provide information about the formation of low-mass companions in wide orbits and/or
help us to speculate about possible migration scenarios. Accurate classification of companions is crucial for testing
formation pathways.
Aims. In this work we further characterise the recently discovered candidate for a planetary-mass companion CS Chab and determine if it is still accreting.
Methods. MUSE is a four-laser-adaptive-optics-assisted medium-resolution integral-field spectrograph in the opticalpart of the spectrum. We observed the CS Cha system to obtain the first spectrum of CS Cha b. The companion ischaracterised by modelling both the spectrum from 6300 Å to 9300 Å and the photometry using archival data fromthe visible to the near-infrared (NIR).
Results. We find evidence of accretion and outflow signatures in Hα and OI emission. The atmospheric models with thehighest likelihood indicate an effective temperature of 3450±50 K with a log g of 3.6±0.5 dex. Based on evolutionarymodels, we find that the majority of the object is obscured. We determine the mass of the faint companion withseveral methods to be between 0.07 M⊙ and 0.71 M⊙ with an accretion rate of Ṁ = 4 × 10−11±0.4 Myr−1 .
Conclusions. Our results show that CS Cha B is most likely a mid-M-type star that is obscured by a highly inclined
disc, which has led to its previous classification using broadband NIR photometry as a planetary-mass companion.
This shows that it is important and necessary to observe over a broad spectral range to constrain the nature of faintcompanions.
16

Accepted by A&A
http://arxiv.org/pdf/2007.07831

22. ALMA Observations of Young Eruptive Stars:

continuum disk sizes and molecular

outflows
Antonio S. Hales1,2 , Sebastián Pérez3 , Camilo Gonzalez-Ruilova4,5 , Lucas A. Cieza5 , Jonathan P.
Williams6 et al.
Joint ALMA Observatory, Avenida Alonso de Córdova 3107, Vitacura 7630355, Santiago, Chile; 2 NRAO, 520
Edgemont Road, Charlottesville, VA 22903-2475, USA; 3 Departamento de Física, Universidad de Santiago de Chile,
Av. Ecuador 3493, Estación Central, Santiago, Chile; 4 Departamento de Astronomía, Universidad de Chile, Casilla
36-D, Santiago 8330015, Chile; 5 Nucleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales,
Av. Ejercito 441, Santiago, Chile; 6 IfA, Univ. Hawaii, Honolulu, HI 96822, USA
1E-mail contact: ahales at alma.cl
We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm observations of four young, eruptive
star-disk systems at 0.′′ 4 resolution: two FUors (V582 Aur and V900 Mon), one EXor (UZ Tau E) and one source with
an ambiguous FU/EXor classification (GM Cha). The disks around GM Cha, V900 Mon and UZ Tau E are resolved.
These observations increase the sample of FU/EXors observed at sub-arcsecond resolution by 15%. The disk sizes andmasses of FU/EXors objects observed by ALMA so far suggest that FUor disks are more massive than Class 0/I disks
in Orion and Class II disks in Lupus of similar size. EXor disks in contrast do not seem to be distinguishable fromthese two populations. We reach similar conclusions when comparing the FU/EXor sample to the Class I and ClassII disks in Ophiuchus. FUor disks around binaries are host to more compact disks than those in single-star systems,
similar to non-eruptive young disks. We detect a wide-angle outflow around GM Cha in 12 CO emission, wider thantypical Class I objects and more similar to those found around some FUor objects. We use radiative transfer models
to fit the continuum and line data of the well-studied disk around UZ Tau E. The line data is well described by akeplerian disk, with no evidence of outflow activity (similar to other EXors). The detection of wide-angle outflows inFUors and not in EXors support to the current picture in which FUors are more likely to represent an accretion burst
in the protostellar phase (Class I), while EXors are smaller accretion events in the protoplanetary (Class II) phase.
Accepted by ApJ
http://arxiv.org/pdf/2007.04348

23. On the orbital evolution of binaries with circumbinary discs
Ryan Heath1 and Chris Nixon1
1School of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK

E-mail contact: cjn at leicester.ac.uk
Circumbinary discs are generally thought to take up angular momentum and energy from the binary orbit over timethrough gravitational torques mediated by orbital resonances. This process leads to the shrinkage of the binary orbit
over time, and is important in a variety of astrophysical contexts including the orbital evolution of stellar binaries, themigration of planets in protoplanetary discs, and the evolution of black hole binaries (stellar and supermassive). The
merger of compact object binaries provides a source of gravitational waves in the Universe. Recently, several groups
have reported numerical simulations of circumbinary discs that yield the opposite result, finding that the binary
expands with time. Here we argue that this result is primarily due to the choice of simulation parameters, made fornumerical reasons, which differ from realistic disc parameters in many cases. We provide physical arguments, andthen demonstrate with 3D hydrodynamical simulations, that thick (high pressure, high viscosity) discs drive sufficientaccretion of high angular momentum material to force binary expansion, while in the more realistic case of thin (lowpressure, low viscosity) discs there is less accretion and the binary shrinks. In the latter case, tides, which generallytransfer angular momentum and energy from the more rapidly rotating object (the binary) to the less rapidly rotating
object (the disc), are the dominant driver of disc-binary evolution. This causes the binary to shrink. We therefore
conclude that for common circumbinary disc parameters, binaries with non- extreme mass ratios are expected to shrink
over time. Expansion of the binary can occur if the disc viscosity is unusually high, which may occur in the very thick17

discs encountered in e.g. circumplanetary discs, super-Eddington AGN, or the outer regions of passive protostellar
discs that are heated by the central protostar. We also provide discussion of the impact that some simplifications to
the problem, that are prevalent in the literature and made usually for numerical convenience, have on the disc-binary
evolution.
Accepted by Astronomy & Astrophysics
https://arxiv.org/pdf/2007.11592

24. Ubiquitous velocity fluctuations throughout the molecular interstellar medium
Jonathan D. Henshaw1 , J.M. Diederik Kruijssen2 , Steven N. Longmore3 , Manuel Riener1 , Adam K.
Leroy4 et al.
Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany; 2 Astronomisches RechenInstitut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, 69120 Heidelberg, Germany; 3
Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill,
Liverpool L3 5RF, United Kingdom; 4 Department of Astronomy, The Ohio State University, 4055 McPherson Laboratory, 140 West 18th Avenue, Columbus, OH 43210, USA

1E-mail contact: jonathan.d.henshaw at gmail.com
The density structure of the interstellar medium (ISM) determines where stars form and release energy, momentum,
and heavy elements, driving galaxy evolution. Density variations are seeded and amplified by gas motion, but theexact nature of this motion is unknown across spatial scale and galactic environment. Although dense star-forming
gas likely emerges from a combination of instabilities, convergent flows, and turbulence, establishing the precise origin
is challenging because it requires quantifying gas motion over many orders of magnitude in spatial scale. Here wemeasure the motion of molecular gas in the Milky Way and in nearby galaxy NGC 4321, assembling observations thatspan an unprecedented spatial dynamic range (10−1 –103 pc). We detect ubiquitous velocity fluctuations across all
spatial scales and galactic environments. Statistical analysis of these fluctuations indicates how star-forming gas is
assembled. We discover oscillatory gas flows with wavelengths ranging from 0.3–400 pc. These flows are coupled toregularly-spaced density enhancements that likely form via gravitational instabilities. We also identify stochastic andscale-free velocity and density fluctuations, consistent with the structure generated in turbulent flows. Our results
demonstrate that ISM structure cannot be considered in isolation. Instead, its formation and evolution is controlled
by nested, interdependent flows of matter covering many orders of magnitude in spatial scale.
Accepted by Nature Astronomy
http://arxiv.org/pdf/2007.01877

25. The Outburst of the Young Star Gaia19bey
Klaus W. Hodapp1 , Larry Denneau2 , Michael Tucker2 , Benjamin J. Shappee2 , Mark E. Huber2 , Anna
V. Payne2 , Aaron Do2 , Chien-Cheng Lin2 , Michael S. Connelley1 , Watson P. Varricatt1 , John Tonry2 ,Kenneth Chambers2 and Eugene Magnier2
Institute for Astronomy, 640 N. Aohoku Place, Hilo, HI 96720; 2 Institute for Astronomy, 2680 Woodlawn Drive,
Honolulu, HI 96822
1

E-mail contact: hodapp at hawaii.edu
We report photometry and spectroscopy of the outburst of the young stellar object Gaia19bey. We have established theoutburst light curve with archival Gaia “G”, ATLAS “Orange”, ZTF r-band and Pan-STARRS “rizy”-filter photometry,showing an outburst of ≈ 4 years duration, longer than typical EXors but shorter than FUors. Its pre-outburst SED
shows a flat far-infrared spectrum, confirming the early evolutionary state of Gaia19bey and its similarity to otherdeeply embedded young stars experiencing outbursts. A lower limit to the peak outburst luminosity is ≈ 182 L⊙ at
an assumed distance of 1.4 kpc, the minimum plausible distance. Infrared and optical spectroscopy near maximum
light showed an emission line spectrum, including H I lines, strong red Ca II emission, other metal emission lines,
infrared CO bandhead emission, and a strong infrared continuum. Towards the end of the outburst, the emission lines
have all but disappeared and the spectrum has changed into an almost pure continuum spectrum. This indicates a
cessation of magnetospheric accretion activity. The near-infrared colors have become redder as Gaia19bey has faded,indicating a cooling of the continuum component. Near the end of the outburst, the only remaining strong emission
18

lines are forbidden shock-excited emission lines. Adaptive optics integral field spectroscopy shows the H2 1–0 S(1)emission with the morphology of an outflow cavity and the extended emission in the [Fe II] line at 1644 nm with themorphology of an edge-on disk. However, we do not detect any large-scale jet from Gaia19bey.
Accepted by The Astronomical Journal
http://arxiv.org/pdf/2008.03396

26.

Migrating Low-Mass Planets in Inviscid Dusty Protoplanetary Discs
He-Feng Hsieh1,2 , Min-Kai Lin2
Institute of Astronomy, National Tsing Hua University, Hsinchu 30013, Taiwan; 2 Institute of Astronomy andAstrophysics, Academia Sinica, Taipei 10617, Taiwan

1E-mail contact: hfhsieh at gapp.nthu.edu.tw
Disc-driven planet migration is integral to the formation of planetary systems. In standard, gas-dominated protoplanetary discs, low-mass planets or planetary cores undergo rapid inwards migration and are lost to the central star.
However, several recent studies indicate that the solid component in protoplanetary discs can have a significant dynamical effect on disc-planet interaction, especially when the solid-to-gas mass ratio approaches unity or larger and thedust-on-gas drag forces become significant. As there are several ways to raise the solid abundance in protoplanetary
discs, for example through disc winds and dust-trapping in pressure bumps, it is important to understand how planets
migrate through a dusty environment. To this end, we study planet migration in dust-rich discs via a systematic setof high-resolution, two-dimensional numerical simulations. We show that the inwards migration of low-mass planets
can be slowed down by dusty dynamical corotation torques. We also identify a new regime of stochastic migration>
applicable to discs with dust-to-gas mass ratios >∼0.3 and particle Stokes numbers ∼0.03. In these cases, disc-planet
interaction leads to the continuous development of small-scale, intense dust vortices that scatter the planet, which canpotentially halt or even reverse the inwards planet migration. We briefly discuss the observational implications of ourresults and highlight directions for future work.
Accepted by MNRAS
http://arxiv.org/pdf/2007.08235

27. Large-scale CO spiral arms and complex kinematics associated with the T Tauri star

RU LupJane Huang1 , Sean M. Andrews1 , Karin I. Öberg1 , Megan Ansdell2 , Myriam Benisty3,4 et al.
Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, United States ofAmerica; 2 National Aeronautics and Space Administration Headquarters, 300 E Street SW, Washington DC 20546,
United States of America; 3 Unidad Mixta Internacional Franco-Chilena de Astronomía, CNRS/INSU UMI 3386,
Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile; 4
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
1

E-mail contact: jane.huang at cfa.harvard.edu
While protoplanetary disks often appear to be compact and well-organized in millimeter continuum emission, CO
spectral line observations are increasingly revealing complex behavior at large distances from the host star. We
present deep ALMA maps of the J=2–1 transition of 12 CO, 13 CO, and C18 O, as well as the J=3–2 transition of
DCO+ , toward the T Tauri star RU Lup at a resolution of ∼0.′′ 3 (∼50 au). The CO isotopologue emission traces
four major components of the RU Lup system: a compact Keplerian disk with a radius of ∼120 au, a non-Keplerian“envelope-like” structure surrounding the disk and extending to ∼260 au from the star, at least five blueshifted spiralarms stretching up to 1000 au, and clumps outside the spiral arms located up to 1500 au in projection from RU Lup.
We comment on potential explanations for RU Lup’s peculiar gas morphology, including gravitational instability,
accretion of material onto the disk, or perturbation by another star. RU Lup’s extended non-Keplerian CO emission,
elevated stellar accretion rate, and unusual photometric variability suggest that it could be a scaled-down Class IIanalog of the outbursting FU Ori systems.
Accepted by ApJ
http://arxiv.org/pdf/2007.02974
1928. Multiwavelength investigation of extended green object G19.88−0.53: Revealing a pro-tocluster

Namitha Issac1 , Anandmayee Tej1 , Tie Liu2,3 , Watson Varricatt4 , Sarita Vig1 et al.
Indian Institute of Space Science and Technology, Thiruvananthapuram 695 547, Kerala, India; 2 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, Peoples Republic of China; 3
Key Laboratory for Research in Galaxies and Cosmology, Chinese Academy of Sciences, 80 Nandan Road, Shanghai
200030, Peoples Republic of China; 4 Institute for Astronomy, UKIRT Observatory, 660 N. Aóhoku place, Hilo, HI
96720, USA

1E-mail contact: namithaissac.16 at res.iist.ac.in
A multiwavelength analysis of star formation associated with the extended green object, G19.88−0.53 is presented inthis paper. With multiple detected radio and millimetre components, G19.88−0.53 unveils as harbouring a protocluster
rather than a single massive young stellar object. We detect an ionized thermal jet using the upgraded Giant Meterwave
Radio Telescope, India, which is found to be associated with a massive, dense and hot ALMA 2.7 mm core driving
a bipolar CO outflow. Near-infrared spectroscopy with UKIRT-UIST shows the presence of multiple shock-excitedH2 lines concurrent with the nature of this region. Detailed investigation of the gas kinematics using ALMA data
reveals G19.88−0.53 as an active protocluster with high-mass star forming components spanning a wide evolutionary
spectrum from hot cores in accretion phase to cores driving multiple outflows to possible UCHII regions.
Accepted by MNRAS
http://arxiv.org/pdf/2007.15186

Distortion of Magnetic Fields in the Dense Core SL42 (CrA-E) in the Corona Australis

29. Molecular Cloud Complex

Ryo Kandori1 , Motohide Tamura1,2,3 , Masao Saito2 , Kohji Tomisaka2 , Tomoaki Matsumoto4 , Ryo
Tazaki5 , Tetsuya Nagata6 , Nobuhiko Kusakabe1 , Yasushi Nakajima2 , Jungmi Kwon3 , Takahiro Nagayama7
and Ken’ichi Tatematsu2
Astrobiology Center of NINS, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan; 2 National Astronomical Observatoryof Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 3 Department of Astronomy, The University of Tokyo,
7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan; 4 Faculty of Sustainability Studies, Hosei University, Fujimi,
Chiyoda-ku, Tokyo 102-8160; 5 Astronomical Institute, Graduate School of Science, Tohoku University, 6-3 Aramaki,
Aoba-ku, Sendai 980-8578, Japan; 6 Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan;
7
Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan1

E-mail contact: r.kandori at gmail.com
Detailed magnetic field structure of the dense core SL42 (CrA-E) in the Corona Australis molecular cloud complex wasinvestigated based on near-infrared polarimetric observations of background stars to measure dichroically polarized
light produced by magnetically aligned dust grains. The magnetic fields in and around SL42 were mapped using 206
stars and curved magnetic fields were identified. On the basis of simple hourglass (parabolic) magnetic field modeling,
the magnetic axis of the core on the plane of sky was estimated to be 40◦ ± 3◦ . The plane-of-sky magnetic fieldstrength of SL42 was found to be 22.4 ± 13.9 µG. Taking into account the effects of thermal/turbulent pressure andthe plane-of-sky magnetic field component, the critical mass of SL42 was obtained to be Mcr = 21.2 ± 6.6 M⊙ , which
is close to the observed core mass of Mcore ≈ 20 M⊙ . We thus conclude that SL42 is in a condition close to the criticalstate if the magnetic fields lie near the plane of the sky. Since there is a very low luminosity object (VeLLO) toward thecenter of SL42, it is unlikely this core is in a highly subcritical condition (i.e., magnetic inclination angle significantly
deviated from the plane of sky). The core probably started to collapse from a nearly kinematically critical state. In
addition to the hourglass magnetic field modeling, the Inoue & Fukui (2013) mechanism may explain the origin of thecurved magnetic fields in the SL42 region.
Accepted by Astrophysical Journal
https://arxiv.org/pdf/2007.15436

20

Molecular Cloud Cores with High Deuterium Fraction: Nobeyama Single-Pointing Sur-30. vey

Gwanjeong Kim1 , Ken’ichi Tatematsu1,2 , Tie Liu3 , Hee-weon Yi4 , Jinhua He5,6,7 , Naomi Hirano8 ,Sheng-Yuan Liu8 , Minho Choi9 , Patricio Sanhueza10 , L. Viktor Tóth11 , Neal J. Evans II12 , Siyi Feng8,10,13 ,Mika Juvela14 , Kee-Tae Kim9 , Charlotte VASTEL15 , Jeong-Eun Lee4 , Quang Nguy˜ên Lu’o’ng9,10,16 ,Miju Kang9 , Isabelle Ristorcelli17, O. Fehér18 , Yuefang Wu19 , Satoshi Ohashi20 , Ke Wang21 , Ryo
Kandori10 , Tomoya Hirota2,10 , Takeshi Sakai22 , Xing Lu10 , Mark A. Thompson23 , Gary A. Fuller24 ,Di Li25 , Hiroko Shinnaga26 and Jungha Kim2,10Nobeyama Radio Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Sciences,
Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305, Japan; 2 Dept of Astronomical Science, SOKENDAI (The
Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 3 Shanghai Astronomical
Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s Republic of China; 4 School ofSpace Research, Kyung Hee University, Seocheon-Dong, Giheung-Gu, Yongin-Si, Gyeonggi-Do, 446-701, South Korea;
5
Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216, P. R.
China; 6 Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories,
CAS, Beijing 100101, China; 7 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile; 8
Academia Sinica Institute of Astronomy and Astrophysics, 11F of Astronomy-Mathematics Building, AS/NTU. No.1,
Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan, R.O.C.; 9 Korea Astronomy and Space Science Institute, Daedeokdaero
776, Yuseong, Daejeon 305-348, South Korea; 10 National Astronomical Observatory of Japan, National Institutes of
Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 11 Dept of Astronomy, Eötvös Loránd University,
Pazmany Péter sétny 1, 1117 Budapest, Hungary; 12 Dept of Astronomy, The University of Texas at Austin, 2515
Speedway, Stop C1400, Austin, TX 78712-1205, USA; 13 Chinese Academy of Sciences Key Laboratory of FAST,
National Astronomical Observatory of China, Datun Road 20, Chaoyang, Beijing, 100012, P. R. China; 14 Dept ofPhysics, P.O.Box 64, FI-00014, University of Helsinki, Finland; 15 IRAP, Universite de Toulouse, CNRS, CNES, UPS,
(Toulouse), France; 16 IBM, Canada; 17 RAP, CNRS (UMR5277), Université Paul Sabatier, 9 avenue du Colonel Roche,
BP 44346, 31028, Toulouse Cedex 4, France; 18 Institut de Radioastronomie Millimetrique, 300 Rue de la Piscine,
38406, Saint Martin d’Heres, France; 19 Dept of Astronomy, Peking University, 100871, Beijing, China; 20 The Instituteof Physical and Chemical Research (RIKEN), 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan; 21 Kavli Institutefor Astronomy and Astrophysics, Peking University, 5 Yiheyuan Road, Haidian District, Beijing 100871, China; 22
Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182-8585,
Japan; 23 Centre for Astrophysics Research, Science & Technology Research Institute, University of Hertfordshire,
Hatfield, AL10 9AB, UK; 24 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University ofManchester, Oxford Road, Manchester, M13 9PL, UK; 25 National Astronomical Observatories, Chinese Academy of
Sciences, Beijing, 100012, China; 26 Department of Physics, Kagoshima University, 1-21-35, Korimoto, Kagoshima,890-0065, Japan1

E-mail contact: gj.kim at nao.ac.jp
We present the results of a single-pointing survey of 207 dense cores embedded in Planck Galactic Cold Clumps
distributed in five different environments (λ Orionis, Orion A, B, Galactic plane, and high latitudes) to identify dense
cores on the verge of star formation for the study of the initial conditions of star formation. We observed these cores ineight molecular lines at 76-94 GHz using the Nobeyama 45-m telescope. We find that early-type molecules (e.g., CCS)
have low detection rates and that late-type molecules (e.g., N2 H+ , c-C3 H2 ) and deuterated molecules (e.g., N2 D+ ,DNC) have high detection rates, suggesting that most of the cores are chemically evolved. The deuterium fraction(D/H) is found to decrease with increasing distance, indicating that it suffers from differential beam dilution between
the D/H pair of lines for distant cores (>1 kpc). For λ Orionis, Orion A, and B located at similar distances, D/H is
not significantly different, suggesting that there is no systematic difference in the observed chemical properties among
these three regions. We identify at least eight high D/H cores in the Orion region and two at high latitudes, which
are most likely to be close to the onset of star formation. There is no clear evidence of the evolutionary change inturbulence during the starless phase, suggesting that the dissipation of turbulence is not a major mechanism for the
beginning of star formation as judged from observations with a beam size of 0.04 pc.
Accepted by ApJS
http://arxiv.org/pdf/2007.12319

2131. 3D structure of HII region Sh2-235 from tunable-filter optical observations
M. S. Kirsanova1 , P. A. Boley2 , A. V. Moiseev3 , D. S. Wiebe1 and R. I. Uklein3
Institute of Astronomy, Russian Academy of Sciences, 119017, 48 Pyatnitskaya Str., Moscow, Russia; 2 Moscow
Institute of Physics and Technology, 141701, 9 Institutskiy per., Dolgoprudny, Moscow Region, Russia; 3 Special
Astrophysical Observatory, Russian Academy of Sciences, Nizhny Arkhyz 369167, Russia
1E-mail contact: kirsanova at inasan.ru
We present observations of the Hα, Hβ, [SII] λλ6716, 6731 and [NII] λ6583 emission lines in the galactic HII region
Sh2-235 with the Mapper of Narrow Galaxy Lines (MaNGaL), a tunable filter at the 1-m telescope of the Special
Astrophysical Observatory of the Russian Academy of Sciences. We show that the HII region is obscured by neutralmaterial with AV ≈ 2 − 4 mag. The area with the highest AV is situated to the south-west from the ionizing star and−3coincides with a maximum detected electron density of >∼300 cm . The combination of these results with archive
AKARI far-infrared data allows us to estimate the contribution of the front and rear walls to the total column densityof neutral material in S235, and explain the three-dimensional structure of the region. The HII region consist of adenser, more compact portion deeply embedded in the neutral medium and the less dense and obscured gas. The
front and rear walls of the HII region are inhomogeneous, with the material in the rear wall having a higher column
density. We find a two-sided photodissociation region in the dense clump S235 East 1, illuminated by a UV field with
G0 = 50 − 70 and 200 Habing units in the western and eastern parts, respectively.
Accepted by MNRAS
https://arxiv.org/pdf/1911.04551

32. The PDR structure and kinematics around the compact HII regions S235A and S235C

with [CII], [13CII], [OI] and HCO+ line profiles

M. S. Kirsanova1 , V. Ossenkopf-Okada2 , L. D. Anderson3 , P. A. Boley4 , J. H. Bieging5, Ya. N.
Pavlyuchenkov1 , M. Luisi6 , N. Schneider2 , M. Andersen7 , M. R. Samal8 , A. M. Sobolev9 , C. Buchbender2 ,R. Aladro10 and Y. Okada2
Institute of Astronomy, Russian Academy of Sciences, 119017, 48 Pyatnitskaya Str., Moscow, Russia; 2 I. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany; 3 Department of Physics andAstronomy, West Virginia University, Morgantown WV 26506; 4 Moscow Institute of Physics and Technology, 141701,
9 Institutskiy per., Dolgoprudny, Moscow Region, Russia; 5 Steward Observatory, The University of Arizona, Tucson,
AZ 85721, USA; 6 Center for Gravitational Waves and Cosmology, West Virginia University, Chestnut Ridge Research
Building, Morgantown, WV 26505; 7 Gemini South, Casilla 603, La Serena, Chile; 8 Physical Research Laboratory,
Navrangpura, Ahmedabad, Gujarat 380009, India; 9 Ural Federal University, 620075, 19 Mira Str., Ekaterinburg,
Russia; 10 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
1E-mail contact: kirsanova at inasan.ru
The aim of the present work is to study structure and gas kinematics in the photodissociation regions (PDRs) aroundthe compact H II regions S235 A and S235 C. We observe the [C II], and [O i] line emission, using SOFIA/upGREAT
and complement them by data of HCO+ and CO. We use the [13 C ii] line to measure the optical depth of the [C ii]
emission, and find that the [C ii] line profiles are influenced by self-absorption, while the [13 C ii] line remains unaffectedby these effects. Hence, for dense PDRs, [13 C ii] emission is a better tracer of gas kinematics. The optical depth of the[C ii] line is up to 10 in S235 A. We find an expanding motion of the [C ii]-emitting layer of the PDRs into the front
molecular layer in both regions. Comparison of the gas and dust columns shows that gas components visible neither
in the [C ii] nor in low-J CO lines may contribute to the total column across S235 A. We test whether the observed
properties of the PDRs match the predictions of spherical models of expanding H II region + PDR + molecular cloud.
Integrated intensities of the [13 C ii], [C ii] and [O i] lines are well-represented by the model, but the models do not
reproduce the double-peaked [C ii] line profiles due to an insufficient column density of C+ . The model predicts thatthe [O i] line could be a more reliable tracer of gas kinematics, but the foreground self-absorbing material does notallow using it in the considered regions.
Accepted by MNRAS
https://arxiv.org/pdf/2007.15708

22

33.

CO Depletion in Protoplanetary Disks: A Unified Picture Combining Physical Sequestration and Chemical Processing
Sebastiaan Krijt1,5 , Arthur D. Bosman2 , Ke Zhang2,5 , Kamber R. Schwarz3,6 , Fred J. Ciesla4 and Edwin
A. Bergin2
Department of Astronomy/Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson,
AZ 85721, USA; 2 University of Michigan, Department of Astronomy, 1085 S. University, Ann Arbor, MI 48109,
USA; 3 Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd, Tucson, AZ 85721, USA; 4
Department of the Geophysical Sciences, The University of Chicago, 5734 S. Ellis Avenue, Chicago, IL 60637, USA; 5
Hubble Fellow; 6 Sagan Fellow

1E-mail contact: skrijt at email.arizona.edu
The gas-phase CO abundance (relative to hydrogen) in protoplanetary disks decreases by up to 2 orders of magnitude
from its ISM value ∼10−4 , even after accounting for freeze-out and photo-dissociation. Previous studies have shownthat while local chemical processing of CO and the sequestration of CO ice on solids in the midplane can bothcontribute, neither of these processes appears capable of consistently reaching the observed depletion factors on therelevant timescale of 1−3 Myr. In this study, we model these processes simultaneously by including a compact
chemical network (centered on carbon and oxygen) to 2D (r + z) simulations of the outer (r > 20 au) disk regions that
include turbulent diffusion, pebble formation, and pebble dynamics. In general, we find that the CO/H2 abundanceis a complex function of time and location. Focusing on CO in the warm molecular layer, we find that only themost complete model (with chemistry and pebble evolution included) can reach depletion factors consistent withobservations. In the absence of pressure traps, highly-efficient planetesimal formation, or high cosmic ray ionization
rates, this model also predicts a resurgence of CO vapor interior to the CO snowline. We show the impact of physicaland chemical processes on the elemental (C/O) and (C/H) ratios (in the gas and ice phases), discuss the use of CO
as a disk mass tracer, and, finally, connect our predicted pebble ice compositions to those of pristine planetesimals asfound in the Cold Classical Kuiper Belt and debris disks.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/2007.09517

34. Unifying low and high mass star formation through density amplified hubs of filaments:

The highest mass stars (>100M⊙ ) form only in hubs

M.S. Nanda Kumar1 , Pedro Palmeirim1, Doris Arzoumanian1 and Shu-Ichiro Inutsuka2
Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, PT4150-762 Porto,
Portugal; 2 Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan1

E-mail contact: nanda at astro.up.pt
Context: Star formation takes place in giant molecular clouds, resulting in mass-segregated young stellar clusters
composed of Sun-like stars, brown dwarves, and massive O-type(50-100 Msun) stars.
Aims: To identify candidate hub-filament systems (HFS) in the Milky-Way and examine their role in the formationof the highest mass stars and star clusters.
Methods: Filaments around ∼35000 HiGAL clumps that are detected using the DisPerSE algorithm. Hub is defined
as a junction of three or more filaments. Column density maps were masked by the filament skeletons and averagedfor HFS and non-HFS samples to compute the radial profile along the filaments into the clumps.
Results: ∼3700(11%) are candidate HFS of which,∼2150 (60%) are pre-stellar,∼1400(40%) are proto-stellar. All
clumps with L>104 Lsun and L>105 Lsun at distances respectively within 2kpc and 5kpc are located in the hubsof HFS. The column-densities of hubs are found to be enhanced by a factor of ∼2 (pre-stellar sources) up to ∼10(proto-stellar sources).
Conclusions: All high-mass stars preferentially form in the density enhanced hubs of HFS. This amplification can drive
the observed longitudinal flows along filaments providing further mass accretion. Radiation pressure and feedback canescape into the inter-filamentary voids. We propose a “filaments to clusters” unified paradigm for star formation, withthe following salient features: a) low-intermediate mass stars form in the filaments slowly (106 yr) and massive stars
quickly (105 yr) in the hub, b) the initial mass function is the sum of stars continuously created in the HFS with all
massive stars formed in the hub, c) Feedback dissipation and mass segregation arise naturally due to HFS properties,
23and c) explain age spreads within bound clusters and formation of isolated OB associations.
Accepted by Astronomy and Astrophysics
https://arxiv.org/pdf/2008.00295

35.

The dependence of episodic accretion on eccentricity during the formation of binarystars
Rajika Kuruwita1 , Christoph Federrath2 and Troels Haugbølle1
1

University of Copenhagen; 2 Australian National University

E-mail contact: rajikakuruwita at gmail.com
Context: Episodic accretion has been observed in short-period binaries, where bursts of accretion occur at periastron.
The binary trigger hypothesis has also been suggested as a driver for accretion during protostellar stages.
Aims: Our goal is to investigate how the strength of episodic accretion bursts depends on eccentricity.
Methods: We investigate the binary trigger hypothesis in longer-period (> 20 yr) binaries by carrying out threedimensional magnetohydrodynamical (MHD) simulations of the formation of low-mass binary stars down to final
separations of ∼10 AU, including the effects of gas turbulence and magnetic fields. We ran two simulations with an
initial turbulent gas core of one solar mass each and two different initial turbulent Mach numbers, M = σv /cs = 0.1
and M = 0.2, for 6500 yr after protostar formation.
Results: We observe bursts of accretion at periastron during the early stages when the eccentricity of the binary
system is still high. We find that this correlation between bursts of accretion and passing periastron breaks down atlater stages because of the gradual circularisation of the orbits. For eccentricities greater than e = 0.2, we observe
episodic accretion triggered near periastron. However, we do not find any strong correlation between the strength of
episodic accretion and eccentricity. The strength of accretion is defined as the ratio of the burst accretion rate to thequiescent accretion rate. We determine that accretion events are likely triggered by torques between the rotation of
the circumstellar disc and the approaching binary stars. We compare our results with observational data of episodic
accretion in short-period binaries and find good agreement between our simulations and the observations.
Conclusions: We conclude that episodic accretion is a universal mechanism operating in eccentric young binary-starsystems, independent of separation, and it should be observable in long-period binaries as well as in short-periodbinaries. Nevertheless, the strength depends on the torques and hence the separation at periastron.
Accepted by A&A
https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202038181

The large-scale magnetic field of the eccentric pre-main-sequence binary system V1878

36. Ori

A. Lavail1 , O. Kochukhov1 , G.A.J. Hussain2 , C. Argiroﬃ3,4 , E. Alecian5 , J. Morin6 , and the BinaMIcS
collaboration
Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden; 2 European
Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany; 3 University of Palermo, Departmentof Physics and Chemistry, Piazza del Parlamento 1, 90134, Palermo, Italy; 4 INAF - Osservatorio Astronomico diPalermo, Piazza del Parlamento 1, 90134, Palermo, Italy; 5 Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble,
France; 6 LUPM, Université de Montpellier, CNRS, Place Eugène Bataillon, 34095 Montpellier, France
1

E-mail contact: alexis.lavail at physics.uu.se
We report time-resolved, high-resolution optical spectropolarimetric observations of the young double-lined spectroscopic binary V1878 Ori. Our observations were collected with the ESPaDOnS spectropolarimeter at the CanadaFrance-Hawaii Telescope through the BinaMIcS large programme. V1878 Ori A and B are partially convective intermediate mass weak-line T Tauri stars on an eccentric and asynchronous orbit. We also acquired X-ray observations
at periastron and outside periastron.
Using the least-squares deconvolution technique (LSD) to combine information from many spectral lines, we clearly
detected circular polarization signals in both components throughout the orbit. We refined the orbital solution for24the system and obtained disentangled spectra for the primary and secondary components. The disentangled spectra
were then employed to determine atmospheric parameters of the two components using spectrum synthesis. Applying
our Zeeman Doppler imaging code to composite Stokes IV LSD profiles, we reconstructed brightness maps and theglobal magnetic field topologies of the two components. We find that V1878 Ori A and B have strikingly different
global magnetic field topologies and mean field strengths. The global magnetic field of the primary is predominantly
poloidal and non-axisymmetric (with a mean field strength of 180 G). while the secondary has a mostly toroidal andaxisymmetric global field (mean strength of 310 G). These findings confirm that stars with very similar parameters
can exhibit radically different global magnetic field characteristics. The analysis of the X-ray data shows no sign ofenhanced activity at periastron, suggesting the lack of strong magnetospheric interaction at this epoch.
Accepted by MNRAS
http://arxiv.org/pdf/2007.01518

37.

Protostellar collapse: the conditions to form dust rich protoplanetary disks
U. Lebreuilly1 , B. Commerçon1 , and G. Laibe1
École normale supérieure de Lyon, CRAL, UMR CNRS 5574, Université de Lyon , 46 Alleé d Italie, 69364 Lyon
Cedex 07, France
1

E-mail contact: ugo.lebreuilly at ens-lyon.fr
Dust plays a key role during star, disk and planet formation. Yet, its dynamics during the protostellar collapse
remains a poorly investigated field. Recent studies seem to indicate that dust may decouple efficiently from the gas
during these early stages. We aim to understand how much and in which regions dust grains concentrate during theearly phases of the protostellar collapse, and see how it depends on the properties of the initial cloud and of thesolid particles. We use the multiple species dust dynamics solver of the grid-based code RAMSES to perform various
simulations of dusty collapses. We perform hydrodynamical and MHD simulations where we vary the maximum grainsize, the thermal-to-gravitational energy ratio and the magnetic properties of the cloud. We simulate the simultaneous
evolution of ten neutral dust grains species with grain sizes varying from a few nm to a few hundredth of microns.
We obtain a significant decoupling between the gas and the dust for grains of typical sizes a few 10 microns. Thisdecoupling strongly depends on the thermal-to-gravitational energy ratio, the grain sizes or the inclusion of a magnetic
field. With a semi-analytic model calibrated on our results, we show that the dust ratio mostly varies exponentiallywith the initial Stokes number at a rate that depends on the local cloud properties. We find that larger grains tend tosettle and drift efficiently in the first-core and in the newly formed disk. This can produce dust-to-gas ratios of several
times the initial value. Dust concentrates in high density regions and is depleted in low density regions. The size at
which grains decouple from the gas depends on the initial properties of the clouds. Since dust can not necessarily be
used as a proxy for gas during the collapse, we emphasize on the necessity of including the treatment of its dynamics
in collapse simulations.
Accepted by A&A
http://arxiv.org/pdf/2007.06050

Clouds associated with the HII Regions/Candidates between l = 207.7
38. The Molecular◦◦and l = 211.7

Chong Li1,2 , Hongchi Wang1,3 , Miaomiao Zhang1 , Yuehui Ma1,2 and Lianghao Lin1,3
Purple Mountain Observatory and Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, 10 Yuanhua
Road, Nanjing 210023, China; 2 University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District,
Beijing 100049, China; 3 School of Astronomy and Space Science, University of Science and Technology of China, 96
Jinzhai Road, Hefei 230026, China
1E-mail contact: chongli at pmo.ac.cn
Using the PMO-13.7 m millimeter telescope at Delingha in China, we have conducted a large-scale simultaneous surveyof 12 CO, 13 CO, and C18 O J = 1 − 0 emission toward the sky region centered at l=209.7◦, b=−2.25◦ with a coverageof 4.0◦ × 4.5◦ . The majority of the emission in the region comes from the clouds with velocities lying in the range
from −3 km s−1 to 55 km s−1 , at kinematic distances from 0.5 kpc to 7.0 kpc. The molecular clouds in the region25

are concentrated into three velocity ranges. The molecular clouds associated with the ten HII regions/candidates are
identified and their physical properties are presented. Massive stars are found within Sh2-280, Sh2-282, Sh2-283, and
BFS54, and we suggest them to be the candidate excitation sources of the HII regions. The distributions of excitation
temperature and line width with the projected distance from the center of HII region/candidate suggest that the
majority of the ten HII regions/candidates and their associated molecular gas are three-dimensional structures, rather
than two-dimensional structures.
Accepted by The Astrophysical Journal Supplement Series
https://arxiv.org/pdf/2008.01453

39. Steady Wind-Blown Cavities within Infalling Rotating Envelopes: Application to the

Broad Velocity Component in Young Protostars

Lichen Liang1 , Doug Johnstone2,3 , Sylvie Cabrit4 and Lars E. Kristensen5
Institute for Computaional Science, University of Zurich, Winterthurerstrasse 190, Zurich CH-8057, Switzerland;
National Research Council Canada, Herzberg Astronomy & Astrophysics, 5071 West Saanich Rd, Victoria, BC,
V9E 2E7, Canada; 3 Department of Physics & Astronomy, University of Victoria, Victoria, BC, V8P 5C2, Canada; 4
Observatoire de Paris, PSL University, Sorbonne Université, CNRS, LERMA, 61 Av. de l’Observatoire, 75014, Paris,
France; 5 Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade
5–7, 1350 Copenhagen K, Denmark1

2E-mail contact: doug.johnstone at nrc-cnrc.gc.ca
Wind-driven outflows are observed around a broad range of accreting objects throughout the Universe, ranging fromforming low-mass stars to super-massive black holes. We study the interaction between a central isotropic wind and an
infalling, rotating, envelope, determining the steady-state cavity shape formed at their interface under the assumptionof weak mixing. The shape of the resulting wind-blown cavity is elongated and self-similar, with a physical size
determined by the ratio between wind ram pressure and envelope thermal pressure. We compute the growth of awarm turbulent mixing-layer between the shocked wind and the deflected envelope, and calculate the resultant broadline profile, under the assumption of a linear (Couette-type) velocity profile across the layer. We then test our model
against the warm broad velocity component observed in CO J=16–15 by Herschel /HIFI in the protostar SerpensMain SMM1. Given independent observational constraints on the temperature and density of the dust envelope
around SMM1, we find an excellent match to all its observed properties (line profile, momentum, temperature) andto the SMM1 outflow cavity width for a physically reasonable set of parameters: a ratio of wind to infall mass-flux≃ 4%, a wind speed vw ≃ 30 km/s, an interstellar abundance of CO and H2 , and a turbulent entrainment efficiency
consistent with laboratory experiments. The inferred ratio of ejection to disk accretion rate, ≃ 6−20%, is in agreementwith current disk wind theories. Thus, the model provides a new framework to reconcile the modest outflow cavity
widths in protostars with the large observed flow velocities. Being self-similar, it is applicable over a broader range ofastrophysical contexts as well.
Accepted by ApJ
https://arxiv.org/pdf/2007.13744

40.

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions - I.
Survey description and a first look at G9.62+0.19
Tie Liu1 , Neal J. Evans2,3 , Kee-Tae Kim3 , Paul F. Goldsmith4, Sheng-Yuan Liu5 , Qizhou Zhang6 ,Ken’ichi Tatematsu7 , Ke Wang8 et al.1
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s
Republic of China; 2 Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Yuseong-gu, Daejeon 34055,
Republic of Korea; 3 Dept of Astronomy, The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX
78712-1205, USA; 4 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena,
CA 91109, USA; 5 Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Section 4, Roosevelt Road., Taipei 10617, Taiwan; 6 Center for Astrophysics, Harvard &Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; 7 National Astronomical Observatory of Japan, Na1

26

tional Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 8 Kavli Institute for Astronomy
and Astrophysics, Peking University, 5 Yiheyuan Road, Haidian District, Beijing, People’s Republic of China
E-mail contact: liutie at shao.ac.cn
The ATOMS, standing for ALMA Three-millimeter Observations of Massive Star-forming regions, survey has observed
146 active star-forming regions with ALMA band 3, aiming to systematically investigate the spatial distribution ofvarious dense gas tracers in a large sample of Galactic massive clumps, to study the roles of stellar feedback in starformation, and to characterize filamentary structures inside massive clumps. In this work, the observations, data
analysis, and example science of the ATOMS survey are presented, using a case study for the G9.62+0.19 complex.
Toward this source, some transitions, commonly assumed to trace dense gas, including CS J = 2-1, HCO+ J = 1-0,
and HCN J = 1-0, are found to show extended gas emission in low-density regions within the clump; less than 25
per cent of their emission is from dense cores. SO, CH3 OH, H13 CN, and HC3 N show similar morphologies in their
spatial distributions and reveal well the dense cores. Widespread narrow SiO emission is present (over ∼1 pc), which
may be caused by slow shocks from large-scale colliding flows or Hii regions. Stellar feedback from an expanding
Hii region has greatly reshaped the natal clump, significantly changed the spatial distribution of gas, and may also
account for the sequential high-mass star formation in the G9.62+0.19 complex. The ATOMS survey data can be
jointly analysed with other survey data, e.g. MALT90, Orion B, EMPIRE, ALMA_IMF, and ALMAGAL, to deepen
our understandings of ’dense gas’ star formation scaling relations and massive protocluster formation.
Accepted by MNRAS (496, 2790)
http://arxiv.org/pdf/2006.01549

41. ATOMS: ALMA three-millimeter observations of massive star-forming regions - II.

Compact objects in ACA observations and star formation scaling relations

Tie Liu1,2 , Neal J. Evans2,3 , Kee-Tae Kim2 , Paul F. Goldsmith4, Sheng-Yuan Liu5 , Qizhou Zhang6 ,Ken’ichi Tatematsu7 , Ke Wang8 et al.1
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s
Republic of China; 2 Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Yuseong-gu, Daejeon 34055,
Republic of Korea; 3 Department of Astronomy, The University of Texas at Austin, 2515 Speedway, Stop C1400,
Austin, TX 78712-1205, USA; 4 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove
Drive, Pasadena, CA 91109, USA; 5 Institute of Astronomy and Astrophysics, Academia Sinica, 11F of AstronomyMathematics Building, AS/NTU No. 1, Section 4, Roosevelt Road., Taipei 10617, Taiwan; 6 Center for Astrophysics,
Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; 7 National Astronomical Observatory ofJapan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 8 Kavli Institute for
Astronomy and Astrophysics, Peking University, 5 Yiheyuan Road, Haidian District, Beijing 100871, People’s Republicof China
1

E-mail contact: liutie at shao.ac.cn
We report studies of the relationships between the total bolometric luminosity (Lbol or LT IR ) and the molecular line
luminosities of J = 1 - 0 transitions of H13 CN, H13 CO+ , HCN, and HCO+ with data obtained from ACA observationsin the ’ATOMS’ survey of 146 active Galactic star-forming regions. The correlations between Lbol and molecular line
luminosities L′mol of the four transitions all appear to be approximately linear. Line emission of isotopologues shows aslarge scatters in Lbol -L′mol relations as their main line emission. The log(Lbol /L′mol ) for different molecular line tracers
have similar distributions. The Lbol -to-L′mol ratios do not change with galactocentric distances (RGC ) and clump
masses (Mclump). The molecular line luminosity ratios (HCN-to-HCO+ , H13 CN-to-H13 CO+ , HCN-to-H13 CN, andHCO+ -to-H13 CO+ ) all appear constant against Lbol, dust temperature (Td ), Mclump , and RGC . Our studies suggestthat both the main lines and isotopologue lines are good tracers of the total masses of dense gas in Galactic molecular
clumps. The large optical depths of main lines do not affect the interpretation of the slopes in star formation relations.
We find that the mean star formation efficiency (SFE) of massive Galactic clumps in the ’ATOMS’ survey is reasonably
consistent with other measures of the SFE for dense gas, even those using very different tracers or examining very
different spatial scales.
Accepted by MNRAS (496, 2821)
http://arxiv.org/pdf/2005.12080
27

42. The Dynamic Proto-atmospheres around Low-Mass Planets with Eccentric Orbits
Chuhong Mai1 , Steven J. Desch1 , Rolf Kuiper2 , Gabriel-Dominique Marleau2,3,4 and Cornelis Dullemond5
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA; 2 Institut für Astronomie
und Astrophysik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany; 3 Physikalisches Institut,
Universität Bern, Gesellschaftsstr. 6, 3012 Bern, Switzerland; 4 Max-Planck-Institut für Astronomie, Königstuhl
17, 69117 Heidelberg, Germany; 5 Institut für Theoretische Astrophysik (ITA), Zentrum für Astronomie (ZAH),
Universität Heidelberg, Albert-Ueberle-Str.2 69120 Heidelberg, Germany
1E-mail contact: chuhong.mai at asu.edu
Protoplanets are able to accrete primordial atmospheres when embedded in the gaseous protoplanetary disk. The
formation and structure of the proto-atmosphere are subject to the planet–disk environment and orbital effects.
Especially, when planets are on eccentric orbits, their relative velocities to the gas can exceed the sound speed.
The planets generate atmosphere-stripping bow shocks. We investigate the proto-atmospheres on low-mass planetswith eccentric orbits with radiation-hydrodynamics simulations. A 2D radiative model of the proto-atmosphere isestablished with tabulated opacities for the gas and dust. The solutions reveal large-scale gas recycling inside a bow
shock structure. The atmospheres on eccentric planets are typically three to four orders of magnitude less massive
than those of planets with circular orbits. Overall, however, a supersonic environment is favorable for planets to keep
an early stable atmosphere, rather than harmful, due to the steady gas supply through the recycling flow. We also
quantitatively explore how such atmospheres are affected by the planet’s relative velocity to the gas, the planet mass,and the background gas density. Our time-dependent simulations track the orbital evolution of the proto-atmospherewith the planet–disk parameters changing throughout the orbit. Atmospheric properties show oscillatory patterns
as the planet travels on an eccentric orbit, with a lag in phase. To sum up, low-mass eccentric planets can retain
small proto-atmospheres despite the stripping effects of bow shocks. The atmospheres are always connected to andinteracting with the disk gas. These findings provide important insights into the impacts of migration and scattering
on planetary proto-atmospheres.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/2007.04398

43. Implementation of stellar heating feedback in simulations of star cluster formation:effects on the initial mass function

Sajay Sunny Mathew1,2 and Christoph Federrath1
Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia; 2
Indian Institute of Technology (ISM) Dhanbad, Jharkhand-826004, India
1

E-mail contact: sajay.18ms0092 at ap.iitism.ac.in
Explaining the initial mass function (IMF) of stars is a long-standing problem in astrophysics. The number of complex
mechanisms involved in the process of star cluster formation, such as turbulence, magnetic fields and stellar feedback,make understanding and modeling the IMF a challenging task. In this paper, we aim to assert the importance of stellar
heating feedback in the star cluster formation process and its effect on the shape of the IMF. We use an analytical subgrid model to implement the radiative feedback in fully three-dimensional magnetohydrodynamical (MHD) simulationsof star cluster formation, with the ultimate objective of obtaining numerical convergence on the IMF. We compare a
set of MHD adaptive-mesh-refinement (AMR) simulations with three different implementations of the heating of thegas: 1) a polytropic equation of state (EOS), 2) a spherically symmetric stellar heating feedback, and 3) our newly
developed polar heating model that takes into account the geometry of the accretion disc and the resulting shieldingof stellar radiation by dust. For each of the three heating models, we analyse the distribution of stellar masses formedin ten molecular cloud simulations with different realizations of the turbulence to obtain a statistically representative
IMF. We conclude that stellar heating feedback has a profound influence on the number of stars formed and plays
a crucial role in controlling the IMF. We find that the simulations with the polar heating model achieve the best
convergence on the observed IMF.
Accepted by Monthly Notices of the Royal Astronomical Society
https://arxiv.org/pdf/2007.01875

28

44.

Ejection of close-in super-Earths around low-mass stars in the giant impact stage
Yuji Matsumoto1 , Pin-Gao Gu1 , Eiichiro Kokubo2 , Shoichi Oshino3 , and Masashi Omiya4
Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan; 2 National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, 181-8588 Tokyo, Japan; 3 Institute for Cosmic Ray Research, University ofTokyo, Hida, Gifu 506-1205, Japan; 4 Astrobiology Center, NINS, 2-21-1, Osawa, Mitaka, 181-8588 Tokyo, Japan1

E-mail contact: ymatsumoto at asiaa.sinica.edu.tw
Earth-sized planets were observed in close-in orbits around M dwarfs. While more and more planets are expected
to be uncovered around M dwarfs, theories of their formation and dynamical evolution are still in their infancy. We
investigate the giant impact growth of protoplanets, which includes strong scattering around low-mass stars. The aim
is to clarify whether strong scattering around low-mass stars affects the orbital and mass distributions of the planets.
We perform N-body simulation of protoplanets by systematically surveying the parameter space of the stellar mass andsurface density of protoplanets. We find that protoplanets are often ejected after twice or three times close-scattering
around late M dwarfs. The ejection sets the upper limit of the largest planet mass. Adopting the surface density
scaling linearly with the stellar mass, we find that as the stellar mass decreases less massive planets are formed inorbits with higher eccentricities and inclinations. Under this scaling, we also find that a few close-in protoplanets are
generally ejected. The ejection of protoplanets plays an important role in the mass distribution of super-Earths aroundlate M dwarfs. The mass relation of observed close-in super-Earths and their central star mass is well reproduced byejection.
Accepted by A&A
http://arxiv.org/pdf/2007.14039

45.

MHD accretion-ejection: jets launched by a non-isotropic accretion disk dynamo. I.
Validation and application of selected dynamo tensorial components
Giancarlo Mattia1 and Christian Fendt1
1

Max Planck Institute for Astronomy, Heidelberg, Germany

E-mail contact: mattia at mpia.de
Astrophysical jets are launched from strongly magnetized systems that host an accretion disk surrounding a central
object. The origin of the jet launching magnetic field is one of the open questions for modeling the accretion-ejection
process. Here we address the question how to generate the accretion disk magnetization and field structure required forjet launching. Applying the PLUTO code, we present the first resistive MHD simulations of jet launching including a
non-scalar accretion disk mean-field α2 Ω-dynamo in the context of large scale disk-jet simulations. Essentially, we findthe αφ -dynamo component determining the amplification of the poloidal magnetic field, which is strictly related tothe disk magnetization (and, as a consequence, to the jet speed, mass and collimation), while the αR and αθ -dynamo
components trigger the formation of multiple, anti-aligned magnetic loops in the disk, with strong consequences on
the stability and dynamics of the disk-jet system. In particular, such loops trigger the formation of dynamo inefficientzones, which are characterized by a weak magnetic field, and therefore a lower value of the magnetic diffusivity. The
jet mass, speed and collimation are strongly affected by the formation of the dynamo inefficient zones. Moreover, theθ-component of the α-dynamo plays a key role when interacting with a non-radial component of the seed magnetic field.
We also present correlations between the strength of the disk toy dynamo coefficients and the dynamical parametersof the jet that is launched.
Accepted by ApJ
https://arxiv.org/pdf/2007.15701

46.

MHD accretion-ejection: jets launched by a non-isotropic accretion disk dynamo. II. A
dynamo tensor defined by the disk Coriolis number
Giancarlo Mattia1 and Christian Fendt1
1

Max Planck Institute for Astronomy, Heidelberg, Germany

E-mail contact: mattia at mpia.de29

Astrophysical jets are launched from strongly magnetized systems that host an accretion disk surrounding a central
object. Here we address the question how to generate the accretion disk magnetization and field structure required
for jet launching. We continue our work from Paper I (Mattia & Fendt 2020a) considering a non-scalar accretion disk
mean-field α2 Ω-dynamo in the context of large scale disk-jet simulations. We now investigate a disk dynamo that
follows analytical solutions of mean-field dynamo theory, essentially based only on a single parameter, the Coriolis
number. We thereby confirm the anisotropy of the dynamo tensor acting in accretion disks, allowing to relate both
the resistivity and mean-field dynamo to the disk turbulence. Our new model recovers previous simulations applying
a purely radial initial field, while allowing for a more stable evolution for seed fields with a vertical component. We
also present correlations between the strength of the disk dynamo coefficients and the dynamical parameters of thejet that is launched, and discuss their implication for observed jet quantities.
Accepted by ApJ
https://arxiv.org/pdf/2008.00772

47. The magnetic obliquity of accreting T Tauri stars
Pauline McGinnis1 , Jérôme Bouvier2 and Florian Gallet2
Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin, Ireland; 2 Univ. Grenoble Alpes, CNRS, IPAG,
F-38000 Grenoble, France

1

E-mail contact: pmcginnis at cp.dias.ie
Classical T Tauri stars (CTTS) accrete material from their discs through their magnetospheres. The geometry of theaccretion flow strongly depends on the magnetic obliquity, i.e., the angle between the rotational and magnetic axes.
We aim at deriving the distribution of magnetic obliquities in a sample of 10 CTTSs. For this, we monitored theradial velocity variations of the HeIλ5876Å line in these stars’ spectra along their rotational cycle. He I is producedin the accretion shock, close to the magnetic pole. When the magnetic and rotational axes are not aligned, the radial
velocity of this line is modulated by stellar rotation. The amplitude of modulation is related to the star’s projectedrotational velocity, v sin i, and the latitude of the hotspot. By deriving v sin i and HeIλ5876 radial velocity curves fromour spectra we thus obtain an estimate of the magnetic obliquities. We find an average obliquity in our sample of
11.4◦ with an rms dispersion of 5.4◦ . The magnetic axis thus seems nearly, but not exactly aligned with the rotational
axis in these accreting T Tauri stars, somewhat in disagreement with studies of spectropolarimetry, which have founda significant misalignment (> 20◦ ) for several CTTSs. This could simply be an effect of low number statistics, or it
may be due to a selection bias of our sample. We discuss possible biases that our sample may be subject to. We alsofind tentative evidence that the magnetic obliquity may vary according to the stellar interior and that there may be
a significant difference between fully convective and partly radiative stars.
Accepted by MNRAS
https://arxiv.org/pdf/2007.06642.pdf

Massive Stars in Molecular Clouds Rich in High-energy Sources:

48. The Bridge of G332.809−0.132 and CS 78 in NGC 6334

Maria Messineo1, Karl M. Menten2 , Donald F. Figer3 , J. Simon Clark4
Key Laboratory for Researches in Galaxies and Cosmology, University of Science and Technology of China, Chinese
Academy of Sciences, Hefei, Anhui, 230026, China; 2 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69,
D-53121 Bonn, Germany; 3 Center for Detectors, Rochester Institute of Technology, 54 Memorial Drive, Rochester,
NY 14623, USA; 4 Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK7
6AA, UK1

E-mail contact: maria.messineo at hotmail.com
Detections of massive stars in the direction of the H II region CS 78 in NGC 6334 and of G332.809−0.132 are here
presented. The region covered by the G332.809−0.132 complex coincides with the RCW 103 stellar association. In its
core (40′ in radius), approximately 110 OB candidate stars (Ks < 10 mag and 0.4 < AKs < 1.6 mag) were identified
using 2MASS, DENIS, and GLIMPSE data. This number of OB stars accounts for more than 50% of the observed
number of Lyman continuum photons from this region. Medium-resolution K-band spectra were obtained for seven30

early types, including one WN 8 star and one Ofpe/WN 9 star; the latter is located near the RCW 103 remnant andits luminosity is consistent with a distance of about 3 kpc. The area analyzed encloses 9 of the 34 OB stars previously
known in RCW 103, as well as IRAS 16115−5044, which we reclassify as a candidate luminous blue variable. Theline of sight is particularly interesting, crossing three spiral arms; a molecular cloud at −50 (with RCW 103 in the
Scutum-Crux arm) and another at −90 km s−1 (in the Norma arm) are detected, both rich in massive stars andsupernova remnants. We also report the detection of a B supergiant as the main ionizing source of CS 78, 2MASSJ17213513−3532415. Medium-resolution H and K band spectra display H I and He I lines, as well as Fe II lines. By
assuming a distance of 1.35 kpc, we estimate a bolometric magnitude of −6.16, which is typical of supergiants.
Accepted by AJ
http://arxiv.org/pdf/2007.11074

49.

Searching for debris discs in the 30 Myr open cluster IC 4665
N. Miret-Roig1, N. Huélamo2 , and H. Bouy1
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac,
France; 2 Centro de Astrobiología (CSIC-INTA), ESAC Campus, Camino Bajo del Castillo s/n, 28692 Villanueva dela Cañada, Madrid, Spain
1

E-mail contact: nuria.miret-roig at u-bordeaux.fr
Context. Debris discs orbiting young stars are key to understand dust evolution and the planetary formation process.
We take advantage of a recent membership analysis of the 30 Myr nearby open cluster IC 4665 based on the Gaia and
DANCe surveys to revisit the disc population of this cluster.
Aims. We aim to study the disc population of IC 4665 using Spitzer (MIPS and IRAC) and WISE photometry.
Methods. We use several colour-colour diagrams with empirical photospheric sequences to detect the sources withan infrared excess. Independently, we also fit the spectral energy distribution (SED) of our debris disc candidates
with the Virtual Observatory SED analyser (VOSA) which is capable of automatically detecting infrared excesses andprovides effective temperature estimates.
Results. We find six candidates debris disc host-stars (five with MIPS and one with WISE) and two of them are new
candidates. We estimate a disc fraction of 24±10% for the B–A stars, where our sample is expected to be complete.
This is similar to what has been reported in other clusters of similar ages (Upper Centaurus Lupus, Lower Centaurus
Crux, the β Pictoris moving group, and the Pleiades). For solar type stars we find a disk fraction of 9±9%, lower thanthat observed in regions with comparable ages.
Conclusions. Our candidates debris disc host-stars are excellent targets to be studied with ALMA or the future James
Webb Space Telescope (JWST).
Accepted by A&A
http://arxiv.org/pdf/2007.04992

50.

Dynamical traceback age of the β Pictoris moving group
N. Miret-Roig1, P.A.B. Galli1 , W. Brandner2 , H. Bouy1 , D. Barrado3 et al.
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac,
France; 2 Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany.; 3 Centro de Astrobiología(CSIC-INTA), ESAC Campus, Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
1

E-mail contact: nuria.miret-roig at u-bordeaux.fr
Context. The β Pictoris moving group is one of the most well-known young associations in the solar neighbourhoodand several members are known to host circumstellar discs, planets, and comets. Measuring its age with precision
is basic to study several astrophysical processes such as planet formation and disc evolution which are strongly age
dependent.
Aims. We aim to determine a precise and accurate dynamical traceback age for the β Pictoris moving group.
Methods. Our sample combines the extremely precise Gaia DR2 astrometry with ground-based radial velocities
measured in an homogeneous manner. We use an updated version of our algorithm to determine dynamical ages. The
new approach takes into account a robust estimate of the spatial and kinematic covariance matrices of the association31

to improve the sample selection process and to perform the traceback analysis.
Results. We estimate a dynamical age of 18.5+2.0−2.4 Myr for the β Pictoris moving group. We investigated the spatial
substructure of the association at birth time and we propose the existence of a core of stars more concentrated. We also
provide precise radial velocity measurements for 81 members of β Pic, including ten stars with the first determinationof their radial velocities.
Conclusions. Our dynamical traceback age is three times more precise than previous traceback age estimates and,more important, for the first time, reconciles the traceback age with the most recent estimates of other dynamical,
lithium depletion boundary, and isochronal ages. This has been possible thanks to the excellent astrometric andspectroscopic precisions, the homogeneity of our sample, and the detailed analysis of binaries and membership.
Accepted by A&A
http://arxiv.org/pdf/2007.10997

51. An APEX survey of outflow and infall toward the youngest protostars in Orion
Z. Nagy1,2,3 , A. Menechella2 , S. T. Megeath2 , J. J. Tobin4 , J. J. Booker2 , W. J. Fischer5 , P. Manoj6 ,T. Stanke7 , A. Stutz8,9 and F. Wyrowski10
Center for Astrochemical Studies, Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748
Garching, Germany; 2 Ritter Astrophysical Research Center, Department of Physics and Astronomy, University ofToledo, 2801 West Bancroft Street, Toledo, OH 43606, USA; 3 Konkoly Observatory, Research Centre for Astronomy
and Earth Sciences, Konkoly Thege Miklós út 15-17, H-1121 Budapest, Hungary; 4 National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA; 5 Space Telescope Science Institute, 3700 San Martin
Drive, Baltimore, MD 21218, USA; 6 Department of Astronomy and Astrophysics, Tata Institute of Fundamental
Research, Colaba, Mumbai 400005, India; 7 European Southern Observatory, 85748 Garching bei München, Germany;
8
Departmento de Astronomía, Facultad Ciencias Físicas y Matemáticas, Universidad de Concepción, Av. Esteban
Iturra s/n Barro Universitario, Casilla 160-C, Concepción, Chile; 9 Max-Planck-Institut für Astronomie, D-69117
Heidelberg, Germany; 10 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121, Bonn, Germany
1E-mail contact: nagy.zsofia at csfk.mta.hu
We aim to characterize the outflow properties of a sample of early Class 0 phase low-mass protostars in Orion, whichwere first identified by the Herschel Space Observatory. We also look for signatures of infall in key molecular lines.
Maps of CO J=3-2 and J=4-3 toward 16 very young Class 0 protostars were obtained using the Atacama Pathfinder
EXperiment (APEX) telescope. We searched the data for line wings indicative of outflows and calculated masses,
velocities, and dynamical times for the outflows. We used additional HCO+ , H13 CO+ , and NH3 lines to look for
infall signatures toward the protostars. We estimate the outflow masses, forces, and mass-loss rates based on the CO
J=3-2 and J=4-3 line intensities for eight sources with detected outflows. We derive upper limits for the outflow
masses and forces of sources without clear outflow detections. The total outflow masses for the sources with clear
outflow detections are in the range between 0.03 and 0.16 M⊙ for CO J=3-2 and between 0.02 and 0.10 M⊙ for CO
J=4-3. The outflow forces are in the range between 1.57 × 10−4 and 1.16 × 10−3 M⊙ km s−1 yr−1 for CO J=3-2 andbetween 1.14 × 10−4 and 6.92 × 10−4 M⊙ km s−1 yr−1 for CO J=4-3. Nine protostars in our sample show asymmetricline profiles indicative of infall in HCO+ , compared to H13 CO+ or NH3 . The outflow forces of the protostars in our
sample show no correlation with the bolometric luminosity, unlike those found by some earlier studies for other Class
0 protostars. The derived outflow forces for the sources with detected outflows are similar to those found for other,more evolved, Class 0 protostars, suggesting that outflows develop quickly in the Class 0 phase.
Accepted by Astronomy & Astrophysics
https://arxiv.org/pdf/2007.12103

52. Unified simulations of planetary formation and atmospheric evolution II: Rapid disk

clearing by photoevaporation yields low-mass super-Earth atmospheres
Masahiro Ogihara1 , Masanobu Kunitomo2, and Yasunori Hori1,3National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, 181-8588 Tokyo, Japan; 2 Kurume University,
67 Asahimachi, kurume, 830-0011 Fukuoka, Japan; 3 Astrobiology Center, 2-21-1, Osawa, Mitaka, 181-8588 Tokyo,
132

JapanE-mail contact: masahiro.ogihara at nao.ac.jp
Super-Earths possess low-mass H2 /He atmospheres (typically less than 10% by mass). However, the origins of superEarth atmospheres have not yet been ascertained. We investigate the role of rapid disk clearing by photoevaporation
during the formation of super-Earths and their atmospheres. We perform unified simulations of super-Earth formation
and atmospheric evolution in evolving disks that consider both photoevaporative winds and magnetically driven disk
winds. For the growth mode of planetary cores, we consider two cases in which planetary embryos grow with andwithout pebble accretion. Our main findings are summarized as follows. (i) The time span of atmospheric accretion isshortened by rapid disk dissipation due to photoevaporation, which prevents super-Earth cores from accreting massive
atmospheres. (ii) Even if planetary cores grow rapidly by embryo accretion in the case without pebble accretion, theonset of runaway gas accretion is delayed because the isolation mass for embryo accretion is small. Together with
rapid disk clearing, the accretion of massive atmospheres can be avoided. (iii) After rapid disk clearing, a number ofhigh-eccentricity embryos can remain in outer orbits. Thereafter, such embryos may collide with the super-Earths,
leading to efficient impact erosion of accreted atmospheres. We, therefore, find that super-Earths with low-mass H2 /He
atmospheres are naturally produced by N-body simulations that consider realistic disk evolution.
Accepted by ApJ
http://arxiv.org/pdf/2007.13717

53.

Solving grain size inconsistency between ALMA polarization and VLA continuum in
the Ophiuchus IRS 48 protoplanetary disk
Satoshi Ohashi1 , Akimasa Kataoka2,3 , Nienke Van der Marel4 , Charles L.H. Hull5,6 , William R.F. Dent6
et al.
RIKEN Cluster for Pioneering Research, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan; 2 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 3 Department of Astronomical Science,
SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 4 Department of Physics and Astronomy, University of Victoria 3800 Finnerty Road, Victoria, BC, V8P 5C2, Canada; 5
National Astronomical Observatory of Japan, NAOJ Chile, Alonso de Córdova 3788, Office 61B, 7630422, Vitacura,Santiago, Chile; 6 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
1

E-mail contact: satoshi.ohashi at riken.jp
The protoplanetary disk around Ophiuchus IRS 48 shows an azimuthally asymmetric dust distribution in (sub)millimeter observations, which is interpreted as a vortex, where millimeter/centimeter-sized particles are trappedat the location of the continuum peak. In this paper, we present 860 µm ALMA observations of polarized dust emission of this disk. The polarized emission was detected toward a part of the disk. The polarization vectors are parallelto the disk minor axis, and the polarization fraction was derived to be 1–2%. These characteristics are consistent withmodels of self-scattering of submillimeter-wave emission, which indicate a maximum grain size of ∼100 µm. However,this is inconsistent with the previous interpretation of millimeter/centimeter dust particles being trapped by a vortex.
To explain both, ALMA polarization and previous ALMA and VLA observations, we suggest that the thermal emission
at 860 µm wavelength is optically thick (τabs ∼ 7.3) at the dust trap with the maximum observable grain size of ∼100
µm rather than an optically thin case with ∼cm dust grains. We note that we cannot rule out that larger dust grains
are accumulated near the midplane if the 860 µm thermal emission is optically thick.
Accepted by ApJ
http://arxiv.org/pdf/2007.15014

54. The Origin of Massive Stars: The Inertial–Inflow Model
Paolo Padoan1,2 , Liubin Pan3 , Mika Juvela4 , Troels Haugbølle5 and Åke Nordlund5
Institut de Ciències del Cosmos, Universitat de Barcelona, IEEC-UB, Martí i Franquès 1, E08028 Barcelona, Spain; 2
ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain; 3 School of Physics and Astronomy, Sun Yat-sen University,
2 Daxue Road, Zhuhai, Guangdong, 519082, China; 4 Department of Physics, PO Box 64, University of Helsinki,
00014, Helsinki, Finland; 5 Centre for Star and Planet Formation, Niels Bohr Institute and Natural History Museum133

of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, DenmarkE-mail contact: ppadoan at icc.ub.edu
We address the problem of the origin of massive stars, namely the origin, path and timescale of the mass flows thatcreate them. Based on extensive numerical simulations, we propose a scenario where massive stars are assembled bylarge-scale, converging, inertial flows that naturally occur in supersonic turbulence. We refer to this scenario of massivestar formation as the Inertial-Inflow Model. This model stems directly from the idea that the mass distribution of stars
is primarily the result of turbulent fragmentation. Under this hypothesis, the statistical properties of the turbulence
determine the formation timescale and mass of prestellar cores, posing definite constraints on the formation mechanismof massive stars. We quantify such constraints by the analysis of a simulation of supernova-driven turbulence in a 250pc region of the interstellar medium, describing the formation of hundreds of massive stars over a time of approximately
30 Myr. Due to the large size of our statistical sample, we can say with full confidence that massive stars in general
do not form from the collapse of massive cores, nor from competitive accretion, as both models are incompatible with
the numerical results. We also compute synthetic continuum observables in Herschel and ALMA bands. We find that,
depending on the distance of the observed regions, estimates of core mass based on commonly-used methods may
exceed the actual core masses by up to two orders of magnitude, and that there is essentially no correlation between
estimated and real core masses.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/1911.04465.pdf

High-resolution spectroscopic monitoring observations of FU Orionis-type object, V960

55. MonSunkyung Park1 , Jeong-Eun Lee1 , Tae-Soo Pyo2 , Daniel T. Jaﬀe3 , Gregory N. Mace3 et al.
School of Space Research, Kyung Hee University 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do, 17104,
Republic of Korea; 2 Subaru Telescope, National Astronomical Observatory of Japan 650 North Aohoku Place, Hilo,
HI 96720, USA; 3 Department of Astronomy, University of Texas at Austin 2515 Speedway, Austin, TX, USA
1E-mail contact: jeongeun.lee at khu.ac.kr
We present the results of high-resolution (R ≥ 30, 000) optical and near-infrared spectroscopic monitoring observationsof a FU Orionis-type object, V960 Mon, which underwent an outburst in 2014 November. We have monitored thisobject with the Bohyunsan Optical Echelle Spectrograph (BOES) and the Immersion GRating INfrared Spectrograph(IGRINS) since 2014 December. Various features produced by a wind, disk, and outflow/jet were detected. The windfeatures varied over time and continually weakened after the outburst. We detected double-peaked line profiles in the
optical and near-infrared, and the line widths tend to decrease with increasing wavelength, indicative of Keplerian disk
rotation. The disk features in the optical and near-infrared spectra fit well with G-type and K-type stellar spectra
convolved with a kernel to account for the maximum projected disk rotation velocity of about 40.3±3.8 km s−1 and
36.3±3.9 km s−1 , respectively. We also report the detection of [S II] and H2 emission lines, which are jet/outflow
tracers and rarely found in FUors.
Accepted by ApJ
http://arxiv.org/pdf/2007.03197

The accretion history of high-mass stars: An ArTéMiS pilot study of Infrared Dark

56. Clouds

N. Peretto1 , A. Rigby1 , Ph. André2 , V. Könives3 , G. Fuller4 , A. Zavagno5,6 , F. Schuller2,7 , D.
Arzoumanian8 , S. Bontemps9 , T. Csengeri9, P. Didelon2 , A. Duarte-Cabral1 , P. Palmeirim8 , S. Pezzuto10 ,V. Revéret2 , H. Roussel11 and Y. Shimajiri12
Cardiff University, School of Physics & Astronomy, Queen’s buildings, The parade, Cardiff CF24 3AA, UK; 2Laboratoire d’Astrophysique (AIM), CEA/DRF, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne
Paris Cité, 91191 Gif-sur-Yvette, France; 3 Jeremiah Horrocks Institute, University of Central Lancashire, Preston
PR1 2HE, UK; 4 Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University ofManchester, Oxford Road, Manchester M13 9PL, UK; 5 Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France;
1

34

Institut Universitaire de France; 7 Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482
Potsdam, Germany; 8 Instituto de Astrofísica e Ciências do Espaco, Universidade do Porto, CAUP, Rua das Estrelas,
PT4150-762 Porto, Portugal; 9 Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Georoy
Saint-Hilaire, 33615 Pessac, France; 10 INAF - IAPS Via fosso del Cavaliere 100, I-00133 Roma, Italy; 11 Institutd’Astrophysique de Paris, Sorbonne Université, CNRS (UMR7095), 75014 Paris, France; 12 National Astronomical
Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
6

E-mail contact: nicolas.peretto at astro.cf.ac.uk
The mass growth of protostars is a central element to the determination of fundamental stellar population properties
such as the initial mass function. Constraining the accretion history of individual protostars is therefore an important
aspect of star formation research. The goal of the study presented here is to determine whether high-mass (proto)stars
gain their mass from a compact (< 0.1 pc) fixed-mass reservoir of gas, often referred to as dense cores, in which
they are embedded, or whether the mass growth of high-mass stars is governed by the dynamical evolution of theparsec-scale clump that typically surrounds them. To achieve this goal, we performed a 350µm continuum mappingof 11 infrared dark clouds, along side some of their neighbouring clumps, with the ArTéMiS camera on APEX. By
identifying about 200 compact ArTéMiS sources, and matching them with Herschel Hi-GAL 70µm sources, we havebeen able to produce mass vs. temperature diagrams. We compare the nature (i.e. starless or protostellar) andlocation of the ArTéMiS sources in these diagrams with modelled evolutionary tracks of both core-fed and clump-fed
accretion scenarios. We argue that the latter provide a better agreement with the observed distribution of high-massstar-forming cores. However, a robust and definitive conclusion on the question of the accretion history of high-massstars requires larger number statistics.
Accepted by MNRAS
https://arxiv.org/pdf/2006.05155.pdf

A protostellar system fed by a streamer of 10,500 au length
57. Jaime E. Pineda1 , Dominique Segura-Cox1 , Paola Caselli1, Nichol Cunningham2 , Bo Zhao1 et al.
Max-Planck-Institut für extraterrestrische Physik (MPE), Gießenbachstr. 1, D-85748 Garching, Germany; 2 Institut
de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406, Saint-Martin d’Hères, France
1

E-mail contact: jaime.e.pineda at gmail.com
Binary formation is an important aspect of star formation. One possible route for close-in binary formation is disk
fragmentation. Recent observations show small scale asymmetries (<300 au) around young protostars, although notalways resolving the circumbinary disk, are linked to disk phenomena. In later stages, resolved circumbinary disk
observations (<200 au) show similar asymmetries, suggesting the origin of the asymmetries arises from binary-disk
interactions. We observed one of the youngest systems to study the connection between disk and dense core. We findfor the first time a bright and clear streamer in chemically fresh material (Carbon-chain species) that originates fromoutside the dense core (>10,500 au). This material connects the outer dense core with the region where asymmetries
arise near disk scales. This new structure type, 10× larger than those seen near disk scales, suggests a different
interpretation of previous observations: large-scale accretion flows funnel material down to disk scales. These results
reveal the under-appreciated importance of the local environment on the formation and evolution of disks in earlysystems and a possible initial condition for the formation of annular features in young disks.
Accepted by Nature Astronomy
http://arxiv.org/pdf/2007.13430

Carina High-contrast Imaging Project for massive Stars (CHIPS). I. Methodology and58. proof of concept on QZ Car (HD93206)
Alan Rainot1 , M. Reggiani1 , H. Sana1 , J. Bodensteiner1 , C. A. Gomez-Gonzalez2 , O. Absil3 , V.
Christiaens3,4,5 , P. Delorme6 , L. A. Almeida7,8 , S. Caballero-Nieves9 , J. De Ridder1 , K. Kratter10 ,S. Lacour11 , J.-B. Le Bouquin6 , L. Pueyo12 and H. Zinnecker13
Institute of Astronomy, KU Leuven, Celestijnlaan 200D, 3001 Leuven, Belgium; 2 Barcelona Supercomputing Center,carrer de John Maynard Keynes, 30, 08034 Barcelona, Spain; 3 Space sciences, Technologies and Astrophysics Research
1

35

(STAR) Institute, Université de Liege, 19 Allé du Six Aout, 4000 Liege, Belgium; 4 Dept. de Astronomia, Universidad
de Chile, Casilla 36-D, Santiago, Chile; 5 School of Physics and Astronomy, Monash University, VIC 3800, Australia;
6
Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France; 7 Dept. de Fisica, Universidade do Estado do
Rio Grande do Norte, Mossor, RN, Brazil; 8 Dept. de Fisica Teorica e Experimental, Universidade Federal do Rio
Grande do Norte, CP 1641, Natal, RN 59072-970, Brazil; 9 Dept. of Aerospace Physics & Space Sciences, Florida
Institute of Technology, 150 West University Blvd, Melbourne, FL 32901, USA; 10 Dept. of Astronomy, Universityof Arizona, Tucson, AZ 85721, USA; 11 LESIA, (UMR 8109), Observatoire de Paris, PSL, CNRS, UPMC, Université
Paris-Diderot, 5 place Jules Janssen, 92195 Meudon, France; 12 STScI, 3700 San Martin Drive, Baltimore, MD 21218,
USA; 13 Universidad Autonoma de Chile, Avda Pedro de Valdivia 425, Providencia, Santiago de Chile
E-mail contact: alan.rainot at kuleuven.be
Massive stars like company. However, low-mass companions have remained extremely difficult to detect at angularseparations (ρ) smaller than 1" ( 1000-3000 au considering typical distance to nearby massive stars) given the largebrightness contrast between the companion and the central star. Constraints on the low-mass end of the companions
mass-function for massive stars are however needed, for example to help distinguishing between various scenarios forthe formation of massive stars. To obtain statistically significant constraint on the presence of low-mass companions
beyond the typical detection limit of current surveys (∆mag≤5 at ρ≤1"), we initiated a survey of O and Wolf-Rayetstars in the Carina region using the SPHERE coronagraphic instrument on the VLT. In this first paper, we aim to
introduce the survey, to present the methodology and to demonstrate the capability of SPHERE for massive stars
using the multiple system QZ Car. High-contrast imaging techniques, such as angular- and spectral-differential imaging
techniques as well as PSF-fitting, were applied to detect and measure the relative flux of companions in each spectral
channel of the instrument. We detected 19 sources around the QZ Car system with detection limits of 9 mag at
ρ>200 mas for IFS and as faint as 13 mag at ρ > 1".8 for IRDIS (corresponding to sub-solar masses for potential
companions). All but two are reported here for the first time. Based on this proof of concept, we showed that
VLT/SPHERE allows us to reach the sub-solar mass regime of the companion mass function. This paves the way forthis type of observation with a large sample of massive stars to provide novel constraints on the multiplicity of massive
stars in a region of the parameter space that has remained inaccessible so far.
Accepted by Astronomy and Astrophysics
https://arxiv.org/pdf/2006.01914

59.

Torques felt by solid accreting planets
Zs. Regály1
Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, 1121, Budapest, Konkoly Thege Miklós
út 15-17, Hungary
1E-mail contact: regaly at konkoly.hu
The solid material of protoplanetary discs forms an asymmetric pattern around a low-mass planet (Mp ≤ 10 MEarth)
due to the combined effect of dust-gas interaction and the gravitational attraction of the planet. Recently, it has beenshown that although the total solid mass is negligible compared to that of gas in protoplanetary discs, a positive torquecan be emerged by a certain size solid species. The torque magnitude can overcome that of gas which may resultin outward planetary migration. In this study, we show that the accretion of solid species by the planet strengthens
the magnitude of solid torque being either positive or negative. We run two-dimensional, high-resolution (1.5K ×
3K) global hydrodynamic simulations of an embedded low-mass planet in a protoplanetary disc. The solid material ishandled as a pressureless fluid. Strong accretion of well-coupled solid species by a Mp < 0.3 MEarth protoplanet resultsin the formation of such a strongly asymmetric solid pattern close to the planet that the positive solid torque canovercome that of gas by two times. However, the accretion of solids in the pebble regime results in increased magnitude
negative torque felt by protoplanets and strengthened positive torque for Earth-mass planets. For Mp ≥ 3 MEarthplanets the magnitude of the solid torque is positive, however, independent of the accretion strength investigated.
We conclude that the migration of solid accreting planets can be substantially departed from the canonical type-I
prediction.
Accepted by MNRAS
http://arxiv.org/pdf/2007.11072
36

Autonomous Gaussian decomposition of the Galactic Ring Survey. II. The Galactic

60. distribution of 13 CO

M. Riener1 , J. Kainulainen2,1 , J. D. Henshaw1 and H. Beuther1
Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany; 2 Chalmers University of Technology, Department of Space, Earth and Environment, SE-412 93 Gothenburg, Sweden
1E-mail contact: riener at mpia-hd.mpg.de
Knowledge about the distribution of CO emission in the Milky Way is essential to understanding the impact of the
Galactic environment on the formation and evolution of structures in the interstellar medium. However, our current
insight as to the fraction of CO in the spiral arm and interarm regions is still limited by large uncertainties in assumed
rotation curve models or distance determination techniques. In this work we use the Bayesian approach from Reidet al. (2016, 2019), which is based on our most precise knowledge at present about the structure and kinematics ofthe Milky Way, to obtain the current best assessment of the Galactic distribution of 13 CO from the Galactic Ring
Survey. We performed two different distance estimates that either included (Run A) or excluded (Run B) a modelfor Galactic features, such as spiral arms or spurs. We also included a prior for the solution of the kinematic distanceambiguity that was determined from a compilation of literature distances and an assumed size-linewidth relationship.
Even though the two distance runs show strong differences due to the prior for Galactic features for Run A and larger
uncertainties due to kinematic distances in Run B, the majority of their distance results are consistent with eachother within the uncertainties. We find that the fraction of 13 CO emission associated with spiral arm features ranges
from 76% to 84% between the two distance runs. The vertical distribution of the gas is concentrated around theGalactic midplane, showing full-width at half-maximum values of ∼ 75 pc. We do not find any significant difference
between gas emission properties associated with spiral arm and interarm features. In particular, the distribution ofvelocity dispersion values of gas emission in spurs and spiral arms is very similar. We detect a trend of higher velocity
dispersion values with increasing heliocentric distance, which we, however, attribute to beam averaging effects causedby differences in spatial resolution. We argue that the true distribution of the gas emission is likely more similar to a
combination of the two distance results discussed, and we highlight the importance of using complementary distanceestimations to safeguard against the pitfalls of any single approach. We conclude that the methodology presented inthis work is a promising way to determine distances to gas emission features in Galactic plane surveys.
Accepted by Astronomy & Astrophysics (A&A)
https://arxiv.org/pdf/2006.03294

61.

Recombination Lines and Molecular Gas from Hypercompact HII regions in W51 A
Rudy Rivera-Soto1 , Roberto Galván-Madrid1 , Adam Ginsburg2,3 , Stan Kurtz1
Instituto de Radioastronomía y Astrofísica (IRyA), UNAM, Apdo. Postal 72-3 (Xangari), Morelia, Michoacán 58089,
Mexico; 2 Jansky Fellow; 3 National Radio Astronomy Observatory, 1003 Lopezville Rd, Socorro, NM 87801, USA; 4
Department of Astronomy, University of Florida, PO Box 112055, USA
1E-mail contact: r.galvan at irya.unam.mx
We present a detailed characterization of the population of compact radio-continuum sources in W51 A using subarcsecond VLA and ALMA observations. We analyzed their 2-cm continuum, the recombination lines (RL’s) H77α andH30α, and the lines of H2 CO (30,3 –20,2 ), H2 CO (32,1 –22,0 ), and SO (65 –54 ). We derive diameters for 10/20 sourcesin the range D ∼ 10−3 to ∼ 10−2 pc, thus placing them in the regime of hypercompact HII regions (HC HII’s).
Their continuum-derived electron densities are in the range ne ∼ 104 to 105 cm−3 , lower than typically considered for
HC HII’s. We combined the RL measurements and independently derived ne , finding the same range of values but
significant offsets for individual measurements between the two methods. We found that most of the sources in our
sample are ionized by early B-type stars, and a comparison of ne vs D shows that they follow the inverse relation
previously derived for ultracompact (UC) and compact HII’s. When determined, the ionized-gas kinematics is always(7/7) indicative of outflow. Similarly, 5 and 3 out of the 8 HC HII’s still embedded in a compact core show evidence
for expansion and infall motions in the molecular gas, respectively. We hypothesize that there could be two different
types of hypercompact (D < 0.05 pc) HII regions: those that essentially are smaller, expanding UC HII’s; and thosethat are also hyperdense (ne > 106 cm−3 ), probably associated with O-type stars in a specific stage of their formationor early life.
37

Accepted by ApJ
http://arxiv.org/pdf/2007.12276

62.

Prebiotic precursors of the primordial RNA world in space: Detection of NH2 OH
Víctor M. Rivilla1,2, Jesús Martín-Pintado1 , Izaskun Jiménez-Serra1 , Sergio Martín3,4 , Lucas F. RodríguezAlmeida1 , Miguel A. Requena-Torres5,6 , Fernando Rico-Villas1, Shaoshan Zeng7 and Carlos Briones1
Centro de Astrobiología (CSIC-INTA), Ctra. de Ajalvir Km. 4, Torrejón de Ardoz, 28850 Madrid, Spain; 2 INAFOsservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125, Florence, Italy; 3 European Southern Observatory,
Alonso de Córdova 3107, Vitacura 763 0355, Santiago, Chile; 4 Joint ALMA Observatory, Alonso de Córdova 3107,
Vitacura 763 0355, Santiago, Chile; 5 University of Maryland, College Park, ND 20742-2421 (USA); 6 Departmentof Physics, Astronomy and Geosciences, Towson University, Towson, MD 21252, USA; 7 Star and Planet Formation
Laboratory, Cluster for Pioneering Research, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan1

E-mail contact: vmrivilla at gmail.com
One of the proposed scenarios for the origin of life is the primordial RNA world, which considers that RNA molecules
were likely responsible for the storage of genetic information and the catalysis of biochemical reactions in primitive
cells, before the advent of proteins and DNA. In the last decade, experiments in the field of prebiotic chemistry haveshown that RNA nucleotides can be synthesized from relatively simple molecular precursors, most of which have beenfound in space. An important exception is hydroxylamine, NH2 OH, which, despite several observational attempts,
it has not been detected in space yet. Here we present the first detection of NH2 OH in the interstellar medium
towards the quiescent molecular cloud G+0.693-0.027 located in the Galactic Center. We have targeted the threegroups of transitions from the J=2−1, 3−2, and 4−3 rotational lines, detecting 5 transitions that are unblended or
only slightly blended. The derived molecular abundance of NH2 OH is (2.1±0.9)×10−10. From the comparison of thederived abundance of NH2 OH and chemically related species, with those predicted by chemical models and measured
in laboratory experiments, we favor the formation of NH2 OH in the interstellar medium via hydrogenation of NO on
dust grain surfaces, with possibly a contribution of ice mantle NH3 oxidation processes. Further laboratory studies
and quantum chemical calculations are needed to completely rule out the formation of NH2 OH in the gas phase.
Accepted by The Astrophysical Journal Letters
https://arxiv.org/pdf/2008.00228

The Role of Outflows, Radiation Pressure, and Magnetic Fields in Massive Star Forma-

63. tion

Anna L. Rosen1 and Mark R. Krumholz2,3Center for Astrophysics ; 2 Harvard & Smithsonian, 60 Garden St, Cambridge, MA 02138, USA; 3 Research Schoolof Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 Australia
1E-mail contact: anna.rosen at cfa.harvard.edu
Stellar feedback in the form of radiation pressure and magnetically-driven collimated outflows may limit the maximum
mass that a star can achieve and affect the star-formation efficiency of massive pre-stellar cores. Here we present a
series of 3D adaptive mesh refinement radiation-magnetohydrodynamic simulations of the collapse of initially turbulent,
massive pre-stellar cores. Our simulations include radiative feedback from both the direct stellar and dust-reprocessedradiation fields, and collimated outflow feedback from the accreting stars. We find that protostellar outflows punches
holes in the dusty circumstellar gas along the star’s polar directions, thereby increasing the size of optically thinregions through which radiation can escape. Precession of the outflows as the star’s spin axis changes due to theturbulent accretion flow further broadens the outflow, and causes more material to be entrained. Additionally, thepresence of magnetic fields in the entrained material leads to broader entrained outflows that escape the core. We
compare the injected and entrained outflow properties and find that the entrained outflow mass is a factor of ∼3larger than the injected mass and the momentum and energy contained in the entrained material are ∼25% and ∼5%of the injected momentum and energy, respectively. As a result, we find that, when one includes both outflows andradiation pressure, the former are a much more effective and important feedback mechanism, even for massive stars
with significant radiative outputs.
38

Accepted by Astronomical Journal
https://arxiv.org/pdf/2006.04829.pdf

64. The one that got away: A unique eclipse in the young brown dwarf Roque 12
Aleks Scholz1 , Dirk Froebrich2 , Koraljka Muzic3 and Jochen Eislöﬀel4
SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, United
Kingdom; 2 Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury
CT2 7NH, UK; 3 CENTRA, Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016 Lisboa,
Portugal; 4 Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany

1E-mail contact: as110 at st-andrews.ac.uk
We report the discovery of a deep, singular eclipse of the bona fide brown dwarf Roque 12, a substellar member of the
Pleiades. The eclipse was 0.65 mag deep, lasted 1.3 h, and was observed with two telescopes simultaneously in October
2002. No further eclipse was recorded, despite continuous monitoring with Kepler/K2 over 70 d in 2015. There istentative (2σ) evidence for radial velocity variations of 5 kms−1 , over timescales of three months. The best explanation
for the eclipse is the presence of a companion on an eccentric orbit. The observations constrain the eccentricity toe > 0.5, the period to P > 70 d, and the mass of the companion to ∼ 0.001 − 0.04 M⊙. In principle it is also possiblethat the eclipse is caused by circum-sub-stellar material. Future data releases by Gaia and later LSST as well as
improved radial velocity constraints may be able to unambiguously confirm the presence of the companion. This
would turn the system into one of the very few known eclipsing binary brown dwarfs with known age.
Accepted by Open Journal of Astrophysics
https://arxiv.org/pdf/2006.03582

65. The importance of magnetic fields for the initial mass function of the first stars
Piyush Sharda1,2 , Christoph Federrath1,2 and Mark R. Krumholz1,2
Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia; 2Australian Research Council Centre for Excellence in All Sky Astrophysics (ASTRO3D), Australia
1E-mail contact: piyush.sharda at anu.edu.au
Magnetic fields play an important role for the formation of stars in both local and high-redshift galaxies. Recent
studies of dynamo amplification in the first dark matter haloes suggest that significant magnetic fields were likely
present during the formation of the first stars in the Universe at redshifts of 15 and above. In this work, we study
how these magnetic fields potentially impact the initial mass function (IMF) of the first stars. We perform 200 highresolution, three-dimensional (3D), magnetohydrodynamic (MHD) simulations of the collapse of primordial clouds withdifferent initial turbulent magnetic field strengths as predicted from turbulent dynamo theory in the early Universe,
forming more than 1100 first stars in total. We detect a strong statistical signature of suppressed fragmentation in
the presence of strong magnetic fields, leading to a dramatic reduction in the number of first stars with masses low
enough that they might be expected to survive to the present-day. Additionally, strong fields shift the transition
point where stars go from being mostly single to mostly multiple to higher masses. However, irrespective of the
field strength, individual simulations are highly chaotic, show different levels of fragmentation and clustering, and theoutcome depends on the exact realization of the turbulence in the primordial clouds. While these are still idealized
simulations that do not start from cosmological initial conditions, our work shows that magnetic fields play a key role
for the primordial IMF, potentially even more so than for the present-day IMF.
Accepted by MNRAS
http://arxiv.org/pdf/2002.11502

66.

Dark dust and UVES search of single-cloud sightlines in the ISM
R. Siebenmorgen1, J. Krełowski2 , J. Smoker3 , G. Galazutdinov4 and S. Bagnulo5
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany; 2 Rzeszów University, al. T. Rejtana 16c, 35-959,
Rzeszów, Poland; 3 ESO, Alonso de Cordova 3107, Vitacura, Santiago, Chile; 4 Instituto de Astronomia, Universidad
139

Catolica del Norte, Av. Angamos 0610, Antofagasta, Chile, and Pulkovo Observatory, Pulkovskoe Shosse 65, SaintPetersburg 196140, Russia; 5 Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK
E-mail contact: Ralf.Siebenmorgen at eso.org
The precise characteristics of clouds and the nature of dust in the diffuse interstellar medium can only be extracted
by inspecting the rare cases of single-cloud sightlines. In our nomenclature such objects are identified by interstellarlines, such as K i, that show at a resolving power of λ/∆λ ∼ 75, 000 one dominating Doppler component that accounts
for more than half of the observed column density. We searched for such sightlines using high-resolution spectroscopy
towards reddened OB stars for which far-UV extinction curves are known. We compiled a sample of 186 spectra, 100of which were obtained specifically for this project with UVES. In our sample we identified 65 single-cloud sightlines,
about half of which were previously unknown. We used the CH/CH+ line ratio of our targets to establish whether
the sightlines are dominated by warm or cold clouds. We found that CN is detected in all cold (CH/CH+ > 1)
clouds, but is frequently absent in warm clouds. We inspected the WISE (3 − 22 µm) observed emission morphology
around our sightlines and excluded a circumstellar nature for the observed dust extinction. We found that mostsightlines are dominated by cold clouds that are located far away from the heating source. For 132 stars, we derived
the spectral type and the associated spectral type-luminosity distance. We also applied the interstellar Ca ii distancescale, and compared these two distance estimates with GAIA parallaxes. These distance estimates scatter by ∼ 40 %.
By comparing spectral type-luminosity distances with those of GAIA, we detected a hidden dust component thatamounts to a few mag of extinction for eight sightlines. This dark dust is populated by >∼1µm large grains andpredominately appears in the field of the cold interstellar medium
Accepted by A&A
http://arxiv.org/pdf/2006.12877

67.

Effect of grain size distribution and size-dependent grain heating on molecular abundances in starless and pre-stellar cores
O. Sipilä1 , B. Zhao1 and P. Caselli1
1

Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstr. 1, 85748 Garching, Germany

E-mail contact: osipila at mpe.mpg.de
We present a new gas-grain chemical model to constrain the effect of grain size distribution on molecular abundances inphysical conditions corresponding to starless and pre-stellar cores. We simultaneously introduce grain-size dependence
for desorption efficiency induced by cosmic rays (CRs) and for grain equilibrium temperatures. The latter were
calculated with a radiative transfer code via custom dust models built for the present work. We explicitly trackedof ice abundances on a set of grain populations. We find that the size-dependent CR desorption efficiency affects ice
abundances in a highly nontrivial way that depends on the molecule. Species that originate in the gas phase, suchas CO, follow a simple pattern in which the ice abundance is highest on the smallest grains and these are the mostabundant in the distribution. Some molecules, such as HCN, are instead concentrated on large grains throughout
the time evolution; others, such as N2 , are initially concentrated on large grains, but at late times on small grains
because of grain-size-dependent competition between desorption and hydrogenation. Most of the water ice is on small
grains at high medium density (n(H2 ) higher than 106 cm−3 ), where the water ice fraction, with respect to the total
water ice reservoir, can be as low as ∼ 10−3 on large (upwards of 0.1 µm) grains. Allowing the grain equilibrium
temperature to vary with grain size induces strong variations in relative ice abundances in low-density conditions inwhich the interstellar radiation field and in particular its ultraviolet component are not attenuated. Our study implies
consequences not only for the initial formation of ices preceding the starless core stage, but also for the relative ice
abundances on the grain populations going into the protostellar stage. In particular, if the smallest grains can lose
their mantles owing to grain-grain collisions as the core is collapsing, the ice composition in the beginning of the
protostellar stage could be very different than in the pre-collapse phase because the ice composition depends strongly
on the grain size.
Accepted by A&A
http://arxiv.org/pdf/2006.09741

40

CO-to-H2 Conversion and Spectral Column Density in Molecular Clouds: The Variabilityof XCO Factor
68.
Yoshiaki Sofue1 and Mikito Kohno2,3

Institute of Astronomy, The University of Tokyo, Mitaka, Tokyo 181-0015, Japan; 2 Department of Physics, Graduate
School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; 3 Astronomy Section,
Nagoya City Science Museum, 2-17-1 Sakae, Naka-ku, Nagoya, Aichi 460-0008, Japan1

E-mail contact: sofue at ioa.s.u-tokyo.ac.jp
Analyzing the Galactic plane CO survey with the Nobeyama 45-m telescope, we compared the spectral column density(SCD) of NH2 calculated for 12 CO (J=1-0) line using the current conversion factor X12 CO to that for 13 CO (J=1-0)line under LTE (local thermal equilibrium) assumption in M16 and W43 regions. Here, SCD is defined by dNH2 /dv
with NH2 and v being the column density and radial velocity, respectively. It is found that the X12 CO method
significantly under-estimates the H2 density in a cloud or region, where SCD exceeds a critical value (∼ 3 × 1021
[H2 cm−2 (km s−1 )−1 ]), but over-estimates in lower SCD regions. We point out that the actual CO-to-H2 conversion
factor varies with the H2 column density or with the CO-line intensity: It increases in the inner and opaque partsof molecular clouds, whereas it decreases in the low-density envelopes. However, in so far as the current X12 CO isused combined with the integrated 12 CO intensity averaged over an entire cloud, it yields a consistent value with that
calculated
the 13 CO intensity by LTE. Based on the analysis, we propose a new CO-to-H2 conversion relation,
R using∗∗∗
NH2 = XCO (TB )TB dv, where XCO(TB ) = (TB /TB∗ )β X12 CO is the modified spectral conversion factor as a function of
the brightness temperature, TB , of the 12 CO (J=1-0) line, and β ∼ 1 − 2 and TB∗ = 12 − 16 K are empirical constants
obtained by fitting to the observed data. The formula corrects for the over/under estimation of the column density
at low/high-CO line intensities, and is applicable to molecular clouds with TB ≥ 1 K (12 CO (J=1-0) line rms noise in
the data) from envelope to cores at sub-parsec scales (spatial resolution).
Accepted by MNRAS
https://arxiv.org/pdf/2007.03413.pdf

Possible Time Correlation Between Jet Ejection and Mass Accretion for RW Aur A
69. Michihiro Takami1 , Tracy L. Beck2 , P. Christian Schneider3 , Hans Moritz Guenther4 , Marc White5 ,Konstantin Grankin6 , Jennifer L. Karr1 , Youichi Ohyama1 , Deirdre Coﬀey7 , Hauyu Baobab Liu1 ,Roberto Galván-Madrid8 , Chun-Fan Liu1 , Misato Fukagawa9 , Nadine Manset10 , Wen-Ping Chen11 ,Tae-Soo Pyo12 , Hsien Shang1 , Thomas P. Ray13 , Masaaki Otsuka14 and Mei-Yin Chou1
Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No.1,
Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan, R.O.C.; 2 The Space Telescope Science Institute, 3700 San Martin Dr.,
Baltimore, MD 21218, USA; 3 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029, Hamburg,
Germany; 4 MIT, Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA
02139, USA; 5 Research School of Astronomy and Astrophysics, College of Physical & Mathematical Sciences, The
Australian National University, Mount Stromlo Observatory, Cotter Rd, Weston Creek ACT 2611, Australia; 6 Crimean
Astrophysical Observatory, Russian Academy of Sciences, 298409 Nauchny, Crimea; 7 University College Dublin,
School of Physics, Belfield, Dublin 4, Ireland; Dublin Institute for Advanced Studies, School of Cosmic Physics, 31
Fitzwilliam Place, Dublin 2, Ireland; 8 Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma
de México, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán, Mexico; 9 National Astronomical Observatory ofJapan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 10 Canada-France-Hawaii Telescope, 65-1238 Mamalahoa Hwy.,
Kamuela, HI 96743, USA; 11 Institute of Astronomy, National Central University, Taiwan 320, Taiwan; 12 Subaru
Telescope, 650 North Aohoku Place, Hilo, HI 96720, USA; 13 Dublin Institute for Advanced Studies, School of Cosmic
Physics, 31 Fitzwilliam Place, Dublin 2, Ireland; 14 Okayama Observatory, Kyoto University, Kamogata, Asakuchi,
Okayama 719-0232, Japan1

E-mail contact: hiro at asiaa.sinica.edu.tw
For the active T-Taur star RW Aur A we have performed long-term (∼10 yr) monitoring observations of (1) jet imaging
in the [Fe II] 1.644 µm emission line using Gemini-NIFS and VLT-SINFONI; (2) optical high-resolution spectroscopyusing CFHT-ESPaDOnS; and (3) V -band photometry using the CrAO 1.25-m telescope and AAVSO. The latter two
observations confirm the correlation of time variabilities between (A) the Ca II 8542 Å and O I 7772 Å line profiles
41

associated with magnetospheric accretion, and (B) optical continuum fluxes. The jet images and their proper motions
show that four knot ejections occurred at the star over the past ∼15 years with an irregular interval of 2-6 years. The
time scale and irregularity of these intervals are similar to those of the dimming events seen in the optical photometrydata. Our observations show a possible link between remarkable (∆V < −1 mag.) photometric rises and jet knot
ejections. Observations over another few years may confirm or reject this trend. If confirmed, this would imply thatthe location of the jet launching region is very close to the star (r≤0.1 au) as predicted by some jet launching models.
Such a conclusion would be crucial for understanding disk evolution within a few au of the star, and therefore possible
ongoing planet formation at these radii.
Accepted by ApJ
https://arxiv.org/pdf/2007.15848

The Excitation Conditions of CN in TW Hya
70. Richard Teague1,2 , Ryan Loomis3
Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; 2 Department of
Astronomy, University of Michigan, 311 West Hall, 1085 S. University Ave, Ann Arbor, MI 48109, USA; 3 National
Radio Astrophysical Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA

1E-mail contact: richard.d.teague at cfa.harvard.edu
We report observations of the cyanide anion, CN, in the disk around TW Hya covering the N=1–0, N=2–1 and
N=3–2 transitions. Using line stacking techniques, 24 hyperfine transitions are detected out of the 30 within theobserved frequency ranges. Exploiting the super-spectral resolution from the line stacking method reveals the splittingof hyperfine components previously unresolved by laboratory spectroscopy. All transitions display a similar emission
morphology, characterized by an azimuthally symmetric ring, peaking at ≈45 au (0.′′ 75), and a diffuse outer tailextending out to the disk edge at ≈200 au. Excitation analyses assuming local thermodynamic equilibrium (LTE) yield
excitation temperatures in excess of the derived kinetic temperatures based on the local line widths for all fine structuregroups, suggesting assumptions of LTE are invalid. Using the 0D radiative transfer code RADEX, we demonstratethat such non-LTE effects may be present when the local H2 density drops to 107 cm−3 and below. Comparison withmodels of TW Hya find similar densities at elevated regions in the disk, typically z/r >∼ 0.2, consistent with model
predictions where CN is formed via vibrationally excited H2 in the disk atmospheric layers where UV irradiation isless attenuated.
Accepted by ApJ
http://arxiv.org/pdf/2007.11906

71.

A wide survey for circumstellar disks in the Lupus complex
P. S Teixeira1 , A. Scholz1 and J. Alves2
Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St. Andrews, North
Haugh, Fife, KY16 9SS, St. Andrews, UK; 2 University of Vienna,Department of Astrophysics, Tuerkenschanzstrasse
17, A-1180 Vienna, Austria

1E-mail contact: psdvt at st-andrews.ac.uk
Previous star formation studies have, out of necessity, often defined a population of young stars confined to theproximity of a molecular cloud. Gaia allows us to examine a wider, three-dimensional structure of nearby star forming
regions, leading to a new understanding of their history. We present a wide-area survey covering 494 square degreesof the Lupus complex, a prototypical low-mass star forming region. Our survey includes all known molecular clouds
in this region as well as parts of the Upper Scorpius (US) and Upper Centaurus Lupus (UCL) groups of the Sco-Cen
complex. We combine Gaia DR2 proper motions and parallaxes as well as ALLWISE mid-infrared photometry to
select young stellar objects (YSOs) with disks. The YSO ages are inferred from Gaia color-magnitude diagrams, andtheir evolutionary stages from the slope of the spectral energy distributions. We find 98 new disk-bearing sources.
Our new sample includes objects with ages ranging from 1 to 15 Myr and masses ranging from 0.05 to 0.5 solar masses, and consists of 56 sources with thick disks and 42 sources with anemic disks. While the youngest members areconcentrated in the clouds and at distances of 160 pc, there is a distributed population of slightly older stars that42

overlap in proper motion, spatial distribution, distance, and age with the Lupus and UCL groups. The spatial andkinematic properties of the new disk-bearing YSOs indicate that Lupus and UCL are not distinct groups. Our new
sample comprises some of the nearest disks to Earth at these ages, and thus provides an important target for follow-up
studies of disks and accretion in very low mass stars, for example with ALMA and ESO-VLT X-Shooter.
Accepted by Astronomy and Astrophysics
http://arxiv.org/pdf/2007.14102

72.

Giant planet formation models with a self-consistent treatment of the heavy elements
Claudio Valletta1 and Ravit Helled1
Center for Theoretical Astrophysics & Cosmology, Institute for Computational Science, University of Zurich, Zurich,
Switzerland
1

E-mail contact: valletta at physik.uzh.ch
We present a new numerical framework to model the formation and evolution of giant planets. The code is basedon the further development of the stellar evolution toolkit Modules for Experiments in Stellar Astrophysics (MESA).
The model includes the dissolution of the accreted planetesimals/pebbles, which are assumed to be made of water
ice, in the planetary gaseous envelope, and the effect of envelope enrichment on the planetary growth and internal
structure is computed self-consistently. We apply our simulations to Jupiter and investigate the impact of different
heavy-element and gas accretion rates on its formation history. We show that the assumed runaway gas accretion
rate significantly affect the planetary radius and luminosity. It is confirmed that heavy-element enrichment leads toshorter formation timescales due to more efficient gas accretion. We find that with heavy-element enrichment Jupiter’s
formation timescale is compatible with typical disks’ lifetimes even when assuming a low heavy-element accretion rate(oligarchic regime). Finally, we provide an approximation for the heavy-element profile in the innermost part of theplanet, providing a link between the internal structure and the planetary growth history.
Accepted by EPSC-DPS Joint Meeting
http://arxiv.org/pdf/2007.13577

Measurements of the Ca II infrared triplet emission lines of pre-main-sequence stars
73.

Mai Yamashita1 , Yoichi Itoh1 , Yuhei Takagi2
Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo, Sayo,
Hyogo 679-5313; 2 Subaru Telescope, National Astoronomical Observatory of Japan, 650 North Aohoku Place, Hilo,
HI 96720, U.S.A.
1

E-mail contact: yamashita at nhao.jp
We investigated the chromospheric activity of 60 pre-main-sequence (PMS) stars in four molecular clouds and five
moving groups. It is considered that strong chromospheric activity is driven by the dynamo processes generated
by the stellar rotation. In contrast, several researchers have pointed out that the chromospheres of PMS stars areactivated by mass accretion from their protoplanetary disks. In this study, the Ca II infrared triplet (IRT) emission
lines were investigated utilizing medium- and high-resolution spectroscopy. The observations were conducted with
Nayuta/MALLS and Subaru/HDS. Additionally, archive data obtained by Keck/HIRES, VLT/UVES, and VLT/XShooter was used. The small ratios of the equivalent widths indicate that Ca II IRT emission lines arise primarily in
dense chromospheric regions. Seven PMS stars show broad emission lines. Among them, four PMS stars have morethan one order of magnitude brighter emission line fluxes compared to the low-mass stars in young open clusters. The
four PMS stars have a high mass accretion rate, which indicates that the broad and strong emission results from alarge mass accretion. However, most PMS stars exhibit narrow emission lines. No significant correlation was foundbetween the accretion rate and flux of the emission line. The ratios of the surface flux of the Ca II IRT lines to the′′stellar bolometric luminosity, RIRT
, of the PMS stars with narrow emission lines are as large as the largest RIRTof thelow-mass stars in the young open clusters. This result indicates that most PMS stars, even in the classical T Tauri
star stage, have chromospheric activity similar to zero-age main-sequence stars.
Accepted by PASJ
http://arxiv.org/pdf/2007.09315
43

Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular

74. clouds

S. Zeng1,2,3 , Q. Zhang2 , I. Jiménez-Serra4 , B.Tercero5,6 , X. Lu7 , J. Martín-Pintado4 , P. de Vicente6 , V.
M. Rivilla8 and S. Li2,9,10
School of Physics and Astronomy, Queen Mary University of London, Mile End Road, E1 4NS London, United
Kingdom; 2 Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; 3 Star
and Planet Formation Laboratory, RIKEN Cluster for Pioneering Research, 2-1, Hirosawa, Wako, Saitama 351-0198,
Japan; 4 Centro de Astrobiología (CSIC/INTA), Ctra, de Torrejón a Ajalvir km 4, Torrejón de Ardoz, 28850 Madrid,
Spain; 5 Observatorio Astronomico Nacional (OAN-IGN), Calle Alfonso XII, 3, 28014 Madrid, Spain; 6 Observatorio
de Yebes (IGN), Cerro de la Palera S/N, 19141, Guadalajara; 7 National Astronomical Observatory of Japan, 2-21-1
Osawa, Mitaka, Tokyo, 181-8588, Japan; 8 INAF-Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125,
Florence, Italy; 9 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai
200030, China; 10 University of Chinese Academy of Sciences, 19A Yuquanlu, Beijing 100049, China
1E-mail contact: shaoshan.zeng at riken.jp
G+0.693-0.03 is a quiescent molecular cloud located within the Sagittarius B2 (Sgr B2) star-forming complex. Recent
spectral surveys have shown that it represents one of the most prolific repositories of complex organic species in
the Galaxy. The origin of such chemical complexity, along with the small-scale physical structure and properties
of G+0.693-0.03, remains a mystery. In this paper, we report the study of multiple molecules with interferometricobservations in combination with single-dish data in G+0.693-0.03. Despite the lack of detection of continuum source,
we find small-scale (0.2 pc) structures within this cloud. The analysis of the molecular emission of typical shock
tracers such as SiO, HNCO, and CH3 OH unveiled two molecular components, peaking at velocities of 57 and 75 km
s−1 . They are found to be interconnected in both space and velocity. The position-velocity diagrams show featuresthat match with the observational signatures of a cloud-cloud collision. Additionally, we detect three series of class
I methanol masers known to appear in shocked gas, supporting the cloud-cloud collision scenario. From the maser
emission we provide constraints on the gas kinetic temperatures (∼30-150 K) and H2 densities (104 -105 cm−2 ). These
properties are similar to those found for the starburst galaxy NGC253 also using class I methanol masers, suggested
to be associated with a cloud-cloud collision. We conclude that shocks driven by the possible cloud-cloud collision is
likely the most important mechanism responsible for the high level of chemical complexity observed in G+0.693-0.03.
Accepted by MNRAS
http://arxiv.org/pdf/2007.14362

75. Fragmentation of star-forming filaments in the X-shape Nebula of the California molec-

ular cloud

Guo-Yin Zhang1,2,3 , Ph. André2 , A. Men’shchikov2 and Ke Wang4,5National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, PR China,
Email: zgyin@nao.cas.cn; 2 Laboratoire d’Astrophysique (AIM), CEA/DRF, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France,
Email: philippe.andre@cea.fr; alexander.menshchikov@cea.fr; 3 University of Chinese Academy of Sciences, Beijing
100049, PR China; 4 Kavli Institute for Astronomy and Astrophysics, Peking University, 5 Yiheyuan Road, Haidian
District, Beijing 100871, PR China,
Email: kwang.astro@pku.edu.cn; 5 European Southern Observatory (ESO) Headquarters, Karl-Schwarzschild-Str. 2,
85748 Garching bei München, Germany
1E-mail contact: guoyin.zhang at cea.fr
Context. Dense molecular filaments are central to the star formation process, but the detailed manner in which they
fragment into prestellar cores is not yet well understood.
Aims. Here, we investigate the fragmentation properties and dynamical state of several star-forming filaments in the
X-shape Nebula region of the California molecular cloud, in an effort to shed some light on this issue.
Methods. We used multi-wavelength far-infrared images from Herschel and the getsources and getfilaments extraction
methods to identify dense cores and filaments in the region and derive their basic properties. We also used a map of
13
CO(2 − 1) emission from the Arizona 10m Submillimeter Telescope (SMT) to constrain the dynamical state of the44

filaments.
Results. We identified 10 filaments with aspect ratios AR > 4 and column density contrasts C > 0.5, as well as 57
dense cores, including 2 protostellar cores, 20 robust prestellar cores, 11 candidate prestellar cores, and 24 unboundstarless cores. All 10 filaments have roughly the same deconvolved FWHM width, with a median value 0.12 ± 0.03
pc, independently of their column densities ranging from < 1021 cm−2 to > 1022 cm−2 . Two star-forming filaments (#8 and # 10) stand out in that they harbor quasi-periodic chains of dense cores with a typical projected core spacingof ∼0.15 pc. These two filaments have thermally supercritical line masses and are not static. Filament 8 exhibits aprominent transverse velocity gradient, suggesting that it is accreting gas from the parent cloud gas reservoir at an
estimated rate of ∼ 40 ± 10 M⊙ Myr−1 pc−1 . Filament 10 includes two embedded protostars with outflows and islikely at a somewhat later evolutionary stage than filament 8. In both cases, the observed (projected) core spacing issimilar to the filament width and significantly shorter than the canonical separation of ∼ 4 times the filament width
predicted by classical cylinder fragmentation theory. Projection effects are unlikely to explain this discrepancy. We
suggest that continuous accretion of gas onto the two star-forming filaments, as well as geometrical bending of thefilaments, may account for the observed core spacing.
Conclusions. Our findings suggest that the characteristic fragmentation lengthscale of molecular filaments is quitesensitive to external perturbations from the parent cloud, such as gravitational accretion of ambient material.
Accepted by Astronomy & Astrophysics
https://arxiv.org/pdf/2002.05984

Abstract submission deadline
The deadline for submitting abstracts and othersubmissions is the first day of the month. Abstracts
submitted after the deadline will appear in the following month’s issue.

45

Dissertation Abstracts

Numerical simulations of star and disc formation
Asmita Bhandare

Max Planck Institute for Astronomy, Heidelberg, Germany
Max Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg, Germany
Address as of 14 September 2020: Centre de Recherche Astrophysique de Lyon/ENS Lyon, 46 Allee D’italie, 69007
Lyon, FranceElectronic mail: bhandare at mpia.de
Ph.D dissertation directed by: Prof. Dr. Thomas Henning
Ph.D degree awarded: June 2020

Magnetized, cold, dense molecular cloud cores provide the birth environment for stars, discs, and planets. The multiscale scenario of low-mass star formation occurs via the formation of two quasi-hydrostatic cores. Furthermore, theconservation of angular momentum can lead to the formation of a disc around the second core (i.e. the forming
protostar). During these early stages of star formation, magnetically driven outflows and jets can be launched fromthe first and second cores, respectively. Star, disc, and outflow formation involve complex physical processes, which
require a robust, self-consistent numerical treatment.
In this thesis, we use numerical simulations to probe the gravitational collapse scenario that involves the transition of
an isolated molecular cloud core to a hydrostatic core with a surrounding disc. We use the PLUTO code to perform
radiation (magneto-)hydrodynamic (MHD) collapse simulations, using one- and two-dimensional (2D) grids. We
include the effects of self-gravity and a grey flux-limited diffusion approximation for the radiative transfer. Additionally,
we use for the gas equation of state density- and temperature-dependent thermodynamic quantities to account for the
dissociation, ionisation, and molecular vibrations and rotations.
Our spherically symmetric simulations span seven orders of magnitude in spatial scale. We survey a wide range ofinitial low- to high-mass (0.5 – 100 M⊙ ) molecular cloud cores, yielding the largest parameter scan so far. Our results
highlight the dependence of the first and second hydrostatic core properties on the initial cloud core properties. Thesesimulations indicate that in the high-mass regime, the first hydrostatic cores do not have enough time to form due tolarge accretion rates.
We further expand our studies to three different sets of 2D simulations using axial and midplane symmetry. First,
we perform 2D simulations for non-rotating molecular cloud cores with masses of 1 M⊙ , 5 M⊙ , 10 M⊙ , and 20 M⊙ .
46

For each of these cases, we use an unprecedented resolution to model the evolution of the second core for ≥ 100 years
after its formation. For the first time, we demonstrate that convection is generated in the outer layers of the second
core. This supports the intriguing possibility that dynamo-driven magnetic fields may be generated during the earliest
phases of star formation. Following which, for the 1 M⊙ case, we analyse the effects of solid-body rotation on theproperties of the hydrostatic cores and disc formation. In this model, the first hydrostatic core evolves into a moreoblate, pseudo-disc like structure and a sub-au disc starts forming after the formation of the second core. Finally, we
explore the effects of ideal and non-ideal (including Ohmic resistivity) MHD during the collapse of rotating molecular
cloud cores. We investigate the dependence of molecular outflows and disc formation on the initial cloud core mass,rotation, resistivity, and magnetic field strength. We find the presence of magnetically driven outflows launched fromboth first and second cores in the resistive models. We also reveal ongoing disc formation in some of our resistive
simulations.
In conclusion, we use detailed thermodynamical modelling to quantify the properties of the hydrostatic cores, outflows,
and discs for collapse scenarios with a wide range of initial cloud core properties. The models presented herein willserve as the foundation for follow-up studies that link these theoretical insights with observational signatures.
http://www.ub.uni-heidelberg.de/archiv/28554

Moving ... ??
If you move or your e-mail address changes, please
send the editor your new address. If the Newsletterbounces back from an address for three consecutive
months, the address is deleted from the mailing list.

47

The Origin of Complex Organic Molecules in Star Forming Regions
Sébastien Manigand

Thesis work conducted at: Niels Bohr Institute, University of Copenhagen, Denmark
Current address: The Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen Ø, Denmark
Electronic mail: sebastien.manigand83@gmail.com
Ph.D dissertation directed by: Jes K. Jørgensen
Ph.D degree awarded: June 2020
Complex organic molecules (COMs, i.e. molecules with six or more atoms with at least one carbon) are present in thegas around young stars in the earliest stages of their evolution. Similar molecules are also found in meteorites andcomets in our Solar System. Their formation may be closely related to the physical processes that led to the formationof the Solar System. Thus, it is important to study the chemistry of COMs around young protostars to understandhow these molecules are formed, how they can form prebiotic molecules, such as amino acids, and investigate whether
they potentially could be important for the origin of life elsewhere. In this thesis, the inventory of oxygen-bearing
COMs towards a young protostellar binary is studied and their chemical formation and evolution discussed.
The low-mass Class 0 protostellar binary IRAS 16293–2422, located in the ρ Ophiuchus molecular cloud, has been
observed with the Atacama Large Millimeter/submillimeter Array (ALMA) as part of the “Protostellar InterferometricLine Survey (PILS)”. This well-studied source is characterised by its great molecular richness and their high abundance,
especially in the innermost region of the envelope of each protostar, the so-called “hot corinos”. The abundances ofthe oxygen-bearing COM were derived from their spectral features towards both components of the binary system.
The comparison between the molecular abundances found towards two binary components and the spatial extent of theemission from different molecules suggests that the hot corino region has a layered structure in terms of its molecularcomposition. This layer-structure seems to be correlated with the desorption temperatures of the different species, i.e.
that the molecules having a higher desorption temperature are located in the inner layers of the hot corino (closer tothe central protostar), compared to molecules with lower desorption temperatures.
The PILS observations allowed for several new detections of molecules in the interstellar medium, some of which arereported in this thesis. These include CHD2 OCHO, a variant of methyl formate (CH3 OCHO) where two hydrogenatoms are substituted by deuterium. The D/H ratio measured for CHD2 OCHO is systematically higher than thoseestimated for the singly-deuterated isotopologues of methyl formate, CH2 DOCHO and CH3 OCDO, suggesting thatthe deuteration enhancement is inherited from their precursor species.
The detection of molecules containing three carbon atoms, C3 -species, towards IRAS 16293B, such as propenal(C2 H3 CHO), propanal (C2 H5 CHO), methyl acetylene (CH3 CCH), propene (C3 H6 ), and trans-ethyl methyl ether(t -C2 H5 OCH3 ), made the study of their formation possible. We compared the observed abundances of these C3 species to those predicted by a three-phase chemical model, NAUTILUS, coupled to a 1D hydrodynamical model of
an infalling protostellar envelope. The simulations could reproduce all the abundances of the observed C3 -species, aswell as those of other COMs, within one order of magnitude. Comparisons between simulations suggest that radicalradical additions and successive hydrogenation contribute equally to the formation of C2 H3 CHO and C2 H5 CHO. Also,a systematic over-production of molecules of the form C3 Hx suggests that the chemical networks lack consumption
channels for those species, which could be related to the chemistry of polycyclic aromatic hydrocarbons (PAHs).
48

The detailed velocity structure and distribution of 13 CO emission in the
Galactic plane
Manuel Riener

Thesis work conducted at: Max Planck Institute for Astronomy, Germany
Current address: Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
Electronic mail: riener@mpia.de
Ph.D dissertation directed by: Jouni Kainulainen
Ph.D degree awarded: July 2020
Studying the detailed velocity structure of molecular gas in our Galaxy is of fundamental importance for understanding
structure formation in the interstellar medium. Knowledge about the detailed gas kinematics is moreover essential tomap the distribution and dynamics of the molecular gas in the Milky Way.
In this thesis I use the method of spectral decomposition to analyse the 13 CO (1–0) observations of the Galactic Ring
Survey (GRS). I developed the GaussPy+ package, specifically designed for the fully automated decomposition oflarge Galactic plane surveys, to fit the ∼ 2.3 million spectra of this large emission line data set. After extensive
validation of the algorithm using synthetic spectra and a GRS test field, I use GaussPy+ to fit the entire data set of
the GRS, resulting in ∼ 4.6 million Gaussian fit components.
These decomposition results provide a new way to analyse the dynamics of the molecular gas over a wide extent of the
Galactic plane and study how its velocity structure looks like and varies at Galactic to sub-cloud scales. I find thatthe velocity dispersion of the gas is increased in the midplane and towards the inner Galaxy, and establish that the
integrated emission of the velocity components correlates well with the complexity of the gas emission and the amountof dust emission along the line of sight. Moreover, I uncover qualitatively similar fluctuations in the centroid velocitiesof the gas components throughout the entire GRS data set, and demonstrate how the fitted linewidths enable theseparation of blended gas emission features that originate from nearby regions and far distances.
Finally, I use a Bayesian approach to obtain the current best assessment of the Galactic distribution of 13 CO. As priorinformation, I use the presently most precise knowledge about the structure and kinematics of the Milky Way andan extensive compilation of distances from literature. I perform two different distance calculations that either include
or exclude a prior for a model of Galactic features, which allows me to characterise possible biases of the distanceestimates and establish more reliable limits on the 13 CO distribution. I establish that the majority (76% to 84%) of
the 13 CO emission is associated with spiral arm features. However, I do not find significant differences between thegas emission properties associated with spiral arm and interarm features.
I conclude that the decomposition results provide a wealth of data enabling new and unexplored ways to interpretthe detailed gas velocity structure of large Galactic plane surveys. The methodology and results presented in thisthesis allowed for a homogeneous study of the dynamics and distribution of the molecular gas over a large fraction of
the Galactic disk. As demonstrated in this work, the information extracted from the detailed gas kinematics and its
combination with complementary tracers of the interstellar medium has enormous potential to further our knowledge
about the physical processes and mechanisms shaping the interstellar medium.
https://archiv.ub.uni-heidelberg.de/volltextserver/28635/1/Riener_PhD_thesis.pdf
49New Jobs

51 Pegasi b Fellowship
The 51 Pegasi b Fellowship Program sponsored by the Heising-Simons Foundation provides an opportunity for promising recent doctoral scientists to conduct novel theoretical, experimental, or observational research in planetary astronomy. The fellowship program supports postdoctoral fellows to advance our fundamental understanding of planet
formation and evolution, solar system science, planetary atmospheres, protoplanetary disks, exoplanet science, orother closely related topics. The fellowship program recognizes early-career investigators of significant potential andprovides them with the opportunity to conduct independent research at a selected host institution.
The Foundation anticipates awarding six to eight fellowships this year. The Heising-Simons Foundation is committed
to diversity, equity, and inclusion within its community. Thus, we particularly welcome applications from individuals
who belong to groups that have been historically underrepresented in planetary sciences and astronomy such as women,
persons with disabilities, racial and ethnic minorities, gender and sexual minorities, and others who may contributeto diversification of the field.
Awarded postdoctoral fellows are expected to carry out a strong, coherent research program. Each recipient will
receive a three-year grant of up to 375,000 dollars to cover salary, benefits, highly-flexible discretionary spending (e.g.,travel, child care, personal computers, etc.), and indirect costs.
51 Pegasi b Fellowship research must be pursued at one of the 14 following host institutions:
California Institute of Technology; University of California, Berkeley; Cornell University; University of California, Los
Angeles; Harvard University / Harvard-Smithsonian; University of California, Santa Cruz; Massachusetts Instituteof Technology; University of Chicago; Pennsylvania State University; University of Michigan; Princeton University;
University of Texas, Austin; University of Arizona; Yale University;
Application Deadline: Friday, October 2, 2020
Apply Here: http://www.51pegasib.org

50

Meetings

Threats from the surroundings:
An e-workshop on the importance of environment for the evolutionof protoplanetary discs and formation of planets
On-line on November 10-12 2020
Website: https://www.eso.org/sci/meetings/2020/tfts2020.html
Conference email: tfts2020@eso.org
Short Scientific Rationale:
Growing evidence indicates that protoplanetary discs (and by extension, forming planets) are significantly affected by
the environment in which they form. In particular, the presence of massive stars and the dynamical history of clusters
and associations impacts the evolution of discs and can lead to photoevaporation, truncation, and chemical enrichment.
We therefore need to move beyond the picture of planet-forming discs as isolated systems. This e-workshop aims tobring together the community to share our current understanding of the different ways that the environment shapes
disc evolution and planet formation, to shape the future direction of research in this regard through new ideas andcollaborations.
Invited speakers: Reiter, Megan (UK Astronomy Technology Centre) Akeson, Rachel (IPAC Caltech) Ndugu, Nelson(Mbarara University Of Science And Technology) Winter, Andrew (MPIA Heidelberg) Kim, J. Serena (University of
Arizona) Coleman, Gavin (Queen Mary University of London) Lugaro, Maria (Konkoly Observatory) Guzmn, Viviana(Pontificia Universidad Catolica de Chile) Vazan, Allona (Hebrew University of Jerusalem/Open University of Israel)
Invited discussion leaders: Rosotti, Giovanni (Leiden University) Pfalzner, Susanne (Max Planck fr Radioastronomie,Bonn) Facchini, Stefano (ESO Garching) Mordasini, Christoph (University of Bern) Drazkowska, Joanna (USM Munich) Clarke, Cathie (IoA Cambridge)
SOC: Manara, Carlo F. (ESO) Petr-Gotzens, Monika (ESO) Ansdell, Megan (NASA) Haworth, Thomas (Queen Mary
University of London) Lichtenberg, Tim (Oxford University)***************************************************************************************************The meeting will be fully online (see https://www.eso.org/sci/meetings/2020/tfts2020/online.html). In orderto facilitate the discussion, the number of talking participants will be limited to about 60 persons, selected by the
SOC based on scientific relevance to the topic, considering all career stages and reflecting diversity.
All other participants will be able to observe and ask questions via chat.
***************************************************************************************************
Important Deadlines
Abstract submission: September 15, 2020
Programme release: October 13, 2020***************************************************************************************************

51

Summary of Upcoming Meetings

Check the websites of these meetings for the latest information on how they are aﬀected by Covid-19
Star Formation in Diﬀerent Environments 202024 - 28 August 2020, Quy Nhon, Vietnam
http://icisequynhon.com/conferences/sfde/
IMPRS Summer School: Planet Formation in Protoplanetary Disks
31 Aug - 4 Sept 2020, Heidelberg, Germany
https://www.imprs-hd.mpg.de/Summer-School
Planetary Science: The Young Solar System
6 - 12 September 2020, Quy Nhon, Vietnam
http://www.icisequynhon.com/conferences/planetary_science/
Conditions and Impact of Star Formation - Across Times and Scales
28 September - 2 October 2020, Chile
https://astro.uni-koeln.de/symposium-star-formation-2020.html
From Clouds to Planets II: The Astrochemical Link
28 September - 2 October 2020, Berlin, Germany
https://events.mpe.mpg.de/event/12/
Threats from the Surroundings – VIRTUAL MEETING
10 - 12 November 2020
http://www.eso.org/sci/meetings/2020/tfts2020.html
Five Years after HL Tau: A New Era in Planet Formation – VIRTUAL MEETING
7 - 11 December 2020
https://www.eso.org/sci/meetings/2020/hltau2020.html
Protostars & Planets VII
1 - 7 April 2021, Kyoto, Japan
http://www.ppvii.org
Gordon Conference on Origins of Solar Systems
19 - 25 June 2021, MA, USA
https://www.grc.org/origins-of-solar-systems-conference/2021
Cool Stars, Stellar Systems, and the Sun 21
Summer 2021, Toulouse, France
https://coolstars21.github.io/Star Formation: From Clouds to Discs - A Tribute to the Career of Lee Hartmann
16 - 19 August 2021, Malahide, Ireland
https://www.dias.ie/cloudstodiscs/
Chemical Processes in Solar-type Star Forming Regions
13 - 17 September 2021, Torino, Italy
https://sites.google.com/inaf.it/aco-conference
Wheel of Star Formation: A conference dedicated to Prof. Jan Palouš
20 - 24 September 2020, Prague, Czech Republic
https://janfest2020.asu.cas.cz
The Physics of Star Formation: From Stellar Cores to Galactic Scales∼June - July 2022, Lyon, France
http:/staratlyon.univ-lyon1.fr/en
52