The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 362 — 28 February 2023
Editor: João Alveswww.starformation.news

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Cover image caption
NGC1850, a "globular-like" star cluster in the LMC, with a mass of about 105 M . NGC1850 contains two clusters, the main
cluster about 100 million years old, and a smaller 4 million years old cluster. Credits: NASA, ESA, and Martino Romaniello(ESO); Image processing by Martino Romaniello, Richard Hook, Bob Fosbury and the Hubble European Space Agency.

Note from the Editor

The Star Formation Newsletter is now on the web at www.starformation.news. This PDF file contains the monthly
Abstracts and links to the different Newsletter sections. Red text in this PDF is a url link. Submitting an abstract to
the SFN is as simple as entering the arXiv ID (e.g., 2006.10139) in a web form on the SFN web site. Do not remove
the LATEX formatting when submitting to the arXiv. If you do, your abstract will not look great either at thearXiv or the SFN.

Abstracts
Stable accretion and episodic outflows in the young transition disk system GM Aurigae
J. Bouvier, A. Sousa, K. Pouilly, J. M. Almenara, J. -F. Donati, S. H. P. Alencar, A. Frasca, K. Grankin, A.
Carmona, G. Pantolmos, B. Zaire, X. Bonfils, A. Bayo, L. M. Rebull, J. Alonso-Santiago, J. F. Gameiro, N. J.
Cook, E. Artigau, the SPIRou Legagy Survey, Consortium F We investigate the structure and dynamics of themagnetospheric accretion region and associated outflows on a scale smaller than 0.1 au around the young transitional
disk system GM Aur. We monitored the variability of the system on timescales ranging from days to months, using
high-resolution optical and near-infrared spectroscopy, multiwavelength photometry, and low-resolution near-infrared
spectroscopy, over a total duration of six months (30 rotational cycles). We analyzed the photometric and line profile
variability to characterize the accretion and ejection processes. The luminosity of the system is modulated by surface
spots at the stellar rotation period of 6.04 days. The Balmer, Paschen, and Brackett hydrogen lines as well as the
HeI 5876 A and HeI 10830 A line profiles are modulated on the same period. The PaB line flux correlates withthe photometric excess in the u’ band, which suggests that most of the line emission originates from the accretion
process. High-velocity redshifted absorptions reaching below the continuum periodically appear in the near-infraredline profiles at the rotational phase in which the veiling and line fluxes are the largest. These are signatures of a stableaccretion funnel flow and associated accretion shock at the stellar surface. This large-scale magnetospheric accretion
structure appears fairly stable over at least 15 and possibly up to 30 rotational periods. In contrast, outflow signatures
randomly appear as blueshifted absorption components in the Balmer and HeI 10830 A line profiles and disappear ona timescale of a few days. The coexistence of a stable, large-scale accretion pattern and episodic outflows supports
magnetospheric ejections as the main process occurring at the star-disk interface. Stable magnetospheric accretionand episodic outflows appear to be physically linked on a scale of a few stellar radii in this system.

2. Young stellar objects, accretion disks, and their variability with Rubin Observatory
LSST

R. Bonito, L. Venuti, S. Ustamujic, P. Yoachim, R. A. Street, L. Prisinzano, P. Hartigan, M. G. Guarcello, K.
G. Stassun, T. Giannini, E. D. Feigelson, A. Caratti o Garatti, S. Orlando, W. I. Clarkson, P. McGehee, E. C.
Bellm, J. E. Gizis F Vera C. Rubin Observatory, through the Legacy Survey of Space and Time (LSST), will allow

us to derive a panchromatic view of variability in young stellar objects (YSOs) across all relevant timescales. Indeed,both short-term variability (on timescales of hours to days) and long-term variability (months to years), predominantly
driven by the dynamics of accretion processes in disk-hosting YSOs, can be explored by taking advantage of the multi-

2

band filters option available in Rubin LSST, in particular the u, g, r, i filters that enable us to discriminate between
photospheric stellar properties and accretion signatures. The homogeneity and depth of sky coverage that will beachieved with LSST will provide us with a unique opportunity to characterize the time evolution of disk accretionas a function of age and varying environmental conditions (e.g. field crowdedness, massive neighbors, metallicity),by targeting different star-forming regions. In this contribution to the Rubin LSST Survey Strategy Focus Issue,
we discuss how implementing a dense observing cadence to explore short-term variability in YSOs represents a key
complementary effort to the Wide-Fast-Deep observing mode that will be used to survey the sky over the full durationof the main survey (≈10 years). The combination of these two modes will be vital to investigate the connection between
the inner disk dynamics and longer-term eruptive variability behaviors, such as those observed on EXor objects.

3. A potential site for wide-orbit giant planet formation in the IM Lup disk

Arthur Bosman, Johan Appelgren, Edwin A. Bergin, Michiel Lambrechts, Anders Johansen F The radialtransport, or drift, of dust has taken a critical role in giant planet formation theory. However, it has been challenging
to identify dust drift pile ups in the hard-to-observe inner disk. We find that the IM Lup disk shows evidence thatit has been shaped by an episode of dust drift. Using radiative transfer and dust dynamical modeling we study theradial and vertical dust distribution. We find that high dust drift rates exceeding 110 Mearth/Myr are necessary to
explain both the dust and CO observations. Furthermore, the bulk of the large dust present in the inner 20 au needs
to be vertically extended, implying high turbulence alpha z > 10−3 and small grains (0.2-1 mm). We suggest that
this increased level of particle stirring is consistent with the inner dust-rich disk undergoing turbulence triggered by
the vertical shear instability. The conditions in the IM Lup disk imply that giant planet formation through pebble
accretion is only effective outside 20 au. If such an early, high turbulence inner region is a natural consequence of highdust drift rates, then this has major implications for understanding the formation regions of giant planets including
Jupiter and Saturn.

Predicting Stellar Mass Accretion: An Optimized Echo-State Network Approach in

4. Time Series Modeling

Gianfranco Bino, Shantanu Basu, Ramit Dey, Sayantan Auddy, Lyle Muller, Eduard I. Vorobyov F Modelingthe dynamics of the formation and evolution of protostellar disks as well as the history of stellar mass accretion
typically involve the numerical solution of complex systems of coupled differential equations. The resulting massaccretion history of protostars is known to be highly episodic due to recurrent instabilities and also exhibits shorttimescale flickering. By leveraging the strong predictive abilities of neural networks, we extract some of the critical
temporal dynamics experienced during the mass accretion including periods of instability. Particularly, we utilize anovel form of the Echo-State Neural Network (ESN), which has been shown to efficiently deal with data having inherent
nonlinearity. We introduce the use of Optimized-ESN (Opt-ESN) to make model-independent time series forecasting ofmass accretion rate in the evolution of protostellar disks. We apply the network to multiple hydrodynamic simulations
with different initial conditions and exhibiting a variety of temporal dynamics to demonstrate the predictability of
the Opt-ESN model. The model is trained on simulation data of ∼ 1 − 2 Myr, and achieves predictions with a low
normalized mean square error (∼ 10−5 to 10−3 ) for forecasts ranging between 100 and 3800 yr. This result shows thepromise of the application of machine learning based models to time-domain astronomy.

5. The evolution of phase space densities in star-forming regions

George A. Blaylock-Squibbs, Richard J. Parker F The multi-dimensional phase space density (both positionand velocity) of star-forming regions may encode information on the initial conditions of star and planet formation.
Recently, a new metric based on the Mahalanobis distance has been used to show that hot Jupiters are more likely to befound around exoplanet host-stars in high 6D phase space density, suggesting a more dynamic formation environment
for these planets. However, later work showed that this initial result may be due to a bias in the age of hot Jupiters
and the kinematics of their host stars. We test the ability of the Mahalanobis distance and density to differentiate
more generally between star-forming regions with different morphologies by applying it to static regions that are either
substructured or smooth and centrally concentrated. We find that the Mahalanobis distance is unable to distinguishbetween different morphologies, and that the initial conditions of the N-body simulations cannot be constrained using
only the Mahalanobis distance or density. Furthermore, we find that the more dimensions in the phase space the lesseffective the Mahalanobis density is at distinguishing between different initial conditions. We show that a combination3

of the mean three-dimensional (x, y, z) Mahalanobis density and the Q-parameter for a region can constrain its initialvirial state. However this is due to the discriminatory power of the Q-parameter and not from any extra information
imprinted in the Mahalanobis density. We therefore recommend continued use of multiple diagnostics for determining
the initial conditions of star-forming regions, rather than relying on a single multi-dimensional metric.

6. Early Evolution and 3D Structure of Embedded Star Clusters

Claude Cournoyer-Cloutier, Alison Sills, William E. Harris, Sabrina M. Appel, Sean C. Lewis, Brooke Polak,
Aaron Tran, Martijn J. C. Wilhelm, Mordecai-Mark Mac Low, Stephen L. W. McMillan, Simon Portegies
Zwart F We perform simulations of star cluster formation to investigate the morphological evolution of embedded

star clusters in the earliest stages of their evolution. We conduct our simulations with Torch, which uses the AMUSE
framework to couple state-of-the-art stellar dynamics to star formation, radiation, stellar winds, and hydrodynamics in
FLASH. We simulate a suite of 104 M clouds at 0.0683 pc resolution for ∼ 2 Myr after the onset of star formation, withvirial parameters α = 0.8, 2.0, 4.0 and different random samplings of the stellar initial mass function and prescriptions
for primordial binaries. Our simulations result in a population of embedded clusters with realistic morphologies (sizes,
densities, and ellipticities) that reproduce the known trend of clouds with higher initial α having lower star formation
efficiencies. Our key results are as follows: (1) Cluster mass growth is not monotonic, and clusters can lose up tohalf of their mass while they are embedded. (2) Cluster morphology is not correlated with cluster mass and changes
over ∼ 0.01 Myr timescales. (3) The morphology of an embedded cluster is not indicative of its long-term evolution
but only of its recent history: radius and ellipticity increase sharply when a cluster accretes stars. (4) The dynamical
evolution of very young embedded clusters with masses . 1000 M is dominated by the overall gravitational potentialof the star-forming region rather than by internal dynamical processes such as two- or few-body relaxation.

7. A Herschel study of the high-mass protostar IRAS20126+4104

R. Cesaroni, F. Faustini, D. Galli, A. Lorenzani, S. Molinari, L. Testi F We performed Herschel observationsof the continuum and line emission from the high-mass star-forming region IRAS20126+4104, which hosts a wellstudied B-type (proto)star powering a bipolar outflow and is associated with a Keplerian circumstellar disk. The
continuum images at six wavelengths allowed us to derive an accurate estimate of the bolometric luminosity and massof the molecular clump enshrouding the disk. The same region has been mapped in 12 rotational transitions of carbon
monoxide, which were used in synergy with the continuum data to determine the temperature and density distribution
inside the clump and improve upon the mass estimate. The maps of two fine structure oxygen far-IR lines were used toestimate the volume density of the shocked region at the surface of the southern lobe of the outflow and the mass-loss
rate. Our findings lend further support to the scenario previously proposed by various authors, confirming that at theorigin of the bolometric luminosity and bipolar outflow from IRAS20126+4104 is a B-type star located at the centreof the Keplerian disk.

8. Addressing Systematics in the Traceback Age of the β Pictoris Moving Group

Dominic Couture, Jonathan Gagné, René Doyon F We characterize the impact of several sources of systematic
errors on the computation of the traceback age of the β Pictoris Moving Group (βPMG). We find that uncorrected
gravitational redshift and convective blueshift bias absolute radial velocity measurements by ∼ 0.6 kms−1 , which leads
to erroneously younger traceback ages by ∼ 2 Myr. Random errors on parallax, proper motion, and radial velocity
measurements lead to an additional bias of ∼ 1.5 Myr on traceback ages. Contamination of astrometric and kinematic
data by kinematic outliers and unresolved multiple systems in the full input sample of 76 members and candidates ofβPMG also erroneously lowers traceback ages by ∼ 3 Myr. We apply our new numerical traceback analysis tool toa core sample of 25 carefully vetted members of βPMG using Gaia Data Release 3 (DR3) data products and otherkinematic surveys. Our method yields a corrected age of 20.4 ± 2.5 Myr, bridging the gap between kinematic ages
(11−19 Myr) and other age-dating methods, such as isochrones and lithium depletion boundary (20−26 Myr). We
explore several association size metrics that can track the spatial extent of βPMG over time, and we determine thatminimizing the variance along the heliocentric curvilinear coordinate ξ 0 (i.e., toward the Galactic Center) offers theleast random and systematic errors, due to the wider UVW space velocity dispersion of members of βPMG along the
U-axis, which tends to maximize the spatial growth of the association along the ξ 0 -axis over time.

4Extinction of Taurus, Orion, Perseus and California Molecular Clouds Based on the

9. LAMOST, 2MASS and Gaia surveys I: Three-dimensional Extinction and Structure

Zhetai Cao, Biwei Jiang, He Zhao, Mingxu Sun F The three-dimensional extinction and structure are studied for

the Taurus, Orion, Perseus and California molecular clouds based on the LAMOST spectroscopy. Stellar color excess
is calculated with the intrinsic color index derived from the atmospheric parameters in the LAMOST DR8 catalog
and the observed color index in the Gaia EDR3 and the 2MASS PSC. In combination with the distance from the Gaia
EDR3 parallax, the three-dimensional dust extinction maps are retrieved in the color excesses EGBP ,GRP and EJ,KS
with an uncertainty of ∼0.03mag and ∼0.07mag respectively. The extinction maps successfully separate the clouds
that overlap in the sky area and manifest the structure of the individual cloud. Meanwhile, a bow-like structure isfound with a distance range from 175pc to 250pc, half of which is a part of the Per-Tau Shell in similar coordinatesand distance while the other half is not. Three low-extinction rings are additionally discovered and briefly discussed.

Probing the Milky Way stellar and brown dwarf initial mass function with modern

10. microlensing observations

Gilles Chabrier, Romain Lenoble F We use recent microlensing observations toward the central bulge of the Galaxy
to probe the overall stellar plus brown dwarf initial mass function (IMF) in these regions well within the brown dwarf
domain. We find that the IMF is consistent with the same Chabrier (2005) IMF characteristic of the Galactic disk.
In contrast, other IMFs suggested in the literature overpredict the number of short-time events, thus of very-low mass
stars and brown dwarfs, compared with observations. This, again, supports the suggestion that brown dwarfs andstars form predominantly via the same mechanism. We show that claims for different IMFs in the stellar and substellar
domains rather arise from an incorrect parameterization of the IMF. Furthermore, we show that the IMF in the central
regions of the bulge seems to be bottom-heavy, as illustrated by the large number of short-time events compared withthe other regions. This recalls our previous analysis of the IMF in massive early type galaxies and suggests the samekind of two-phase formation scenario, with the central bulge initially formed under more violent, burst-like conditions
than the rest of the Galaxy.

Near-Infrared Polarimetry and H emission toward Massive Young Stars: Discovery of2
11. a Bipolar Outflow associated to S235
e2s3

R. Devaraj, A. Caratti o Garatti, L. K. Dewangan, R. Fedriani, T. P. Ray, A. Luna F We present a near-infrared

H band polarimetric study toward the S235 e2s3 protostar, obtained using the POLICAN instrument on the 2.1m
OAGH telescope. The images reveal a bipolar outflow with a total length of about 0.5pc. The outflow nebulosity
presents a high degree of linear polarization (∼ 80%) and reveals a centrosymmetric pattern with the polarization
position angles. The polarization characteristics suggest their origin to be single scattering associated with dust in
the outflow. Using multiwavelength archival data, we performed spectral energy distribution (SED) fitting based onradiative transfer models of turbulent core accretion theory. The best-fit SED model indicated that the protostar has
a mass of 6.8 ± 1.2 M , with a disk accretion rate of 3.6 ± 1.2 × 10−4 M yr−1 and a total bolometric luminosity of
9.63 ± 2.1 × 103 L . Narrowband H2 (2.12 µm) observations show shocked emission along the bipolar lobes tracing
the jet’s interaction with the surrounding medium. The estimated H2 luminosity of the outflow is 2.3+3.5−1.3 L , whichmatched the known power-law correlation with the source bolometric luminosity, similar to other high-mass outflows.
The orientation of the bipolar outflow was found to be parallel to the local magnetic field direction. The overall results
assert the fact that the S235 e2s3 source is a massive young star driving a highly collimated bipolar outflow throughdisk accretion.

Magnetospheric accretion at the late phases of the Pre-Main-Sequence evolution. The

12. case of RZ Psc

D. V. Dmitriev, V. P. Grinin, I. S. Potravnov, T. A. Ermolaeva F It has been shown that during the outburstof accretion activity observed in UX Ori type star RZ Psc in 2013, the accretion rate increased approximately by anorder of magnitude. This means that the accretion process at the late stages of the Pre-Main Sequence evolution isvery unstable. Using the spectra obtained during this episode we have studied the magnetospheric emission in theHα line. Models of magnetospheric accretion are calculated to obtain the parameters of the magnetosphere fromthis observation. In present work we have taken into account the influence of the recombination delay effect duringgas motion in the stellar magnetosphere. The accounting for this effect and the presence of the magnetospheric5absorption in the IR CaII triplet lines and its absence in D Na I resonance lines allowed us to place a lower limit on thetemperature in the magnetosphere at ≈ 10000 K, which significantly improved precision of our estimate of accretion
rate. According to the best fit model the logarithm of accretion rate is log Ṁ = −10.1 ± 0.3 (Ṁ ≈ 7 × 10−11 M yr−1 )and the inclination angle of RZ Psc is 43 ± 3◦ . It is less than the inclination, typical for the UX Ori stars (about70◦ ), that explains the weak photometric variability of this star. Using the obtained accretion rate and magnetosphereradius we estimate the strength of the dipole component of the magnetic field of RZ Psc ≈ 0.1 kGs.

IC 5146 dark Streamer: is a first reliable candidate of edge collapse, hub-filament sys-

13. tems, and intertwined sub-filaments?

L. K. Dewangan, N. K. Bhadari, A. Men’shchikov, E. J. Chung, R. Devaraj, C. W. Lee, A. K. Maity, T. BaugF The paper presents an analysis of multi-wavelength data of a nearby star-forming site IC 5146 dark Streamer (d∼600 pc), which has been treated as a single and long filament, fl. Two hub-filament systems (HFSs) are known toward
the eastern and the western ends of fl. Earlier published results favor the simultaneous evidence of HFSs and theend-dominated collapse (EDC) in fl. Herschel column density map (resolution ∼1300 .5) reveals two intertwined subfilaments (i.e., fl-A and fl-B) toward fl, displaying a nearly double helix-like structure. This picture is also supportedby the C18 O(3-2) emission. The scenario "fray and fragment" may explain the origin of intertwined sub-filaments. In
the direction of fl, two cloud components around 2 and 4 km s−1 are depicted using the 13 CO(1-0) and C18 O(1-0)
emission, and are connected in velocity space. The HFSs are spatially found at the overlapping areas of these cloudcomponents and can be explained by the cloud-cloud collision scenario. Non-thermal gas motion in fl with larger
Mach number is found. The magnetic field position angle measured from the filament’s long axis shows a linear trend
along the filament. This signature is confirmed in the other nearby EDC filaments, presenting a more quantitative
confirmation of the EDC scenario. Based on our observational outcomes, we witness multiple processes operational in
IC 5146 Streamer. Overall, the Streamer can be recognized as the first reliable candidate of edge collapse, HFSs, andintertwined sub-filaments together.

Formation of the First Planetesimals via the Streaming Instability in Globally Turbu-

14. lent Protoplanetary Disks?

Paul R. Estrada, Orkan M. Umurhan F Using self-consistent models of turbulent particle growth in an evolving protoplanetary nebula of solar composition we find that recently proposed local metallicity and Stokes number
criteria necessary for the streaming instability to generate gravitationally bound particle overdensities are generally
not approached anywhere in the disk during the first million years, an epoch in which meteoritic and observational
evidence strongly suggests that the formation of the first planetesimals and perhaps giant planet core accretion isalready occurring.

of CH3CHCO in TMC-1 with the QUIJOTE line survey
15. Discovery
R. Fuentetaja, C . Bermúdez, C. Cabezas, M. Agúndez, B. Tercero, N. Marcelino, J. R. Pardo, L. Margulès,
R. A. Motiyenko, J. -C. Guillemin, P. de Vicente, J. Cernicharo F We report the detection of methyl ketene

towards TMC-1 with the QUIJOTE line survey. Nineteen rotational transitions with rotational quantum numbers
ranging from J = 3 up to J = 5 and Ka =< 2 were identified in the frequency range 32.0-50.4 GHz, 11 of which arise
above the 3σ level. We derived a column density for CH3CHCO of N=1.5x1011 cm−2 and a rotational temperatureof 9 K. Hence, the abundance ratio between ketene and methyl ketene, CH2CO/CH3CHCO, is 93. This species is
the second C3H4O isomer detected. The other, trans-propenal (CH2CHCHO), corresponds to the most stable isomerand has a column density of N=(2.2+-0.3)x1011 cm−2 , which results in an abundance ratio CH2CHCHO/CH3CHCO
of 1.5. The next non-detected isomer with the lowest energy is cis-propenal, which is therefore a good candidate for
future discovery. We have carried out an in-depth study of the possible gas-phase chemical reactions involving methyl
ketene to explain the abundance detected, achieving good agreement between chemical models and observations.

A survey for variable young stars with small telescopes: VI – Analysis of the outbursting

16. Be stars NSW284, Gaia19eyy, and VES263

Dirk Froebrich, et al. F This paper is one in a series reporting results from small telescope observations of variable

young stars. Here, we study the repeating outbursts of three likely Be stars based on long-term optical, near-infrared,
and mid-infrared photometry for all three objects, along with follow-up spectra for two of the three. The sources are6characterised as rare, truly regularly outbursting Be stars. We interpret the photometric data within a framework formodelling light curve morphology, and find that the models correctly predict the burst shapes, including their larger
amplitudes and later peaks towards longer wavelengths. We are thus able to infer the start and end times of massloading into the circumstellar disks of these stars. The disk sizes are typically 3-6 times the areas of the central star.
The disk temperatures are 40%, and the disk luminosities are 10% of those of the central Be star, respectively. The
available spectroscopy is consistent with inside-out evolution of the disk. Higher excitation lines have larger velocity
widths in their double-horned shaped emission profiles. Our observations and analysis support the decretion disk
model for outbursting Be stars.

17. 300: An ACA 870 µm Continuum Survey of Orion Protostars and their Evolution

Samuel Federman, S. Thomas Megeath, John J. Tobin, Patrick D. Sheehan, Riwaj Pokhrel, Nolan Habel,
Amelia M. Stutz, William J. Fischer, Lee Hartmann, Thomas Stanke, Mayank Narang, Mayra Osorio, Prabhani
Atnagulov, Rohan Rahatgaonkar F We present an 870 µm continuum survey of 300 protostars from the HerschelOrion Protostar Survey using the Atacama Compact Array (ACA). These data measure protostellar flux densities onenvelope scales ≤8000 au (20") and resolve the structure of envelopes with 1600 au (4") resolution, a factor of 3-5
improvement in angular resolution over existing single-dish 870 µm observations. We compare the ACA observations
to Atacama Large Millimeter/submillimeter Array 12 m array observations at 870 µm with ∼0.1 (40 au) resolution.
Using the 12 m data to measure the fluxes from disks and the ACA data within 2500 au to measure the combined
disk plus envelope fluxes, we calculate the 12 m/ACA 870 µm flux ratios. Our sample shows a clear evolution inthis ratio. Class 0 protostars are mostly envelope-dominated with ratios <0.5. In contrast, Flat Spectrum protostars
are primarily disk-dominated with ratios near 1, although with a number of face-on protostars dominated by theirenvelopes. Class I protostars span the range from envelope to disk-dominated. The increase in ratio is accompanied
by a decrease in the envelope fluxes and estimated mass infall rates. We estimate that 80% of the mass is accreted
during the envelope-dominated phase. We find that the 12 m/ACA flux ratio is an evolutionary indicator that largely
avoids the inclination and foreground extinction dependence of spectral energy distribution-based indicators.

A Three-Dimensional Analytical Model of the Interstellar Extinction within the Nearest

18. Kiloparsec

G. A. Gontcharov, A. V. Mosenkov, S. S. Savchenko, V. B. Il’in, A. A. Marchuk, A. A. Smirnov, P. A.
Usachev, D. M. Polyakov, N. Hebdon F We present a new version of our analytical model of the spatial interstellar

extinction variations within the nearest kiloparsec. This model treats the 3D dust distribution as a superpositionof three overlapping layers: (1) the layer along the Galactic midplane, (2) the layer in the Gould Belt, and (3) thelayer passing through the Cepheus and Chamaeleon dust cloud complexes. In each layer the dust density decreases
exponentially with increasing distance from the midplane of the layer. In addition, there are sinusoidal longitudinal
extinction variations along the midplane of each layer. We have found the most probable values of 29 parameters of
our model using four data sets: the 3D stellar reddening maps by Gontcharov (2017), Lallement et al. (2019), andGreen et al. (2019) and the extinctions inferred by Anders et al. (2022) for 993291 giants from the Gaia EDR3. All of
the data give similar estimates of the model parameters. The extinction for a star or a point in space is predicted byour model with an accuracy from σ(AV ) = 0.07 to 0.37 for high and low Galactic latitudes, respectively. The naturalfluctuations of the dust medium dominate in these values. When ignoring the fluctuations of the medium, the average
extinction for an extended object (a galaxy, a star cluster, a dust cloud) or a small region of space is predicted byour model with an accuracy from σ(AV ) = 0.04 to 0.15 for high and low Galactic latitudes, respectively. Green et al.
(2019) and Anders et al. (2022) give in unison an estimate of AV = 0.12m for the extinction at high latitudes acrossthe whole Galactic dust half-layer above or below the Sun with the natural fluctuations of the medium σ(AV ) = 0.06m .
Our model is a step to explain how a substantial amount of dust ended up far from the Galactic midplane.

of 9 eruptive young variables using TANSPEC
19. Spectroscopy
Arpan Ghosh, Saurabh Sharma, Joe P. Ninan, Devendra K. Ojha, A. S. Gour, Rakesh Pandey, Tirthendu
Sinha, Aayushi Verma, Koshvendra Singh, Supriyo Ghosh, Harmeen Kaur F In recent times, 3.6m Devasthal
Optical Telescope (DOT) has installed an optical to near infra-red spectrograph, TANSPEC, which provides spectral
coverage from 0.55-2.5 microns. Using TANSPEC, we have obtained a single epoch spectrum of a set 9 FUors andEXors. We have analysed line profiles of the sources and compared with the previously published spectra of these7

objects. Comparing the line profile shapes with the existing theoretical predictions, we have tried to interpret thephysical processes that are responsible for the current disc evolution and the present accretion dynamics. Our study
has shown the importance for time evolved spectroscopic studies for better understanding the evolution of the accretionmechanisms. This in turn can help in better categorisation of the young stars displaying episodic accretion behaviour.

20. Dynamical age of the Tucana-Horologium young stellar association

Phillip A. B. Galli, Núria Miret-Roig, Hervé Bouy, Javier Olivares, David Barrado F The Tucana-Horologium

association is one of the closest young stellar groups to the Sun and despite the close proximity its age is still debatedin the literature. We take advantage of the state-of-the-art astrometry delivered by the third data release of theGaia space mission combined with precise radial velocity measurements obtained from high-resolution spectroscopy toinvestigate the dynamical age of the association. We perform an extensive traceback analysis using a combination ofdifferent samples of cluster members, metrics to evaluate the minimum size of the association in the past and models
for the galactic potential to integrate the stellar orbits back in time. The dynamical age of 38.5+1.6−8.0 Myr that we derivein this paper is consistent with the various age estimates obtained from isochrone fitting in the literature (30-50 Myr)and reconciles, for the first time, the dynamical age of the Tucana-Horologium association with the age obtained fromlithium depletion (∼ 40 Myr). Our results are independent from stellar models and represent one more step towards
constructing a self-consistent age scale for the young stellar groups of the Solar neighbourhood based on the 3D spacemotion of the stars.

Crescent-Shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha

21. Revealed by ALMA

Naoto Harada, Kazuki Tokuda, Hayao Yamasaki, Asako Sato, Mitsuki Omura, Shingo Hirano, Toshikazu
Onishi, Kengo Tachihara, Masahiro N. Machida F We report on an Atacama Large Millimeter/submillimeter

Array (ALMA) study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The
12CO (J=2-1) images have an angular resolution of 1” ( 250 au) and show high-velocity blueshifted (>70 km s-1)
and redshifted (>50 km s-1) emissions which have 3000 au scale crescent-shaped structures around the protostellar
disk traced in the 1.3mm continuum. Because the high-velocity components of the CO emission are associated withthe protostar, we concluded that the emission traces the pole-on outflow. The blueshifted outflow lobe has a clear
layered velocity gradient with a higher velocity component located on the inner side of the crescent shape, which canbe explained by a model of an outflow with a higher velocity in the inner radii. Based on the directly driven outflow
scenario, we estimated the driving radii from the observed outflow velocities and found that the driving region extends
over two orders of magnitude. The 13CO emission traces a complex envelope structure with arc-like substructures withlengths of 1000au. We identified the arc-like structures as streamers because they appear to be connected to a rotating
infalling envelope. DK Cha is useful for understanding characteristics that are visible by looking at nearly face-on
configurations of young protostellar systems, providing an alternative perspective for studying the star-formation
process.

The Evolution of Protostellar Outflow Cavities, Kinematics, and Angular Distribution

22. of Momentum and Energy in Orion A: Evidence for Dynamical Cores

Cheng-Han Hsieh, Héctor G. Arce, Zhi-Yun Li, Michael Dunham, Stella Offner, Ian W. Stephens, Amelia Stutz,
Tom Megeath, Shuo Kong, Adele Plunkett, John J. Tobin, Yichen Zhang, Diego Mardones, Jaime E. Pineda,
Thomas Stanke, John Carpenter F We present Atacama Large Millimeter/submillimeter Array observations ofthe ∼10 kAU environment surrounding 21 protostars in the Orion A molecular cloud tracing outflows. Our sample iscomposed of Class 0 to flat-spectrum protostars, spanning the full ∼1 Myr lifetime. We derive the angular distributionof outflow momentum and energy profiles and obtain the first two-dimensional instantaneous mass, momentum, andenergy ejection rate maps using our new approach: the Pixel Flux-tracing Technique (PFT). Our results indicate thatby the end of the protostellar phase, outflows will remove ∼2 to 4 M from the surrounding ∼1 M low-mass core.
These high values indicate that outflows remove a significant amount of gas from their parent cores and continuous coreaccretion from larger scales is needed to replenish core material for star formation. This poses serious challenges tothe concept of “cores as well-defined mass reservoirs", and hence to the simplified core-to-star conversion prescriptions.
Furthermore, we show that cavity opening angles, and momentum and energy distributions all increase with theprotostar evolutionary stage. This is clear evidence that even garden-variety protostellar outflows: (a) effectively

8inject energy and momentum into their environments on 10 kAU scales, and (b) significantly disrupt their natal
cores, ejecting a large fraction of the mass that would have otherwise fed the nascent star. Our results support theconclusion that protostellar outflows have a direct impact on how stars get their mass, and that the natal sites ofindividual low-mass star formation are far more dynamic than commonly accepted theoretical paradigms.

Origin of Water in the Terrestrial Planets: Insights from Meteorite Data and Planet

23. Formation Models

Andre Izidoro, Laurette Piani F Water condensed as ice beyond the water snowline, the location in the Sun’s natal
gaseous disk where temperatures were below 170 K. As the disk evolved and cooled, the snowline moved inwards. A
low temperature in the terrestrial planet-forming region is unlikely to be the origin of water on the planets, and thedistinct isotopic compositions of planetary objects formed in the inner and outer disks suggest limited early mixingof inner and outer Solar System materials. Water in our terrestrial planets has rather been derived from H-bearing
materials indigenous to the inner disk and delivered by water-rich planetesimals formed beyond the snowline andscattered inwards during the growth, migration, and dynamical evolution of the giant planets.

24. On the density regime probed by HCN emission

Gerwyn H. Jones, Paul C. Clark, Simon C. O. Glover, Alvaro Hacar F HCN J = 1 − 0 emission is commonlyused as a dense gas tracer, thought to mainly arise from gas with densities ∼ 104 − 105 cm−3 . This has made it apopular tracer in star formation studies. However, there is increasing evidence from observational surveys of ‘resolved’
molecular clouds that HCN can trace more diffuse gas. We investigate the relationship between gas density and HCN
emission through post-processing of high resolution magnetohydrodynamical simulations of cloud-cloud collisions. We
find that HCN emission traces gas with a mean volumetric density of ∼ 3 × 103 cm−3 and a median visual extinctionof ∼ 5 mag. We therefore predict a characteristic density that is an order of magnitude less than the "standard"characteristic density of n ∼ 3 × 104 cm−3 . Indeed, we find in some cases that there is clear HCN emission from thecloud even though there is no gas denser than this standard critical density. We derive luminosity-to-mass conversion
factors for the amount of gas at AV > 8 or at densities n > 2.85 × 103 cm−3 or n > 3 × 104 cm−3 , finding values of
αHCN = 6.79, 8.62 and 27.98 M (K km s−1 pc2 ), respectively. In some cases, the luminosity to mass conversion factor
predicted mass in regions where in actuality there contains no mass.

ACA study of the H2 S/OCS ratio in low-mass protostars
25. ALMA
Tanya Kushwahaa, Maria N. Drozdovskaya, Łukasz Tychoniec, Benoît Tabone F The identification of the main
sulfur reservoir on its way from the diffuse interstellar medium to the cold dense star-forming cores and eventually to
protostars is a long-standing problem. Despite sulfur’s astrochemical relevance, the abundance of S-bearing molecules
in dense cores and regions around protostars is still insufficiently constrained. The goal of this investigation is toderive the gas-phase H2 S/OCS ratio for several low-mass protostars, which could provide crucial information about
the physical and chemical conditions in the birth cloud of Sun-like stars. Using ALMA ACA Band 6 observations,
H2 S, OCS, and their isotopologs are searched for in 10 Class 0/I protostars with different source properties such asage, mass, and environmental conditions. An LTE model is used to fit synthetic spectra to the detected lines andto derive the column densities based solely on optically thin lines. The H2 S and OCS column densities span fourorders of magnitude across the sample. The H2 S/OCS ratio is found to be in the range from 0.2 to above 9.7. IRAS
16293-2422 A and Ser-SMM3 have the lowest ratio, while BHR71-IRS1 has the highest. Only the H2 S/OCS ratioof BHR71-IRS1 agress within uncertainties with the ratio in comet 67P/C−G. The determined gas-phase H2 S/OCS
ratios can be below the upper limits on the solid-state ratios by as much as an order of magnitude. The H2 S/OCS
ratio depends significantly on the environment of the birth cloud, such as UV-irradiation and heating received prior to
the formation of a protostar. The highly isolated birth environment of BHR71-IRS1 is hypothesized to be the reason
for its high gaseous H2 S/OCS ratio due to lower rates of photoreactions and more efficient hydrogenation reactions
under such dark, cold conditions. The gaseous inventory of S-bearing molecules in BHR71-IRS1 appears to be mostsimilar to that of interstellar ices.

9Multi-frequency VLBI observations of maser lines during the 6.7 GHz maser flare in

26. the high-mass young stellar object G24.33+0.14

A. Kobak, A. Bartkiewicz, M. Szymczak, M. Olech, M. Durjasz, P. Wolak, J. O. Chibueze, T. Hirota, J.
Eislöffel, B. Stecklum, A. Sobolev, O. Bayandina, G. Orosz, R. A. Burns, Kee-Tae Kim, S. P. van den Heever

F Recent studies have shown that 6.7 GHz methanol maser flares can be a powerful tool for verifying the mechanismsof maser production and even the specific signatures of accretion rate changes in the early stages of high-mass starformation. We characterize the spatial structure and evolution of methanol and water masers during a flare of methanol
maser emission at 6.7 GHz in the HMYSO G24.33+0.14. VLBA was used to image the 6.7 and 12.2 GHz methanol and22.2 GHz water vapor masers at three epochs guided by monitoring the methanol line with the Torun 32m telescope.
The 6.7 GHz maser maps were also obtained with the EVN and LBA during the flare. WISE data were used to findcorrelations between the 6.7 GHz maser and IR fluxes. The 6.7 GHz methanol maser cloudlets are distributed over∼3500 au, and the morphology of most of them is stable although their brightness varies following the course of thetotal flux density on a timescale of two months. The 12.2 GHz methanol maser cloudlets cover an area an order ofmagnitude smaller than that of 6.7 GHz emission, and both transitions emerge from the same masing gas. The 22.2
GHz maser cloudlets lie in the central region and show a systematic increase in brightness and moderate changes
in size and orientation, together with the velocity drift of the strongest cloudlet during two months of the VLBI
observing period. Time lag estimates imply the propagation of changes in the physical conditions of the masing region
with a subluminal speed (∼0.3c). A tight correlation of IR (4.6µm) and 6.7 GHz flux densities is found, supporting
the radiative pumping model. Comparison with the 230 GHz ALMA data indicates that the methanol masers are
distributed in the inner part of the rotating disk, whereas the 22.2 GHz emission traces the compact inner componentof the bipolar outflow or a jet structure.

27. Analysing the SEDs of protoplanetary disks with machine learning

T. Kaeufer, P. Woitke, M. Min, I. Kamp, C. Pinte F ABRIDGED. The analysis of spectral energy distributions(SEDs) of protoplanetary disks to determine their physical properties is known to be highly degenerate. Hence, aBayesian analysis is required to obtain parameter uncertainties and degeneracies. The challenge here is computational
speed, as one radiative transfer model requires a couple of minutes to compute. We performed a Bayesian analysis for 30
well-known protoplanetary disks to determine their physical disk properties, including uncertainties and degeneracies.
To circumvent the computational cost problem, we created neural networks (NNs) to emulate the SED generation
process. We created two sets of radiative transfer disk models to train and test two NNs that predict SEDs forcontinuous and discontinuous disks. A Bayesian analysis was then performed on 30 protoplanetary disks with SED
data collected by the DIANA project to determine the posterior distributions of all parameters. We ran this analysis
twice, (i) with old distances and additional parameter constraints as used in a previous study, to compare results, and(ii) with updated distances and free choice of parameters to obtain homogeneous and unbiased model parameters. We
evaluated the uncertainties in the determination of physical disk parameters from SED analysis, and detected andquantified the strongest degeneracies. The NNs are able to predict SEDs within 1ms with uncertainties of about 5%
compared to the true SEDs obtained by the radiative transfer code. We find parameter values and uncertainties thatare significantly different from previous values obtained by χ2 fitting. Comparing the global evidence for continuousand discontinuous disks, we find that 26 out of 30 objects are better described by disks that have two distinct radialzones. Also, we created an interactive tool that instantly returns the SED predicted by our NNs for any parameter
combination.

28. The PDR fronts in M17-SW localized with FIFI-LS onboard SOFIA

Randolf Klein, Alexander Reedy, Christian Fischer, Leslie Looney, Sebastian Colditz, Dario Fadda, Alexander
G. G. M. Tielens, Willam D. Vacca F To understand star formation rates, studying feedback mechanisms that

regulate star formation is necessary. The radiation emitted by nascent massive stars play a significant role in feedbackby photo-dissociating and ionizing their parental molecular clouds. To gain a detailed picture of the physical processes,
we mapped the photo-dissociation region (PDR) M17-SW in several fine structure and high-J CO lines with FIFI-LS,
the far-infrared imaging spectrometer aboard SOFIA. An analysis of the CO and [O I]146µm line intensities, combinedwith the far infrared intensity, allows us to create a density and UV intensity map using a one dimensional model.
The density map reveals a sudden change in the gas density crossing the PDR. The strengths and limits of the modeland the locations of the ionization and photo-dissociation front of the edge-on PDR are discussed.

1029. CMR exploration I – filament structure with synthetic observations

Shuo Kong, Volker Ossenkopf-Okada, Héctor G. Arce, Ralf S. Klessen, Duo Xu F In this paper, we carry out apilot parameter exploration for the collision-induced magnetic reconnection (CMR) mechanism that forms filamentary
molecular clouds. Following Kong et al. (2021), we utilize Athena++ to model CMR in the context of resistive
magnetohydrodynamics (MHD), considering the effect from seven physical conditions, including the Ohmic resistivity(η), the magnetic field (B), the cloud density (ρ), the cloud radius R, the isothermal temperature T , the collisionvelocity vx , and the shear velocity vz . Compared to their fiducial model, we consider a higher and a lower value
for each one of the seven parameters. We quantify the exploration results with five metrics, including the density
probability distribution function (ρ-PDF), the filament morphology (250 µm dust emission), the B-ρ relation, thedominant fiber width, and the ringiness that describes the significance of the ring-like sub-structures. The exploration
forms straight and curved CMR-filaments with rich sub-structures that are highly variable in space and time. The
variation translates to fluctuation in all the five metrics, reflecting the chaotic nature of magnetic reconnection in
CMR. A temporary B ∝ ρ relation is noticeable during the first 0.6 Myr. Overall, the exploration provides useful
initial insights to the CMR mechanism.

30. Scattered polarized radiation of extrasolar circumplanetary rings

M. Lietzow, S. Wolf F We have investigated the impact of circumplanetary rings consisting of spherical micrometersized particles on the net scattered light polarization of extrasolar gas giants. Using the three-dimensional Monte
Carlo radiative transfer code POLARIS, we studied the impact of the macroscopic parameters that define the ring,such as its radius and inclination, and the chemical composition of the ring particles on the net scattered polarization.
For the spherical ring particles, we applied the Mie scattering theory. We studied the flux and polarization of thescattered stellar radiation as a function of planetary phase angle and wavelength from the optical to the near-infrared.
For the chosen grain size distribution, the dust particles in the ring show strong forward scattering at the considered
wavelengths. Thus, the reflected flux of the planet dominates the total reflected and polarized flux at small phaseangles. However, the scattered and polarized flux of the ring increase at large phase angles and exceeds the totalreflected planetary flux. For large rings that contain silicate particles, the total reflected flux is dominated by theradiation scattered by the dust in the ring at all phase angles. As a result, the orientation of polarization is parallel tothe scattering plane at small phase angles. In contrast, for a ring that contains water ice particles, the orientation ofpolarization is parallel to the scattering plane at large phase angles. Depending on the ring inclination and orientation,
the total reflected and polarized flux show a specific distribution as well. Large particles show a strong polarization atlarge phase angles compared to smaller particles. For a Jupiter-like atmosphere that contains methane and aerosols,
methane absorption features are missing in the spectrum of a ringed planet.

Structure and Kinematics of Sh2-138 – A distant hub-filament system in the outer

31. Galactic plane

Kshitiz Mallick, Lokesh Dewangan, Devendra Ojha, Tapas Baug, Igor Zinchenko F We present a molecularline study of the Sh2-138 (IRAS 22308+5812) hub-filament system with an aim to investigate its structure andkinematics. Archival CO molecular line data from the Canadian Galactic Plane Survey (CO(J=1-0)) for the wider
region (50arcminx50arcmin) and the James Clerk Maxwell Telescope (CO(3-2), 13CO(3-2), and C18O(3-2)) for thecentral portion (5arcminx5arcmin) have been utilised. Analysis of the CO(1-0) spectra for the extended region in
conjunction with the hub and filament identification using column density map and the getsf tool, respectively, reveals
a complex structure with the spectral extraction for the central position displaying multiple velocity components.
Based on the Herschel 70 micron warm dust emission, one of the filaments in the extended region was inferred to be
associated with active star formation, and is host to a Bolocam 1.1 mm clump of 1606 Msun. Integrated intensity mapof 13CO(3-2) emission, constructed from clumps detected at above 5sigma in position-position-velocity space, reveals
three filamentary structures (labelled W-f, SW-f, and SE-f) in the central portion. Velocity gradients observed in
13CO(3-2) position-velocity slices point to longitudinal gas flow along the filaments into the central region. Filaments
W-f, SW-f, and SE-f were calculated to have observed line masses of 32, 33.5, and 50 Msun/pc , respectively. The
cloud was found to be dominated by supersonic and non-thermal motions, with high Mach numbers (>3) and low
thermal to non-thermal pressure ratio (0.01-0.1).

11

Disk fragmentation around a massive protostar: a comparison of two three-dimensional

32. codes

Raphaël Mignon-Risse, André Oliva, Matthias González, Rolf Kuiper, Benoît Commerçon F (Abridged) Most

massive stars are located in multiple systems. The modeling of disk fragmentation, a possible mechanism leading tostellar multiplicity, relies on parallel 3D simulation codes whose agreement remains to be evaluated. Using the Cartesian
AMR code RAMSES, we compare disk fragmentation in a centrally-condensed protostellar system to the study of Oliva& Kuiper (2020) performed on a grid in spherical coordinates using PLUTO. Two RAMSES runs are considered andgive qualitatively distinct pictures. When allowing for unlimited sink particle creation, gas fragmentation leads to a
multiple stellar system whose multiplicity is affected by the grid when triggering fragmentation and by numericallyassisted mergers. On the other hand, using a unique, central, fixed sink particle, a centrally-condensed system forms,
similar to that reported in PLUTO. The RAMSES-PLUTO comparison is performed with the latter: agreement
between the two codes is found regarding the first rotationally-supported disk formation, the presence of an accretion
shock onto it, the first fragmentation phase. Gaseous fragments form and their properties are in agreement between
the two codes. As a minor difference, fragments dynamics causes the disk structure to be sub-Keplerian in RAMSES
whereas it is found to be Keplerian and reaches quiescence in PLUTO. We attribute this discrepancy to the central star
being twice less massive in RAMSES because of the different stellar accretion subgrid models. In a centrally-condensed
system, the agreement between RAMSES and PLUTO regarding many of the collapse properties and fragmentation
process is good. Fragmentation occurring in the innermost region and numerical choices (use of sink particles, grid)
have a crucial impact when similar but smooth initial conditions are employed - more crucial than the code’s choice on the system’s outcome, multiple or centrally-condensed.

33. A CCD Search for Variable Stars in the Open Cluster NGC 6611

G. Michalska, Z. Kołaczkowski, R. Leiton, O. Szewczyk, K. Kinemuchi, V., M. Kalari F We present the resultsof the U BV IC variability survey in the young open cluster NGC 6611 based on observations obtained during 34 nights
spanning one year. In total, we found 95 variable stars. Most of these stars are classified as periodic and irregularpre-main sequence (PMS) stars. The analysis of the JHKS 2MASS photometry and four-colour IRAC photometry
revealed 165 Class II young stellar sources, 20 of which are irregular variables and one is an eclipsing binary. These
classifications, complemented by JHK UKIDSS photometry and riHα VPHAS photometry, were used to identify
24 candidates for classical T Tauri stars and 30 weak-lined T Tauri stars. In addition to the PMS variables, we
discovered eight δ Scuti candidates. None of these were previously known. Furthermore, we detected 17 eclipsingbinaries where two were previously known. Based on the proper motions provided by the Gaia EDR3 catalogue, we
calculated the cluster membership probabilities for 91 variable stars. For 61 variables, a probability higher than 80%
was determined, which makes them cluster members. Only 25 variables with a probability less than 20% were regarded
to be non-members.

34. Spiral Structure and Massive Star formation in the Hub-Filament-System G326.27-0.49

Bhaswati Mookerjea, V. S. Veena, Rolf Guesten, F. Wyrowski, Akhil Lasrado F Hub-filament systems (HFSs) arepotential sites of formation of star clusters and high mass stars. To understand the HFSs and to provide observational
constraints on current theories that attempt to explainstar formation globally, we report a study of the region associatedwith G326.27-0.49 using infrared data of dust continuum and newly obtained observations on molecular tracers using
the APEX telescope. We use the spectroscopic observations to identify velocity-coherent structures (filaments andclumps) and study their properties at a resolution of 0.4 pc. The region contains two main velocity components: firstcomponent shows four filaments between -63 and -55 km/s forming a spiral structure converging in a hub, the second
filamentary component at -72 km/s harbors a massive young stellar object and possibly interacts with the hub. The
clumps harbouring the three main YSOs in the region are massive (187-535 Msun), have luminosities consistent with
B-type stars, have central densities of 106 cm−3 and drive large outflows. Majority of the velocity-coherent clumps
in the region show virial parameters between 2-7, which considering the detection of protostars implies collapse to be
gradual. We conclude that the region consists of a network of filaments through which mass accretes ( 10−4 Msun/yr)
onto the hub. The hub and some of the ends of filaments appear to be undergoing collapse to form new stars. This
study identifies a target region for future high resolution observations that could probe the link between the core andfilament evolution.

12

35. Investigating the morphology and CO gas kinematics of Sh2-112 region

Kshitiz Mallick, Saurabh Sharma, Lokesh Dewangan, Devendra Ojha, Neelam Panwar, Tapas Baug F We
present a study of the molecular cloud in Sh2-112 massive star forming region using the 3-2 transition of CO isotopologues - CO, 13CO, and C18O; supplemented in part by CGPS HI line emission and MSX data. Sh2-112 is an
optically visible region powered by an O8V type massive star BD +45 3216, and hosts two Red MSX Survey sources G083.7962+03.3058 and G083.7071+03.2817 - classified as HII region and young stellar object, respectively. Reduced
spectral data products from the James Clerk Maxwell Telescope archive, centered on the two RMS objects with 7’x7’
field of view each, were utilised for the purpose. The 13CO(3-2) channel map of the region shows the molecular
cloud to have filamentary extensions directed away from the massive star, which also seems to be at the edge of acavity like structure. Multiple molecular cloud protrusions into this cavity structure host local peaks of emission.
The integrated emission map of the region constructed from only those emission clumps detected above 5σ level inthe position-position-velocity space affirms the same. MSX sources were found distributed along the cavity boundary
where the gas has the been compressed. Spectral extraction at these positions yielded high Mach numbers and low
ratios of thermal to non-thermal pressure, suggesting a dominance of supersonic and non-thermal motion in the cloud.

Takeout and Delivery: Erasing the Dusty Signature of Late-stage Terrestrial Planet

36. Formation

Joan R. Najita, Scott J. Kenyon F The formation of planets like Earth is expected to conclude with a series oflate-stage giant impacts that generate warm dusty debris, the most anticipated visible signpost of terrestrial planet
formation in progress. While there is now evidence that Earth-sized terrestrial planets orbit a significant fraction ofsolar-type stars, the anticipated dusty debris signature of their formation is rarely detected. Here we discuss several
ways in which our current ideas about terrestrial planet formation imply transport mechanisms capable of erasing the
anticipated debris signature. A tenuous gas disk may be regenerated via "takeout" (i.e., the liberation of planetaryatmospheres in giant impacts) or "delivery" (i.e., by asteroids and comets flung into the terrestrial planet region) at
a level sufficient to remove the warm debris. The powerful stellar wind from a young star can also act, its delivered
wind momentum producing a drag that removes warm debris. If such processes are efficient, terrestrial planets may
assemble inconspicuously, with little publicity and hoopla accompanying their birth. Alternatively, the rarity of warm
excesses may imply that terrestrial planets typically form very early, emerging fully formed from the nebular phasewithout undergoing late-stage giant impacts. In either case, the observable signposts of terrestrial planet formation
appear more challenging to detect than previously assumed. We discuss observational tests of these ideas.

Early water delivery to terrestrial planet regions during the stages of Jupiter’s formation

37. and migration in the Grand Tack model

Masahiro Ogihara, Hidenori Genda, Yasuhito Sekine F The formation and subsequent migration of gas giants could

significantly affect the material mixing in the Solar System. In this study, we use N-body simulations to investigate
how much water is transported into the region of the terrestrial planet formation during the growth and migration
phases of Jupiter in the Grand Tack model. We found that Jupiter’s growth was accompanied by significant masstransport, and that a substantial amount of water (about 10 times Earth’s ocean mass for the initial planetesimal
distribution based on the minimum-mass solar nebula) was transported into the terrestrial planet region. The total
amount delivered increased further during Jupiter’s migration phase (totaling about 10-40 times Earth’s ocean mass),
which was less dependent on simulation parameters. In addition, at these stages, terrestrial planets were not fullygrown. Therefore, water supplied during these early stages could interact with metallic iron during the core formationof protoplanets and/or growing Earth. Since hydrogen in water molecules can dissolve into their cores, this could
explain the density deficit observed in the current Earth core. Notably, Jupiter could play an important role as a”barrier” in explaining the dichotomy of the isotopic compositions between noncarbonaceous (NC) and carbonaceous(CC) meteorites. This study’s results show that Jupiter’s growth necessitates some mixing of NC and CC materials.

38. ALMA Band 6 high-resolution observations of the transitional disk around SY Cha
Ryuta Orihara, Munetake Momose, Takayuki Muto, Jun Hashimoto, Hauyu Baobab Liu, Takashi Tsukagoshi, Tomoyuki Kudo, Sanemichi Takahashi, Yi Yang, Yasuhiro Hasegawa, Ruobing Dong, Mihoko Konishi,
Eiji Akiyama F In this study, we reported the results of high-resolution (0.14 arcsec) Atacama Large Millime-

ter/submillimeter Array (ALMA) observations of the 225 GHz dust continuum and CO molecular emission lines from13the transitional disk around SY Cha. Our high-resolution observations clearly revealed the inner cavity and the central
point source for the first time. The radial profile of the ring can be approximated by a bright narrow ring superimposedon a fainter wide ring. Furthermore, we found that there is a weak azimuthal asymmetry in dust continuum emission.
For gas emissions, we detected 12 CO(2−1), 13 CO(2−1) and C18 O(2−1), from which we estimated the total gas massof the disk to be 2.2 × 10−4 M , assuming a CO/H2 ratio of 10−4 . The observations showed that the gas is present
inside the dust cavity. The analysis of the velocity structure of the 12 CO(2−1) emission line revealed that the velocity
is distorted at the location of the dust inner disk, which may be owing to warping of the disk or radial gas flow within
the cavity of the dust disk. High-resolution observations of SY Cha showed that this system is composed of a ring anda distorted inner disk, which may be common, as indicated by the survey of transitional disk systems at a resolutionof ∼0.1 arcsec.

39. Survey of Hα emission-line stars in the star-forming region IC 5070

Neelam Panwar, Jessy Jose, Rishi C F Actively accreting young stellar objects show Hα emission line in theirspectra. We present the results of survey for Hα emission-line stars in the star-forming region IC 5070 taken with
2-m Himalyan Chandra Telescope. Based on the Hα slitless spectroscopy data, we identified 131 emission-line stars in∼ 0.29 square degrees area of the IC 5070 region. Using Gaia Early Data Release 3, we estimated the mean propermotion and parallax of the emission-line stars. We also estimated the mean distance and reddening toward the region
using the emission-line stars, that are ∼ 833 pc and ∼2 mag, respectively. By examining the locations of these stars
in the color-magnitude diagrams constructed using Gaia and PanSTARRS1 data, we found that a majority of the Hαemitters are young low-mass (< 1.5 M ) stars. We also compared our catalog of emission-line stars with the available
young stellar catalogs and found that most of them are Class II/ flat spectrum sources with the spectral type ranging
from K to M. Based on the proper motion/ parallax values and locations on the color-magnitude diagrams, about 20
emission-line stars are flagged as non-members. The relative proper motion of the emission-line stars with respect tothe ionizing source suggest the possibility of the ‘rocket effect’ scenario in the remnant cloud (BRC 31).

of HOPS Out to 500 ParSecs (eHOPS). I. Identification and Modeling of
40. Extension
Protostars in the Aquila Molecular Clouds
Riwaj Pokhrel, S. Thomas Megeath, Robert A. Gutermuth, Elise Furlan, William J. Fischer, Samuel Federman,
John J. Tobin, Amelia M. Stutz, Lee Hartmann, Mayra Osorio, Dan M. Watson, Thomas Stanke, P. Manoj,
Mayank Narang, Prabhani Atnagulov, Nolan Habel, Wafa Zakri F We present a Spitzer/Herschel focused surveyof the Aquila molecular clouds (d ∼ 436 pc) as part of the eHOPS (extension of HOPS Out to 500 ParSecs) census
of nearby protostars. For every source detected in the Herschel/PACS bands, the eHOPS-Aquila catalog contains 1850 µm SEDs assembled from 2MASS, Spitzer, Herschel, WISE, and JCMT/SCUBA-2 data. Using a newly developed
set of criteria, we classify objects by their SEDs as protostars, pre-ms sequence stars with disks, and galaxies. A totalof 172 protostars are found in Aquila, tightly concentrated in the molecular filaments that thread the clouds. Of these,
71 (42%) are Class 0 protostars, 54 (31%) are Class I protostars, 43 (25%) are flat-spectrum protostars, and 4 (2%)
are Class II sources. Ten of the Class 0 protostars are young PACS Bright Red Sources similar to those discovered inOrion. We compare the SEDs to a grid of radiative transfer models to constrain the luminosities, envelope densities,
and envelope masses of the protostars. A comparison of the eHOPS-Aquila to the HOPS protostars in Orion finds thatthe protostellar luminosity functions in the two star-forming regions are statistically indistinguishable, the bolometrictemperatures/envelope masses of eHOPS-Aquila protostars are shifted to cooler temperatures/higher masses, and theeHOPS-Aquila protostars do not show the decline in luminosity with evolution found in Orion. We briefly discuss
whether these differences are due to biases between the samples, diverging star formation histories, or the influence ofenvironment on protostellar evolution.

Starlight-polarization-based tomography of the magnetized interstellar medium: PASIPHAE’s

41. line-of-sight inversion method

V. Pelgrims, G. V. Panopoulou, K. Tassis, V. Pavlidou, A. Basyrov, D. Blinov, E. Gjerløw, S. Kiehlmann, N.
Mandarakas, A. Papadaki, R. Skalidis, A. Tsouros, R. M. Anche, H. K. Eriksen, T. Ghosh, J. A. Kypriotakis, S.
Maharana, E. Ntormousi, T. J. Pearson, S. B. Potter, A. N. Ramaprakash, A. C. S. Readhead, I. K. Wehus F

We present the first Bayesian method for tomographic decomposition of the plane-of-sky orientation of the magnetic
field with the use of stellar polarimetry and distance. This standalone tomographic inversion method presents an

14

important step forward in reconstructing the magnetized interstellar medium (ISM) in 3D within dusty regions. We
develop a model in which the polarization signal from the magnetized and dusty ISM is described by thin layers at
various distances. Our modeling makes it possible to infer the mean polarization (amplitude and orientation) induced
by individual dusty clouds and to account for the turbulence-induced scatter in a generic way. We present a likelihood
function that explicitly accounts for uncertainties in polarization and parallax. We develop a framework for reconstructing the magnetized ISM through the maximization of the log-likelihood using a nested sampling method. We
test our Bayesian inversion method on mock data taking into account realistic uncertainties from Gaia and as expected
for the optical polarization survey PASIPHAE according to the currently planned observing strategy. We demonstratethat our method is effective at recovering the cloud properties as soon as the polarization induced by a cloud to its
background stars is higher than ∼ 0.1% for the adopted survey exposure time and level of systematic uncertainty. Our
method makes it possible to recover not only the mean polarization properties but also to characterize the intrinsic
scatter, thus creating new ways to characterize ISM turbulence and the magnetic field strength. Finally, we apply
our method to an existing data set of starlight polarization with known line-of-sight decomposition, demonstrating
agreement with previous results and an improved quantification of uncertainties in cloud properties.

The ALMA view of MP Mus (PDS 66): a protoplanetary disk with no visible gaps

42. down to 4 au scales

Á. Ribas, E. Macías, P. Weber, S. Pérez, N. Cuello, R. Dong, A. Aguayo, C. Cáceres, J. Carpenter, W. R. F.
Dent, I. de Gregorio-Monsalvo, G. Duchêne, C. C. Espaillat, P. Riviere-Marichalar, M. Villenave F We present

ALMA multiwavelength observations of the protoplanetary disk around the nearby (d∼100 pc) young solar analog MP
Mus (PDS 66). These observations at 0.89 mm, 1.3 mm, and 2.2 mm have angular resolutions of ∼ 1", 0.05", and 0.25",
respectively, and probe the dust and gas in the system with unprecedented detail and sensitivity. The disk appears
smooth down to the 4 au resolution of the 1.3 mm observations, in contrast with most disks observed at comparable
spatial scales. The dust disk has a radius of 60±5 au, a dust mass of 0.14+0.11−0.06 MJup , and a mm spectral index < 2in the inner 30 au, suggesting optically thick emission from grains with high albedo in this region. Several molecular
gas lines are also detected extending up to 130±15 au, similar to small grains traced by scattered light observations.
Comparing the fluxes of different CO isotopologues with previous models yields a gas mass of 0.1 − 1MJup , implying
a gas to dust ratio of 1-10. We also measure a dynamical stellar mass of Mdyn =1.30±0.08 M and derive an age of
7-10 Myr for the system. The survival of large grains in an evolved disk without gaps/rings is surprising, and it ispossible that existing substructures remain undetected due to optically thick emission at 1.3 mm. Alternatively, small
structures may still remain unresolved with the current observations. Based on simple scaling relations for gap-opening
planets and gap widths, this lack of substructures places upper limits to the masses of planets in the disk as low as 2
M⊕ -0.06 MJup at r > 40 au. The lack of mm emission at radii r > 60 au also suggests that the gap in scattered lightbetween 30-80 au is likely not a gap in the disk density, but a shadow cast by a puffed-up inner disk.

43. Empirical constraints on turbulence in proto-planetary discs

Giovanni P. Rosotti F Proto-planetary discs, the birth environment of planets, are an example of a structure commonly found in astrophysics, accretion discs. Identifying the mechanism responsible for accretion is a long-standing
problem, dating back several decades. The common picture is that accretion is a consequence of turbulence, withseveral instabilities proposed for its origin. While traditionally this field used to be a purely theoretical endeavour,the landscape is now changing thanks mainly to new observational facilities such as the ALMA radio interferometer.
Thanks to large improvements in spatial and spectral resolution and sensitivity (which have enabled the study of discsubstructure, kinematics and surveys of large disc populations), multiple techniques have been devised to observationally measure the amount of turbulence in discs. This review summarises these techniques, ranging from attempts at
direct detection of turbulence from line broadening, to more indirect approaches that rely on properties of the dust or
consider the evolution of global disc properties (such as masses, radii and accretion rates) for large samples, and what
their findings are. Multiple lines of evidence suggest that discs are in fact not as turbulent as thought one decade ago.
On the other hand, direct detection of turbulence in some discs and the finite radial extent of dust substructures and insome cases the finite vertical extent strongly indicate that turbulence must be present at some level in proto-planetary
discs. It is still an open question whether this amount of turbulence is enough to power accretion or if this is instead
driven by other mechanisms, such as MHD winds.

15

44. Planetary nurseries: vortices formed at smooth viscosity transition

Zs. Regaly, K. Kadam, D. Tarczay-Nehez F Excitation of Rossby wave instability and development of a large-scalevortex at the outer dead zone edge of protoplanetary discs is one of the leading theories that explains horseshoe-likebrightness distribution in transition discs. Formation of such vortices requires a relatively sharp viscosity transition.
Detailed modelling, however, indicates that viscosity transitions at the outer edge of the dead zone is relatively smooth.
In this study, we present 2D global, non-isothermal, gas-dust coupled hydrodynamic simulations to investigate thepossibility of vortex excitation at smooth viscosity transitions. Our models are based on a recently postulated scenario,
wherein the recombination of charged particles on the surface of dust grains results in reduced ionisation fraction andin turn the turbulence due to magnetorotational instability. Thus, the alpha-parameter for the disc viscosity depends
on the local dust-to-gas mass ratio. We found that the smooth viscosity transitions at the outer edge of the dead zone
can become Rossby unstable and form vortices. A single large-scale vortex develops if the dust content of the disc iswell coupled to the gas, however, multiple small-scale vortices ensue for the case of less coupled dust. As both typeof vortices are trapped at the dead zone outer edge, they provide sufficient time for dust growth. The solid content
collected by the vortices can exceed several hundred Earth masses, while the dust-to-gas density ratio within often
exceeds unity. Thus, such vortices function as planetary nurseries within the disc, providing ideal sites for formationof planetesimals and eventually planetary systems.

45. Direct imaging discovery of a super-Jovian around the young Sun-like star AF Leporis

Robert J. De Rosa, Eric L. Nielsen, Zahed Wahhaj, Jean-Baptise Ruffio, Paul G. Kalas, Anne E. Peck, Lea
A. Hirsch, William Roberson F (abridged) Expanding the sample of directly imaged companions to nearby, youngstars that are amenable to detailed astrometric and spectroscopic studies is critical for the continued development andvalidation of theories of their evolution and atmospheric processes. The recent release of the Gaia astrometric catalogue
allows us to efficiently search for these elusive companions by targeting those stars that exhibit the astrometric reflex
motion induced by an orbiting companion. The nearby (27 pc), young (24 Myr) star AF Leporis (AF Lep) was
targeted because of its astrometric acceleration, consistent with a wide-orbit planetary companion detectable withhigh-contrast imaging. We used the SPHERE instrument on the VLT to search for faint substellar companions in theimmediate vicinity of AF Lep. We used observations of a nearby star interleaved with those of AF Lep to efficiently
subtract the residual point spread function. This provided sensitivity to faint planetary-mass companions within 1
arcsec (∼30 au) of the star. We detected the companion AF Lep b at a separation of 339 mas (9 au), within the inneredge of its unresolved debris disk. The measured K-band contrast and the age of the star yield a model-dependent
mass of 4 and 6 MJup , consistent with the mass derived from an orbital fit of 4.3+2.9−1.2 MJup . The near-infrared SEDof the planet is consistent with an object at the L–T spectral type transition, but under-luminous with respect tofield-gravity objects. AF Lep b joins a growing number of substellar companions imaged around stars in the youngβ Pic moving group. With a mass of between 3 and 7 MJup , it occupies a gap in this isochronal sequence between
the hotter, more massive companions like PZ Tel B and β Pic b, and the cooler 51 Eri b, which is sufficiently cool formethane to form within its photosphere.

of the first infrared spectrum of quasi-bound H2 line emission in Herbig-Haro
46. Analysis
7
Evelyne Roueff, Michael G. Burton, Thomas R. Geballe, Hervé Abgrall F Context. Highly excited molecularhydrogen H2 has been observed in many regions of shocked molecular gas. A recently published K-band spectrum of
Herbig-Haro 7 (HH7) contains several vibration-rotation lines of H2 from highly excited energy levels that have notbeen detected elsewhere, including a line at 2.179 µm identified as arising from the v=2 J=29 level, which lies above
the dissociation limit of H2. One emission line at 2.104 µm in this spectrum was unidentified. Aims. We aim tocomplete the analysis of the spectrum of HH7 by including previously missing molecular data that have been recently
computed. Methods. We re-analysed the K-band spectrum, emphasising the physics of quasi-bound upper levels thatcan produce infrared emission lines in the K band. Results. We confirm the identification of the 2 − 1 S(27) line
at 2.1785 µm and identify the line at 2.1042 µm as due to the 1-0 S(29) transition of H2, whose upper level energy
is also higher than the dissociation limit. This latter identification, its column density, and the energy of its upper
level further substantiate the existence of a hot thermal component at 5000 K in the HH7 environment. Conclusion.
The presence of the newly identified 1 − 0 S(29) line, whose quasi-bound upper level (v=1, J=31) has a significant
spontaneous dissociation probability, shows that dissociation of H2 is occurring. The mechanism by which virtually
all of the H2 levels with energies from 20,000 K to 53,000 K is maintained in local thermodynamic equilibrium at a16

single temperature of ∼5,000 K remains to be understood.

47. Searching for Molecular Jets from High-Mass Protostars

Tatiana M. Rodriguez, Peter Hofner, Isaac Edelman, Esteban D. Araya, Viviana Rosero F We report Very Large

Array (VLA) observations in the Q-band toward 10 ionized jet candidates to search for SiO emission, a well-known
shocked gas tracer. We detected 7 mm continuum counterparts toward 90% of the jet candidates. In most cases, the jet
candidate is located toward the center of the 7 mm core, and the high masses (≈ 100 M ) and densities (≈ 107 cm−3 )of the cores suggest that the central objects are very young high-mass protostars. We detected SiO J = 1 − 0 emission
associated with 6 target sources. In all cases, the morphology and spectrum of the emission is consistent with whatis expected for molecular jets along an outflow axis, thus confirming the jet nature of 60% of our sample. Our datasuggest a positive correlation between the SiO luminosity LSiO , and both the bolometric luminosity LBol and theradio luminosity Sν d2 of the driving sources.

carbon as a tracer of the assembly of interstellar clouds
48. IonizedNicola Schneider, Lars Bonne, Sylvain Bontemps, Slawa Kabanovic, Robert Simon, Volker Ossenkopf-Okada,
Christof Buchbender, Juergen Stutzki, Marc Mertens, Oliver Ricken, Timea Csengeri, Alexander G. G. M.
Tielens F Molecular hydrogen clouds are a key component of the interstellar medium because they are the birthplaces

for stars. They are embedded in atomic gas that pervades the interstellar space. However, the details of how molecular
clouds assemble from and interact with the atomic gas are still largely unknown. As a result of new observations of
the 158 µm line of ionized carbon CII in the Cygnus region within the FEEDBACK program on SOFIA (Stratospheric
Observatory for Infrared Astronomy), we present compelling evidence that CII unveils dynamic interactions between
cloud ensembles. This process is neither a head-on collision of fully molecular clouds nor a gentle merging ofonly atomic
clouds. Moreover, we demonstrate that the dense molecular clouds associated with the DR21 and W75N star-forming
regions and a cloud at higher velocity are embedded in atomic gas and all components interact over a large range of
velocities (20 km/s). The atomic gas has a density of 100 cm−3 and a temperature of 100 K. We conclude that the
CII 158 µm line is an excellent tracer to witness the processes involved in cloud interactions and anticipate further
detections of this phenomenon in other regions

The Effelsberg survey of FU Orionis and EX Lupi objects I. – Host environments of

49. FUors/EXors traced by NH3

Zs. M. Szabó, Y. Gong, K. M. Menten, W. Yang, C. J. Cyganowski, Á. Kóspál, P. Ábrahám, A. Belloche, F.
Wyrowski F FU Orionis (FUor) and EX Lupi (EXor) type objects represent two small, but rather spectacular groupsof low-mass, young eruptive stars. Outbursts of several magnitudes are observed, attributed to enhanced accretionfrom the circumstellar disk onto the central protostar. The host molecular environments of FUors/EXors are poorly
explored due to the scarcity of systematic molecular line observations. We carried out the first dedicated survey of themolecular environments of a large sample of FUors/EXors, observing a total of 51 sources with the aim of studying theammonia (NH3 ) emission in their host environments. We observed the ammonia (J,K)=(1,1), (2,2), and (3,3) inversion
transitions using the Effelsberg 100-m radio telescope. We derived H2 column densities and dust temperatures usingarchival Herschel SPIRE data. We detected the (1,1) transition toward 28 sources and the (2,2) transition toward 12
sources, while the (3,3) transition was detected toward only two sources. We find kinetic temperatures between 12 K
and 21 K, ammonia column densities from 5.2 × 1013 cm−2 to 3.2 × 1015 cm−2 , and fractional ammonia abundanceswith respect to H2 from 4.7 × 10−9 to 1.5 × 10−7 . The results are comparable to those found in infrared dark clouds(IRDCs). Kinetic analysis suggests that most of the eruptive stars in our sample reside in rather quiescent (sonicor transonic) host environments. Our NH3 observations and analysis of the SPIRE dust-based H2 column density
maps confirm the presence of dense material toward 7 sources in our sample; additional sources might also harbour
dense gas based on their NH2 (2,2) detections, might indicate an earlier phase than originally classified. Based on our
results, we suggest observations targeting additional molecular lines would help to refine the evolutionary classificationof eruptive stars.

17

Density Structure of Centrally Concentrated Prestellar Cores from Multi-scale Obser-

50. vations

Dipen Sahu, Sheng-Yuan Liu, Doug Johnstone, Tie Liu, Neal J. Evans II, Naomi Hirano, Kenichi Tatematsu,
James Di Francesco, Chin-Fei Lee, Kee-Tae Kim, Somnath Dutta, Shih-Ying Hsu, Shanghuo Li, Qiu-Yi Luo,
Patricio Sanhueza, Hsien Shang, Alessio Traficante, Mika Juvela, Chang Won Lee, David J. Eden, Paul F.
Goldsmith, Leonardo Bronfman, Woojin Kwon, Jeong-Eun Lee, Yi-Jehng Kuan, Isabelle Ristorcelli F Starlesscores represent the initial stage of evolution toward (proto)star formation, and a subset of them, known as prestellar cores, with high density ( 106 cm−3 or higher) and being centrally concentrated are expected to be embryos of(proto)stars. Determining the density profile of prestellar cores, therefore provides an important opportunity to gauge
the initial conditions of star formation. In this work, we perform rigorous modeling to estimate the density profiles ofthree nearly spherical prestellar cores among a sample of five highly dense cores detected by our recent observations.
We employed multi-scale observational data of the (sub)millimeter dust continuum emission including those obtained
by SCUBA-2 on the JCMT with a resolution of 5600 au and by multiple ALMA observations with a resolution as
high as 480 au. We are able to consistently reproduce the observed multi-scale dust continuum images of the coreswith a simple prescribed density profile, which bears an inner region of flat density and a r−2 profile toward the outerregion. By utilizing the peak density and the size of the inner flat region as a proxy for the dynamical stage of thecores, we find that the three modeled cores are most likely unstable and prone to collapse. The sizes of the inner flat
regions, as compact as 500 au, signify them being the highly evolved prestellar cores rarely found to date.

51. Witnessing the fragmentation of a filament into prestellar cores in Orion B/NGC 2024

Y. Shimajiri, Ph. André, N. Peretto, D. Arzoumanian, E. Ntormousi, V. Könyves F Recent Herschel observationsof nearby clouds have shown that filamentary structures are ubiquitous and that most prestellar cores form in filaments.
Probing the density (n) and velocity (V ) structure of filaments is crucial for the understanding of the star formation
process. To characterize both the n and the V field of a fragmenting filament, we mapped NGC2024. 13CO, C18O,
and H13CO+ trace the filament seen in the NH2 data. The radial profile from the NH2 data shows DHP 0.081 pc,
which is similar to the Herschel findings. The DHP from 13CO and C18O are broader, while the DHP from H13CO+
is narrower, than DHP from Herschel. These results suggest that 13CO and C18O trace only the outer part of thefilament and H13CO+ only the inner part. The H13CO+ Vcentroid map reveals V gradients along both filament axis,
as well as V oscillations with a period λ 0.2 pc along the major axis. Comparison between the V and the n distribution
shows a tentative λ/4 shift in H13CO+ or C18O. This λ/4 shift is not simultaneously observed for all cores in any single
tracer but is tentatively seen in either H13CO+ or C18O. We produced a toy model taking into account a transverse
V gradient, a longitudinal V gradient, and a longitudinal oscillation mode caused by fragmentation. Examination ofsynthetic data shows that the oscillation component produces an oscillation pattern in the velocity structure function(VSF) of the model. The H13CO+ VSF shows an oscillation pattern, suggesting that our observations are partly
tracing core-forming motions and fragmentation. We also found that the mean Mcore corresponds to the effective
MBE in the filament. This is consistent with a scenario in which higher-mass cores form in higher line-mass filaments.

Wind Feedback from High-mass Protostars. II. The Evolutionary Sequence
52. Disk
Jan E. Staff, Kei E. I. Tanaka, Jon P. Ramsey, Yichen Zhang, Jonathan C. Tan F Star formation is ubiquitously
associated with the ejection of accretion-powered outflows that carve bipolar cavities through the infalling envelope.
This feedback is expected to be important for regulating the efficiency of star formation from a natal pre-stellar core.
These low-extinction outflow cavities greatly affect the appearance of a protostar by allowing the escape of shorter
wavelength photons. Doppler-shifted CO line emission from outflows is also often the most prominent manifestationof deeply embedded early-stage star formation. Here, we present 3D magneto-hydrodynamic simulations of a disk
wind outflow from a protostar forming from an initially 60 M core embedded in a high pressure environment typicalof massive star-forming regions. We simulate the growth of the protostar from m∗ = 1 M to 26 M over a period of∼100,000 years. The outflow quickly excavates a cavity with half opening angle of ∼ 10◦ through the core. This angle
remains relatively constant until the star reaches 4M . It then grows steadily in time, reaching a value of ∼ 50◦ by theend of the simulation. We estimate a lower limit to the star formation efficiency (SFE) of 0.43. However, accounting
for continued accretion from a massive disk and residual infall envelope, we estimate that the final SFE may be as highas ∼ 0.7. We examine observable properties of the outflow, especially the evolution of the cavity opening angle, total
mass and momentum flux, and velocity distributions of the outflowing gas, and compare with the massive protostars
G35.20-0.74N and G339.88-1.26 observed by ALMA, yielding constraints on their intrinsic properties.
18

53. Analytic characterization of sub-Alfvénic turbulence energetics

R. Skalidis, K. Tassis, V. Pavlidou F Magnetohydrodynamic (MHD) turbulence is a cross-field process relevant

to many systems. A prerequisite for understanding these systems is to constrain the role of MHD turbulence, andin particular the energy exchange between kinetic and magnetic forms. The energetics of strongly magnetized andcompressible turbulence has so far resisted attempts to understand them. Numerical simulations reveal that kinetic
energy can be orders of magnitude larger than fluctuating magnetic energy. We solve this lack-of-balance puzzle bycalculating the energetics of compressible and sub-Alfvénic turbulence based on the dynamics of coherent cylindrical
fluid parcels. Using the MHD Lagrangian, we prove analytically that the bulk of the magnetic energy transferred
to kinetic is the energy stored in the coupling between the ordered and fluctuating magnetic field. The analytical
relations are in striking agreement with numerical data, up to second order terms.

Fractal aggregates of sub-micron-sized grains in the young planet-forming disk around

54. IM Lup

Ryo Tazaki, Christian Ginski, Carsten Dominik F Despite rapidly growing disk observations, it remains a mysterywhat primordial dust aggregates look like and what the physical and chemical properties of their constituent grains(monomers) are in young planet-forming disks. Confrontation of models with observations to answer this mystery has
been a notorious task because we have to abandon a commonly used assumption, perfectly spherical grains, and take
into account particles with complex morphology. In this Letter, we present the first thorough comparison between
near-infrared scattered light of the young planet-forming disk around IM Lup and the light-scattering properties ofcomplex-shaped dust particles. The availability of scattering observations at multiple wavelengths and over a significant
range of scattering angles allows for the first determination of the monomer size, fractal dimension, and size of dust
aggregates in a planet-forming disk. We show that the observations are best explained by fractal aggregates with afractal dimension of 1.5 and a characteristic radius larger than ∼ 2 µm. We also determined the radius of the monomer
to be ∼ 200 nm, and monomers much smaller than this size can be ruled out on the premise that the fractal dimension
is less than 2. Furthermore, dust composition comprising amorphous carbon is found to be favorable to simultaneously
account for the faint scattered light and the flared disk morphology. Our results support that planet formation begins
with fractal coagulation of sub-micron-sized grains. All the optical properties of complex dust particles computed inthis study are publicly available.

Compositional Dimension of Planet Formation
55. TheDiego Turrini F The great diversity of the thousands of planets known to date is proof of the multitude of ways inwhich formation and evolution processes can shape the life of planetary systems. Multiple formation and evolution
paths, however, can result in the same planetary architecture. Because of this, unveiling the individual histories ofplanetary systems and their planets can prove a challenging task. The chemical composition of planets provides us
with a guiding light for navigate this challenge, but to understand the information it carries we need to properly link
it to the chemical composition and characteristics of the environments in which the planets formed. To achieve thisgoal it is necessary to combine the information and perspectives provided by a growing number of different fields ofstudy, spanning the whole lifecycle of stars and their planetary systems. The aim of this chapter is to provide theunifying perspective needed to understand and connect such diverse information, and illustrate the process throughwhich we can decode the message contained into the composition of planetary bodies.

on the non-thermal desorption of methanol in the cold core LDN 429-C
56. Constraints
A. Taillard, V. WakelaM, P. Gratier, E. Dartois, M. Chabot, J. A. Noble, J. V. Keane, A. C. A. Boogert, D.
Harsono F Cold cores are an early step of star formation, characterized by densities > 104 cm−3 , low temperatures (<15 K), and very low external UV radiation. We investigate the physico-chemical processes at play to tracing the originof molecules that are predominantly formed via reactions on dust grain surfaces. We observed the cold core LDN 429-C
with the NOEMA interferometer and the IRAM 30m single dish telescope in order to obtain the gas-phase abundancesof key species, including CO and CH3 OH. Comparing the observed gas phase of methanol to its solid phase previously
observed with Spitzer allows us to put quantitative constraints on the efficiency of the non-thermal desorption ofthis species. With physical parameters determined from available Herschel data, we computed abundance maps of
11 detected molecules with a non-local thermal equilibrium radiative transfer model. These observations allowed us
to probe the molecular abundances as a function of density and visual extinction, with the variation in temperature

19

being restrained between 12 and 18 K. We then compared the observed abundances to the predictions of the Nautilus
astrochemical model. We find that all molecules have lower abundances at high densities and visual extinctions withrespect to lower density regions, except for methanol. Comparing these observations with a grid of chemical models
based on the local physical conditions, we were able to reproduce these observations, allowing only the parameter time
to vary. Comparing the observed gas-phase abundance of methanol with previous measurements of the methanol ice,
we estimate a non-thermal desorption efficiency between 0.002% and 0.09%, increasing with density. The apparent
increase in the desorption efficiency cannot be reproduced by our model unless the yield of cosmic-ray sputtering isaltered due to the ice composition varying as a function of density.

57. Modest dust settling in the IRAS04302+2247 Class I protoplanetary disk

M. Villenave, L. Podio, G. Duchene, K. R. Stapelfeldt, C. Melis, C. Carrasco-Gonzalez, V. J. M. Le Gouellec,
F. Menard, M. De Simone, C. Chandler, A. Garufi, C. Pinte, E. Bianchi, C. Codella F We present new VLA

observations, between 6.8mm and 66mm, of the edge-on Class I disk IRAS04302+2247. Observations at 6.8mm and
9.2mm lead to the detection of thermal emission from the disk, while shallow observations at the other wavelengths areused to correct for emission from other processes. The disk radial brightness profile transitions from broadly extended
in previous ALMA 0.9mm and 2.1mm observations to much more centrally brightened at 6.8mm and 9.2mm, which
can be explained by optical depth effects. The radiative transfer modeling of the 0.9mm, 2.1mm, and 9.2mm datasuggests that the grains are smaller than 1cm in the outer regions of the disk and allows us to obtain the first lower
limit for the scale height of grains emitting at millimeter wavelengths in a protoplanetary disk. We find that themillimeter dust scale height is between 1au and 6au at a radius 100au from the central star, while the gas scale heightis estimated to be about 7au, indicating a modest level of settling. The estimated dust height is intermediate between
less evolved Class 0 sources, that are found to be vertically thick, and more evolved Class II sources, which show asignificant level of settling. This suggests that we are witnessing an intermediate stage of dust settling.

58. A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)?

Y. X. Wang, J. S. Zhang, H. Z. Yu, Y. Wang, Y. T. Yan, J. L. Chen, J. Y. Zhao, Y. P. Zou F We conducted
observations of multiple HC3N (J = 10-9, 12-11, and 16-15) lines and the N2H+ (J = 1-0) line toward a large sample of
61 ultracompact (UC) H II regions, through the Institutde Radioastronomie Millmetrique 30 m and the Arizona Radio
Observatory 12 m telescopes. The N2H+ J = 1-0 line is detected in 60 sources and HC3N is detected in 59 sources,
including 40 sources with three lines, 9 sources with two lines, and 10 sources with one line. Using the rotational
diagram, the rotational temperature and column density of HC3N were estimated toward sources with at least two
HC3N lines. For 10 sources with only one HC3N line, their parameters were estimated, taking one average value ofTrot. For N2H+, we estimated the optical depth of the N2H+ J = 1-0 line, based on the line intensity ratio of its
hyperfine structure lines. Then the excitation temperature and column density were calculated. When combining our
results in UC H II regions and previous observation results on high-mass starless cores and high-mass protostellar
cores, the N(HC3N)/N(N2H+) ratio clearly increases from the region stage. This means that the abundance ratiochanges with the evolution of high-mass star-forming regions (HMSFRs). Moreover, positive correlations between theratio and other evolutionary indicators (dust temperature, bolometric luminosity, and luminosity-to-mass ratio) arefound. Thus we propose the ratio of N(HC3N)/N(N2H+) as a reliable chemical clock of HMSFRs.

59. First BISTRO observations of the dark cloud Taurus L1495A-B10: the role of themagnetic field in the earliest stages of low-mass star formation

Derek Ward-Thompson and the BISTRO team F We present BISTRO Survey 850 µm dust emission polarisation
observations of the L1495A-B10 region of the Taurus molecular cloud, taken at the JCMT. We observe a roughly
triangular network of dense filaments. We detect 9 of the dense starless cores embedded within these filaments inpolarisation, finding that the plane-of-sky orientation of the core-scale magnetic field lies roughly perpendicular to thefilaments in almost all cases. We also find that the large-scale magnetic field orientation measured by Planck is notcorrelated with any of the core or filament structures, except in the case of the lowest-density core. We propose ascenario for early prestellar evolution that is both an extension to, and consistent with, previous models, introducing
an additional evolutionary transitional stage between field-dominated and matter-dominated evolution, observed here
for the first time. In this scenario, the cloud collapses first to a sheet-like structure. Uniquely, we appear to be seeing
this sheet almost face-on. The sheet fragments into filaments, which in turn form cores. However, the material must20

reach a certain critical density before the evolution changes from being field-dominated to being matter-dominated.
We measure the sheet surface density and the magnetic field strength at that transition for the first time and show
consistency with an analytical prediction that had previously gone untested for over 50 years (Mestel 1965).

60. Radiation shielding of protoplanetary discs in young star-forming regions
Martijn J. C. Wilhelm, Simon Portegies Zwart, Claude Cournoyer-Cloutier, Sean C. Lewis, Brooke Polak,
Aaron Tran, Mordecai-Mark Mac Low F Protoplanetary discs spend their lives in the dense environment of a star

forming region. While there, they can be affected by nearby stars through external photoevaporation and dynamic
truncations. We present simulations that use the AMUSE framework to couple the Torch model for star cluster
formation from a molecular cloud with a model for the evolution of protoplanetary discs under these two environmental
processes. We compare simulations with and without extinction of photoevaporation-driving radiation. We findthat the majority of discs in our simulations are considerably shielded from photoevaporation-driving radiation for
at least 0.5 Myr after the formation of the first massive stars. Radiation shielding increases disc lifetimes by anorder of magnitude and can let a disc retain more solid material for planet formation. The reduction in external
photoevaporation leaves discs larger and more easily dynamically truncated, although external photoevaporation
remains the dominant mass loss process. Finally, we find that the correlation between disc mass and projecteddistance to the most massive nearby star (often interpreted as a sign of external photoevaporation) can be erased by
the presence of less massive stars that dominate their local radiation field. Overall, we find that the presence anddynamics of gas in embedded clusters with massive stars is important for the evolution of protoplanetary discs.

61. Magnetic topologies of two weak-line T Tauri stars TAP 4 and TAP 40

Yue Xiang, Shenghong Gu, J. -F. Donati, G. A. J. Hussain, A. Collier Cameron, the MaTYSSE collaboration

F We present a Zeeman-Doppler imaging study of two weak-line T Tauri stars TAP 4 and TAP 40, based on the highresolution spectropolarimetric observations with ESPaDOnS at the Canada-France-Hawaii Telescope in November
2013, in the framework of the MaTYSSE large programme. We apply two Zeeman-Doppler imaging codes to the
Stokes I and V profiles to reconstruct their brightness and large-scale magnetic field images. The results given by
the two imaging codes are in good agreement with each other. TAP 4 shows a large polar cool spot and several
intermediate-latitude warm spots on its surface, whereas TAP 40 exhibits very weak variations in its Stokes I profiles
suggesting a mostly unspotted photosphere. We detect Zeeman signatures in the Stokes V profiles of both stars. The
reconstructed magnetic maps reveal dominantly toroidal fields, which enclose about 60 per cent of the total magnetic
energy for both of TAP 4 and TAP 40. Both stars show prominent circular ring features of the azimuthal magnetic
field. We derive a solar-like surface differential rotation on TAP 4 from the tomographic modelling. The brightness
image of TAP 4 is used to predict the radial velocity jitters induced by its activity. After filtering out the activity
jitter, the RMS of its RVs is reduced from 1.7 km s−1 to 0.2 km s−1 , but we do not detect any periodic signals in thefiltered RVs of TAP 4, implying that it is unlikely to host a close-in exoplanet more massive than ∼3.5 MJup at 0.1
au.

Revisiting collisional dust growth in Class 0/I protostellar disks: Sweep-up can convert

62. a few 10M⊕ of dust into kg pebbles in 0.1 Myr

Wenrui Xu, Philip J. Armitage F Recent observations suggest that the first stages of planet formation likely takeplace in the Class 0/I phase of Young Stellar Object evolution, when the star and the disk are still embedded in
an infalling envelope. In this study we perform grain coagulation calculations to investigate the very first stage ofplanet formation, the collisional growth of dust grains, in Class 0/I disks. We find that the slow increase in grainmass by high-velocity collision with much smaller grains ("sweep-up") allows ∼ 50M⊕ of grains to grow well beyond
the fragmentation barrier into ∼kg pebbles by the end of Class 0/I (0.1 Myr). We analyze the linear growth andsaturation of sweep-up to understand our results quantitatively, and test whether the sweep-up outcome is sensitive
to disk parameters and details of the grain coagulation model. The sweep-up pebble population could be importantfor planet formation, because they are less well-coupled to the gas (compared to the main population below thefragmentation barrier) and therefore more favorable to known mechanisms of dust clump formation (which initiate
planetesimal formation). It also contains enough mass to form all planet cores, based on observational estimates ofthe planet mass budget. Our findings motivate future studies of grain growth and planetesimal formation in Class 0/I
disks, including the subsequent evolution of this sweep-up population.

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