THESTAR

FORMATION

NEWSLETTER

An electronic publication dedicated to early stellar/planetary evolution and molecular clouds
No. 324 — 17 December 2019

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

List of Contents
The Star Formation Newsletter

Interview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Editor: Bo Reipurthreipurth@ifa.hawaii.edu

Abstracts of Newly Accepted Papers . . . . . . . . . . . 5

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

Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

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

Short Announcements . . . . . . . . . . . . . . . . . . . . . . . . 43

New Jobs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Summary of Upcoming Meetings . . . . . . . . . . . . . 42

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
IC 1318 is an HII region in Cygnus divided into
three parts, A, B, and C. The figure shows thetwo parts B and C, bifurcated by the dark cloud
L889. The distance to IC 1318 is uncertain, but isassumed to be about 1.5 kpc. The bright star in
the foreground is γ Cygni.
Image courtesy of Steve Mazlin
http://www.fourthdimensionastroimaging.com

Submitting your abstracts
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submitting
abstractsand dissertation abstracts (by e-mail toreipurth@ifa.hawaii.edu)
areappendedtoeach Call for Abstracts.
You can also
submitvia
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to the cold, dark limit in dense molecular clouds. CH remains a good indirect tracer of molecular hydrogen.

John BlackI tried to learn everything about the CH molecule. This
led me to try to detect the microwave lines of CH near 3
GHz frequency in Comet Kohoutek in 1974 with the Harvard 25 meter radio telescope. This comet (1973f) had
been discovered well in advance of its perihelion passage
so there was time to prepare. At first, the idea was touse the comet as a spectroscopic source for determining
the frequencies of the three ground-state Λ-doubling transitions, because these were not well measured. In retrospect that would have been impossible given the weaknessof the lines and the narrow bandwidth of the spectrometer. Fortunately, in the meantime, Olof Rydbeck and his
team at Onsala Space Observatory detected the CH lines
in interstellar clouds and published accurate rest frequencies. Our detection of one line in the comet was at the 10σ
level. Coincidentally, Onsala, Sweden, has been my home
Q: In 1973, while you were still a PhD student, you and for the last twenty-four years.
Alex Dalgarno published a highly cited paper on the cosmic
Q: A few years later you and Alex wrote a paper on how
abundance of deuterium. What were the key insights?
molecular hydrogen in diffuse clouds absorbs ultraviolet raA: It’s interesting that you bring up this paper, because diation, and you predicted how the resulting fluorescence
there is so much background hidden behind the strict should lead to the emission of infrared photons.
four-page limit on a Letter at that time. The hope was
A: This was the original focus of my PhD thesis. We
to measure the interstellar deuterium abundance because
found that the depth-dependent attenuation of the ultraprimordial deuterium constrains cosmological parameters
violet starlight and the rest of the interstellar chemistry(baryon mass density, number of neutrino species, etc.)
were crucial to understanding the stratified structure ofthrough the theory of Big Bang Nucleosynthesis. The
the atomic/molecular transition zone. A diffuse interstelearly Copernicus observations of ultraviolet absorption lines
lar cloud is just a low-flux version of the photodissociationof H2 and HD required detailed models of the chemistry
regions (PDR) that dominate the infrared emission fromand structure of diffuse interstellar clouds, because theluminous star-forming regions.
molecular abundances must vary strongly with depth. We
extracted only a loose constraint on D/H, but rich insight Q: In 1977 you and Alex developed a model of the Zeta
into the importance of depth-dependent models. These Ophiuchi diffuse cloud to take advantage of the UV line
were among the first attempts to describe in detail what data from the Copernicus satellite. What were the main
we now call photodissociation regions (PDR). It also be- ingredients in this model?
came clear that cosmic-ray ionization drives part of the A: The backbone of such a PDR model is the treatment ofrich chemical activity (oxygen into OH and water) while the depth-dependence of the ultraviolet absorption by H2
ultraviolet starlight controls other aspects (atomic carbon in a self-consistent way with its formation and destruction.
into CH, the H2 /H ratio). Interstellar absorption spec- Approximately 15% of the ultraviolet line absorptions leadtroscopy, astrochemistry, and cosmic ray interactions have to dissociation of the molecule while the rest produce thebeen persistent themes in my work ever since.
UV fluorescence and infrared cascade. The overall yield is
Q: That same year you, again with Alex, also published a around three IR photons for every UV photon absorbed.
paper on the formation of CH in interstellar clouds. How The other processes that excite H2 , such as inelastic collisions with other atoms and molecules, are included. The
have these results held up with time?
populations of all the states of H2 are computed by solving
A: The key suggestion of a radiative association process,a
system of rate equations. Thus the calculated column+
C+ + H2 → CH2 + γ, has held up well. Subsequent dedensities, state-by-state in H2 , could be compared directly
tailed models with Alex and later with Ewine van Dishoeckwith the observations from the Princeton spectrometer on
demonstrated good quantitative agreement with observed
Copernicus. The ion chemistry related to the abundancescolumn densities of C+ , CH, C2 , and H2 in diffuse molecof HD and OH was also included, along with the ionizationular clouds. Ewine and I then tried to extend absorption
equilibria of several atomic species. We also tried to asline observations to thicker lines of sight, in order to see
sess the heating and cooling processes in the gas, in orderthe transition from translucent, starlight-driven chemistry

in conversation with Bo Reipurth3to account for the temperatures suggested by the populations of the lowest states of H2 . At the time, the diffuse
molecular cloud toward ζ Oph was the best studied region,
based on the classic study by George Herbig (1968).

confirmed that the temperature of the cosmic microwave
background does indeed scale as (1 + z). There is now along list of measured molecular column densities (including isotope ratios). I confess I am slightly surprised that
Our knowledge of chemical processes and the amount of the chemistry at z = 0.89 is so similar to what we see in
observational data both increased rapidly during the fol- translucent clouds in the Milky Way.
lowing decade, so that Ewine van Dishoeck and I were Q: In the late 1980s you and Ewine van Dishoeck re-visitedable to expand and improve this comprehensive approach the question of the fluorescent excitation of interstellar H2
to cloud models. This was explained in several long pa- in an important paper that is still today highly cited. Whatpers in the late 1980s, including our detailed investigation were the new insights?
of the photochemistry of carbon monoxide. We tried very A: This was spurred by the advances in infrared astronhard to test the models against all of the available ob- omy in the decade 1977-1987, which included observations
servations and to predict new observables; as a result, the of H emission in a variety of sources. In some cases, the2referee of our 1986 paper even allowed us to keep the word signature of fluorescence was evident. Perhaps the paper“comprehensive” in the title.
is still cited because we presented tables of predicted line

In parallel with the work on models, we extended absorption spectroscopy to thicker translucent clouds, that issightlines toward early type stars with visual extinction
greater than 3 magnitudes. We reported surveys of CH,
CN, CH+ , and C2 molecules. As Ewine and I had shown
earlier, the rotational populations in C2 could be used toinfer the density and temperature in these regions.

fluxes and scaling formulae that could be simply applied
to infrared spectra. I was fortunate to learn about infrared
astronomy from a pioneer, Ed Ney, and the talented people around him at the University of Minnesota, during mytime there, 1975-1978.
Q: What are your current interests?
A: I am very interested in the spectroscopy of mass-losing
stars. The Atacama Large Millimeter/submillimeter Array (ALMA) provides very sensitive, broad-band line surveys with good angular resolution. I like to explore complicated excitation processes of molecules in which the infrared radiation of the star competes with collisions in controlling the line emission that emerges at millimeter andsubmillimeter wavelengths. With ALMA and with the optical/infrared interferometer at the ESO Very Large Telescope, it is also possible now to resolve central components
of atomic and molecular line emission that lie well insidethe dust-forming zones of evolved, mass-losing stars. I’m
hopeful that the studies of these extended chromospheres
will lead to a better understanding of conditions in theregions where winds are launched and solids begin to condense. I am working on simple models to unify the description of visible, infrared, and mm-wave emission-line
regions for this purpose.

The chemical networks in these models made rather specific predictions about the abundances of unseen molecules
+
+
+
+
+
like H+
3 , OH , H2 O , H3 O , HCl , and H2 Cl . It has
been very exciting to witness the later discoveries of all ofthese molecular ions.
Q: Interstellar absorption spectroscopy has taken you evenfurther afield, hasn’t it?
A: That’s right. When it became clear that the UV absorption by H2 was so widespread in the Milky Way, it was
tempting to look for molecular lines in QSO absorption
spectra at high redshift. A redshift of z > 2 puts the farultraviolet lines within the comfort zone of a ground-based
telescope. Marc Aaronson, Chris McKee, and I searched
for the H2 fingerprint in published lists of QSO absorption lines in 1974. In 1985, Levshakov and Varshalovich
identified the telltale pattern in a line list and in 1988
Craig Foltz, Fred Chaffee, and I confirmed their identification with better observations and a direct comparison
with simulated spectra at z = 2.8 toward PKS 0528 − 250.
It has been gratifying to see the enormous progress in thisarea in recent years. Patrick Petitjean and collaborators
have assembled a large sample of molecular absorbers at
high redshift. Some of these systems even have detectable
HD and CO. It was also possible to follow up on a suggestion by Rodger Thompson that measurements of highly
redshifted H2 could be sensitive to a possible cosmological variation of the ratio of masses of electron and proton.
During the last few years, I have been fortunate to be partof Sebastien Muller’s program to study molecular absorption at z = 0.89 toward a gravitationally lensed QSO. We

Some of your earlier questions remind me that models ofthermal and fluorescent infrared emission should also be
combined with models of H2 exposed to hot electrons (tensof eV) that come from interactions with cosmic rays or Xrays. There are some hints of electron-excited H2 emission
in the disks around young stellar objects. I am also curious
whether the IR fluorescence of H2 might be detectablefrom a cold, dark cloud (or circumstellar envelope), as ameasure of the response to starlight at its surface and tocosmic-ray-induced ultraviolet radiation in its interior.
Finally, I still hope to pursue a serious, non-astronomical
hobby someday.

4

Abstracts of recently accepted papers

1

A Swift view of X-ray and UV radiation in the planet-forming T-Tauri system PDS 70
Simon R.G. Joyce1 , John P. Pye1 , Jonathan D. Nichols1 , Kim L. Page1 , Richard Alexander1 , ManuelGüdel2 , Yanina Metodieva2
School of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK; 2 Universityof Vienna, Dept. of Astrophysics, Turkenschanzstr. 17, 1180 Vienna, Austria
1E-mail contact: sj328 at leicester.ac.uk
PDS 70 is a ∼5 Myr old star with a gas and dust disc in which several proto-planets have been discovered. We present
the first UV detection of the system along with X-ray observations taken with the Neil Gehrels Swift Observatory
satellite. PDS 70 has an X-ray flux of 3.4 × 10−13 erg cm−2 s−1 in the 0.3–10.0 keV range, and UV flux (U band) of
3.5 × 10−13 erg cm−2 s−1 . At the distance of 113.4 pc determined from Gaia DR2 this gives luminosities of 5.2 × 1029
erg s−1 and 5.4 × 1029 erg s−1 respectively. The X-ray luminosity is consistent with coronal emission from a rapidlyXrotating star close to the log LLbol∼ −3 saturation limit. We find the UV luminosity is much lower than would be
expected if the star were still accreting disc material and suggest that the observed UV emission is coronal in origin.
Accepted by MNRAS Letters
http://arxiv.org/pdf/1911.00297

2

Simultaneous photometric and spectral analysis of a new outburst of V1686 Cyg
Hasmik Andreasyan1 , Tigran Magakian1 and Tigran Movsessian1
1

Byurakan Observatory NAS Armenia, Byurakan, Aragatsotn prov., 0213, Armenia

E-mail contact: hasmik.andreasyan at gmail.com
We present an analysis of the optical observations of Herbig AeBe star V1686 Cyg, which is associated with a small
isolated star-forming region around HAeBe star BD+40◦ 4124. We observed this star as a part of our project of young
eruptive stars investigation. Observations were held on 2.6m telescope of Byurakan Observatory from 2015 to 2017.
For this period we obtained V1686 Cyg direct images and 14 medium- and low-resolution spectra. In the course ofobservations we noticed that this star underwent a not-typical brightness outburst. After data reduction we foundthat the full rise and decline of V1686 Cyg brightness had almost 3 magnitudes amplitude and lasted about 3 months.
We were also able to trace the changes of the stellar spectrum during the outburst, which are correlated with thephotometric variations.
Accepted by Research in Astronomy and Astrophysics
http://arxiv.org/pdf/1912.01262

3

Modeling the accretion disk around the high-mass protostar GGD 27-MM1
Nacho Añez-López1,3 , Mayra Osorio2 , Gemma Busquet1,3 , Josep Miquel Girart1,3 , Enrique Macías4,5,6 ,Carlos Carrasco-González7 , Salvador Curiel8 , Robert Estalella9, Manuel Fernández-López10 , Roberto
Galván-Madrid7 , Jungmi Kwon11 and Jose María Torrelles1,21Institut de Ciències de l’Espai (ICE-CSIC), Carrer de Can Magans s/n 08193 Cerdanyola del Vallés, Barcelona; 2Instituto de Astrofísica de Andalucía, Glorieta de la Astronomía, s/n, 18008, Granada; 3 Institut d’Estudis Espacials
de Catalunya, Gran Capità, 2-4, Edifici Nexus, Desp. 201, 08034 Barcelona; 4 Department of Astonomy, Boston
University, 725 Commonwelth Avenue, Boston, MA 02215, EEUU; 5 Joint ALMA Observatory, Llano de Chanjnantor,
Desierto de Atacama, Chile; 6 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei
München, Germany; 7 Instituto de Radioastronomía y Astrofísica, Antigua Carretera a Pátzcuaro # 8701, Ex-Hda.

5

San José de la Huerta, 58341 Morelos, Mich., México; 8 Instituto de Astronomía de la Universidad Nacional Autónoma
de México, Circuito Exterior, área de la Investigación Científica, Ciudad Universitaria, México, CDMX., C.P. 04510;
9Departament de Física Quántica i Astrofísica, Institut de Ciències del Cosmos (ICC),Martí i Franqués, 1 08028
Barcelona; 10 Instituto Argentino de Radioastronomía (CCT-La Plata, CONICET; CICPBA), C.C. No. 5, 1894, Villa
Elisa, Buenos Aires, Argentina; 11 The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
E-mail contact: nacho.anyez at gmail.com
Recent high-angular resolution (≃ 40 mas) ALMA observations at 1.14 mm resolve a compact (R ≃ 200 au) flattened
dust structure perpendicular to the HH 80–81 jet emanating from the GGD 27-MM1 high-mass protostar, making it
a robust candidate for a true accretion disk. The jet/disk system (HH 80–81/GGD 27-MM1) resembles those foundin association with low- and intermediate-mass protostars. We present radiative transfer models that fit the 1.14 mm
ALMA dust image of this disk which allow us to obtain its physical parameters and predict its density and temperature
structure. Our results indicate that this accretion disk is compact ( Rdisk ≃ 170 au) and massive (≃ 5 M⊙ ), about
20% of the stellar mass of ≃ 20 M⊙ . We estimate the total dynamical mass of the star-disk system from the molecularline emission finding a range between 21 and 30 M⊙ , which is consistent with our model. We fit the density andtemperature structures found by our model with power law functions. These results suggest that accretion disks
around massive stars are more massive and hotter than their low-mass siblings, but they still are quite stable. We also
compare the temperature distribution in the GGD 27–MM1 disk with that found in low- and intermediate-mass stars
and discuss possible implications on the water snow line. We have also carried out a study of the distance based on
Gaia DR2 data and the population of young stellar objects (YSOs) in this region, and from the extinction maps. We
conclude that the source distance is within 1.2 and 1.4 kpc, closer than what was derived in previous studies (1.7 kpc).
Accepted by Astrophysical Journal
https://arxiv.org/pdf/1911.12398.pdf

4

Uncovering a 260 pc wide, 35 Myr old filamentary relic of star formation
Giacomo Beccari1 , Henri M.J. Boﬃn1 , and Tereza Jerabkova1,2,3,4,5,6
European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München; 2 Helmholtz Institut
für Strahlen und Kernphysik, Universität Bonn, Nussallee 14–16, 53115 Bonn, Germany; 3 Astronomical Institute,Charles University in Prague, V Holešovičkách 2, CZ-180 00 Praha 8, Czech Republic; 4 Astronomical Institute, Czech
Academy of Sciences, Fričova 298, 25165, Ondřejov, Czech Republic; 5 Instituto de Astrofísica de Canarias, E-38205
La Laguna, Tenerife, Spain; 6 GRANTECAN, Cuesta de San Jose s/n, 38712 Brena Baja, La Palma, Spain
1

E-mail contact: gbeccari at eso.org
Several recent studies have shown that the Vela OB2 region hosts a complex constellation of sub-populations withages in the range 10 to 50 Myr. Such populations might represent the best example of the outcome of clustered starformation in Giant Molecular clouds (GMC). We use Gaia DR2 data over an area of 40◦ radius around the open cluster
Collinder 135 to extend the study of the stellar populations of the Vela OB2 region over an area of several hundreds ofparsecs on sky. Detailed clustering algorithms combined with the exquisite astrometric quality of the GAIA catalogue
allow us to detect a new cluster named BBJ 1 that shows the same age as NGC 2547 (30 to 35 Myr), but locatedat a distance of 260 pc from it. Deeper investigation of the region via clustering in 5D parameter space and in thecolour-magnitude diagram allows us to detect a filamentary structure of stars that bridges the two clusters. Given theextent in space of such structure (260 pc) and the young age (∼35 Myr), we exclude that such population originates by
the same mechanism responsible to create tidal streams around older clusters. Even if we miss a complete picture of
the 3D motion of the studied stellar structure because of the lack of accurate radial velocity measurements, we proposethat such structure represent the detection of a 35 Myr old outcome of a mechanism of filamentary star formation ina GMC.
Accepted by MNRAS
http://arxiv.org/pdf/1911.05709

5

The Forgotten Quadrant Survey. 12 CO and 13 CO (1–0) survey of the Galactic Plane in
the range 220◦ < l < 240◦ −2.◦ 5 < b < 0◦
M. Benedettini1, S. Molinari1 , A. Baldeschi2,1 , M.T. Beltrán3 , J. Brand4
6

INAF – Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, 00133 Roma, Italy; 2 Center forInterdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern
University, Evanston, IL 60208; 3 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Firenze, Italy;
4
INAF – Istituto di Radioastronomia & Italian ALMA Regional Centre, via P. Gobetti 101, 40129, Bologna
1E-mail contact: milena.benedettini at inaf.it
We present the Forgotten Quadrant Survey (FQS), an ESO large project that used the 12m antenna of the ArizonaRadio Observatory to map the Galactic Plane in the range 220◦ < l < 240◦ and −2.◦ 5 < b < 0◦ , both in 12 CO(1–0) and
13
CO(1–0), at a spectral resolution of 0.65 km s−1 and 0.26 km s−1 . Our dataset allows us to easily identify how themolecular dense gas is organised at different spatial scales: from the giant clouds with their denser filamentary networks,
down to the clumps and cores that host the newborn stars and to obtain reliable estimates of their key physicalparameters. We present the first release of the FQS data and discuss their quality. Spectra with 0.65 km s−1 velocity
channels have a noise ranging from 0.8 K to 1.3 K for 12 CO(1–0) and from 0.3 K to 0.6 K for 13 CO(1–0). In this paper,
we used the 12 CO(1–0) spectral cubes to produce a catalogue of 263 molecular clouds. This is the first selfconsistent,
statistical catalogue of molecular clouds of the outer Galaxy, obtained with a subarcminute spatial resolution andtherefore able to detect not only the classical giant molecular clouds, but also the small clouds and to resolve thecloud structure at the subparsec scale up to a distance of a few kpc. We found two classes of objects: structures withsize above a few parsecs that are typical molecular clouds and may be self-gravitating, and subparsec structures thatcannot be in gravitational equilibrium and are likely transient or confined by external pressure. We used the ratio
between the Herschel H2 column density and the integrated intensity of the CO lines to calculate the CO conversion
factor and we found mean values of (3.3±1.4)×1020 cm−2 (K km s−1 )−1 and (1.2±0.4)×1021 cm−2 (K km s−1 )−1 , for12
CO(1–0) and 13 CO(1–0), respectively.
Accepted by A&A
http://arxiv.org/pdf/1911.11545

6

Astrochemistry as a tool to follow the protostellar evolution: the Class I stage
Eleonora Bianchi1 , Cecilia Ceccarelli1 , Claudio Codella2,1 , Juan Enrique-Romero1 , Cecile Favre1 andBertrand Leﬂoch1
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France; 2 INAF-Osservatorio Astrofisico di Arcetri, L.go E.
Fermi 5, I-50125 Firenze, Italy
1E-mail contact: eleonora.bianchi at univ-grenoble-alpes.fr
The latest developments in astrochemistry have shown how some molecular species can be used as a tool to study
the early stages of the solar-type star formation process. Among them, the more relevant species are the interstellar
complex organic molecules (iCOMs) and the deuterated molecules. Their analysis give us information on the present
and past history of protostellar objects. Among the protostellar evolutionary stages, Class I protostars represent a
perfect laboratory in which to study the initial conditions for the planet formation process. Indeed, from a physicalpoint of view, the Class I stage is the bridge between the Class 0 phase, dominated by the accretion process, and theprotoplanetary disk phase, when planets form. Despite their importance, few observations of Class I protostars exist
and very little is known about their chemical content. In this paper we review the (few) existing observations of iCOMs
and deuterated species in Class I protostars. In addition, we present new observations of deuterated cyanoacetylene
and thioformaldehyde towards the Class I protostar SVS13-A. These new observations allow us to better understandthe physical and chemical structure of SVS13-A and compare the cyanoacetylene and thioformaldehyde deuteration
with other sources in different evolutionary phases.
Accepted by ACS Earth and Space Chemistry
http://arxiv.org/pdf/1911.08991

7

The dry and carbon poor inner disk of TW Hya: evidence for a massive icy dust trap
Arthur D. Bosman1 and Andrea Banzatti2
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands; 2 Department of Physics,
Texas State University, 749 N Comanche Street, San Marcos, TX 78666, USA17

E-mail contact: arbos at umich.edu
Gas giants accrete their envelopes from the gas and dust of proto-planetary disks, so it is important to determine thecomposition of the inner few AU, where most giant planets are expected to form. We aim to constrain the elemental
carbon and oxygen abundance in the inner disk (R < 2.3 AU) of TW Hya and compare with the outer disk (R > 2.3
AU) where carbon and oxygen appear underabundant by a factor of ∼50. Archival infrared observations of TW
Hya are compared with a detailed thermo-chemical model, DALI. The inner disk gas mass and elemental C and O
abundances are varied to fit the infrared CO, H2 and H2 O line fluxes. Best fitting models have an inner disk that has
a gas mass of 2 × 10−4 M⊙ with C/H ≈ 3 × 10−6 and O/H ≈ 6 × 10−6 . The elemental oxygen and carbon abundancesof the inner disk are ∼50 times underabundant compared to the ISM and are consistent with those found in the outerdisk. The uniformly low volatile abundances imply that the inner disk is not enriched by ices on drifting bodies that
evaporate. This indicates that drifting grains are stopped in a dust trap outside the water ice line. Such a dust trap
would also form a cavity as seen in high resolution sub-millimeter continuum observations. If CO is the major carbon
carrier in the ices, dust needs to be trapped efficiently outside the CO ice line of ∼20 AU. This would imply that theshallow sub-millimeter rings in the TW Hya disk outside of 20 AU correspond to very efficient dust traps. The more
likely scenario is that more than 98% of the CO has been converted into less volatile species, e.g. CO2 and CH3 OH.
A giant planet forming in the inner disk would be accreting gas with low carbon and oxygen abundances as well asvery little icy dust, potentially leading to a planet atmosphere with strongly substellar C/H and O/H ratios.
Accepted by A&A Letters
http://arxiv.org/pdf/1911.11152

8

Jupiter formed as a pebble pile around the N2 ice line
A.D. Bosman1 , A.J. Cridland1 , and Y. Miguel1
1

Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

E-mail contact: arbos at umich.edu
The region around the H2 O ice line, due to its higher surface density, seems to be the ideal location to form planets.
The core of Jupiter, as well as the cores of close in gas giants are thus thought to form in this region of the disk.
Actually constraining the formation location of individual planets has proven to be difficult, however. We aim to use
the Nitrogen abundance in Jupiter, which is around 4 times solar, in combination with Juno constraints on the total
mass of heavy elements in Jupiter, to narrow down its formation scenario. Different pathways of enrichment of Jupiter’s
atmosphere, such as the accretion of enriched gas, pebbles or planetesimals are considered and their implications forthe oxygen abundance of Jupiter is discussed. The super solar Nitrogen abundance in Jupiter necessitates the accretionof extra N2 from the proto-solar nebula. The only location of the disk that this can happen is outside, or just inside
the N2 ice line. These constraints favor a pebble accretion origin of Jupiter, both from the composition as well as froma planet formation perspective. We predict that Jupiter’s oxygen abundance is between 3.6 and 4.5 times solar.
Accepted by A&A
http://arxiv.org/pdf/1911.11154

9

VLBI observations of the G25.65+1.05 water maser superburst
Ross A. Burns1,2,3 , Gabor Orosz4,5 , Olga Bayandina1,6 , Gabrielle Surcis7 , Mateusz Olech8 , Gordon
MacLeod9,10 , Alexandr Volvach6,11 , Gerogij Rudnitskii12 , Tomoya Hirota2 , Katharnia Immer1 , Jay
Blanchard1,13 , Benito Marcote1 , Huib van Langevelde1,14 , James O. Chibueze15,16 , Koichiro Sugiyama2,17 ,Kee-Tae Kim3,18 , Irina Valtts6 , Nadya Shakhvorostova6,19 , Busaba Kramer17,20 , Willem A. Baan5,21 ,Crystal Brogan22 , Todd Hunter22 , Stan Kurtz23 , Andrey M. Sobolev19 , Jan Brand24 and Larisa Volvach6,11
Joint Institute for VLBI ERIC, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands.; 2 Mizusawa
VLBI Observatory, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; 3
Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea;
4
School of Natural Sciences, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia; 5 Xinjiang
Astronomical Observatory, Chinese Academy of Sciences, 150 Science 1-Street, Urumqi, Xinjiang 830011, China;
6Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Leninskiy Prospekt 53, Moscow

1

8

119333, Russia; 7 INAF Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, Italy; 8 Centre for
Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100
Torun, Poland; 9 The University of Western Ontario, 1151 Richmond Street. London, ON N6A 3K7, Canada; 10Hartebeesthoek Radio Astronomy Observatory, PO Box 443, Krugersdorp 1740, South Africa; 11 Radio Astronomy
and Geodinamics Department of Crimean Astrophysical Observatory, Katsively, RT-22 Crimea; 12 Lomonosov Moscow
State University, Sternberg Astronomical Institute, Moscow 119234, Russia; 13 National Radio Astronomy Observatory,
P.O. Box O, 1003 Lopezville Rd., Socorro, NM 87801; 14 Sterrewacht Leiden, Leiden University, Postbus 9513, 2300
RA Leiden, the Netherlands; 15 South African Radio Astronomy Observatory (SARAO), 3rd Floor, The Park, Park
Road, Pinelands, Cape Town, 7405, South Africa; 16 Space Research Unit, Physics Department, North West University,
Potchefstroom 2520, South Africa; 17 National Astronomical Research Institute of Thailand, 260 M.4, T. Donkaew,
Amphur Maerim, Chiang Mai, 50180, Thailand; 18 University of Science and Technology, Korea (UST), 217 Gajeongro, Yuseong-gu, Daejeon 34113, Republic of Korea; 19 Astronomical Observatory, Ural Federal University, Lenin
Ave. 51, Ekaterinburg 620083, Russia; 20 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn,
Germany; 21 Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo; 22 NRAO,
520 Edgemont Road, Charlottesville, VA 22903, USA; 23 Instituto de Radioastronomia y Astrofisica, Universidad
Nacional Autonoma de Mexico, Apartado Postal 3-72, Morelia 58089, Meexico; 24 INAF-Istituto di Radioastronomia
and Italian ALMA Regional Centre, via P. Gobetti 101, 40129, Bologna, Italy
E-mail contact: rossburns88 at googlemail.com
This paper reports observations of a 22 GHz water maser ‘superburst’ in the G25.65+1.05 massive star forming region,
conducted in response to an alert from the Maser Monitoring Organisation (M2O). Very long baseline interferometry(VLBI) observations using the European VLBI Network (EVN) recorded a maser flux density of 1.2 × 104 Jy. The
superburst was investigated in the spectral, structural and temporal domains and its cause was determined to be anincrease in maser path length generated by the superposition of multiple maser emitting regions aligning in the lineof sight to the observer. This conclusion was based on the location of the bursting maser in the context of the star
forming region, its complex structure, and its rapid onset and decay.
Accepted by MNRAS
http://arxiv.org/pdf/1911.12634

10

The dynamically young outflow of the Class 0 protostar Cha-MMS1
L.A. Busch1,2 , A. Belloche1 , S. Cabrit3,4 , P. Hennebelle5, B. Commerco̧n6Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany; 2 Argelander-Institut fr Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany; 3 LERMA, Observatoire de Paris, PSL
Research University, CNRS, Sorbonne Université, UPMC Univ. Paris 06, 75014 Paris, France; 4 Université Grenoble
Alpes, CNRS, IPAG, 38000 Grenoble, France; 5 AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot,
Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France; 6 Centre de Recherche Astrophysique de Lyon UMR5574, ENS de
Lyon, Univ. Lyon1, CNRS, Université de Lyon, 69007 Lyon, France
1

E-mail contact: labusch at mpifr-bonn.mpg.deOn the basis of its low luminosity, its chemical composition, and the absence of a large-scale outflow, the dense core
Cha-MMS1 located in the Chamaeleon I molecular cloud was proposed as a first hydrostatic core (FHSC) candidatea decade ago. Our goal is to test this hypothesis by searching for a slow, compact outflow driven by Cha-MMS1 thatwould match the predictions of MHD simulations for this short phase of star formation. We use the Atacama Large
Millimetre/submillimetre Array (ALMA) to map Cha-MMS1 at high angular resolution in CO 3–2 and 13 CO 3–2 aswell as in continuum emission. We report the detection of a bipolar outflow emanating from the central core, alonga (projected) direction roughly parallel to the filament in which Cha-MMS1 is embedded and perpendicular to thelarge-scale magnetic field. The morphology of the outflow indicates that its axis lies close to the plane of the sky. We
measure velocities corrected for inclination of more than 90 km s−1 which is clearly incompatible with the expected
properties of a FHSC outflow. Several properties of the outflow are determined and compared to previous studies ofClass 0 and Class I protostars. The outflow of Cha-MMS1 has a much smaller momentum force than the outflows ofother Class 0 protostars. In addition, we find a dynamical age of 200–3000yr indicating that Cha-MMS1 might be
one of the youngest ever observed Class 0 protostars. While the existence of the outflow suggests the presence of adisk, no disk is detected in continuum emission and we derive an upper limit of 55 au to its radius. We conclude that9

Cha-MMS1 has already gone through the FHSC phase and is a young Class 0 protostar, but it has not brought its
outflow to full power yet.
Accepted by A&A
http://arxiv.org/pdf/1911.11194

Variable warm dust around the Herbig Ae star HD 169142: Birth of a ring?

11 Lei Chen , Attila Moór , Alexander Kreplin , Ágnes Kóspál , Peter Ábrahám et al.
1

1

2

1,3

1

Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Konkoly-Thege Miklós út 15-17, 1121
Budapest, Hungary; 2 University of Exeter, Department of Physics and Astronomy, Stocker Road, Exeter, Devon EX4
4QL, UK; 3 Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
1E-mail contact: lei.chen at csfk.mta.hu
The Herbig Ae star HD 169142 is known to have a gaseous disk with a large inner hole, and also a photometricallyvariable inner dust component in the sub-au region. Following up our previous analysis, we further studied thetemporal evolution of inner dust around HD 169142, which may provide information on the evolution from late-stage
protoplanetary disks to debris disks. We used near-infrared interferometric observations obtained with VLTI/PIONIER
to constrain the dust distribution at three epochs spanning six years. We also studied the photometric variability of
HD 169142 using our optical-infrared observations and archival data. Our results indicate that a dust ring at ∼0.3
au formed at some time between 2013 and 2018, and then faded (but did not completely disappear) by 2019. The
short-term variability resembles that observed in extreme debris disks, and is likely related to short-lived dust of
secondary origin, though variable shadowing from the inner ring could be an alternative interpretation. If confirmed,
this is the first direct detection of secondary dust production inside a protoplanetary disk.
Accepted by ApJL
http://arxiv.org/pdf/1911.10253

Evidence of a substellar companion to AB Dor C

12 J.B. Climent , J.P. Berger , J.C. Guirado , J.M. Marcaide , I. Martí-Vidal , A. Mérand , E.
1

2

1,3

1

1,3

4

Tognelli5 and M. Wittkowski4

1
Departament d’Astronomia i Astrofísica, Universitat de València, C. Dr. Moliner 50, 46100 Burjassot, València,
Spain; 2 Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France; 3 Observatori Astronómic, Universitat deValéncia, Parc Científic, C. Catedrático José Beltrán 2, 46980 Paterna, València, Spain; 4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany; 5 Department of Physics E. Fermi,
University of Pisa, Largo Bruno Pontecorvo 3, 56127, Pisa, Italy

E-mail contact: j.bautista.climent at uv.es
Studies of fundamental parameters of very low-mass objects are indispensable to provide tests of stellar evolution
models that are used to derive theoretical masses of brown dwarfs and planets. However, only objects with dynamicallydetermined masses and precise photometry can effectively evaluate the predictions of stellar models. AB Dor C (0.090
M⊙ ) has become a prime benchmark for calibration of theoretical evolutionary models of low-mass young stars. Oneof the ambiguities remaining in AB Dor C is the possible binary nature of this star. We observed AB Dor C with
the VLTI/AMBER instrument in low-resolution mode at the J, H and K bands. The interferometric observablesat the K-band are compatible with a binary brown dwarf system with tentative components AB Dor Ca/Cb with aK-band flux ratio of 5±1% and a separation of 38±1 mas. This implies theoretical masses of 0.072±0.013 M⊙ and
0.013±0.001 M⊙ for each component, near the hydrogen-burning limit for AB Dor Ca, and near the deuterium-burning
limit, straddling the boundary between brown dwarfs and giant planets, for AB Dor Cb. The possible binarity of AB
Dor C alleviates the disagreement between observed magnitudes and theoretical mass-luminosity relationships.
Accepted by ApJL
http://arxiv.org/pdf/1911.04736

10

ALMA Observations of the Extraordinary Carina Pillars: HH 901/902

13 Geovanni Cortes-Rangel , Luis A. Zapata , Jesús A. Toalá , Paul T. P. Ho , Satoko Takahashi , Adal
1

Mesa-Delgado , Josep M. Masqué
6

1

1

2,3

4,5

7

Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090,
Morelia, Michoacán, México; 2 Academia Sinica Institute of Astronomy and Astrophysics, PO Box 23-141, Taipei,
10617, Taiwan.; 3 East Asian Observatory, 666 N. A’ohoku Place, Hilo, Hawaii 96720, USA; 4 Joint ALMA Observatory,
Alonso de Cordova 3108, Vitacura, Santiago, Chile 5 Department of Astronomical Science, School of Physical Sciences,
SOKENDAI, Mitaka, Tokyo 181-8588, Japan; 6 Instituto de Astrofísica, Facultad de Física, Pontificia Universidad
Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile ; 7 Departamento de Astronomía,
Universidad de Guanajuato, Apdo. Postal 144, 36000 Guanajuato, México
1

E-mail contact: lzapata@irya.unam.mx
We present Atacama Large Millimeter/Submillimeter Array (ALMA) 1.3 mm continuum and C18 O(2−1), N2 D+ (3−2),
CS(5−4), and 12 CO(2−1) line sensitive and high angular resolution (∼0.3′′ ) observations of the famous carina pillars
and protostellar objects HH 901/902. Our observations reveal for the first time, the bipolar CO outflows and the dusty
disks (plus envelopes) that are energizing the extended and irradiated HH objects far from the pillars. We find thatthe masses of the disks+envelopes are about 0.1 M⊙ and of the bipolar outflows are between 10−3 - 10−4 M⊙ , whichsuggests that they could be low- or maybe intermediate- mass protostars. Moreover, we suggest that these young
low-mass stars are likely embedded Class 0/I protostars with high-accretion rates. We also show the kinematics ofthe gas in the pillars together with their respective gas masses (0.1 – 0.2 M⊙ ). We estimate that the pillars will be
photo-evaporated in 104 to 105 years by the massive and luminous stars located in the Trumpler 14 cluster. Finally,
given the short photo-evaporated timescales and that the protostars in these pillars are still very embedded, we suggestthat the disks inside of the pillars will be quickly affected by the radiation of the massive stars, forming proplyds, likethose observed in Orion.
13

Accepted by The Astronomical Journal
https://arxiv.org/pdf/1911.11026.pdf

New insights in giant molecular cloud hosting S147/S153 complex: signatures of inter-14 acting clouds

J.S. Dhanya1 , L.K. Dewangan2 , D.K. Ojha3 , and S. Mandal1
Malaviya National Institute of Technology (MNIT), Jaipur - 302 017, Rajasthan, India; 2 Physical Research Laboratory, Navrangpura, Ahmedabad - 380 009, India; 3 Department of Astronomy and Astrophysics, Tata Institute ofFundamental Research, Homi Bhabha Road, Mumbai - 400 005, India

1

E-mail contact: jsdhanya89 at gmail.com
In order to understand the formation of massive OB stars, we report a multi-wavelength observational study of a giant
molecular cloud hosting the S147/S153 complex (size ∼90 pc × 50 pc). The selected complex is located in the Perseus
arm, and contains at least five HII regions (S147, S148, S149, S152, and S153) powered by massive OB stars having
dynamical ages of ∼0.2–0.6 Myr. The Canadian Galactic Plane Survey 12 CO line data (beam size ∼100.′′ 4) trace thecomplex in a velocity range of [−59, −43] km s−1 , and also reveal the presence of two molecular cloud components
around −54 and −49 km s−1 in the direction of the complex. Signatures of the interaction/collision between these
extended cloud components are investigated through their spatial and velocity connections. These outcomes suggest
the collision of these molecular cloud components about 1.6 Myr ago. Based on the observed overlapping zones of
the two clouds, the collision axis appears to be parallel to the line-of-sight. Deep near-infrared photometric analysisof point-like sources shows the distribution of infrared-excess sources in the direction of the overlapping zones of themolecular cloud components, where all the HII regions are also spatially located. All elements put together, the birthof massive OB stars and embedded infrared-excess sources seems to be triggered by two colliding molecular clouds inthe selected site. High resolution observations of dense gas tracer will be required to further confirm the proposed
scenario.
Accepted by PASJ
http://arxiv.org/pdf/1911.08740

11

15

Cloudlet capture by Transitional Disk and FU Orionis stars
C.P. Dullemond1, M. Küﬀmeier1, F. Goicovic1 , M. Fukagawa2 , V. Oehl1 , M. Kramer1
Zentrum für Astronomie, Heidelberg University, Albert Ueberle Str. 2, 69120 Heidelberg, Germany 2 Division ofParticle and Astrophysical Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya,
Aichi 464-8602, Japan1

E-mail contact: dullemond at uni-heidelberg.de
After its formation, a young star spends some time traversing the molecular cloud complex in which it was born. It istherefore not unlikely that, well after the initial cloud collapse event which produced the star, it will encounter one ormore low mass cloud fragments, which we call “cloudlets” to distinguish them from full-fledged molecular clouds. Someof this cloudlet material may accrete onto the star+disk system, while other material may fly by in a hyperbolic orbit.
In contrast to the original cloud collapse event, this process will be a “cloudlet flyby” and/or “cloudlet capture” event:
A Bondi-Hoyle-Lyttleton type accretion event, driven by the relative velocity between the star and the cloudlet. As
we will show in this paper, if the cloudlet is small enough and has an impact parameter similar or less than GM⋆ /v∞ 2(with v∞ being the approach velocity), such a flyby and/or capture event would lead to arc-shaped or tail-shapedreflection nebulosity near the star. Those shapes of reflection nebulosity can be seen around several transitional disks
and FU Orionis stars. Although the masses in the those arcs appears to be much less than the disk masses in thesesources, we speculate that higher-mass cloudlet capture events may also happen occasionally. If so, they may lead tothe tilting of the outer disk, because the newly infalling matter will have an angular momentum orientation entirely
unrelated to that of the disk. This may be one possible explanation for the highly warped/tilted inner/outer disk
geometries found in several transitional disks. We also speculate that such events, if massive enough, may lead to FU
Orionis outbursts.
Accepted by A&A
http://arxiv.org/pdf/1911.05158

16

Multi-planet disc interactions in binary systems
Alessia Franchini1 , Rebecca G. Martin1 and Stephen H. Lubow2
Department of Physics and Astronomy, University of Nevada, 4505 South Maryland Parkway, Las Vegas, NV 89154,
USA; 2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
1E-mail contact: alessia.franchini at unlv.edu
We investigate the evolution of a multi–planet–disc system orbiting one component of a binary star system. The
planet–disc system is initially coplanar but misaligned to the binary orbital plane. The planets are assumed to be
giants that open gaps in the disc. We first study the role of the disc in shaping the mutual evolution of the two planets
using a secular model for low initial tilt. In general we find that the planets and the disc do not remain coplanar,in agreement with Lubow & Martin (2016) for the single planet case. Instead, the planets and the disc undergo tilt
oscillations. A high mass disc between the two planets causes the planets and the disc to nodally precess at the same
average rate but they are generally misaligned. The amplitude of the tilt oscillations between the planets is larger while
the disc is present. We then consider higher initial tilts using hydrodynamical simulations and explore the possibilityof the formation of eccentric Kozai-Lidov (KL) planets. We find that the inner planet’s orbit undergoes eccentricity
growth for a large range of disc masses and initial misalignments. For a low disc mass and large initial misalignment
both planets and the disc can undergo KL oscillations. Furthermore, we find that sufficiently massive discs can cause
the inner planet to increase its inclination beyond 90◦ and therefore to orbit the binary in a retrograde fashion. The
results have important implications for the explanation of very eccentric planets and retrograde planets observed in
multi-planet systems.
Accepted by MNRAS
http://arxiv.org/pdf/1911.00520

17

Disks Around T Tauri Stars with SPHERE (DARTTS-S) II: Twenty-one new polarimetric images of young stellar disks
A. Garuﬁ1 , H. Avenhaus2 , S. Perez3 , S. P. Quanz4 , R. G. van Holstein5,6, G. H.-M. Bertrang7 , S.

12

Casassus8 , L. Cieza9 , D. A. Principe10 , G. van der Plas11 and A. Zurlo9
INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy; 2 Lakeside Labs, LakesidePark B04b, 9020 Klagenfurt, Austria; 3 Universidad de Santiago de Chile, Av. Libertador Bernardo O’Higgins 3363,
Estacion Central, Santiago, Chile; 4 Institute for Particle Physics and Astrophysics, ETH Zurich, Wolfgang-PauliStrasse 27, 8093 Zurich, Switzerland; 5 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The
Netherlands; 6 European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago, Chile; 7
Max Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg, Germany; 8 Departamento de Astronomia,
Universidad de Chile, Casilla 36-D Santiago, Chile; 9 Facultad de Ingenieria y Ciencias, Nucleo de Astronomia,
Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile; 10 Kavli Institute for Astrophysics and Space Research,
Massachusetts Institute of Technology, Cambridge, MA 02139, USA; 11 Univ. Grenoble Alpes, CNRS, IPAG, F-38000
Grenoble, France

1

E-mail contact: agarufi at arcetri.astro.it
Near-IR polarimetric images of protoplanetary disks provide the ability to characterize sub-structures that are potentially due to the interaction with (forming) planets. The available census is, however, strongly biased towardmassive disks around old stars. The DARTTS program aims at alleviating this bias by imaging a large number of
T Tauri stars with diverse properties. DARTTS-S employs VLT/SPHERE to image the polarized scattered lightfrom disks. In parallel, DARTTS-A is providing ALMA images of the same targets for a comparison of different dust
components. In this work, we present new SPHERE images of 21 circumstellar disks, which is the largest sample ofthis time yet to be released. A re-calculation of some relevant stellar and disk properties following Gaia DR2 is also
performed. The targets of this work are significantly younger than those published thus far with polarimetric NIR
imaging. Scattered light is unambiguously resolved in 11 targets while some polarized unresolved signal is detectedin 3 additional sources. Some disk sub-structures are detected. However, the paucity of spirals and shadows fromthis sample reinforces the trend for which these NIR features are associated with Herbig stars, either because older
or more massive. Furthermore, disk rings that are apparent in ALMA observations of some targets do not appear
to have corresponding detections with SPHERE. Inner cavities larger than 15 au are also absent from our images
despite being expected from the SED. On the other hand, 3 objects show extended filaments at larger scale that are
indicative of strong interaction with the surrounding medium. All but one of the undetected disks are best explainedby their limited size (approximately 20 au) and the high occurrence of stellar companions in these sources suggest
an important role in limiting the disk size. One undetected disk is massive and very large at millimeter wavelengths
implying it is self-shadowed in the near-IR. This work paves the way towards a more complete and less biased sampleof scattered-light observations, which is required to interpret how disk features evolve throughout the disk lifetime.
Accepted by A&A
https://arxiv.org/pdf/1911.10853

clusters survey. I. Rotation in the young benchmark open cluster Blanco 1
18 NGTS
Edward Gillen , Joshua T. Briegal , Simon T. Hodgkin , Daniel Foreman-Mackey , Floor Van Leeuwen
1

1

2

3

2

et al.
Astrophysics Group, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK; 2 Institute of Astronomy, University of Cambridge, Madingley Rise, Cambridge CB3 0HA, UK; 3 Center for Computational Astrophysics,
Flatiron Institute, New York, NY
1

E-mail contact: ecg41 at cam.ac.uk
We determine rotation periods for 127 stars in the ∼115 Myr old Blanco 1 open cluster using ∼200 days of photometric>monitoring with the Next Generation Transit Survey (NGTS). These stars span F5–M3 spectral types (1.2 >∼M ∼0.3 M⊙ ) and increase the number of known rotation periods in Blanco 1 by a factor of four. We determine rotation
periods using three methods: Gaussian process (GP) regression, generalised autocorrelation (G-ACF) and LombScargle (LS) periodograms, and find that GPs and G-ACF are more applicable to evolving spot modulation patterns.
Between mid-F and mid-K spectral types, single stars follow a well-defined rotation sequence from ∼2 to 10 days,
whereas stars in photometric multiple systems typically rotate faster. This may suggest that the presence of a moderateto-high mass ratio companion inhibits angular momentum loss mechanisms during the early pre-main sequence, andthis signature has not been erased at ∼100 Myr. The majority of mid-F to mid-K stars display evolving modulation

13

patterns, whereas most M stars show stable modulation signals. This morphological change coincides with the shift
from a well-defined rotation sequence (mid-F to mid-K stars) to a broad rotation period distribution (late-K and M
stars). Finally, we compare our rotation results for Blanco 1 to the similarly-aged Pleiades: the single star populations
in both clusters possess consistent rotation period distributions, which suggests that the angular momentum evolutionof stars follows a well-defined pathway that is, at least for mid-F to mid-K stars, strongly imprinted by ∼100 Myr.
Accepted by MNRAS
http://arxiv.org/pdf/1911.09705

19

Searching for further evidence for cloud-cloud collisions in L1188
Y. Gong1,2 , X.D. Tang3,1 , C. Henkel1,4,3 , K.M. Menten1 , R.Q. Mao2 et al.
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany; 2 Purple Mountain Observatory & Key Laboratory for Radio Astronomy, Chinese Academy of Sciences, 10 Yuanhua Road, 210033 Nanjing, PR
China; 3 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 830011 Urumqi, PR China; 4 Astronomy
Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
1

E-mail contact: ygong at mpifr-bonn.mpg.de
In order to search for further observational evidence of cloud-cloud collisions in one of the promising candidates, L1188,
we carried out observations of multiple molecular lines toward the intersection region of the two nearly orthogonal
filamentary molecular clouds in L1188. Based on these observations, we find two parallel filamentary structures,
both of which have at least two velocity components being connected with broad bridging features. We also found a
spatially complementary distribution between the two molecular clouds, as well as enhanced 13 CO emission and 12 CO
self-absorption toward their abutting regions. At the most blueshifted velocities, we unveil a 1 pc-long arc ubiquitously
showing 12 CO line wings. We discover two 22 GHz water masers, which are the first maser detections in L1188. An
analysis of line ratios at a linear resolution of 0.2 pc suggests that L1188 is characterised by kinetic temperatures of
13–23 K and H2 number densities of 103 –103.6 cm−3 . On the basis of previous theoretical predictions and simulations,
we suggest that these observational features can be naturally explained by the scenario of a cloud-cloud collision in
L1188, although an additional contribution of stellar feedback from low-mass young stellar objects cannot be ruledout.
Accepted by A&A
http://arxiv.org/pdf/1911.09687

20

Short and long term near-infrared spectroscopic variability of eruptive protostars from
VVV
Zhen Guo1 , Philip W. Lucas1 , C. Contreras Peña2 , R. G. Kurtev3,4 , L. C. Smith5 , J. Borissova3,4 , J.
Alonso-García4,6 , D. Minniti4,7,8 , A. Caratti o Garatti9 and D. Froebrich10
Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK; 2 Department of Physics
and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4SB, UK; 3 Instituto de Física y Astronomía,
Universidad de Valparaíso, ave. Gran Bretaña, 1111, Casilla 5030, Valparaíso, Chile; 4 Millennium Institute of
Astrophysics, Av. Vicuna Mackenna 4860, 782-0436, Macul, Santiago, Chile; 5 Institute of Astronomy, Universityof Cambridge, Madingley Road, Cambridge, CB3 0HA, UK; 6 Centro de Astronomia (CITEVA), Universidad deAntofagasta, Av. Angamos 601, Antofagasta, Chile; 7 Departamento de Ciencias Fisicas, Universidad Andres Bello,
Republica 220, Santiago, Chile; 8 Vatican Observatory, V00120 Vatican City State, Italy; 9 Dublin Institute forAdvanced Studies, School of Cosmic Physics, Astronomy and Astrophysics Section, 31 Fitzwilliam Place, Dublin 2,
Ireland; 10 Centre for Astrophysics and Planetary Science, University of Kent, Canterbury CT2 7NH, UK
1E-mail contact: z.guo4 at herts.ac.uk
Numerous eruptive variable young stellar objects (YSOs), mostly Class I systems, were recently detected by thenear-infrared Vista Variables in the Via Lactea (VVV) survey. We present an exploratory near-infrared spectroscopic
variability study of 14 eruptive YSOs. The variations were sampled over 1-day and 1 to 2-year intervals and analysedin combination with VVV light curves. CO overtone absorption features are observed on 3 objects with FUor-like
spectra: all show deeper absorption when they are brighter. This implies stronger emission from the circumstellar disc14

with a steeper vertical temperature gradient when the accretion rate is higher. This confirms the nature of fast VVV
FUor-like events, in line with the accepted picture for classical FUors. The absence of Brγ emission in a FUor-likeobject declining to pre-outburst brightness suggests that reconstruction of the stellar magnetic field is a slow process.
Within the 1-day timescale, 60% of H2 -emitting YSOs show significant but modest variation, and 2/6 sources havelarge variations in Brγ. Over year-long timescales, H2 flux variations remain modest despite up to 1.8 mag variation in
Ks . This indicates that emission from the molecular outflow usually arises further from the protostar and is unaffectedby relatively large changes in accretion rate on year-long timescales. Two objects show signs of on/off magnetosphericaccretion traced by Brγ emission. In addition, a 60% inter-night brightening of the H2 outflow is detected in one YSO.
Accepted by MNRAS
https://arxiv.org/pdf/1912.00729

21 HCN/HNC intensity ratio: a new chemical thermometer for the molecular ISM
A. Hacar1 , A. Bosman1 and E. F. van Dishoeck1

1

Leiden Observatory, Leiden University, P.O. Box 9513, 2300-RA Leiden, The Netherlands

E-mail contact: hacar at strw.leidenuniv.nl
Context. The gas kinetic temperature (TK ) determines the physical and chemical evolution of the Interestellar Medium(ISM). However, obtaining reliable TK estimates usually requires expensive observations including the combination ofmulti-line analysis and dedicated radiative transfer calculations.
Aims. This work explores the use of HCN and HNC observations, and particularly its I(HCN)/I(HNC) intensity ratioof their J=1–0 lines, as direct probe of the gas kinetic temperature in the molecular ISM.
Methods. We obtained a new set of large-scale observations of both HCN and HNC (1–0) lines along the Integral
Shape Filament (ISF) in Orion. In combination with ancillary gas and dust temperature measurements, we finda systematic temperature dependence of the observed I(HCN)/I(HNC) intensity ratio across our maps. Additional
comparisons with chemical models demonstrate that these observed I(HCN)/I(HNC) variations are driven by theeffective destruction and isomerization mechanisms of HNC under low energy barriers.
Results. The observed variations of I(HCN)/I(HNC) with TK can be described with a two-part linear function.
This empirical calibration is then used to create a temperature map of the entire ISF. Comparisons with similar dust
temperature measurements in this cloud, as well as in other regions and galactic surveys, validate this simple technique
to obtain direct estimates of the gas kinetic temperature in a wide range of physical conditions and scales with an
optimal working range between 15 K ≤ TK ≤ 40 K.
Conclusions. Both observations and models demonstrate the strong sensitivity of the I(HCN)/I(HNC) ratio to thegas kinetic temper- ature. Since these lines are easily obtained in observations of local and extragalactic sources, ourresults highlight the potential use of this observable as new chemical thermometer for the ISM.
Accepted by Astronomy and Astrophysics
https://ui.adsabs.harvard.edu/pdf/2019arXiv191013754H/abstract

22

AVIATOR: Morphological object reconstruction in 3D. An application to dense cores
Birgit Hasenberger1 and João Alves1,2
Department for Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria; 2 Radcliffe Institute for Advanced Study, Harvard University, 10 Garden Street, Cambridge, MA 02138, USA
1E-mail contact: birgit.hasenberger at univie.ac.at
Reconstructing 3D distributions from their 2D projections is a ubiquitous problem in various scientific fields, particularly so in observational astronomy. In this work, we present a new approach to solving this problem: a Vienna
inverse-Abel-transform based object reconstruction algorithm AVIATOR. The reconstruction that it performs is basedon the assumption that the distribution along the line of sight is similar to the distribution in the plane of projection, which requires a morphological analysis of the structures in the projected image. The output of the AVIATOR
algorithm is an estimate of the 3D distribution in the form of a reconstruction volume that is calculated without the
problematic requirements that commonly occur in other reconstruction methods such as symmetry in the plane ofprojection or modelling of radial profiles. We demonstrate the robustness of the technique to different geometries,
15

density profiles, and noise by applying the AVIATOR algorithm to several model objects. In addition, the algorithm
is applied to real data: We reconstruct the density and temperature distributions of two dense molecular cloud coresand find that they are in excellent agreement with profiles reported in the literature. The AVIATOR algorithm is thus
capable of reconstructing 3D distributions of physical quantities consistently using an intuitive set of assumptions.
Accepted by Astronomy & Astrophysics
https://arxiv.org/pdf/1912.01005

nitrogen reservoirs in a protoplanetary disk at the epoch of comet and giant
23 Multiple
planet formation
P. Hily-Blant1 , V. Magalhaes de Souza2 , J. Kastner3 , and T. Forveille1
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France; 2 IRAM, 300 rue de la Piscine, Grenoble, France; 3
Chester F. Carlson Center for Imaging Science, School of Physics & Astronomy, and Laboratory for Multiwavelength
Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester NY 14623 USA
1E-mail contact: pierre.hily-blant at univ-grenoble-alpes.fr
The isotopic ratio of nitrogen measured in primitive Solar System bodies shows a broad range of values, the origin of
which remains unknown. One key question is whether these isotopic reservoirs of nitrogen predate the comet formation
stage or are posterior to it. Another central question is elucidating the processes that can produce the observed
variations in the 14 N/15 N isotopic ratio. Disks that orbit pre-main-sequence stars provide unique opportunities forobserving the chemical content of analogs of the protosolar nebula and therefore for building a comprehensive scenario
for the origin of nitrogen in the Solar System and in planet-forming disks. We present spectrally and spatially resolved
observations of the hyperfine structure of the 4–3 rotational transition of HCN and its main isotopologs H13 CN and
HC15 N in the disk orbiting the 8 Myr old T Tauri star TW Hya. The spatially averaged HCN/H13 CN and HCN/HC15 N
abundance ratios are 86±4 and 223±21, respectively. The latter value is significantly lower than the CN:C15 N ratio
323±30 in this disk and thus provides the first evidence that two isotopic reservoirs of nitrogen are present in a disk at
the stage of giant planet and comet formation. Furthermore, we find clear evidence for an increase in the ratio of HCN
to HC15 N with radius. The ratio in the outer disk is 339±28, in excellent agreement with direct measurements in thelocal interstellar medium, and with the bulk nitrogen isotopic ratio predicted from galactic evolution calculations. In
the comet formation region at r = 20 au, the ratio is a factor ∼3 lower, 121±11. This radial increase qualitatively
agrees with the scenario in which selective photodissociation of N2 is the dominant fractionation process. However,
our isotopic ratios and kinetic temperature of the HCN-emitting layers quantitatively disagree with models of nitrogenchemistry in disks.
Accepted by A&A
http://arxiv.org/pdf/1911.06676

Resolved Scattered-Light Images of Four Debris Disks in Scorpius-Centaurus with
24 First
the Gemini Planet Imager
Justin Hom1 , Jennifer Patience1 , Thomas M. Esposito2, Gaspard Duchêne2,3 , Kadin Worthen1 et al.
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA; 2 Astronomy Department,
University of California, Berkeley, CA 94720, USA; 3 Université Grenoble Alpes / CNRS, Institut de Planétologie etd’Astrophysique de Grenoble, 38000 Grenoble, France
1

E-mail contact: jrhom at asu.edu
We present the first spatially resolved scattered-light images of four debris disks around members of the ScorpiusCentaurus (Sco-Cen) OB Association with high-contrast imaging and polarimetry using the Gemini Planet Imager(GPI). All four disks are resolved for the first time in polarized light and one disk is also detected in total intensity. The
three disks imaged around HD 111161, HD 143675, and HD 145560 are symmetric in both morphology and brightness
distribution. The three systems span a range of inclinations and radial extents. The disk imaged around HD 98363
shows indications of asymmetries in morphology and brightness distribution, with some structural similarities to the
HD 106906 planet-disk system. Uniquely, HD 98363 has a wide co-moving stellar companion Wray 15-788 with arecently resolved disk with very different morphological properties. HD 98363 A/B is the first binary debris disk
16

system with two spatially resolved disks. All four targets have been observed with ALMA, and their continuum fluxes
range from one non-detection to one of the brightest disks in the region. With the new results, a total of 15 A/F-stars
in Sco-Cen have resolved scattered light debris disks, and approximately half of these systems exhibit some form ofasymmetry. Combining the GPI disk structure results with information from the literature on millimeter fluxes andimaged planets reveals a diversity of disk properties in this young population. Overall, the four newly resolved disks
contribute to the census of disk structures measured around A/F-stars at this important stage in the development ofplanetary systems.
Accepted by AJ
http://arxiv.org/pdf/1911.09667

25

Late encounter events as source of disks and spiral structures. Forming second generation disks
M. Kuﬀmeier1, F. G. Goicovic1 and C. P. Dullemond1
Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2,69120 Heidelberg

1E-mail contact: kuffmeier at uni-heidelberg.de
Observations of arc-like structures and luminosity bursts of stars > 1 Myr in age indicate that at least some stars
undergo late infall events. We investigate scenarios of replenishing the mass reservoir around a star via capturing andinfalling events of cloudlets. We carried out a total of 24 three-dimensional hydrodynamical simulations of cloudlet
encounters with a Herbig star of mass 2.5 M⊙ using the moving-mesh code arepo. To account for the two possibilities
of a star or a cloudlet traveling through the interstellar medium (ISM), we put either the star or the cloudlet atrest with respect to the background gas. For absent cooling in the adiabatic runs, almost none of the cloudlet gas
is captured as a result of high thermal pressure. However, second-generation disks easily form when accounting forcooling of the gas. The disk radii range from several 100 au to ∼1000 au and associated arc-like structures up to 104
au in length form around the star for runs with and without stellar irradiation. Consistent with angular momentum
conservation, the arcs and disks are larger for larger impact parameters. Accounting for turbulence in the cloudlet only
mildly changes the model outcome. In the case of the star being at rest with the background gas, the disk formationand mass replenishment process is more pronounced and the associated arc-shaped streamers are longer lived. The
results of our models confirm that late encounter events lead to the formation of transitional disks associated witharc-shaped structures such as observed for AB Aurigae or HD 100546. In addition, we find that second-generation
disks and their associated filamentary arms are longer lived (> 105 yrs) in infall events, when the star is at rest withthe background gas.
Accepted by A&A
https://ui.adsabs.harvard.edu/pdf/2019arXiv191104833K/abstract

26

The Formation and Evolution of Wide-orbit Stellar Multiples in Magnetized Clouds
Aaron Y. Lee1 , Stella S. R. Oﬀner2 , Kaitlin M. Kratter3 , Rachel A. Smullen3 and Pak Shing Li4
St. Mary’s College of California, Moraga, CA 94575; 2 University of Texas Austin, Austin, TX, 78712; 3 Universityof Arizona, Tucson, AZ 85721; 4 University of California Berkeley, Berkeley, CA 94720

1

E-mail contact: atl8 at stmarys-ca.edu
Stars rarely form in isolation. Nearly half of the stars in the Milky Way have a companion, and this fraction increases
in star- forming regions. However, why some dense cores and filaments form bound pairs while others form single
stars remains unclear. We present a set of three-dimensional, gravo-magnetohydrodynamic simulations of turbulent
star-forming clouds, aimed at understanding the formation and evolution of multiple-star systems formed throughlarge scale (103 AU) turbulent fragmentation. We investigate three global magnetic field strengths, with global massto-flux ratios of µφ = 2, 8, and 32. The initial separations of protostars in multiples depends on the global magnetic
field strength, with stronger magnetic fields (e.g., µφ = 2) suppressing fragmentation on smaller scales. The overall
multiplicity fraction (MF) is between 0.4 - 0.6 for our strong and intermediate magnetic field strengths, which is inagreement with observations. The weak field case has a lower fraction. The MF is relatively constant throughout
17

the simulations, even though stellar densities increase as collapse continues. While the MF rarely exceeds 60% in all
three simulations, over 80% of all protostars are part of a binary system at some point. We additionally find that the
distribution of binary spin mis-alignment angles is consistent with a randomized distribution. In all three simulations,several binaries originate with wide separations and dynamically evolve to ∼ 102 AU separations. We show that asimple model of mass accretion and dynamical friction with the gas can explain this orbital evolution.
Accepted by ApJ
https://arxiv.org/pdf/1911.07863

27

The circumstellar environment around the embedded protostar EC 53
Seokho Lee1 , Jeong-Eun Lee1 , Yuri Aikawa2 , regory Herczeg3 , Doug Johnstone4,5
School of Space Research, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si,Gyeonggi-do, Korea;
Department of Astronomy, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; 3 Kavli Institutefor Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, 100871, Beijing, PR China; 4
NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Rd, Victoria, BC, V9E 2E7, Canada; 5 Departmentof Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1, Canada

12E-mail contact: jeongeunlee at khu.ac.kr
EC53 is an embedded protostar with quasi-periodic emission in the near-IR and sub-mm. We use ALMA highresolution observations of continuum and molecular line emission to describe the circumstellar environment of EC 53.
The continuum image reveals a disk with a flux that suggests a mass of 0.075 M⊙ , much less than the estimated massin the envelope, and an in-band spectral index that indicates grain growth to centimeter sizes. Molecular lines trace
the outflow cavity walls, infalling and rotating envelope, and/or the Keplerian disk. The rotation profile of the C17 O
3–2 line emission cannot isolate the Keplerian motion clearly although the lower limit of the protostellar mass can becalculated as 0.3±0.1 M⊙ if the Keplerian motion is adopted. The weak CH3 OH emission, which is anti-correlatedwith the HCO+ 4–3 line emission, indicates that the water snow line is more extended than what expected from thecurrent luminosity, attesting to bygone outburst events. The extended snow line may persist for longer at the disk
surface because the lower density increases the freeze-out timescale of methanol and water.
Accepted by ApJ
http://arxiv.org/pdf/1911.10318

28

Numerical Simulation and Completeness Survey of Bubbles in the Taurus and Perseus
Molecular Clouds
Mengting Liu1,2 , Di Li1,2,3 , Marko Krčo1 , Luis C. Ho4,5 , Duo Xu6 and Huixian Li1
1
CAS Key Laboratory of FAST, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101,
People’s Republic of China; 2 University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China;
3
NAOC-UKZN Computational Astrophysics Centre, University of KwaZulu-Natal, Durban 4000, South Africa; 4Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of China;
5Department of Astronomy, School of Physics, Peking University, Beijing 100871, People’s Republic of China; 6Department of Astronomy, The University of Texas at Austin, Austin, TX 78712, USA

E-mail contact: liumengting at nao.cas.cn
Previous studies have analyzed the energy injection into the interstellar matter due to molecular bubbles. They foundthat the total kinetic energies of bubbles are comparable to, or even larger than, those of outflows but still less than
the gravitational potential and turbulence energies of the hosting clouds. We examined the possibility that previous
studies underestimated the energy injection due to being unable to detect dim or incomplete bubbles. We simulated
typical molecular bubbles and inserted them into the 13 CO Five College Radio Astronomical Observatory maps of
the Taurus and Perseus Molecular Clouds. We determined bubble identification completeness by applying the sameprocedures to both simulated and real data sets. We proposed a detectability function for both the Taurus and Perseus
molecular clouds based on a multivariate approach. In Taurus, bubbles with kinetic energy less than ∼1 × 1044 erg
are likely to be missed. We found that the total missing kinetic energy in Taurus is less than a couple of 1044 erg,
which only accounts for around 0.2% of the total kinetic energy of identified bubbles. In Perseus, bubbles with kinetic
18

energy less than ∼2 × 1044 erg are likely to be missed. We found that the total missing kinetic energy in Perseus
is less than 1045 erg, which only accounts for around 1% of the total kinetic energy of identified bubbles. We thus
conclude that previous manual bubble identification routines used in Taurus and Perseus can be considered to beenergetically complete. Therefore, we confirm that energy injection from dynamic structures, namely outflows andbubbles, produced by star formation feedback are sufficient to sustain turbulence at a spatial scale from∼0.1 to ∼2.8
pc.
Accepted by ApJ
http://arxiv.org/pdf/1911.04100

29

Aggregate Growth and Internal structures of Chondrite Parent Bodies Forming from
Dense Clumps
Yuji Matsumoto1 , Shigeru Wakita2,3,4 , Yasuhiro Hasegawa5 & Shoichi Oshino6,7
Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan; 2 Earth-Life Science Institute,Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8550, Japan; 3 Department of Earth, Environmental
and Planetary Sciences, Brown University, Providence, RI 02912, USA; 4 Department of Earth, Atmospheric, andPlanetary Sciences, Purdue University, West Lafayette, IN 47907, USA; 5 Jet Propulsion Laboratory, California
Institute of Technology, Pasadena, CA 91109, USA; 6 Center for Computational Astrophysics, National Astronomical
Observatory of Japan, Osawa, Mitaka, Tokyo, 181-8588, Japan; 7 Institute for Cosmic Ray Research, University ofTokyo, Hida, Gifu 506-1205, Japan1

E-mail contact: ymatsumoto at asiaa.sinica.edu.tw
Major components of chondrites are chondrules and matrix. Measurements of the volatile abundance in Semarkona
chondrules suggest that chondrules formed in a dense clump that had a higher solid density than the gas density in thesolar nebula. We investigate collisions between chondrules and matrix in the surface region of dense clumps using fluffy
aggregate growth models. Our simulations show that the collisional growth of aggregates composed of chondrules andmatrix takes place in the clumps well before they experience gravitational collapse. The internal structure of chondrite
parent bodies (CPBs) can be thereby determined by aggregate growth. We find that the aggregate growth generates
two scales within CPBs. The first scale is involved with the small scale distribution of chondrules and determined by
the early growth stage, where chondrules accrete aggregates composed of matrix grains. This accretion can reproduce
the thickness of the matrix layer around chondrules found in chondrites. The other scale is related to the large scale
distribution of chondrules. Its properties (e.g., the abundance of chondrules and the overall size) depend on the gas
motion within the clump, which is parameterized in this work. Our work thus suggests that the internal structure of
CPBs may provide important clues about their formation conditions and mechanisms.
Accepted by ApJ
http://arxiv.org/pdf/1911.10467

30

NaCo polarimetric observations of Sz 91 transitional disk: a remarkable case of dust
filtering
Karina Maucó1,2 , Johan Olofsson2,1, Hector Canovas3 , Matthias R. Schreiber2,1 , Valentin Christiaens4 ,Amelia Bayo2,1 , Alice Zurlo5 , Claudio Cáceres6,1 , Christophe Pinte4 , Eva Villaver7 , Julien H. Girard8 ,Lucas Cieza5 and Matías Montesinos1,2,9
Núcleo Milenio Formación Planetaria - NPF, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso, Chile;
Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, 5030
Casilla, Valparaíso, Chile; 3 European Space Astronomy Centre (ESA/ESAC), Operations Department, Villanueva dela Cañada (Madrid), Spain; 4 School of Physics and Astronomy, Monash University, Clayton Victoria, 3168, Australia;
5
Núcleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago,
Chile; 6 Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Av. Fernandez
Concha 700, Las Condes, Santiago, Chile; 7 Departamento de Física Teórica, Universidad Autónoma de Madrid,
Cantoblanco, 28049, Madrid, Spain; 8 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218,
USA; 9 Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS,
1

2

19

Beijing 100012, China
E-mail contact: karina.mauco at uv.cl
We present polarized light observations of the transitional disk around Sz 91 acquired with VLT/NaCo at H (1.7µm)
and Ks (2.2µm) bands. We resolve the disk and detect polarized emission up to ∼0."5 (∼80 au) along with a central
cavity at both bands. We computed a radiative transfer model that accounts for the main characteristics of thepolarized observations. We found that the emission is best explained by small, porous grains distributed in a disk
with a ∼45 au cavity. Previous ALMA observations have revealed a large sub-mm cavity (∼83 au) and extended gas
emission from the innermost (<16 au) regions up to almost 400 au from the star. Dynamical clearing by multiple
low-mass planets arises as the most probable mechanism for the origin of Sz 91’s peculiar structure. Using new L′band ADI observations we can rule out companions more massive than Mp ≥ 8 MJup beyond 45 au assuming hot-startmodels. The disk is clearly asymmetric in polarized light along the minor axis, with the north side brighter than thesouth side. Differences in position angle between the disk observed at sub-mm wavelengths with ALMA and our NaCoobservations were found. This suggests that the disk around Sz 91 could be highly structured. Higher signal-to-noise
near-IR and sub-mm observations are needed to confirm the existence of such structures and to improve the current
understanding in the origin of transitional disks.
Accepted by Monthly Notices of the Royal Astronomical Society (MNRAS)
http://arxiv.org/pdf/1912.01925

31

Shadowing and multiple rings in the protoplanetary disk of HD 139614
G.A. Muro-Arena1 , M. Benisty2,3 , C. Ginski1 , C. Dominik1 , S. Facchini4 et al.
Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904,1098XH Amsterdam, The
Netherlands 2 Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France; 3 Unidad Mixta Internacional FrancoChilena de Astronomía (CNRS, UMI 3386), Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile; 4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748
Garching, Germany
1E-mail contact: g.a.muroarena at uva.nl
Shadows in scattered light images of protoplanetary disks are a common feature and support the presence of warps or
misalignments between disk regions. These warps are possibly due to an inclined (sub-)stellar companion embeddedin the disk. We study the morphology of the protoplanetary disk around the Herbig Ae star HD 139614 based on
the first scattered light observations of this disk, which we model with the radiative transfer code MCMax3D. We
obtained J- and H-band observations in polarized scattered light with VLT/SPHERE that show strong azimuthal
asymmetries. In the outer disk, beyond ∼30 au, a broad shadow spans a range of ∼240◦ in position angle, in the East.
A bright ring at ∼16 au also shows an azimuthally asymmetric brightness, with the faintest side roughly coincidental
with the brightest region of the outer disk. Additionally, two arcs are detected at ∼34 au and ∼50 au. We created asimple 4-zone approximation to a warped disk model of HD 139614 in order to qualitatively reproduce these features.
The location and misalignment of the disk components were constrained from the shape and location of the shadowsthey cast. We find that the shadow on the outer disk covers a range of position angle too wide to be explainedby a single inner misaligned component. Our model requires a minimum of two separate misaligned zones — or acontinuously warped region — to cast this broad shadow on the outer disk. A small misalignment of ∼4◦ between
adjacent components can reproduce most of the observed shadow features. Multiple misaligned disk zones, potentially
mimicing a warp, can explain the observed broad shadows in the HD 139614 disk. A planetary mass companion in thedisk, located on an inclined orbit, could be responsible for such a feature and for the dust depleted gap responsible
for a dip in the SED.
Accepted by A&A
http://arxiv.org/pdf/1911.09612

32

SUBARU Near-Infrared Imaging Polarimetry of Misaligned Disks Around SR24 Hierarchical Triple System
Satoshi Mayama1 , Sebastián Pérez2 , Nobuhiko Kusakabe3,4 , Takayuki Muto5 , Takashi Tsukagoshi4 , et20

al.
SOKENDAI (The Graduate University for Advanced Studies), Shonan International Village, Hayama-cho, Miuragun, Kanagawa 240-0193, Japan; 2 Universidad de Santiago de Chile, Av. Libertador Bernardo O’Higgins 3363,
Estación Central, Santiago, Chile; 3 Astrobiology Center, NINS, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan; 4National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences (NINS), 2-21-1 Osawa,
Mitaka, Tokyo 181-8588, Japan; 5 Division of Liberal Arts, Kogakuin University, 1-24-2, Nishi-Shinjuku, Shinjuku-ku,
Tokyo, 163-8677, Japan1

E-mail contact: mayama_satoshi at soken.ac.jp
The SR24 multi-star system hosts both circumprimary and circumsecondary disks, which are strongly misaligned
from each other. The circumsecondary disk is circumbinary in nature. Interestingly, both disks are interacting, andthey possibly rotate in opposite directions. To investigate the nature of this unique twin disk system, we present
0.′′ 1 resolution near-infrared polarized intensity images of the circumstellar structures around SR24, obtained with
HiCIAO mounted on the Subaru 8.2 m telescope. Both the circumprimary disk and the circumsecondary disk areresolved and have elongated features. While the position angle of the major axis and radius of the NIR polarization disk
around SR24S are 55◦ and 137 au, respectively, those around SR24N are 110◦ and 34 au, respectively. As an overallmorphology, the circumprimary disk around SR24S shows strong asymmetry, whereas the circumsecondary disk around
SR24N shows relatively strong symmetry. Our NIR observations confirm the previous claim that the circumprimaryand circumsecondary disks are misaligned from each other. Both the circumprimary and circumsecondary disks show
similar structures in 12 CO observations in terms of its size and elongation direction. This consistency is because both
NIR and 12 CO are tracing surface layers of the flared disks. As the radius of the polarization disk around SR24N isroughly consistent with the size of the outer Roche lobe, it is natural to interpret the polarization disk around SR24N
as a circumbinary disk surrounding the SR24Nb-Nc system.
Accepted by AJ
http://arxiv.org/pdf/1911.10941

33

Flyby-induced misalignments in planet-hosting discs
Rebecca Nealon1 , Nicolás Cuello2,1,3 and Richard Alexander1
School of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK; 2 Institutode Astrofísica, Pontificia Universidad Católica de Chile, Santiago, Chile; 3 Núcleo Milenio de Formación Planetaria(NPF), Chile

1

E-mail contact: rebecca.nealon at leicester.ac.uk
We now have several observational examples of misaligned broken protoplanetary discs, where the disc inner regions
are strongly misaligned with respect to the outer disc. Current models suggest that this disc structure can be generated
with an internal misaligned companion (stellar or planetary), but the occurrence rate of these currently unobserved
companions remains unknown. Here we explore whether a strong misalignment between the inner and outer disc canbe formed without such a companion. We consider a disc that has an existing gap — essentially separating the disc
into two regions — and use a flyby to disturb the discs, leading to a misalignment. Despite considering the most
optimistic parameters for this scenario, we find maximum misalignments between the inner and outer disc of ∼45◦
and that these misalignments are short-lived. We thus conclude that the currently observed misaligned discs must
harbour internal, misaligned companions.
Accepted by MNRAS
http://arxiv.org/pdf/1911.05760

34

The Gemini Planet Imager Exoplanet Survey: Dynamical Mass of the Exoplanet β
Pictoris b from Combined Direct Imaging and Astrometry
Eric L. Nielsen1, Robert J. De Rosa1 , Jason J. Wang2 , Johannes Sahlmann3 , Paul Kalas4,5,6
Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA; 2 Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA; 3 Space Telescope Science Institute,

121

Baltimore, MD 21218, USA; 4 Department of Astronomy, University of California, Berkeley, CA 94720, USA; 5 SETI
Institute, Carl Sagan Center, 189 Bernardo Ave., Mountain View CA 94043, USA; 6 Institute of Astrophysics, FORTH,
GR-71110 Heraklion, Greece
E-mail contact: enielsen at stanford.edu
We present new observations of the planet β Pictoris b from 2018 with GPI, the first GPI observations following
conjunction. Based on these new measurements, we perform a joint orbit fit to the available relative astrometry
from ground-based imaging, the Hipparcos Intermediate Astrometric Data (IAD), and the Gaia DR2 position, anddemonstrate how to incorporate the IAD into direct imaging orbit fits. We find a mass consistent with predictionsof hot-start evolutionary models and previous works following similar methods, though with larger uncertainties:+0.04
12.8+5.3−3.2 MJup . Our eccentricity determination of 0.12−0.03 disfavors circular orbits. We consider orbit fits to several
different imaging datasets, and find generally similar posteriors on the mass for each combination of imaging data. Our
analysis underscores the importance of performing joint fits to the absolute and relative astrometry simultaneously,
given the strong covariance between orbital elements. Time of conjunction is well constrained within 2.8 days of2017 September 13, with the star behind the planet’s Hill sphere between 2017 April 11 and 2018 February 16 (±18days). Following the recent radial velocity detection of a second planet in the system, β Pic c, we perform additional
two-planet fits combining relative astrometry, absolute astrometry, and stellar radial velocities. These joint fits finda significantly smaller mass for the imaged planet β Pic b, of 8.0±2.6 MJup , in a somewhat more circular orbit. We
expect future ground-based observations to further constrain the visual orbit and mass of the planet in advance of therelease of Gaia DR4.
Accepted by AJ
http://arxiv.org/pdf/1911.11273

35

The jet/counterjet symmetry of the HH 212 outflow
A. Noriega-Crespo1 , A.C. Raga2 , V. Lora3 and J.C. Rodríguez-Ramírez4
STScI, 3700 San Martin Drive, Baltimore MD 21218, USA; 2 ICN-UNAM, 04510 Cd. Mx., México; 3 IRyA-UNAM,
58089 Morelia, Michoacán, México; 4 IAG-USP, R. do Matão 1226, 05508-090 SP, Brasil

1

E-mail contact: noriega at stsci.edu
We present Spitzer (IRAC) images observations and a VLT 2.1 µm image of the HH 212 outflow. We find that thisoutflow has a strong symmetry, with jet/counterjet knot pairs with ∆x < 1′′ position offsets. We deduce that the
jet/counterjet knots are ejected with time differences ∆τ0 ∼ 6 yr and velocity differences ∆v0 ∼ 2 km s−1 . We also
analyze the deviations of the knot positions perpendicular to the outflow axis, and interpret them in terms of a binary
orbital motion of the outflow source. Through this model, we deduce a ∼ 0.7 M⊙ mass for the outflow source, anda separation of ∼ 80 AU between the components of the binary (assuming equal masses for the two components).
Finally, using the IRAC data and the VLT 2.1 µm image we have measured the proper motion velocities, obtaining
values from 50 to 170 km s−1 .
Accepted by RMxAA
http://arxiv.org/pdf/1911.12297

36

Kinematic study of the molecular gas associated with two cometary globules in Sh2-236
M.E. Ortega1 , S. Paron1,2 , M.B. Areal1 , and M. Rubio3
1
CONICET - Universidad de Buenos Aires, Instituto de Astronomía y Física del Espacio (IAFE), CP 1428 Buenos
Aires, Argentina; 2 Universidad de Buenos Aires, Facultad de Arquitectura, Diseño y Urbanismo, Buenos Aires,
Argentina; 3 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile

E-mail contact: mortega at iafe.uba.ar
Cometary globules, dense molecular gas structures exposed to the UV radiation, are found inside HII regions. Understanding the nature and origin of these structures through a kinematic study of the molecular gas is useful toadvance in our knowledge of the interplay between radiation and molecular gas. Using ASTE we carried out molecularobservations towards two cometary globules (Sim129 and Sim130) in the HII region Sh2-236. We mapped two regions
22

with the 12 CO J=3–2 and HCO+ J=4–3 lines. Additionally, two single pointings of C2 H (N=4–3), HNC and HCN
J=4–3 were observed. We combined our observations with public infrared and optical data to analyse the distribution
and kinematics of the gas. We found kinematic signatures of infalling gas in the 12 CO J=3–2 and C2 H J=4–3 spectra
towards Sim129 . We detected HCO+ , HCN, and HNC J=4–3 only towards Sim130. The HCN/HNC integrated ratio
of about 3 found in Sim130 suggests that the possible star formation activity within the globule has not yet ionized
the gas. The location of NVSS 052255+33315, which peaks towards the brightest border of the globule, supports this
scenario. The non-detection of these molecules towards Sim129 could be due to the radiation arising from the starformation activity inside this globule. The ubiquitous presence of the C2 H molecule towards both globules shows theaction of nearby O-B stars irradiating their external layers. Based on mid-infrared emission, we identified two new
structures: a region of diffuse emission (R1) located, in projection, in front of the head of Sim129, and a pillar-likefeature (P1) placed besides Sim130. Based on 12 CO J=3–2, we found molecular gas associated with Sim129, Sim130,
R1 and P1 at radial velocities of −1.5, −11, +10, and +4 km s−1 , respectively. Therefore, while Sim129 and P1 arelocated at the far side of the shell, Sim130 is placed at the near side, consistent with earlier results.
Accepted by A&A
http://arxiv.org/pdf/1911.06604

37

The density gradient inside molecular-gas clumps as a booster of their star formation
activity
Geneviève Parmentier1
Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, D-69120
Heidelberg, Germany

1E-mail contact: gparm at ari.uni-heidelberg.de
Star-forming regions presenting a density gradient experience a higher star formation rate than if they were of uniform
density. We refer to the ratio between the star formation rate of a spherical centrally-concentrated gas clump and thestar formation rate that this clump would experience if it were of uniform density as the magnification factor ζ. We
map ζ as a function of clump mass, radius, initial volume density profile and star formation time-span. For clumps
with a steep density profile (i.e. power-law slope ranging from −3 to −4, as observed in some high-density regions of
Galactic molecular clouds), we find the star formation rate to be at least an order of magnitude higher than its top-hat
equivalent. This implies that such clumps experience faster and more efficient star formation than expected based on
their mean free-fall time. This also implies that measurements of the star formation efficiency per free-fall time ofclumps based on their global properties, namely, mass, mean volume density and star formation rate, present wide
fluctuations. These reflect the diversity in the density profile of star-forming clumps, not necessarily variations in thephysics of star formation. Steep density profiles inside star-cluster progenitors may be instrumental in the formationof multiple stellar populations, such as those routinely observed in old globular clusters.
Accepted by Astrophysical Journal
https://arxiv.org/pdf/1911.04994

38

Resolving the FU Ori System with ALMA: Interacting Twin Disks?
Sebastián Pérez1,2 , Antonio Hales3,4 , Hauyu Baobab Liu5 , Zhaohuan Zhu6 , Simon Casassus2
Universidad de Santiago de Chile, Av. Libertador Bernardo O’Higgins 3363, Estación Central, Santiago 2 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago; 3 National Radio Astronomy Observatory, 520
Edgemont Road, Charlottesville, VA 22903-2475; 4 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 7630355, Santiago; 5 Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan;
6
Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV
89154, USA
1E-mail contact: sebastian.astrophysics at gmail.com
FU Orionis objects are low-mass pre-main sequence stars characterized by dramatic outbursts of several magnitudes
in brightness. These outbursts are linked to episodic accretion events in which stars gain a significant portion of theirmass. The physical processes behind these accretion events are not yet well understood. The archetypical FU Ori
23system, FU Orionis, is composed of two young stars with detected gas and dust emission. The continuum emitting
regions have not been resolved until now. Here, we present 1.3 mm observations of the FU Ori binary system with
ALMA. The disks are resolved at 40 mas resolution. Radiative transfer modeling shows that the emission from FU
Ori north (primary) is consistent with a dust disk with a characteristic radius of ∼11 au. The ratio between major
and minor axes shows that the inclination of the disk is ∼37 deg. FU Ori south is consistent with a dust disk ofsimilar inclination and size. Assuming the binary orbit shares the same inclination angle as the disks, the deprojecteddistance between north and south components is 0.′′ 6, i.e. ∼250 au. Maps of 12 CO emission show a complex kinematic
environment with signatures disk rotation at the location of the northern component, and also (to a lesser extent) for
FU Ori south. The revised disk geometry allows us to update FU Ori accretion models (Zhu et al.), yielding a stellar
mass and mass accretion rate of FU Ori north of 0.6 M⊙ and 3.8 × 10−5 M⊙ yr−1 , respectively.
Accepted by ApJ
http://arxiv.org/pdf/1911.11282

39

A Survey for High-Mass Eclipsing Binaries
F. Pozo Nuñez1,2 , R. Chini1,3 , A. Barr Domínguez4 , Ch. Fein1 , M. Hackstein1 , G. Pietrzyński2 and M.
Murphy5Astronomisches Institut, Ruhr–Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany; 2 Centrum
Astronomiczne im. Mikolaja Kopernika, PAN, Bartycka 18, 00-716 Warsaw, Poland; 3 Instituto de Astronomía,
Universidad Católica del Norte, Avenida Angamos 0610, Casilla 1280,Antofagasta, Chile; 4 Centro de Investigación
Multidisciplinario de la Araucanía, Facultad de Ingeniería, Universidad Autonoma de Chile, Avenida Alemania 01090,
Temuco, Chile; 5 Departamento de Física, Universidad Católica del Norte, Avenida Angamos 0610, Casilla 1280
Antofagasta, Chile
1

E-mail contact: francisco.pozon at gmail.com
We report results from a search for galactic high-mass eclipsing binaries. The photometric monitoring campaign was
performed in Sloan r and i with the robotic twin refractor RoBoTT at the Universitätssternwarte Bochum in Chile andcomplemented by Johnson U BV data. Comparison with the SIMBAD database reveals 260 variable high-mass stars.
Based on well-sampled light curves we discovered 35 new eclipsing high-mass systems and confirm the properties of six
previously known systems. For all objects, we provide the first light curves and determine orbital periods through theLafler-Kinman algorithm. Apart from GSC 08173-0018 and Pismis 24-13 (P = 19.47 d and 20.14 d) and the exceptional
short-period system TYC 6561-1765-1 (P = 0.71 d), all systems have orbital periods between 1 and 9 days. We model
the light curves of 26 systems within the framework of the Roche geometry and calculate fundamental parameters
for each system component. The Roche lobe analysis indicates that 14 systems have a detached geometry while 12
systems have a semi-detached geometry; seven of them are near-contact systems. The deduced mass ratios q = M2 /M1reach from 0.4 to 1.0 with an average value of 0.8. The similarity of masses suggests that these high-mass binaries
were created during the star formation process rather than by tidal capture.
Accepted by Monthly Notices of the Royal Astronomical Society

40

The young stellar content of the giant HII regions M8, G333.6−0.2, and NGC6357 with
VLT/KMOS
M.C. Ramírez-Tannus1,2 , J. Poorta2 , A. Bik3 , L. Kaper2 , A. de Koter2,4 et al.
Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany; 2 Astronomical Institute ‘Anton
Pannekoek’, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; 3 Department of
Astronomy, Stockholm University, Oskar Klein Center, SE-106 91 Stockholm, Sweden; 4 Institute of Astronomy, KU
Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium
1E-mail contact: ramirez at mpia.de
Context. The identification and characterisation of populations of young massive stars in (giant) HII regions provides
important constraints on i) the formation process of massive stars and their early feedback on the environment, andii) the initial conditions for population synthesis models predicting the evolution of ensembles of stars.
Aims. We identify and characterise the stellar populations of the following young giant HII regions: M8, G333.6−0.2,24and NGC6357.
Methods. We acquired H- and K-band spectra of around 200 stars using The K-band KMOS on the ESO Very
Large Telescope. The targets for M8 and NGC6357 were selected from the MYStIX project, which combines Xray observations with near-infrared and mid-infrared data. For G333.6−0.2, the sample selection is based on thenear-infrared colours combined with X-ray data. We introduce an automatic spectral classification method in order toobtain temperatures and luminosities for the observed stars. We analyse the stellar populations using their photometric,
astrometric, and spectroscopic properties and compared the position of the stars in the Hertzprung-Russell diagramwith stellar evolution models to constrain their ages and mass ranges.
Results. We confirm the presence of candidate ionising sources in the three regions and report new ones, including
the first spectroscopically identified O stars in G333.6−0.2. In M8 and NGC6357, two populations are identified: i)
OB main-sequence stars (M > 5 M⊙ ) and ii) pre-main sequence stars (M ≈ 0.5–5 M⊙ ). The ages of the clusters
are ∼1–3 Myr, <3 Myr, and ∼0.5–3 Myr for M8, G333.6−0.2, and NGC6357, respectively. We show that MYStIX
selected targets have >90% probability of being members of the HII region, whereas a selection based on near infrared(NIR) colours leads to a membership probability of only ∼70%.
Accepted by A&A
http://arxiv.org/pdf/1911.09558

41

Autonomous Gaussian decomposition of the Galactic Ring Survey. I. Global statistics
and properties of the 13 CO emission data
M. Riener1 , J. Kainulainen2 , H. Beuther1 , J. D. Henshaw1 , J. H. Orkisz2 and Y. Wang1
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
The analysis of large molecular line surveys of the Galactic plane is essential for our understanding of the gas kinematics
on Galactic scales and, in particular, its link with the formation and evolution of dense structures in the interstellar
medium. An approximation of the emission peaks with Gaussian functions allows for an efficient and straightforward
extraction of useful physical information contained in the shape and Doppler-shifted frequency of the emission lines
contained in these enormous data sets. In this work, we present an overview and the first results of a Gaussian
decomposition of the entire Galactic Ring Survey (GRS) 13 CO (1 − 0) data that consists of about 2.3 million spectra.
We performed the decomposition with the fully automated GaussPy+ algorithm and fitted about 4.6 million Gaussiancomponents to the GRS spectra. These decomposition results enable novel and unexplored ways to interpret and study
the gas velocity structure. We discuss the statistics of the fit components and relations between the fitted intensities,
velocity centroids, and velocity dispersions. We find that the magnitude of the velocity dispersion values increase
towards the inner Galaxy and around the Galactic midplane, which we speculate is partly due to the influence of
the Galactic bar and regions with higher non-thermal motions located in the midplane, respectively. We also used
our decomposition results to infer global properties of the gas emission and find that the number of fit components
used per spectrum is indicative of the amount of structure along the line of sight. We find that the emission lines
from regions located on the far side of the Galaxy show increased velocity dispersion values, which are likely due tobeam averaging effects. We demonstrate how this trend has the potential to aid in characterising Galactic structure
by disentangling emission that belongs to the nearby Aquila Rift molecular cloud from emission that is more likely
associated with the Perseus and Outer spiral arms. With this work, we also make our entire decomposition results
available.
Accepted by Astronomy & Astrophysics
https://arxiv.org/pdf/1911.06860

42

ALMA and ROSINA detections of phosphorus-bearing molecules: the interstellar thread
between star-forming regions and comets
V.M. Rivilla1, M. N. Drozdovskaya2 , K. Altwegg3 , P. Caselli4, M. T. Beltrán1 , F. Fontani1 , F.F.S. van
der Tak5,6 , R. Cesaroni1 , A. Vasyunin7,8 , M. Rubin2 , F. Lique9 , S. Marinakis10,11 , L. Testi1,12,13 and the
ROSINA team14
25

INAF-Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125, Florence, Italy; 2 Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, CH-3012 Bern, Switzerland; 3 Physikalisches Institut, Universityof Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland; 4 Max-Planck-Institute for Extraterrestrial Physics, Garching,
Germany; 5 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands;
6
Kapteyn Astronomical Institute, University of Groningen, The Netherlands; 7 Ural Federal University, Ekaterinburg, Russia; 8 Visiting Leading Researcher, Engineering Research Institute ’Ventspils International Radio Astronomy
Centre’ of Ventspils University of Applied Sciences, Inzenieru 101, Ventspils LV-3601, Latvia; 9 LOMC - UMR 6294,
CNRS-Université du Havre, France; 10 School of Health, Sport & Bioscience, University of East London, Stratford
Campus, Water Lane, London E15 4LZ, UK; 11 Department of Chemistry and Biochemistry, School of Biological andChemical Sciences, Queen Mary University of London, Joseph Priestley Building, Mile End Road, London E1 4NS,
UK; 12 ESO/European Southern Observatory, Karl Schwarzschild str. 2, D-85748, Garching, Germany; 13 Excellence Cluster "Universe", Boltzmann str. 2, D-85748 Garch- ing bei Muenchen, Germany; 14 The ROSINA team: H.
Balsiger, J. J. Berthelier, J. De Keyser, B. Fiethe, S. A. Fuselier, S. Gasc, T. I. Gombosi, T. Sémon, C. -y. Tzou
1E-mail contact: vmrivilla at gmail.com, rivilla at arcetri.astro.it
To understand how Phosphorus-bearing molecules are formed in star-forming regions, we have analysed ALMA observations of PN and PO towards the massive star-forming region AFGL 5142, combined with a new analysis of the dataof the comet 67P/Churyumov-Gerasimenko taken with the ROSINA instrument onboard Rosetta. The ALMA maps
show that the emission of PN and PO arises from several spots associated with low-velocity gas with narrow linewidths
in the cavity walls of a bipolar outflow. PO is more abundant than PN in most of the spots, with the PO/PN ratio
increasing as a function of the distance to the protostar. Our data favor a formation scenario in which shocks sputter
phosphorus from the surface of dust grains, and gas-phase photochemistry induced by UV photons from the protostar
allows efficient formation of the two species in the cavity walls. Our analysis of the ROSINA data has revealed that
PO is the main carrier of P in the comet, with PO/PN>10. Since comets may have delivered a significant amount ofprebiotic material to the early Earth, this finding suggests that PO could contribute significantly to the phosphorus
reservoir during the dawn of our planet. There is evidence that PO was already in the cometary ices prior to the birthof the Sun, so the chemical budget of the comet might be inherited from the natal environment of the Solar System,
which is thought to be a stellar cluster including also massive stars.
Accepted by Monthly Notices of the Royal Astronomical Society
https://arxiv.org/pdf/1911.11647

43

Global axisymmetric simulations of photoevaporation and magnetically driven protoplanetary disk winds
P.J. Rodenkirch1,2 , H. Klahr2 , C. Fendt2 , and C.P. Dullemond1
Institute for Theoretical Astrophysics, Zentrum für Astronomie, Heidelberg University, Albert Überle Str. 2, 69120
Heidelberg, Germany; 2 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
1E-mail contact: rodenkirch at stud.uni-heidelberg.de
Photoevaporation and magnetically driven winds are two independent mechanisms to remove mass from protoplanetary disks. In addition to accretion, the effect of these two principles acting concurrently could be significant and thetransition between those two has not been extensively studied and quantified in the literature yet. In order to contribute to the understanding of disk winds, we present the phenomena emerging in the framework of two-dimensional
axisymmetric, non-ideal magnetohydrodynamic simulations including EUV-/ X-ray driven photoevaporation. Of particular interest are the examination of the transition region between photoevaporation and magnetically driven wind,
the possibility of emerging magneto-centrifugal wind effects, as well as the morphology of the wind itself dependingon the strength of the magnetic field. We use the PLUTO code in a 2.5D axisymmetric configuration with additional treatment of EUV-/ X-ray heating and dynamic ohmic diffusion based on a semi-analytical chemical model.
We identify the transition between both outflow types to occur for values of the initial plasma beta β ≤ 107 , whilemagnetically driven winds generally outperform photoevaporation for stronger fields. In our simulations we observe
irregular and asymmetric outflows for stronger magnetic fields. In the weak field regime the photoevaporation rates
are slightly lowered by perturbations of the gas density in the inner regions of the disk. Overall, our results predicta wind with a lever arm smaller than 1.5, consistent with a hot magneto-thermal wind. Stronger accretion flows arepresent for values of β < 107 .
26

Accepted by A&A
http://arxiv.org/pdf/1911.04510

44

Massive Star Formation via the Collapse of Subvirial and Virialized Turbulent Massive
Cores
Anna L. Rosen1 , Pak Shing Li2 , Qizhou Zhang1 and Blakesley Burkhart3,4
Center for Astrophysics | Harvard & Smithsonian, 60 Garden St, Cambridge, MA 02138, USA; 2 Astronomy Department, University of California, Berkeley, CA 94720, USA; 3 Center for Computational Astrophysics, Flatiron
Institute,162 Fifth Avenue, New York, NY 10010, USA; 4 Department of Physics and Astronomy, Rutgers, The State
University of New Jersey, 136 Frelinghuysen Rd, Piscataway, NJ 08854, USA

1E-mail contact: anna.rosen at cfa.harvard.edu
Similar to their low-mass counterparts, massive stars likely form via the collapse of pre-stellar molecular cores. Recent
observations suggest that most massive cores are subvirial (i.e., not supported by turbulence) and therefore are likely
unstable to gravitational collapse. Here we perform radiation hydrodynamic simulations to follow the collapse of
turbulent massive pre-stellar cores with subvirial and virialized initial conditions to explore how their dynamic state
affects the formation of massive stars and core fragmentation into companion stars. We find that subvirial cores
undergo rapid monolithic collapse resulting in higher accretion rates at early times as compared to the collapse ofvirialized cores that have the same physical properties. In contrast, we find that virialized cores undergo a slower,
gradual collapse and significant turbulent fragmentation at early times resulting in numerous companion stars. In theabsence of strong magnetic fields and protostellar outflows we find that the faster growth rate of massive stars thatare born out of subvirial cores leads to an increase in the radiative heating of the core thereby further suppressing
fragmentation at early times when turbulent fragmentation occurs for virialized cores. Regardless of initial condition,
we find that the massive accretion disks that form around massive stars dominant the accretion flow onto the star atlate times and eventually become gravitationally unstable and fragment to form companion stars at late times.
Accepted by Astrophysical Journal
https://arxiv.org/pdf/1902.10153

45

Spiral arms in the proto-planetary disc HD100453 detected with ALMA: evidence forbinary-disc interaction and a vertical temperature gradient
G.P. Rosotti1,2, M. Benisty3,4 , A. Juhász2 , R. Teague5,6 , C. Clarke2 , C. Dominik7 , C.P. Dullemond8,
P.D. Klaassen9 , L. Matrà6 , T. Stolker10
Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, the Netherlands; 2 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA, UK; 3 Unidad Mixta Internacional
Franco-Chilena de Astronomía (CNRS, 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;
5
Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109, USA; 6
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; 7 Anton Pannekoek
Institute for Astronomy, University of Amsterdam, Science Park 904,1098XH Amsterdam, The Netherlands; 8 Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany; 9 UK
Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK; 10 Institutefor Particle Physics and Astrophysics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
1

E-mail contact: rosotti at strw.leidenuniv.nl
Scattered light high-resolution imaging of the proto-planetary disc orbiting HD100453 shows two symmetric spiralarms, possibly launched by an external stellar companion. In this paper we present new, sensitive high-resolution(∼30 mas) Band 7 ALMA observations of this source. This is the first source where we find counterparts in the
sub-mm continuum to both scattered light spirals. The CO J=3–2 emission line also shows two spiral arms; in thiscase they can be traced over a more extended radial range, indicating that the southern spiral arm connects to thecompanion position. This is clear evidence that the companion is responsible for launching the spirals. The pitch
angle of the sub-millimeter continuum spirals (∼6◦ ) is lower than the one in scattered light (∼16◦ ). We show that27

hydrodynamical simulations of binary-disc interaction can account for the difference in pitch angle only if one takes
into account that the midplane is colder than the upper layers of the disc, as expected for the case of externally
irradiated discs.
Accepted by MNRAS
http://arxiv.org/pdf/1911.00518

46

Physical Properties of the star-forming clusters in NGC 6334
M. Sadaghiani1 , Á. Sánchez-Monge1 , P. Schilke1 , H.B. Liu2 , S.D. Clarke1 et al.
I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany; 2 Academia Sinica
Institute of Astronomy and Astrophysics, 11F of Astro-Math Bldg, 1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan
1E-mail contact: sadaghiani at ph1.uni-koeln.de
We have studied the high-mass star-forming complex NGC 6334 with ALMA in the continuum emission at a frequencyof 87.6 GHz, achieving a spatial resolution of 1300 au. Detecting 142 compact sources distributed over the wholeobserved area, we then used machine learning algorithms to group the compact cores in different clusters. A totalof four main clusters were identified: NGC 6334-E, NGC 6334-I, NGC 6334-I(N) and NGC 6334-I(NW). The typical
separations between cluster members (4000–12000 au) together with the core masses (0.2–100 M⊙ ) are in agreementwith turbulent fragmentation at scales of 0.1 pc. We find that the CMFs (core mass functions) show an excess ofmassive cores compared to the IMF. Typical uncertainties in temperature or unresolved multiplicity may mimic theobserved excess of massive cores. Evidence of mass segregation in NGC 6334-I and NGC 6334-I(N), with the most
massive cores located closer to the center, was found. Correlations between the physical properties of the clusters
and their evolutionary stage were searched for, and found to show a larger separation between cores in the more
evolved clusters, favouring the role of gas expulsion and stellar ejection over time. From these results, we suggest thatNGC 6334-I(N) was primordially segregated, while NGC 6334-I may have become mass-segregated over time due todynamical effects. Finally, the lack of massive cores in the most evolved cluster suggests that the gas reservoir may
be already exhausted, while the less evolved clusters still have access to a larger gas mass reservoir. In general, thefragmentation in NGC 6334 at large scales (about 1 pc) is governed by turbulent pressure, while at smaller scales (afew hundred au), thermal pressure regulates the fragmentation process.
Accepted by A&A
http://arxiv.org/pdf/1911.06579

47

Demographics of disks around young very low-mass stars and brown dwarfs in Lupus
E. Sanchis1,2 , L. Testi1,3,4 , A. Natta4,5 , C.F. Manara1 , B. Ercolano2,3 et al.
European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München, Germany; 2 UniversitätsSternwarte, Ludwig-Maximilians-Universität München, Scheinerstrasse 1, D-81679 München, Germany; 3 Excellence
Cluster Origins, Boltzmannstrasse 2, D-85748 Garching bei München, Germany; 4 INAF/Osservatorio Astrofisico di
Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy; 5 School of Cosmic Physics, Dublin Institute for Advanced Studies,
31 Fitzwilliams Place, Dublin 2, Ireland1E-mail contact: esanchis at eso.org
We present new 890 µm continuum ALMA observations of 5 brown dwarfs (BDs) with infrared excess in Lupus I and
III – which, in combination with 4 BDs previously observed, allowed us to study the mm properties of the full known
BD disk population of one star-forming region. Emission is detected in 5 out of the 9 BD disks. Dust disk mass,
brightness profiles and characteristic sizes of the BD population are inferred from continuum flux and modeling of theobservations. Only one source is marginally resolved, allowing for the determination of its disk characteristic size. We
conduct a demographic comparison between the properties of disks around BDs and stars in Lupus. Due to the small
sample size, we cannot confirm or disprove if the disk mass over stellar mass ratio drops for BDs, as suggested for
Ophiuchus. Nevertheless, we find that all detected BD disks have an estimated dust mass between 0.2 and 3.2 M⊕ ;these results suggest that the measured solid masses in BD disks can not explain the observed exoplanet population,
analogous to earlier findings on disks around more massive stars. Combined with the low estimated accretion rates, andassuming that the mm-continuum emission is a reliable proxy for the total disk mass, we derive ratios of Ṁacc /Mdisk
28

significantly lower than in disks around more massive stars. If confirmed with more accurate measurements of disk
gas masses, this result could imply a qualitatively different relationship between disk masses and inward gas transport
in BD disks.
Accepted by A&A
http://arxiv.org/pdf/1911.06005

48

Photometric and spectroscopic study of 5 pre-main sequence stars in the vicinity ofNGC 7129
E.H. Semkov1 , S.I. Ibryamov2 and S.P. Peneva1
Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, 72, Tsarigradsko
Shose Blvd., 1784 Sofia, Bulgaria; 2 Department of Physics and Astronomy, Faculty of Natural Sciences, University of
Shumen, 115, Universitetska Str., 9712 Shumen, Bulgaria

1E-mail contact: esemkov at astro.bas.bg
We present results from long-term optical photometric and spectroscopic observations of 5 pre-main sequence stars,
located in the vicinity of the bight nebula NGC 7129. We obtained UBVRI photometric observations in the field
centered on the star V391 Cep, north-west of the bright nebula NGC 7129. Our multicolor CCD observations spanned
the period from February 1998 to November 2016. At the time of our photometric monitoring, a total of thirteen
medium-resolution optical spectra of the stars were obtained. The results from our photometric study show that allstars exhibit strong variability in all optical passbands. Long-term light curves of the five stars indicate the typicalof classical T Tauri stars variations in brightness with large amplitudes. We did not find any reliable periodicity inthe brightness variations of all five stars. The results from spectral observations showed that all studied stars can beclassified as a classical T Tauri stars with reach emission line spectra and strong variability in the profiles and intensityof emission lines.
Accepted by Serbian Astronomical Journal
http://arxiv.org/pdf/1911.06604

49

Time-resolved photometry of the young dipper RX J1604.3-2130A: Unveiling the structure and mass transport through the innermost disk
A. Sicilia-Aguilar1 , C.F. Manara2 , J. de Boer3 , M. Benisty4,5 , P. Pinilla6 and J. Bouvier4
SUPA, School of Science and Engineering, University of Dundee, DD1 4HN, Dundee, UK; 2 European Southern
Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany; 3 Leiden Observatory, Leiden
University, PO Box 9513, 2300 RA, Leiden, The Netherlands; 4 Universite Grenoble Alpes, CNRS, IPAG, 38000
Grenoble, France; 5 Unidad Mixta Internacional Franco-Chilena de Astronomia (CNRS, UMI 3386), Departamento de
Astronomia, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile; 6 Max-Planck-Institut
für Astronomie, Koenigstuhl 17, 69117, Heidelberg, Germany

1E-mail contact: asiciliaaguilar at dundee.ac.uk
RX J1604.3-2130A is a young, dipper-type, variable star in the Upper Scorpius association, suspected to have an
inclined inner disk, with respect to its face-on outer disk. We aim to study the eclipses to constrain the inner disk
properties. We used time-resolved photometry from the Rapid Eye Mount telescope and Kepler 2 data to study themulti-wavelength variability, and archival optical and infrared data to track accretion, rotation, and changes in disk
structure. The observations reveal details of the structure and matter transport through the inner disk. The eclipses
show 5d quasi-periodicity, with the phase drifting in time and some periods showing increased/decreased eclipse depth
and frequency. Dips are consistent with extinction by slightly processed dust grains in an inclined, irregularly-shaped
inner disk locked to the star through two relatively stable accretion structures. The grains are located near the dust
sublimation radius (∼0.06 au) at the corotation radius, and can explain the shadows observed in the outer disk. The
total mass (gas and dust) required to produce the eclipses and shadows is a few % of a Ceres mass. Such an amountof mass is accreted/replenished by accretion in days to weeks, which explains the variability from period to period.
Spitzer and WISE infrared variability reveal variations in the dust content in the innermost disk on a timescale of afew years, which is consistent with small imbalances (compared to the stellar accretion rate) in the matter transport
29

from the outer to the inner disk. A decrease in the accretion rate is observed at the times of less eclipsing variability
and low mid-IR fluxes, confirming this picture. The vsini=16 km/s confirms that the star cannot be aligned with theouter disk, but is likely close to equator-on and to be aligned with the inner disk. This anomalous orientation is achallenge for standard theories of protoplanetary disk formation.
Accepted by A&A
https://arxiv.org/pdf/1911.04938.pdf

50

X-ray Emission and Disk Irradiation of HL Tau and HD 100546
Stephen L. Skinner1 and Manuel Guedel2
CASA, Univ. of Colorado, Boulder, CO 80309-0389 USA; 2 Dept. of Astrophysics, Univ. of Vienna, A-1180 Vienna,
Austria1

E-mail contact: stephen.skinner at colorado.edu
We present new X-ray observations of the optically-obscured protostar HL Tau and the intermediate mass Herbig Be
star HD 100546. Both objects are surrounded by spectacular disks showing complex morphology including rings andgaps that may have been sculpted by protoplanets. HL Tau was detected as a variable hard X-ray source by Chandra,
typical of late-type magnetically-active coronal sources. No extended X-ray emission was seen along the HL Tau jet, oralong the jet of the T Tauri binary system XZ Tau located 23 arcsecs to its east. In contrast, HD 100546 was detectedby XMM-Newton as a soft X-ray source with no short-term (<1 day) variability. Its X-ray properties are remarkably
similar to the Herbig stars AB Aur and HD 163296, strongly suggesting that their X-ray emission arises from thesame mechanism and is intrinsic to the Herbig stars themselves, not due to unseen late-type companions. We consider
several possible emission mechanisms and conclude that the X-ray properties of HD 100546 are consistent with anaccretion shock origin, but higher resolution grating spectra capable of providing information on individual emission
lines are needed to more reliably distinguish between accretion shocks and alternatives. We show that X-ray ionizationand heating are mainly confined to the upper disk layers in both HL Tau and HD 100546, and any exoplanets near
the midplane at distances >1 au are well-shielded from X-rays produced by the central star.
Accepted by ApJ
https://arxiv.org/pdf/1911.11131

51

The Mean Magnetic Field Strength of CI Tau
Kimberly R. Sokal1 , Christopher M. Johns-Krull2 , Gregory N. Mace1 , Larissa Noﬁ3 , L. Prato3 , JaeJoon Lee4 and Daniel T. Jaﬀe1
1
Department of Astronomy, The University of Texas at Austin, Austin, TX, 78712, USA; 2 Department of Physics
and Astronomy, Rice University, 6100 Main Street, MS-108, Houston, TX 77005, USA; 3 Lowell Observatory, 1400
W. Mars Hill Rd., Flagstaff, AZ 86001, USA; 4 Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro,
Yuseong-gu, Daejeon 34055, Korea

E-mail contact: ksokal at utexas.edu
We present a blind comparison of two methods to measure the mean surface magnetic field strength of the classicalT Tauri star CI Tau based on Zeeman broadening of sensitive spectral lines. Our approach takes advantage of thegreater Zeeman broadening at near-infrared compared to optical wavelengths. We analyze a high signal-to-noise, highspectral resolution spectrum from 1.5–2.5um observed with IGRINS (Immersion GRating INfrared Spectrometer)on the Discovery Channel Telescope. Both stellar parameterization with MoogStokes (which assumes an uniform
magnetic field) and modeling with SYNTHMAG (which includes a distribution of magnetic field strengths) yieldconsistent measurements for the mean magnetic field strength of CI Tau is B of ∼2.2 kG. This value is typicalcompared with measurements for other young T Tauri stars and provides an important contribution to the existing
sample given it is the only known developed planetary system hosted by a young classical T Tauri star. Moreover, wepotentially identify an interesting and suggestive trend when plotting the effective temperature and the mean magnetic
field strength of T Tauri stars. While a larger sample is needed for confirmation, this trend appears only for a subsetof the sample, which may have implications regarding the magnetic field generation.

30

Accepted by ApJ
http://arxiv.org/pdf/1911.00784

52

ALMA view of the 12 C/13 C isotopic ratio in starburst galaxies
X. D. Tang1,2,3 , C. Henkel3,4,1 , K. M. Menten3 , Y. Gong3 , S. Martín5,6 , S. Muhle7 , S. Aalto8 , S. Muller8 ,S. García-Burillo9 , S. Levshakov10 , R. Aladro3 , M. Spaans11 , S. Viti12 , H. M. Asiri4 , Y. P. Ao13 , J. S.
Zhang14 , X. W. Zheng15 , J. Esimbek1,2 and J. J. Zhou1,2
Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 830011 Urumqi, PR China; 2 Key Laboratoryof Radio Astronomy, Chinese Academy of Sciences, 830011 Urumqi, PR China; 3 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany; 4 Astronomy Department, King Abdulaziz University, PO Box
80203, 21589 Jeddah, Saudi Arabia; 5 European Southern Observatory, Alonso de Córdova 3107, Vitacura Casilla
763 0355, Santiago, Chile; 6 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura Casilla 763 0355, Santiago,
Chile; 7 Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany; 8 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Observatory, 43992 Onsala, Sweden;
9
Observatorio de Madrid, OAN-IGN, Alfonso XII, 3, E-28014-Madrid, Spain; 10 Ioffe Physical-Technical Institute,
Polytekhnicheskaya Str. 26, 194021 St. Petersburg, Russia; 11 Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands; 12 Department of Physics and Astronomy, UCL, Gower St.,
London, WC1E 6BT, UK; 13 Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, PR China;
14
Center for Astrophysics, Guangzhou University, 510006 Guangzhou, PR China; 15 School of Astronomy and Space
Science, Nanjing University, 210093 Nanjing, PR China
1E-mail contact: tangxindi at xao.ac.cn
We derive molecular-gas-phase 12 C/13 C isotope ratios for the central few hundred parsecs of the three nearby starburst
galaxies NGC 253, NGC 1068, and NGC 4945 making use of the λ ∼ 3 mm 12 CN and 13 CN N = 1–0 lines in the ALMABand 3. The 12 C/13 C isotopic ratios derived from the ratios of these lines range from 30 to 67 with an average of
41.6 ± 0.2 in NGC 253, from 24 to 62 with an average of 38.3 ± 0.4 in NGC 1068, and from 6 to 44 with an average of
16.9 ± 0.3 in NGC 4945. The highest 12 C/13 C isotopic ratios are determined in some of the outskirts of the nuclear
regions of the three starburst galaxies. The lowest ratios are associated with the northeastern and southwestern
molecular peaks of NGC 253, the northeastern and southwestern edge of the mapped region in NGC 1068, and thevery center of NGC 4945. In the case of NGC 1068, the measured ratios suggest inflow from the outer part of NGC 1068
into the circum-nuclear disk through both the halo and the bar. Low 12 C/13 C isotopic ratios in the central regions ofthese starburst galaxies indicate the presence of highly processed material.
Accepted by A&A
https://arxiv.org/pdf/1906.06638

53

Exploring the Grain Properties in the Disk of HL Tau with an Evolutionary Model
Carlos Tapia1 , Susana Lizano1 , Carlos Carrasco-González1 and Elly Bayona-Bobadilla2
Instituto de Radioastronomía y Astrofisica, Universidad Nacional Autónoma de México, Apartado Postal 3-72, C.P.
58089 Morelia, Michoacan, México; 2 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México,
Apartado Postal 70468, C.P. 04510 Cd. Mx., México
1

E-mail contact: c.tapia at irya.unam.mx
We model the ALMA and VLA millimeter radial profiles of the disk around HL Tau to constrain the properties of thedust grains. We adopt the disk evolutionary models of Lynden-Bell & Pringle and calculate their temperature anddensity structure and emission. These disks are heated by the internal viscosity and irradiated by the central star anda warm envelope. We consider a dust size distribution n(a)da ∝ a−3.5 da, and vary the maximum grain size in theatmosphere and the midplane, amax = 100 µm, 1 mm, and 1cm. We also include dust settling and vary the dust-to-gas
mass ratio from 1 to 9 times the ISM value. We find that the models that can fit the observed level of emission along
the profiles at all wavelengths have an atmosphere with a maximum grain size amax = 100 µm, and a midplane withamax = 1 cm. The disk substructure, with a deficit of emission in the gaps, can be due to dust properties in theseregions that are different from those in the rings. We test an opacity effect (different amax ) and a dust mass deficit
31

(smaller dust-to-gas mass ratio) in the gaps. We find that the emission profiles are better reproduced by models witha dust deficit in the gaps, although a combined effect is also possible. These models have a global dust-to-gas mass
ratio twice the ISM value, needed to reach the level of emission of the 7.8 mm VLA profile.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/1911.05108

54

Long lived dust rings around HD169142
Claudia Toci1 , Giuseppe Lodato2,1 , Davide Fedele3 , Leonardo Testi4,6 and Christophe Pinte5
INAF OA Brera, Via Brera 28, I-20121 Milan, Italy; 2 Universita degli Studi di Milano, Via Giovanni Celoria 16, I20133 Milan, Italy; 3 INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125, Florence, Italy; 4 European
Southern Observatory Karl-Schwarzschild-Str 2, D-85748 Garching, Germany; 5 Monash Centre for Astrophysics(MoCA) and School of Physics and Astronomy, Monash University, Clayton Vic 3800, Australia; 6 Excellence Cluster
ORIGINS, Boltzmann-Str. 2, D-85748 Garching, Germany
1E-mail contact: claudia.toci at inaf.it
Recent ALMA observations of the protoplanetary disc around HD 169142 reveal a peculiar structure made of concentric
dusty rings: a main ring at ∼20 au, a triple system of rings at ∼55-75 au in millimetric continuum emission and a
perturbed gas surface density from the 12 CO,13 CO and C18 O (J=2-1) surface brightness profile. In this Letter, we
perform three-dimensional numerical simulations and radiative transfer modeling exploring the possibility that two
giant planets interacting with the disc and orbiting in resonant locking can be responsible for the origin of the observed
dust inner rings structure. We find that in this configuration the dust structure is actually long lived while the gas
mass of the disc is accreted onto the star and the giant planets, emptying the inner region. In addition, we also findthat the innermost planet is located at the inner edge of the dust ring, and can accrete mass from the disc, generatinga signature in the dust ring shape that can be observed in mm ALMA observations.
Accepted by ApJL
https://arxiv.org/pdf/1911.08580

55

Chemical and kinematic structure of extremely high-velocity molecular jets in the Serpens Main star-forming regionŁukasz Tychoniec1 , Charles L. H. Hull2,3,9 , Lars E. Kristensen4 , John J. Tobin5 , Valentin J. M. Le
Gouellec6,7 and Ewine F. van Dishoeck1,8
1
Leiden Observatory, Leiden University, PO Box 9513, 2300RA, Leiden, The Netherlands; 2 National Astronomical
Observatory of Japan, NAOJ Chile Observatory, Alonso de Córdova 3788, Office 61B, Vitacura 763 0422, Santiago,
Chile; 3 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763 0355, Santiago, Chile; 4 Centre for Star
and Planet Formation, Niels Bohr Institute and Natural History Museum of Denmark, University of Copenhagen,øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark; 5 National Radio Astronomy Observatory, Charlottesville, VA
22903; 6 European Southern Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile; 7 AIM, CEA, CNRS,
Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, F-91191 Gif-sur-Yvette, France; 8 Max-PlanckInstitut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching, Germany; 9 NAOJ Fellow

E-mail contact: tychoniec at strw.leidenuniv.nl
Context. Outflows are one of the first signposts of ongoing star formation. The fastest molecular component ofprotostellar outflows, extremely high-velocity (EHV) molecular jets, are still puzzling since they are seen only rarely.
As they originate deep inside the embedded protostar-disk system, they provide vital information about the outflowlaunching process in the earliest stages.
Aim. The first aim is to analyze the interaction between the EHV jet and the slow outflow by comparing their outflow
force content. The second aim is to analyze the chemical composition of the different outflow velocity components andto reveal the spatial location of molecules.
Methods. The Atacama Large Millimeter/submillimeter Array (ALMA) 3 mm (Band 3) and 1.3 mm (Band 6) observations of five outflow sources at 0.3 – 0.6 arcsec(130 – 260 au) resolution in the Serpens Main cloud are presented.
32

Observations of CO, SiO, H2 CO, and HCN reveal the kinematic and chemical structure of those flows. The following
three velocity components are distinguished: the slow and the fast wing, and the EHV jet.
Results. Out of five sources, three have the EHV component. The comparison of outflow forces reveals that only
the EHV jet in the youngest source, Ser-emb 8 (N), has enough momentum to power the slow outflow. The SiO
abundance is generally enhanced with velocity, while HCN is present in the slow and the fast wing, but disappears in
the EHV jet. For Ser-emb 8 (N), HCN and SiO show a bow-shock shaped structure surrounding one of the EHV peaks,
thus suggesting sideways ejection creating secondary shocks upon interaction with the surroundings. Also, the SiO
abundance in the EHV gas decreases with distance from this protostar, whereas it increases in the fast wing. H2 CO
is mostly associated with low-velocity gas, but, surprisingly, it also appears in one of the bullets in the Ser-emb 8 (N)EHV jet. No complex organic molecules are found to be associated with the outflows.
Conclusions. The high detection rate suggests that the presence of the EHV jet may be more common than previously
expected. The EHV jet alone does not contain enough outflow force to explain the entirety of the outflowing gas. The
origin and temporal evolution of the abundances of SiO, HCN, and H2 CO through high-temperature chemistry are
discussed. The data are consistent with a low C/O ratio in the EHV gas versus a high C/O ratio in the fast and slow
wings.
Accepted by A&A
https://arxiv.org/pdf/1910.07857

56

Temperature profiles of young disk-like structures: The case of IRAS 16293A
Merel L.R. van ’t Hoﬀ1 , Ewine F. van Dishoeck1,2 , Jes K. Jørgensen3 and Hannah Calcutt4
Leiden Observatory, Leiden University, P.O. box 9513, 2300 RA Leiden, The Netherlands; 2 Max-Planck-Institut
für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany; 3 Niels Bohr Institute, University of
Copenhagen, Öster Voldgade 5–7, 1350 Copenhagen K., Denmark; 4 Department of Space, Earth and Environment,
Chalmers University of Technology, 41296, Gothenburg, Sweden
1E-mail contact: vthoff at strw.leidenuniv.nl
Temperature is a crucial parameter in circumstellar disk evolution and planet formation because it governs the resistance of the gas to gravitational instability and sets the chemical composition of the planet-forming material. We
set out to determine the gas temperature of the young disk-like structure around the Class 0 protostar IRAS 16293–
2422A. We used Atacama Large Millimeter/submillimeter Array (ALMA) observations of multiple H2 CS J = 7 − 6
and J = 10 − 9 lines from the Protostellar Interferometric Line Survey (PILS) to create a temperature map for the
inner ∼200 AU of the disk-like structure. This molecule is a particularly useful temperature probe because transitions
between energy levels with different Ka quantum numbers operate only through collisions. Based on the H2 CS line
ratios, the temperature is between ∼100–175 K in the inner ∼150 AU, and drops to ∼75 K at ∼200 AU. At thecurrent resolution (0.5′′ ∼70 AU), no jump is seen in the temperature at the disk–envelope interface. The temperature
structure derived from H2 CS is consistent with envelope temperature profiles that constrain the temperature from1000 AU scales down to ∼100 AU, but does not follow the temperature rise seen in these profiles at smaller radii.
Higher angular resolution observations of optically thin temperature tracers are needed to establish whether cooling by
gas-phase water, the presence of a putative disk, or the dust optical depth influences the gas temperature at <∼100 AU
scales. The temperature at 100 AU is higher in IRAS 16293A than in the embedded Class 0/I disk L1527, consistent
with the higher luminosity of the former.
Accepted by Astronomy & Astrophysics
https://arxiv.org/pdf/1911.03495

57

Multiwavelength Polarimetry of the Filamentary Cloud IC5146: II. Magnetic Field
Structures
Jia-Wei Wang1,2 , Shih-Ping Lai1 , Dan P. Clemens3, Patrick M. Koch2 , Chakali Eswaraiah4,5 , Wen-Ping
Chen6 and Anil K. Pandey7
Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan; 2
Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan; 3 Institute for As1

33

trophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA; 4 CAS Key Laboratoryof FAST, NAOC, Chinese Academy of Sciences, Beijing 100101, Peoples Republic of China; 5 National Astronomical Observatories, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, Peoples Republicof China; 6 Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan; 7 Aryabhatta ResearchInstitute of Observational-Sciences (ARIES), Nainital - 263001, India
E-mail contact: jwwang at gapp.nthu.edu.tw
The IC5146 cloud is a nearby star-forming region in Cygnus, consisting of molecular gas filaments in a variety ofevolutionary stages. We used optical and near-infrared polarization data toward the IC5146 cloud, reported in thefirst paper of this series, to reveal the magnetic fields in this cloud. Using the newly released Gaia data, we foundthat the IC5146 cloud may contain two separate clouds: a first cloud, including the densest main filament at a
distance of ∼600 pc, and a second cloud, associated with the Cocoon Nebula at a distance of ∼800 pc. The spatiallyaveraged H-band polarization map revealed a well-ordered magnetic field morphology, with the polarization segments
perpendicular to the main filament but parallel to the nearby sub-filaments, consistent with models assuming that themagnetic field is regulating cloud evolution. We estimated the magnetic field strength using the Davis-ChandrasekharFermi method, and found that the magnetic field strength scales with volume density with a power-law index of ∼0.5
in the density range from NH2 ∼ 10 to 3000 cm−3 , which indicates an anisotropic cloud contraction with a preferred
direction along the magnetic field. In addition, the mass-to-flux ratio of the cloud gradually changes from subcriticalto supercritical from the cloud envelope to the deep regions. These features are consistent with strong magnetic fieldstar-formation models and suggest that the magnetic field is important in regulating the evolution of the IC5146 cloud.
Accepted by ApJ
http://arxiv.org/pdf/1911.11364

58

Measurements of Low Temperature Rate Coefficients for the Reaction of CH with CH2 O
and Application to Dark Cloud and AGB Stellar Wind Models.
Niclas A. West1 , Tom J. Millar2,3 , Marie Van de Sande4 , Edward Rutter1 , Mark A. Blitz1 , Leen Decin4
and Dwayne E. Heard1
School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK; 2 Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN, UK; 3 Institute of Theory
and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA; 4
Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
1E-mail contact: D.E.Heard at leeds.ac.uk
Rate coefficients have been measured for the reaction of CH radicals with formaldehyde, CH2 O, over the temperature
range 31 - 133 K using a pulsed Laval nozzle apparatus combined with pulsed laser photolysis and laser induced fluorescence spectroscopy. The rate coefficients are very large and display a distinct decrease with decreasing temperature
below 70 K, although classical collision rate theory fails to reproduce this temperature dependence. The measured
rate coefficients have been parameterized and used as input for astrochemical models for both dark cloud and AGB
stellar outflow scenarios. The models predict a distinct change (up to a factor of two) in the abundance of ketene,
H2 CCO, which is the major expected molecular product of the CH + CH2 O reaction.
Accepted by The Astrophysical Journal (November 2019)https://arxiv.org/pdf/1910.07996

59

Morphological signatures induced by dust back reaction in discs with an embedded
planetChao-Chin Yang1 and Zhaohuan Zhu1
Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Box 454002,
Las Vegas, NV 89154-4002, USA
1E-mail contact: ccyang at unlv.edu
Recent observations have revealed a gallery of substructures in the dust component of nearby protoplanetary discs,
34

including rings, gaps, spiral arms, and lopsided concentrations. One interpretation of these substructures is theexistence of embedded planets. Not until recently, however, most of the modelling effort to interpret these observations
ignored the dust back reaction to the gas. In this work, we conduct local-shearing-sheet simulations for an isothermal,
inviscid, non-self-gravitating, razor-thin dusty disc with a planet on a fixed circular orbit. We systematically examine
the parameter space spanned by planet mass (0.1Mth ≤ Mp ≤ 1Mth , where Mth is the thermal mass), dimensionlessstopping time (10−3 ≤ τs ≤ 1), and solid abundance (0 < Z ≤ 1). We find that when the dust particles are tightly
coupled to the gas (τs < 0.1), the spiral arms are less open and the gap driven by the planet becomes deeper withincreasing Z, consistent with a reduced speed of sound in the approximation of a single dust-gas mixture. By contrast,<
when the dust particles are marginally coupled (0.1<∼ τs ∼1), the spiral structure is insensitive to Z and the gap structurein the gas can become significantly skewed and unidentifiable. When the latter occurs, the pressure maximum radiallyoutside of the planet is weakened or even extinguished, and hence dust filtration by a low-mass (Mp < Mth ) planet
could be reduced or eliminated. Finally, we find that the gap edges where the dust particles are accumulated as wellas the lopsided large-scale vortices driven by a massive planet, if any, are unstable, and they are broken into numerous
small-scale dust-gas vortices.
Accepted by MNRAS
http://arxiv.org/pdf/1911.06433

60

Dense Cores, Filaments and Outflows in the S255IR Region of High Mass Star Formation
Igor I. Zinchenko1 , Sheng-Yuan Liu2 , Yu-Nung Su2 , Kuo-Song Wang2 and Yuan Wang3
Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul’yanov str., 603950 Nizhny Novgorod, Russia;
Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan, R.O.C.; 3
Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
1

2

E-mail contact: zin at appl.sci-nnov.ru
We investigate at a high angular resolution the spatial and kinematic structure of the S255IR high mass star-forming
region, which demonstrated recently the first disk-mediated accretion burst in the massive young stellar object. The
observations were performed with ALMA in Band 7 at an angular resolution ∼ 0.′′ 1, which corresponds to ∼ 180 AU.
The 0.9 mm continuum, C34 S(7–6) and CCH N = 4 − 3 data show a presence of very narrow (∼ 1000 AU), very dense(n ∼ 107 cm−3 ) and warm filamentary structures in this area. At least some of them represent apparently dense walls
around the high velocity molecular outflow with a wide opening angle from the S255IR-SMA1 core, which is associatedwith the NIRS3 YSO. This wide-angle outflow surrounds a narrow jet. At the ends of the molecular outflow there
are shocks, traced in the SiO(8–7) emission. The SiO abundance there is enhanced by at least 3 orders of magnitude.
The CO(3–2) and SiO(8–7) data show a collimated and extended high velocity outflow from another dense core inthis area, SMA2. The outflow is bent and consists of a chain of knots, which may indicate periodic ejections possibly
arising from a binary system consisting of low or intermediate mass protostars. The C34 S emission shows evidence ofrotation of the parent core. Finally, we detected two new low mass compact cores in this area (designated as SMM1
and SMM2), which may represent prestellar objects.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/1911.11447

35

New Jobs

15 Double-degree PhD fellowships in proto-planetary disk
and exoplanet research
The fellowships are part of the Marie Sklodowska-Curie Innovative Training Network (ITN) CHAMELEON – ’virtual laboratories for exoplanets and planet forming disks’, which combines the expertise of eight European research
institutes (Universities of St Andrews, Groningen, Copenhagen, Edinburgh, Leuven and Antwerp, the Max-Planck
Institute in Heidelberg and the Netherlands Institute for Space Research) to cover relevant aspects of this complex
modelling task, joining the expertise in protoplanetary disks and exoplanetary atmospheres, including observation andinterpretation. The network will consist of 15 Early Stage Researchers (PhD students) and the respective supervisorsand local research groups. Deadline for applying is February 3, 2020. Starting date is September 1, 2020 or as soon
as possible thereafter. Students of all nationalities are welcomed. A detailed description of all the 15 announced PhD
fellowships of the network is listed at http://chameleon.wp.st-andrews.ac.uk/recruitment/.

Postdoctoral Position in Star Formation Studies
Applications are invited for a two-year postdoctoral position in star formation studies at The University of Western
Ontario. The successful applicant will work with Prof. Shantanu Basu, and experience with computational simulationsof present-day star formation or first stars in the universe is preferred.
The applications will be assessed by the background and research interests of the candidate and the synergy of possible
research with the Basu group. To apply, please send a cover letter, a cv including a publication list and list of references,
and a brief description of research experience and interests, to basu@uwo.ca. Applications will be considered from 3
January, 2020.
A description of ongoing research projects in the group and a list of recent publications can be obtained fromhttp://physics.uwo.ca/~basu/.

Postdoc Position in Star Formation
The Department of Astronomy at the College of Liberal Arts and Sciences is seeking a Post-doctoral Associate in starformation. This position will be working in a project on the formation of the initial mass function led by Dr. Adam
Ginsburg and Dr. Elizabeth Lada in the Department of Astronomy.
The applicant must have PhD in astrophysics by the date of appointment. Experience with radio and millimeter data
reduction, infrared stellar photometry, and/or stellar population synthesis modeling is preferred. This position will
be initially awarded for one year, and, contingent upon strong performance and conduct and availability of funds,
may be renewed on a year-to-year contract for up to three years. The salary is competitive and commensurate withqualifications and experience, and includes a full benefits package.
Minimum Qualifications: PhD in astrophysics by the date of appointment.
Preferred Qualifications: Experience with radio and millimeter data reduction, infrared stellar photometry, and/or
stellar population synthesis modeling is preferred.
36

Application Instructions: For full consideration, applications must be submitted online at http://apply.interfolio.com/71803
and must include: (1) a short (limited to three pages) statement of scientific interests, (2) a CV including list of publications, (3) and the names and email addresses for three references must be provided on the application. Afterinitial review, applicants who are chosen to receive further consideration will be asked to request confidential lettersof recommendation from the references.
For full consideration, applications should be submitted by January 15, and a decision will be made by February
28, 2020. The position can start as soon as March 1, 2020, but no later than September 1, 2020. For additional
information you may address your specific questions to Adam Ginsburg at adamginsburg@ufl.edu.
All candidates for employment are subject to a pre-employment screening which includes a review of criminal records,
reference checks, and verification of education.
The selected candidate will be required to provide an official transcript to the hiring department upon hire. A transcript
will not be considered ’official’ if a designation of ’Issued to Student’ is visible. Degrees earned from an educational
institution outside of the United States require evaluation by a professional credentialing service provider approved by
the National Association of Credential Evaluation Services (NACES), which can be found at http://www.naces.org/.
The University of Florida is an equal opportunity institution dedicated to building a broadly diverse and inclusive
faculty and staff. Searches are conducted in accordance with Florida’s Sunshine Law. If an accommodation due todisability is needed in order to apply for this position, please call (352) 392-2477 or the Florida Relay System at (800)955-8771 (TDD).
https://apply.interfolio.com/71803

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37

Meetings

Star Formation: From Clouds to Discs
A Tribute to the Career of Lee Hartmann
17 - 20 August 2020, Malahide, Ireland

The Dublin Institute for Advanced Studies is proud to announce the upcoming conference “Star Formation: From
Clouds to Discs - A Tribute to the Career of Lee Hartmann". It will be held on 17th -20th August, 2020, inMalahide, County Dublin, Ireland.
Scientiﬁc Rationale:Star formation involves many physical processes, scales, and different types of objects, the origin of which are subject
to intense debate. How do molecular clouds form and how do they evolve? What are the key processes that define theinitial stellar mass function? What are the physical properties of small stellar groups, as well as stellar clusters? How
do accretion discs evolve to allow grain growth and planet formation? How is angular momentum redistributed withtime from molecular cloud scales down to those of individual stars? What can we learn from episodic accretion andoutflow? What is the role of stellar feedback in the rapid dispersal of the parent cloud, as well as in sequential starformation? Our understanding of how stars are born to their dispersal as young moving groups has grown enormously
in the last decade. In part this is due to new facilities like ALMA and space observatories such as Herschel and GAIA,
but also increasingly more powerful and realistic simulations of the processes involved.
This conference will celebrate the career of Lee Hartmann, who has made enormous contributions to our field during
his productive life. For over 3 decades Lee has been a leading pioneer in characterizing the physics of molecular clouds,
stars and planet formation. His scientific breadth and impact can be seen in his studies on molecular cloud formationand cloud lifetimes. This has led to a change in our paradigm of star formation towards more rapid evolution. He has
been among the first to recognize the importance of accretion and magnetic fields in the phenomena observed in youngstars, and has led ground-breaking efforts characterizing these effects. As a tribute to Lee, but also recognizing that
we stand on the threshold of a new era with the arrival of JWST, E-ELT and SKA, it is appropriate to take stock of
the most fascinating developments in our field, emphasizing those areas where Lee has made significant contributions.
Scientiﬁc Organizing Committee:
Javier Ballesteros-Paredes (Co-Chair, UNAM, Mexico), John Bally (U. of Colorado Boulder, USA), Ian Bonnell (U. of
St. Andrews, UK), Jerome Bouvier (IPAG, France), Andreas Burkert (LMU, Germany), Nuria Calvet (U. of Michigan,USA), Suzan Edwards (Smith College, USA), Bruce Elmegreen (IBM Research Division, USA), Catherine Espaillat(Boston U., USA), Thomas Henning (MPIA, Germany), Tom Ray (Co-Chair, DIAS, Ireland), Leonardo Testi (ESO,
Germany).
Local Organizing Committee:
Alessio Caratti o Garatti, Eileen Flood, Pauline McGinnis, Simon Purser, Devaraj Rangaswamy (all of DIAS, Ireland).
Registration and abstract submission will open on 3rd February, 2020.
For more details, please see: https://www.dias.ie/cloudstodiscs/38

Call for Review Proposals: Protostars & Planets VII
Deadline April 1, 2020
Kyoto, April 1 (Thu) - 7 (Wed), 2021
The Protostars Planets series has served the community for more than three decades with state-of-the-art compilationsof the current knowledge in the fields of star and planet formation. The previous volume PPVI was published in 2014.
Since then, the field of Protostars & Planets has advanced significantly. The next Protostars & Planets conference
will take place in Kyoto, Japan, April 1-7, 2021. For more details about the schedule and location, please visit theconference website: http://ppvii.org.
A primary outcome of the conference will be a book of review articles as “Protostars and Planets VII”. This announcement is a call for proposals for review chapters in the book and associated talks. The organizers have deﬁned
rules in the submission of proposals, such as “one proposal per person” rule, please refer to the website.
Since the organizers would like to have sufficient time to evaluate the proposals, we ask you to submit proposals byApril 1, 2020. The respective deadlines and dates are the following:
Dec. 13, 2019 (this announcement): Call for review chapters and talk proposals
Apr. 1, 2020 (15:00JST): Deadline for the submission of proposals
Oct. 1, 2020: Decision on review chapters and talks
Oct. 1, 2020: Start of registration
Dec. 1, 2020: End of early registration
Feb. 1, 2021: Submission of extended skeleton papers
Mar. 1, 2021: Submission of the final review article
Apr. 1, 2021: Start of PP7 meeting
Scientific Advisory Committee:João Alves (Austria), Philippe André (France), Isabelle Baraffe (UK), John Carpenter (Chile), Paola Caselli (Germany), Wen-Ping Chen (Taiwan), Kees Dullemond (Germany), Tristan Guillot (France), Alyssa Goodman (USA),
Lynne Hillenbrand (USA), Thomas Henning (Germany), Shigeru Ida (Japan), Doug Johnstone (Canada), Inga Kamp
(Netherlands), Mark Krumholz (Australia), Jeong-Eun Lee (Korea), Victoria Meadows (USA), Michael Meyer (USA),
Richard Nelson (UK), Toshikazu Onishi (Japan), Eve Ostriker (USA), Ilaria Pascucci (USA), Yasuhito Sekine (Japan),
Shogo Tachibana (Japan), Mario Tafalla (Spain), Ewine van Dishoeck (Netherland), and Jonathan Williams (USA)
List of Editors:
Shu-ichiro Inutsuka (Nagoya University), Motohide Tamura (University of Tokyo), Yuri Aikawa (University of Tokyo),
Takayuki Muto (Kogakuin University), and Kengo Tomida (Osaka University)

AIP Thinkshop on Protoplanetary Disk Chemodynamics
11 - 15 May 2020, Leibnitz Institute for Astrophysics Potsdam, Germany
More information/registration at: https://meetings.aip.de/event/1
Protoplanetary disk dynamics are crucial in defining the ecosystem for planet formation. The shift away from turbulence as the main agent for driving disk evolution towards disk winds has recently gained momentum in the community.
At the same time, both the absence of significant levels of turbulence and the presence of large-scale outflows are
gaining observational support. Yet, we are still lacking clear diagnostics for magnetic fields during the T Tauri phase.
The task of extracting useful knowledge about the conditions in planet-forming disks, for instance from molecular-line
ALMA data, is paramount. It demands an approach based on forward modelling combined with synthetic observation
to understand the relevant dynamical and chemical processes shaping the detected emission features.
Highlighting recent developments, we aim to orient the workshop around this chemo-dynamical link with a special
focus on the potential role played by magnetic fields.
39Wheel of Star Formation: A conference dedicated to Prof. Jan PaloušPrague, 14-18th September 2020
https://janfest2020.asu.cas.cz
Dear colleagues,
We would like to announce the forthcoming conference, “Wheel of Star Formation”, to be held in Prague in September
2020. This meeting will celebrate the lifetime work and contributions to astronomy of Professor Jan Palouš.
A key area of Jan’s research is the gas cycle in galaxies, in particular how star formation influences their evolution.
With the advance of new instruments and computational facilities, in recent years there have been many unexpecteddiscoveries from observations and increasingly sophisticated simulations. This brings a desire to think anew about
these topics, and try to connect these sometimes conflicting findings with the greater picture of star formation as amajor element in the evolution of the Universe. The goal of the meeting is to gather researchers actively working in
the field, to present and discuss the latest advances and discoveries, as well as identify the important questions andinitiate discussions on their solution strategies. The topics that will be covered in particular are:• Clusters of galaxies• Inflow into galaxies• Formation of molecular clouds, stars, and star clusters• Stellar kinematics, dynamics, and feedback• The evolution of structures in the ISM• Gas loss from galaxies
The meeting will be five days of contributed and invited talks and posters (14th-18th September 2020).
Pre-registration is now open : https://janfest2020.asu.cas.cz/page/registration
Pre-registration can be cancelled at any time. Further announcements will be sent regarding the dates for registration
and abstract submission in due course.
The conference will take place in the Refectory Hall of the Conference and Social Centre “House for Professed” locatedin the historical centre of Prague. It is a beautiful baroque hall that can accommodate up to 160 people. Moreinformation can be found on the conference web site.
We look forward to welcoming you to Prague !
On behalf of Janfest2020 Organisers

40

The Sharpest Eyes on the Sky:A 2020 vision for high angular resolution astronomy
April 20-24th 2020, University of Exeter, UK
Dear colleagues,
We invite you to join us at the University of Exeter, UK for our conference on high angular resolution astronomy.
The conference will focus on discussing the latest scientific results obtained with optical interferometry and otherhigh angular resolution imaging techniques (ALMA, SPHERE, GPI, ...). There will be presentations on operational
aspects, ongoing and future instrumentation development activities at CHARA and VLTI, and opportunities to discusssynergies between facilities.
We are charging a fee of GBP (£) 95 per delegate (with financial support from ERC project “ImagePlanetFormDiscs”
and the University of Exeter). This cost covers all conference events for the delegate including a ticket for the conference
dinner and attendance at one of two excursions we are offering for the Wednesday afternoon. For more information
as well as details of how to register your attendance and submit a talk/poster abstract, please visit the conference
website at: http://sites.exeter.ac.uk/sharpesteyes2020/
Please note that the deadline for registration and abstract submission is March 6th 2020.
Confirmed Invited Speakers: Arnaud Cassan (IAP Paris, France), Mercedes Filho (University of Porto, Portugal),
Violeta Games (University of Leiden, Netherlands), Tyler Gardner (University of Michigan, USA), Doug Gies (Georgia
State University, USA), Susanne Hoefner (Uppsala University, Sweden), Evgenia Koumpia (University of Leeds, UK),
Jacques Kluska (University of Leuven, Belgium), Sylvestre Lacour (Observatoire de Paris, France), Keiichi Ohnaka(University of Antofagasta, Chile)
Scientific Organisers: Fabien Baron (Georgia State University, USA), Claire Davies (University of Exeter, UK), Sebastian Hoenig (University of Southampton, UK), Stefan Kraus (University of Exeter, UK), Antoine Mérand (European
Southern Observatory, Germany), Claudia Paladini (European Southern Observatory, Chile), Rachael Roettenbacher(Yale University, USA), Gail Schaefer (CHARA Array, USA).

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.

41Summary of Upcoming Meetings

First Stars VI
1 - 6 March 2020 Concepcion, Chile
http://www.astro.udec.cl/FirstStarsVI/
Interstellar Shocks School
22 - 27 March 2020, Les Houches, France
https://www.sciencesconf.org/browse/conference/?confid=8899
Linking Dust, Ice, and Gas in Space19 - 24 April 2020, Capri Islands, Italy
http://www.frcongressi.it/ecla2020/
AIP Thinkshop on Protoplanetary Disk Chemodynamics
11 - 15 May 2020, Leibnitz Institute for Astrophysics Potsdam, Germany
https://meetings.aip.de/event/1
Planet Formation: From Dust Coagulation to Final Orbital Assembly
1 - 26 June 2020, Munich, Germany
http://www.munich-iapp.de/planetformation
Cool Stars, Stellar Systems, and the Sun 21
21 - 26 June 2020, Toulouse, France
https://coolstars21.github.io/
The Physics of Star Formation: From Stellar Cores to Galactic Scales; 29 June - 3 July 2020, Lyon,
Francehttp:/staratlyon.univ-lyon1.fr/en
Illuminating the Dusty Universe: A Tribute to the Work of Bruce Draine
6 - 10 July 2020, Florence, Italy
https://web.astro.princeton.edu/IlluminatingTheDusty Universe
The Early Phase of Star Formation
12 - 17 July 2020, Ringberg, Germany
http://www.mpia.de/homes/stein/EPoS/2020/2020.php
Star Formation: From Clouds to Discs - A Tribute to the Career of Lee Hartmann
17 - 20 August 2020, Malahide, Ireland
https://www.dias.ie/cloudstodiscs/
Star Formation in Diﬀerent Environments 202024 - 28 August 2020, Quy Nhon, Vietnam
http://icisequynhon.com/conferences/sfde/
Planetary Science: The Young Solar System
6 - 12 September 2020, Quy Nhon, Vietnam
http://www.icisequynhon.com/conferences/planetary_science/
Wheel of Star Formation: A conference dedicated to Prof. Jan Palouš
14 - 18 September 2020, Prague, Czech Republic
https://janfest2020.asu.cas.cz
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

42

From Clouds to Planets II: The Astrochemical Link
28 September - 2 October 2020, Berlin, Germany
https://events.mpe.mpg.de/event/12/
The Aftermath of a Revolution: Planet Formation Five Years after HL Tau
7 - 11 December 2020, Chile
https://www.eso.org/sci/meetings/2020/hltau2020.html
Protostars & Planets VII
1 - 7 April 2021, Kyoto, Japan
http://www.ppvii.org

Short Announcements

100th Anniversary of George Herbig
George Herbig was born on January 2, 1920. He was one of the great figures of 20th century astronomy, and when hepassed away at age 93, he had succeeded, in a career spanning more than 70 years, to build the foundation upon which
our present-day understanding of star birth and young stars rests. His pioneering studies of the T Tauri stars weresynthesized in his famous 1962 review, which sparked a general awareness and interest in the nature of young low-massstars. His identification of intermediate-mass young stars, the Herbig Ae/Be stars, has led to thousands of detailed
studies, and his recognition that Herbig-Haro objects move supersonically away from embedded young stars led to anunderstanding of bipolar outflows from young stars. His 1977 paper on the FU Orionis phenomenon established thatearly stellar evolution is not a steady progression, but is punctuated by violent episodes. At an age when most people
retire, Herbig and his students embarked on a series of observational studies of very young clusters of stars, which
supported the idea that star formation in clusters proceeds over an extended period, with low-mass stars forming
first, until the birth of massive stars suddenly destroys the stellar cradle and brings further star formation to a rapid
halt. Herbig was a brilliant trailblazer, who found and lit the way that he knew future generations would continue toexplore.
A scientific biography of George Herbig can be downloaded from http://ifa.hawaii.edu/SP1
The book discusses the circumstances of Herbig’s main achievements and puts them into the context of current results.
The following lists the chapters of the book:
1 The Budding Astronomer
2 T Tauri Stars
3 Herbig-Haro Objects
4 The Herbig Ae/Be Stars
5 FUors and EXors
6 Clustered Star Formation
7 The Interstellar Medium
8 Molecular Spectroscopy
9 Variable and Exotic Stars
10 From Astronomer to Professor
11 Instruments and Telescopes
12 Closing Remarks
Bo Reipurth43