The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 361 — 31 January 2023
Editor: João Alveswww.starformation.news

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Cover image caption
The spectacular HH24 in the Orion B cloud, at about 400 pc from Earth. “The HH 24 complex harbors five collimated jets
emanating from a small protostellar multiple system (...) Chaotic N-body dynamics likely will eject several more (...) objects.
The ejection of stars from their feeding zones sets their masses. Dynamical decay of non-hierarchical systems can thus be amajor contributor to establishing the initial mass function”. Reipurth et al. 2023, see below.
Credi: NASA, ESA, the Hubble Heritage (STScI/AURA)/Hubble-Europe (ESA) Collaboration, D. Padgett (GSFC), T. Megeath(University of Toledo), and B. Reipurth (University of Hawaii)

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
1. On the Number of Stars in the Sun’s Birth Cluster

Sota Arakawa, Eiichiro Kokubo F The Sun is thought to be formed within a star cluster. The coexistence of 26 Al-richand 26 Al-poor calcium–aluminum-rich inclusions indicates that a direct injection of 26 Al-rich materials from a nearby
core-collapse supernova should occur in the first 105 years of the solar system. Therefore, at least one core-collapse
supernova should occur within the duration of star formation in the Sun’s birth cluster. Here we revisit the numberof stars in the Sun’s birth cluster from the point of view of the probability for acquiring at least one core-collapse
supernova within the finite duration of star formation in the birth cluster. We find that the number of stars in thebirth cluster can be significantly larger than that previously considered, depending on the duration of star formation.

The physical and chemical processes in protoplanetary disks: constraints on the com-

2. position of comets

Yuri Aikawa, Satoshi Okuzumi, Klaus Pontoppidan F We review the recent observations of protoplanetary disks
together with relevant theoretical studies with an emphasis on the evolution of volatiles. In the last several years
Atacama Large Millimeter/submillimeter Array (ALMA) provided evidence of grain growth, gas-dust decoupling, andsub-structures such as rings and gaps in the dust continuum. Molecular line observations revealed radial and vertical
distributions of molecular abundances and also provided significant constraints on the gas dynamics such as turbulence. While sub-millimeter and millimeter observations mainly probe the gas and dust outside the radius of several
au, ice and inner warm gas are investigated at shorter wavelengths. Gas and dust dynamics are key to connecting
these observational findings. One of the emerging trends is inhomogeneous distributions of elemental abundances,most probably due to dust-gas decoupling.

3. Dust processing in protoplanetary envelopes as the origin of hot minerals in comets

Mohamad Ali-Dib F Crystalline silicates are found in a large number of comets. These pose a long-standing conundrum for solar system formation models as they can only be created in the inner hot disk at temperatures higher
than 800 K, and there is no obvious mechanism to transport them out into the comets formation region. Here we
propose that these particles could have formed inside the hydrostatic envelopes surrounding young protoplanets still2

embedded in the protoplanetary disk. Using a simplified 1D model we investigate the thermal structure of theseenvelopes, and find that for core masses ranging from 0.08 to 1.5 MEarth , located anywhere between 1 and 30 AU, thetemperature and pressure at the base of the envelopes are high enough to quickly vaporize silicate particles of various
sizes. Moreover, if the grain abundance is at least solar, these envelopes become fully convective, allowing for dust
ejection across the Bondi radius back into the disk. Amorphous silicates are hence thermally processed into crystalline
particles in these envelopes, and then transported back to disk through convective diffusion to be finally incorporated
into the cometary building blocks.

Lyman-alpha Scattering Models Trace Accretion and Outflow Kinematics in T Tauri
Systems
Nicole Arulanantham, Max Gronke, Eleonora Fiorellino, Jorge Filipe Gameiro, Antonio Frasca, Joel Green,
Seok-Jun Chang, Rik A. B. Claes, Catherine C. Espaillat, Kevin France, Gregory J. Herczeg, Carlo F. Manara,
Laura Venuti, Péter Ábrahám, Richard Alexander, Jerome Bouvier, Justyn Campbell-White, Jochen Eislöffel,
William J. Fischer, Ágnes Kóspál, Miguel Vioque F T Tauri stars produce broad Lyman-alpha emission linesthat contribute ∼88Lyman-alpha photons are generated at the accretion shocks and in the protostellar chromospheres
and must travel through accretion flows, winds and jets, the protoplanetary disks, and the interstellar medium before
reaching the observer. This trajectory produces asymmetric, double-peaked features that carry kinematic and opacity
signatures of the disk environments. To understand the link between the evolution of Lyman-alpha emission lines
and the disks themselves, we model HST-COS spectra from targets included in Data Release 3 of the Hubble UV
Legacy Library of Young Stars as Essential Standards (ULLYSES) program. We find that resonant scattering in a
simple spherical expanding shell is able to reproduce the high velocity emission line wings, providing estimates of theaverage velocities within the bulk intervening H I. The model velocities are significantly correlated with the K band
veiling, indicating a turnover from Lyman-alpha profiles absorbed by outflowing winds to emission lines suppressedby accretion flows as the hot inner disk is depleted. Just 30% of targets in our sample have profiles with red-shifted
absorption from accretion flows, many of which have resolved dust gaps. At this stage, Lyman-alpha photons may
no longer intersect with disk winds along the path to the observer. Our results point to a significant evolution of
Lyman-alpha irradiation within the gas disks over time, which may lead to chemical differences that are observablewith ALMA and JWST.

5. Unbound stars hold the key to young star cluster history

Arunima Arunima, Susanne Pfalzner, Amith Govind F Aims. GAIA delivers the positions and velocities of stars

at unprecedented precision. Therefore, for star clusters, there exists much higher confidence in whether a specific staris a member of a particular group. However, membership determination is still challenging for young star clusters. At
ages 2-10 Myr, the gas is expelled, leading to cluster expansion, while many former members become unbound. We
aim to assess the accuracy of the methods used to distinguish between bound and unbound cluster members. After
identifying the most suitable technique, we wish to understand which of the two populations provides more insights
into the initial configuration and the dynamic history of a cluster. Methods. Here, we perform N-body simulationsof the dynamics of such young star clusters. We investigate how cluster dynamics and observational limitations affectthe recovered information about the cluster from a theoretical perspective. Results. We find that the much-usedmethod of distance and velocity cutoffs for membership determination often leads to false negatives and positives
alike. Often observational studies focus on the stars remaining bound. However, they quickly lose the memory of the
pre-gas expulsion phase due to interactions with other cluster members. Our study shows that the unbound stars
hold the key to charting a cluster’s dynamic history. Backtracking unbound stars can provide the original cluster
size and determine the time of gas expulsion. This information is lost in the bound population. In addition, former
members are often better indicators for disc lifetimes or initial binary fractions. We apply the backtracking analysis,
with varying success, to the clusters: Upper Scorpius and NGC 6530. For highly substructured clusters such as Upper
Scorpius, backtracking to the individual subcluster centres will provide better results in the future (abridged).

3

and sub-millimetre spectroscopy of doubly deuterated acetaldehyde (CHD2CHO)
6. Millimetre
and first detection towards IRAS 16293-2422
J. Ferrer Asensio, S. Spezzano, L. H. Coudert, V. Lattanzi, C. P. Endres, J. K. Jørgensen, P. Caselli F The

abundances of deuterated molecules with respect to their main isotopologue counterparts have been determined to beorders of magnitude higher than expected from the cosmic abundance of deuterium relative to hydrogen. The increasing number of singly and multi-deuterated species detections helps us to constrain the interplay between gas-phase andsolid-state chemistry and to understand better deuterium fractionation in the early stages of star formation. Acetaldehyde is one of the most abundant complex organic molecules (COMs) in star-forming regions and its singly deuterated
isotopologues have already been observed towards protostars. A spectroscopic catalogue for astrophysical purposes
is built for doubly deuterated acetaldehyde CHD2CHO from measurements in the laboratory. Submillimetre wave
transitions were measured for the non-rigid doubly deuterated acetaldehyde CHD2CHO displaying hindered internalrotation of its asymmetrical CHD2 methyl group. A line position analysis is carried out allowing us to reproduce 853
transition frequencies with a weighted root mean square standard deviation of 1.7, varying 40 spectroscopic constants.
A spectroscopic catalogue for astrophysical purposes is built from the analysis results. Using this catalogue we wereable to detect for the first time CHD2CHO towards the low-mass protostellar system IRAS 16293-2422 utilizing datafrom the ALMA Protostellar Interferometric Line Survey. The first detection of the CHD2CHO species allows forthe derivation of its column density with a value of 1.3x1015 cm−2 and an uncertainty of 10-20%. The resulting
D2/D ratio of 20% is found to be coincident with D2/D ratios derived for other complex organic molecules towards
IRAS 16293-2422, pointing at a common formation environment with enhanced deuterium fractionation.

Chemical modeling of Orion Nebula Cluster disks: evidence for massive, compact gas

7. disks with ISM-like gas-to-dust ratios

Ryan D. Boyden, Josh A. Eisner F The stellar cluster environment is expected to play a central role in the evolutionof circumstellar disks. We use thermochemical modeling to constrain the dust and gas masses, disk sizes, UV and X-ray
radiation fields, viewing geometries, and central stellar masses of 20 Class II disks in the Orion Nebula Cluster (ONC).
We fit a large grid of disk models to 350 GHz continuum, CO J = 3 − 2, and HCO+ J = 4 − 3 ALMA observations ofeach target, and we introduce a procedure for modeling interferometric observations of gas disks detected in absorption
against a bright molecular cloud background. We find that the ONC disks are massive and compact, with typical radii< 100 AU, gas masses ≥ 10−3 M , and gas-to-dust ratios ≥ 100. The ISM-like gas-to-dust ratios derived from ourmodeling suggest that compact, externally-irradiated disks in the ONC are less prone to gas-phase CO depletion thanthe massive and extended gas disks that are commonly found in nearby low-mass star-forming regions. The presenceof massive gas disks indicates that external photoevaporation may have only recently begun operating in the ONC,
though it remains unclear whether other cluster members are older and more evaporated than the ones in our sample.
Finally, we compare our dynamically-derived stellar masses with the stellar masses predicted from evolutionary models
and find excellent agreement. Our study has significantly increased the number of dynamical mass measurements inthe mass range ≤ 0.5 M , demonstrating that the ONC is an ideal region for obtaining large samples of dynamical
mass measurements towards low-mass M-dwarfs.

Orbital Migration of Protoplanets in a Marginally Gravitationally Unstable Disk. II.

8. Migration, Merging, and Ejection

Alan P. Boss F Protoplanets formed in a marginally gravitationally unstable (MGU) disk by either core accretionor disk instability will be subject to dynamical interactions with massive spiral arms, possibly resulting in inward or
outward orbital migration, mergers with each other, or even outright ejection from the protoplanetary system. The
latter process has been hypothesized as a possible formation scenario for the unexpectedly high frequency of unboundgas giant exoplanets (free floating planets, FFP). Previous calculations with the EDTONS fixed grid three dimensional(3D) hydrodynamics code found that protoplanets with masses from 0.01 M⊕ to 3 MJup could undergo chaotic orbital
evolutions in MGU disks for ∼ 1000 yrs without undergoing monotonic inward or outward migration. Here the Enzo
2.5 adaptive mesh refinement (AMR) 3D hydrodynamics code is used to follow the formation and orbital evolution of
protoplanets in MGU disks for up to 2000 yrs. The Enzo results confirm the basic disk fragmentation results of the
EDTONS code, as well as the absence of monotonic inward or outward orbital migration. In addition, Enzo allows
protoplanet mergers to occur, unlike EDTONS, resulting in a significant decrease in the number of protoplanets thatsurvive for 1000 to 2000 yrs in the Enzo models. These models also imply that gas giants should be ejected frequently
in MGU disks that fragment into large numbers of protoplanets, supporting ejection as a possible source mechanism
4

for the observed FFPs.

9. Herbig Stars: A Quarter Century of Progress

Sean D. Brittain, Inga Kamp, Gwendolyn Meeus, René D. Oudmaijer, L. B. F. M. Waters F Herbig Ae/Bestars are young contracting stars on the radiative track in the HR diagram on their way to the main sequence. Thesestars provide a valuable link between high and low mass stars. Here we review the progress that has been made in our
understanding of these fascinating objects and their disks since the last major review on this topic published in 1998.
We begin with a general overview of these stars and their properties. We then discuss the accretion of circumstellar
material onto these stars. Next we discuss the dust and gas properties of the circumstellar disk before exploring theevidence for planet formation in these disks. We conclude with a brief discussion of future prospects for deepening
our understanding of these sources and propose a new working definition of Herbig Ae/Be stars.

10. Longterm Stability of Planetary Systems formed from a Transitional Disk

Rory Bowens, Andrew Shannon, Rebekah Dawson, Jiayin Dong F Transitional disks are protoplanetary disks withlarge and deep central holes in the gas, possibly carved by young planets. Dong, R., & Dawson, R. 2016, ApJ, 825, 7
simulated systems with multiple giant planets that were capable of carving and maintaining such gaps during the disk
stage. Here we continue their simulations by evolving the systems for 10 Gyr after disk dissipation and compare theresulting system architecture to observed giant planet properties, such as their orbital eccentricities and resonances.
We find that the simulated systems contain a disproportionately large number of circular orbits compared to observed
giant exoplanets. Large eccentricities are generated in simulated systems that go unstable, but too few of our systems
go unstable, likely due to our demand that they remain stable during the gas disk stage to maintain cavities. We also
explore whether transitional disk inspired initial conditions can account for the observed younger ages of 2:1 resonant
systems orbiting mature host stars. Many simulated planet pairs lock into a 2:1 resonance during the gas disk stage,
but those that are disrupted tend to be disrupted early, within the first 10 Myr. Our results suggest that systems ofgiant planets capable of carving and maintaining transitional disks are not the direct predecessors of observed giant
planets, either because the transitional disk cavities have a different origin or another process is involved, such as
convergent migration that pack planets close together at the end of the transitional disk stage.

11. 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 combinationof 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.

and ALMA Investigate Magnetic Fields and Gas Structures in Massive Star
12. SOFIA
Formation: The Case of the Masquerading Monster in BYF 73
Peter J. Barnes, Stuart D. Ryder, Giles Novak, Richard M. Crutcher, Laura M. Fissel, Rebecca L. Pitts,
William J. Schap III F We present SOFIA+ALMA continuum and spectral-line polarisation data on the massive

molecular cloud BYF 73, revealing important details about the magnetic field morphology, gas structures, and energetics in this unusual massive star formation laboratory. The 154µm HAWC+ polarisation map finds a highly organised
magnetic field in the densest, inner 0.55×0.40 pc portion of the cloud, compared to an unremarkable morphology in5the cloud’s outer layers. The 3mm continuum ALMA polarisation data reveal several more structures in the inner domain, including a pc-long, ∼500 M "Streamer" around the central massive protostellar object MIR 2, with magnetic
fields mostly parallel to the east-west Streamer but oriented north-south across MIR 2. The magnetic field orientation
changes from mostly parallel to the column density structures to mostly perpendicular, at thresholds Ncrit = 6.6×1026
m−2 , ncrit = 2.5×1011 m−3 , and Bcrit = 42±7 nT. ALMA also mapped Goldreich-Kylafis polarisation in 12 CO acrossthe cloud, which traces in both total intensity and polarised flux, a powerful bipolar outflow from MIR 2 that interacts
strongly with the Streamer. The magnetic field is also strongly aligned along the outflow direction; energetically, it
may dominate the outflow near MIR 2, comprising rare evidence for a magnetocentrifugal origin to such outflows. A
portion of the Streamer may be in Keplerian rotation around MIR 2, implying a gravitating mass 1350±50 M forthe protostar+disk+envelope; alternatively, these kinematics can be explained by gas in free fall towards a 950±35
M object. The high accretion rate onto MIR 2 apparently occurs through the Streamer/disk, and could account for∼33% of MIR 2’s total luminosity via gravitational energy release.

13. Formation of Rocky Super-Earths From A Narrow Ring of Planetesimals

Konstantin Batygin, Alessandro Morbidelli F The formation of super-Earths, the most abundant planets in the
Galaxy, remains elusive. These planets have masses that typically exceed that of the Earth by a factor of a few;
appear to be predominantly rocky, although often surrounded by H/He atmospheres; and frequently occur in multiples.
Moreover, planets that encircle the same star tend to have similar masses and radii, whereas those belonging to different
systems exhibit remarkable overall diversity. Here, we advance a theoretical picture for rocky planet formation thatsatisfies the aforementioned constraints: building upon recent work - which demonstrates that planetesimals canform rapidly at discrete locations in the disk - we propose that super-Earths originate inside rings of silicate-richplanetesimals at approximately 1 AU. Within the context of this picture, we show that planets grow primarily throughpairwise collisions among rocky planetesimals, until they achieve terminal masses that are regulated by isolation andorbital migration. We quantify our model with numerical simulations and demonstrate that our synthetic planetarysystems bear a close resemblance to compact, multi-resonant progenitors of the observed population of short-period
extrasolar planets. Our results thus indicate that the absence of short-period super-Earths within the solar system can
simply be attributed to the comparatively low mass of the primordial planetesimal ring within the protosolar nebula.

Depletion in the Early Solar System
14. Carbon
Fabian Binkert, Til Birnstiel F Earth and other rocky objects in the inner Solar System are depleted in carbon
compared to objects in the outer Solar System, the Sun, or the ISM. It is believed that this is a result of the selective
removal of refractory carbon from primordial circumstellar material. In this work, we study the irreversible releaseof carbon into the gaseous environment via photolysis and pyrolysis of refractory carbonaceous material during thedisk phase of the early Solar System. We analytically solve the one-dimensional advection equation and derive an
explicit expression that describes the depletion of carbonaceous material in solids under the influence of radial andvertical transport. We find both depletion mechanisms individually fail to reproduce Solar System abundances undertypical conditions. While radial transport only marginally restricts photodecomposition, it is the inefficient verticaltransport that limits carbon depletion under these conditions. We show explicitly that an increase in the vertical mixing
efficiency, and/or an increase in the directly irradiated disk volume, favors carbon depletion. Thermal decomposition
requires a hot inner disk (> 500 K) beyond 3 AU to deplete the formation region of Earth and chondrites. We find FU
Ori-type outbursts to produce these conditions such that moderately refractory compounds are depleted. However,such outbursts likely do not deplete the most refractory carbonaceous compounds beyond the innermost disk region.
Hence, the refractory carbon abundance at 1 AU typically does not reach terrestrial levels. Nevertheless, under specificconditions, we find photolysis and pyrolysis combined to reproduce Solar System abundances.

15. Massive pre-main-sequence stars in M17 – Modelling hydrogen and dust in MYSO disksFrank Backs, J. Poorta, Ch. Rab, A. R. Derkink, A. de Koter, L. Kaper, M. C. Ramírez-Tannus, I. Kamp

F The young massive-star-forming region M17 contains optically visible massive pre-main-sequence stars that are
surrounded by circumstellar disks. Such disks are expected to disappear when these stars reach the main sequence.
The physical and dynamical structure of these remnant disks are poorly constrained, especially the inner regions
where accretion, photo-evaporation, and companion formation and migration may be ongoing. We aim to constrain
the physical properties of the inner parts of the circumstellar disks of massive young stellar objects B243 (6 Msun) and6

B331 (12 Msun), two systems for which the central star has been detected and characterized previously despite strong
dust extinction. Two-dimensional radiation thermo-chemical modelling with ProDiMo of double-peaked hydrogenlines of the Paschen and Brackett series observed with X-shooter was used to probe the properties of the inner disks.
Additionally, the dust structure was studied by fitting the optical and near-infrared spectral energy distribution. B243
features a hot gaseous inner disk with dust at the sublimation radius at 3 AU. The disk appears truncated at roughly
6.5 AU; a cool outer disk of gas and dust may be present, but it cannot be detected with our data. B331 also has a
hot gaseous inner disk. A gap separates the inner disk from a colder dusty outer disk starting at up to 100 AU. In
both sources the inner disk extends to almost the stellar surface. Chemistry is essential for the ionization of hydrogenin these disks. The lack of a gap between the central objects and these disks suggests that they accrete throughboundary-layer accretion. This would exclude the stars having a strong magnetic field. Their structures suggestthat both disks are transitional in nature, that is to say they are in the process of being cleared, either throughboundary-layer accretion, photo-evaporation, or through companion activity.

16. Gaia-ESO Survey: massive stars in the Carina Nebula. A new census of OB stars
S. R. Berlanas, J. Maíz Apellániz, A. Herrero, L. Mahy, R. Blomme, I. Negueruela, R. Dorda, F. Comerón,
E. Gosset, M. Pantaleoni González, J. A. Molina Lera, A. Sota, T. Furst, E. J. Alfaro, M. Bergemann, G.
Carraro, J. E. Drew, L. Morbidelli, J. S. Vink F The Gaia-ESO survey sample of massive OB stars in the Carina

Nebula consists of 234 stars. The addition of brighter sources from the Galactic O-Star Spectroscopic Survey andadditional sources from the literature allows us to create the most complete census of massive OB stars done so far
in the region. It contains a total of 316 stars, being 18 of them in the background and four in the foreground. Of
the 294 stellar systems in Car OB1, 74 are of O type, 214 are of non-supergiant B type and 6 are of WR or non-O
supergiant (II to Ia) spectral class. We identify 20 spectroscopic binary systems with an O-star primary, of which 6
are reported for the first time, and another 18 with a B-star primary, of which 13 are new detections. The averageobserved double-lined binary fraction of O-type stars in the surveyed region is 0.35, which represents a lower limit.
We find a good correlation between the spectroscopic n-qualifier and the projected rotational velocity of the stars.
The fraction of candidate runaways among the stars with and without the n-qualifier is 4.4% and 2.4%, respectively,
although non resolved double-lined binaries can be contaminating the fast rotators sample.

Cyanopolyyne chemistry in the L1544 prestellar core: new insights from GBT observa-

17. tionsEleonora Bianchi, Anthony Remijan, Claudio Codella, Cecilia Ceccarelli, Francois Lique, Silvia Spezzano, Nadia
Balucani, Paola Caselli, Eric Herbst, Linda Podio, Charlotte Vastel, Brett McGuire F We report a comprehen-sive study of the cyanopolyyne chemistry in the prototypical prestellar core L1544. Using the 100m Robert C. Byrd
Green Bank Telescope (GBT) we observe 3 emission lines of HC3 N, 9 lines of HC5 N, 5 lines of HC7 N, and 9 lines of
HC9 N. HC9 N is detected for the first time towards the source. The high spectral resolution (∼ 0.05 km s−1 ) reveals
double-peak spectral line profiles with the redshifted peak a factor 3-5 brighter. Resolved maps of the core in othermolecular tracers indicates that the southern region is redshifted. Therefore, the bulk of the cyanopolyyne emission
is likely associated with the southern region of the core, where free carbon atoms are available to form long chains,thanks to the more efficient illumination of the interstellar field radiation. We perform a simultaneous modelling of
the HC5 N, HC7 N, and HC9 N lines, to investigate the origin of the emission. To enable this analysis, we performed
new calculation of the collisional coefficients. The simultaneous fitting indicates a gas kinetic temperature of 5–12
K, a source size of 80 arcsec, and a gas density larger than 100 cm−3 . The HC5 N:HC7 N:HC9 N abundance ratios
measured in L1544 are about 1:6:4. We compare our observations with those towards the the well-studied starlesscore TMC-1 and with the available measurements in different star-forming regions. The comparison suggests that acomplex carbon chain chemistry is active in other sources and it is related to the presence of free gaseous carbon.
Finally, we discuss the possible formation and destruction routes in the light of the new observations.

18. What does a typical full-disc around a post-AGB binary look like? – Radiative transfer
models reproducing PIONIER, GRAVITY, and MATISSE data

A. Corporaal, J. Kluska, H. Van Winckel, D. Kamath, M. Min F (abridged) Stable circumbinary discs aroundevolved post-Asymptotic Giant branch (post-AGB) binary systems show many similarities with protoplanetary discs
around young stellar objects. These discs can provide constraints on both binary evolution and the formation of7macrostructures within circumstellar discs. Here we focus on one post-AGB binary system: IRAS08544-4431. We aim
to refine the physical model of IRAS08544-4431 with a radiative transfer treatment and continue the near-infraredand mid-infrared interferometric analysis covering the H-, K-, L-, and N-bands. We aim to capture the previously
detected amount of over-resolved flux and the radial intensity profile at and beyond the inner dust disc rim to put
constraints on the physical processes in the inner disc regions. We used a Monte Carlo radiative transfer code toinvestigate the physical structure of the disc by reproducing both the photometry and the multi-wavelength infraredinterferometric data set. We developed a strategy to identify the models which perform best to reproduce our data
set. We found a family of models that successfully fit the infrared photometric and interferometric data in all bands.
Some over-resolved flux component was recovered in all bands but the optimised models still fall short to explain all
the over-resolved flux. This suggests that another dusty structure within the system plays a role. Multi-wavelength
infrared interferometric observations of circumstellar discs allow to study the inner disc regions in unprecedented detail.
The refined physical models can reproduce most of the investigated features, including the photometric characteristics,
the radial extent, and the overall shape of the visibility curves. Our multi-wavelength interferometric observations
combined with photometry show that the disc is similar to protoplanetary discs with similar dust masses and efficientdust growth.

Climbing the Cliffs: Classifying YSOs in the Cosmic Cliffs using a ML Approach with

19. JWST Data

B. L. Crompvoets, H. Teimoorinia, J. Di Francesco F The James Webb Space Telescope (JWST) observed a sectionof the star forming region NGC 3324 during its Early Release Observations. We make use of the Probabilistic Random
Forest machine learning model to identify YSOs within the field of view. We build a matched catalog from photometry
data products available on the Mikulski Space Telescope Archive and retrieve 8632 objects, of which Spitzer previously
detected 458. We use previously classified data from Spitzer to train on a sample of the Webb data. We retrieve a
total of 72 YSO candidates within the data field, 52 of which are only visible with JWST.

Dynamics of dust grains in turbulent molecular clouds. Conditions for decoupling and

20. limits of different numerical implementationsBenoît Commerçon, Ugo Lebreuilly, Daniel J. Price, Francesco Lovascio, Guillaume Laibe, Patrick Hennebelle

F Dust grain dynamics in molecular clouds is regulated by its interplay with supersonic turbulent gas motions. The
conditions under which dust grains decouple from the dynamics of gas remain poorly constrained. We first aim
to investigate the critical dust grain size for dynamical decoupling, using both analytical predictions and numericalexperiments. Second, we aim to set the range of validity of two fundamentally different numerical implementations forthe evolution of dust and gas mixtures in turbulent molecular clouds. We carried out a suite of numerical experiments
using two different schemes. First, we used a monofluid formalism in the terminal velocity approximation (TVA) on
a Eulerian grid. Second, we used a two-fluid scheme, in which the dust dynamics is handled with Lagrangian superparticles, and the gas dynamics on a Eulerian grid. The monofluid results are in good agreement with the theoreticalcritical size for decoupling. We report dust dynamics decoupling for Stokes number St>0.1, that is, dust grains ofs > 4 µm in size. We find that the TVA is well suited for grain sizes of 10 µm in molecular clouds, in particularin the densest regions. However, the maximum dust enrichment measured in the low-density material where St>1 isquestionable. In the Lagrangian dust experiments, we show that the results are affected by the numerics for all dust
grain sizes. At St«1, the dust dynamics is largely affected by artificial trapping in the high-density regions, leading
to spurious variations of the dust concentration. At St>1, the maximum dust enrichment is regulated by the grid
resolution used for the gas dynamics. The results of previous similar numerical work should therefore be revisited withrespect to the limitations we highlight in this study. Dust enrichment of submicron dust grains is unlikely to occur inthe densest parts of molecular clouds.

21. Mercury’s formation within the Early Instability Scenario

Matthew S. Clement, John E. Chambers, Nathan A. Kaib, Sean N. Raymond, Alan P. Jackson F The innersolar system’s modern orbital architecture provides inferences into the epoch of terrestrial planet formation; a 100
Myr time period of planet growth via collisions with planetesimals and other proto-planets. While classic numericalsimulations of this scenario adequately reproduced the correct number of terrestrial worlds, their semi-major axes
and approximate formation timescales, they struggled to replicate the Earth-Mars and Venus-Mercury mass ratios.

8In a series of past independent investigations, we demonstrated that Mars’ mass is possibly the result of Jupiter andSaturn’s early orbital evolution, while Mercury’s diminutive size might be the consequence of a primordial mass deficit
in the region. Here, we combine these ideas in a single modeled scenario designed to simultaneously reproduce theformation of all four terrestrial planets and the modern orbits of the giant planets in broad strokes. By evaluating
our Mercury analogs’ core mass fractions, masses, and orbital offsets from Venus, we favor a scenario where Mercury
forms through a series of violent erosive collisions between a number of Mercury-mass embryos in the inner part of
the terrestrial disk. We also compare cases where the gas giants begin the simulation locked in a compact 3:2 resonant
configuration to a more relaxed 2:1 orientation and find the former to be more successful. In 2:1 cases, the entire
Mercury-forming region is often depleted due to strong sweeping secular resonances that also tend to overly excite theorbits of Earth and Venus as they grow. While our model is quite successful at replicating Mercury’s massive coreand dynamically isolated orbit, the planets’ low mass remains extremely challenging to match. Finally, we discuss the
merits and drawbacks of alternative evolutionary scenarios and initial disk conditions.

22. 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.

23. A Complete HCN Survey of the Perseus Molecular Cloud
T. M. Dame, Charles J. Lada F We present a survey of the Perseus molecular cloud in the J = 1→0 transition of

HCN, a widely used tracer of dense molecular gas. The survey was conducted with the CfA 1.2 m telescope, which
at 89 GHz has a beam width of 11’ and a spectral resolution of 0.85 km s−1 . A total of 8.1 deg2 was surveyed ona uniform 10’ grid to a sensitivity of 14 mK per channel. The survey was compared with similar surveys of CO anddust in order to study and calibrate the HCN line as a dense gas tracer. We find the HCN emission to extend overa considerable fraction of the cloud. We show that the HCN intensity remains linear with H2 column density wellinto the regime where the CO line saturates. We use radiative transfer modeling to show that this likely results fromsubthermal excitation of HCN in a cloud where the column and volume densities of H2 are positively correlated. To
match our HCN observations the model requires an exponential decrease in HCN abundance with increasing extinction,
consistent with HCN depletion onto grains. The modeling also reveals that the mean volume density of H2 in the
HCN emitting regions is ∼ 104 cm−3 , well below the HCN critical density. For the first time, we obtain a direct
measurement of the ratio of dense gas mass to HCN luminosity for an entire nearby molecular cloud: α(HCN) = 92
M /(K km s−1 pc2 ).

magnetic field in star formation processes of L1521 F revealed by submillimeter
24. Twisted
dual band polarimetry using James Clerk Maxwell Telescope
Sakiko Fukaya, Hiroko Shinnaga, Ray S. Furuya, Kohji Tomisaka, Masahiro N. Machida, Naoto Harada F

Understanding the initial conditions of star formation requires both observational studies and theoretical works taking
into account the magnetic field, which plays an important role in star formation processes. Herein, we study the young
nearby dense cloud core L1521 F (n(H2 ) ∼ 104−6 cm−3 ) in the Taurus Molecular Cloud. This dense core hosts a 0.2
M protostar, categorized as a Very Low Luminosity Objects with complex velocity structures, particularly in thevicinity of the protostar. To trace the magnetic field within the dense core, we conducted high sensitivity submillimeterpolarimetry of the dust continuum at λ= 850 µm and 450 µm using the POL-2 polarimeter situated in front of the
SCUBA-2 submillimeter bolometer camera on James Clerk Maxwell Tetescope. This was compared with millimeterpolarimetry taken at λ= 3.3 mm with ALMA. The magnetic field was detected at λ= 850 µm in the peripheral region,

9

which is threaded in a north-south direction, while the central region traced at λ= 450 µm shows a magnetic field withan east-west direction, i.e., orthogonal to that of the peripheral region. Magnetic field strengths are estimated to be∼70 µG and 200 µG in the peripheral- and central-regions, respectively, using the Davis-Chandrasekhar-Fermi method.
The resulting mass-to-flux ratio of 3 times larger than that of magnetically critical state for both regions indicates that
L1521 F is magnetically supercritical, i.e., gravitational forces dominate over magnetic turbulence forces. Combining
observational data with MHD simulations, detailed parameters of the morphological properties of this puzzling object
are derived for the first time.

25. Forbidden emission lines in protostellar outflows and jets with MUSE

Lizxandra Flores-Rivera, Mario Flock, Nicolás Kurtovic, Bernd Husemann, Andrea Banzatti, Simon C. Ringqvist,
Sebastian Kamann, André Müller, Christian Fendt, Rebeca Garcia Lopez, Gabriel-Dominique Marleau, Thomas
Henning, Carlos Carrasco-Gonzalez, Roy van Boekel, Miriam Keppler, Ralf Launhardt, Yuhiko Aoyama F For-bidden emission lines in protoplanetary disks are a key diagnostic in studies of the evolution of the disk and the hoststar. We report spatially resolved emission lines, [OI] 6300, 6363, [NII] 6548, 6583, Hα, and [SII] 6716, 6730 Angstromthat are believed to be associated with jets and magnetically driven winds in the inner disks. Observations were carriedout with the optical integral field spectrograph of the Multi Unit Spectroscopic Explorer (MUSE), at the Very Large
Telescope (VLT). With a resolution of 0.025 X 0.025 arcsec2 , we aim to derive the position angle of the outflow/jet(PAoutf low/jet ) that is connected with the inner disk. The forbidden emission lines analyzed here have their origin at
the inner parts of the protoplanetary disk. From the maximum intensity emission along the outflow/jet in DL Tau, CI
Tau, DS Tau, IP Tau, and IM Lup, we were able to reliably measure the PAoutf low/jet for most of the identified lines.
We found that our estimates agree with PAdust for most of the disks. These estimates depend on the signal-to-noiselevel and the collimation of the outflow (jet). The outflows/jets in CIDA 9, GO Tau, and GW Lup are too compact
for a PAoutf low/jet to be estimated. Based on our kinematics analysis, we confirm that DL Tau and CI Tau host astrong outflow/jet with line-of-sight velocities much greater than 100 km s−1 , whereas DS Tau, IP Tau, and IM Lup
velocities are lower and their structures encompass low-velocity components to be more associated with winds. Ourestimates for the mass-loss rate, Ṁloss , range between (1.1-6.5)X10−7 -10−8 M yr−1 for the disk-outflow/jet systems
analyzed here. The outflow/jet systems analyzed here are aligned within around 1 degree between the inner and outerdisk. Further observations are needed to confirm a potential misalignment in IM Lup.

A High-resolution Optical Survey of Upper Sco: Evidence for Coevolution of Accretion

26. and Disk Winds

Min Fang, Ilaria Pascucci, Suzan Edwards, Uma Gorti, Lynne A. Hillenbrand, John M. Carpenter F Mag-

netohydrodynamic (MHD) and photoevaporative winds are thought to play an important role in the evolution anddispersal of planet-forming disks. Here, we analyze high-resolution (∆v ∼ 7 kms−1 ) optical spectra from a sample
of 115 T Tauri stars in the ∼ 5 − 10 Myr Upper Sco association and focus on the [O I]λ6300 and Hα lines to trace
disk winds and accretion, respectively. Our sample covers a large range in spectral type and we divide it into Warm
(G0-M3) and Cool (later than M3) to facilitate comparison with younger regions. We detect the [O I]λ6300 line in
45 out of 87 upper sco sources with protoplanetary disks and 32 out of 45 are accreting based on Hα profiles andequivalent widths. All [O I] λ6300 Upper Sco profiles have a low-velocity (centroid < −30 kms−1 , LVC) emission
and most (36/45) can be fit by a single Gaussian (SC). The SC distribution of centroid velocities and FWHMs is
consistent with MHD disk winds. We also find that the Upper Sco sample follows the same accretion luminosity−LVC[O I]λ6300 luminosity relation and the same anti-correlation between SC FWHM and WISE W3-W4 spectral index
as the younger samples. These results indicate that accretion and disk winds coevolve and that, as inner disks clear
out, wind emission arises further away from the star. Finally, our large spectral range coverage reveals that Cool stars
have larger FWHMs normalized by stellar mass than Warm stars indicating that [O I]λ6300 emission arises closer intowards lower mass/lower luminosity stars.

The active weak-line T Tauri star LkCa 4 observed with SPIRou and TESS

27. Benjamin Finociety, Jean-François Donati, Konstantin Grankin, Jérôme Bouvier, Silvia Alencar, François
Ménard, Tom P. Ray, Ágnes Kóspál, the SLS consortium F We report results of a spectropolarimetric andphotometric monitoring of the weak-line T Tauri star LkCa 4 within the SPIRou Legacy Survey large programme,
based on data collected with SPIRou at the Canada-France-Hawaii Telescope and the TESS space probe between

10October 2021 and January 2022. We applied Zeeman-Doppler Imaging to our spectropolarimetric and photometricdata to recover a surface brightness distribution compatible with TESS photometry, as well as the large-scale magnetic
topology of the star. As expected from the difference in wavelength between near-infrared and optical data, therecovered surface brightness distribution is less contrasted than the previously published one based on ESPaDOnS
data, but still features mid-latitude dark and bright spots. The large-scale magnetic field is consistent in shapeand strength with the one derived previously, with a poloidal component resembling a 2.2 kG dipole and a toroidal
component reaching 1.4 kG and encircling the star at the equator. Our new data confirm that the surface differential
rotation of LkCa 4 is about 10 times weaker than that of the Sun, and significantly different from zero. Using ourbrightness reconstruction and Gaussian Process Regression, we were able to filter the radial velocity activity jitter
down to a precision of 0.45 and 0.38 km s−1 (from an amplitude of 6.10 km s−1 ), respectively, yielding again noevidence for a close-in massive planet orbiting the star.

Reflections on nebulae around young stars: A systematic search for late-stage infall of

28. material onto Class II disks

Aashish Gupta, Anna Miotello, Carlo F. Manara, Jonathan P. Williams, Stefano Facchini, Giacomo Beccari,
Til Birnstiel, Christian Ginski, Alvaro Hacar, Michael Küffmeier, Leonardo Testi, Lukasz Tychoniec, Hsi-Wei
Yen F Context. While it is generally assumed that Class II sources evolve largely in isolation from their environment,

many still lie close to molecular clouds and may continue to interact with them. This may result in late accretionof material onto the disk that can significantly influence disk processes and planet formation. Aims. In order tosystematically study late infall of gas onto disks, we identify candidate Class II sources in close vicinity to a reflection
nebula (RN) that may be undergoing this process. Methods. First we targeted Class II sources with known kilo-au
scale gas structures - possibly due to late infall of material - and we searched for RNe in their vicinity in optical andnear-infrared images. Second, we compiled a catalogue of Class II sources associated with RNe and looked for thelarge-scale CO structures in archival ALMA data. Using the catalogues of protostars and RNe, we also estimated theprobability of Class II sources interacting with surrounding material. Results. All of the sources with large-scale gas
structures also exhibit some reflection nebulosity in their vicinity. Similarly, at least five Class II objects associatedwith a prominent RNe, and for which adequate ALMA observations are available, were found to have spirals or
stream-like structures which may be due to late infall. We report the first detection of these structures around S
CrA. Conclusions. Our results suggest that a non-negligible fraction of Class II disks in nearby star-forming regions
may be associated with RNe and could therefore be undergoing late accretion of gas. Surveys of RNe and kilo-au
scale gas structures around Class II sources will allow us to better understand the frequency and impact of late-infall
phenomena.

29. Molecular Mapping of DR Tau’s Protoplanetary Disk, Envelope, Outflow, and LargeScale Spiral Arm

Jane Huang, Edwin A. Bergin, Jaehan Bae, Myriam Benisty, Sean M. Andrews F DR Tau has been noted

for its unusually high variability in comparison with other T Tauri stars. Although it is one of the most extensively
studied pre-main sequence stars, observations with millimeter interferometry have so far been relatively limited. We
present NOEMA images of 12 CO, 13 CO, C18 O, SO, DCO+ , and H2 CO toward DR Tau at a resolution of ∼ 0.500(∼ 100 au). In addition to the protoplanetary disk, CO emission reveals an envelope, a faint asymmetric outflow,
and a spiral arm with a clump. The ∼ 1200 au extent of the CO arm far exceeds that of the spiral arms previously
detected in scattered light, which underlines the necessity of sensitive molecular imaging for contextualizing the disk
environment. The kinematics and compact emission distribution of C18 O, SO, DCO+ , and H2 CO indicate that they
originate primarily from within the Keplerian circumstellar disk. The SO emission, though, also exhibits an asymmetrythat may be due to interaction with infalling material or unresolved substructure. The complex environment of DR
Tau is reminiscent of those of outbursting FUor sources and some EXor sources, suggesting that DR Tau’s extreme
stellar activity could likewise be linked to disk instabilities promoted by large-scale infall.

1130. Has the dust clump in the debris disk of Beta Pictoris moved?

Yinuo Han, Mark C. Wyatt, William R. F. Dent F The edge-on debris disk of the nearby young star Beta Pictoris
shows an unusual brightness asymmetry in the form of a clump. The clump has been detected in both the mid-IR
and CO and its origin has so far remained uncertain. Here we present new mid-IR observations of Beta Pic to track
any motion of the dust clump. Together with previous observations, the data span a period of 12 years. We measured
any projected displacement of the dust clump over the 12-yr period to be 0.2+1.3−1.4 au away from the star based on
the median and 1σ uncertainty, and constrain this displacement to be <11 au at the 3σ level. This implies that theobserved motion is incompatible with Keplerian motion at the 2.8σ level. It has been posited that a planet migrating
outwards may trap planetesimals into a 2:1 resonance, resulting in the observed clump at pericentre of their orbitsthat trails the planet. The observed motion is also incompatible with such resonant motion at the 2.6σ level. While
Keplerian motion and resonant motion is still possible, the data suggest that the dust clump is more likely stationary.
Such a stationary dust clump could originate from the collision or tidal disruption of a planet-sized body, or fromsecular perturbations due to a planet that create regions with enhanced densities in the disk.

31. X-Shooter Survey of Young Intermediate Mass Stars – I. Stellar Characterization andDisc Evolution

Daniela P. Iglesias, Olja Panić, Mario van den Ancker, Monika G. Petr-Gotzens, Lionel Siess, Miguel Vioque,
Ilaria Pascucci, René Oudmaijer, James Miley F Intermediate mass stars (IMSs) represent the link between

low-mass and high-mass stars and cover a key mass range for giant planet formation. In this paper, we present aspectroscopic survey of 241 young IMS candidates with IR-excess, the most complete unbiased sample to date within
300 pc. We combined VLT/X-Shooter spectra with BVR photometric observations and Gaia DR3 distances to estimate
fundamental stellar parameters such as Teff, mass, radius, age, and luminosity. We further selected those stars within
the intermediate mass range 1.5 <= Mstar/Msun <= 3.5 and discarded old contaminants. We used 2MASS and
WISE photometry to study the IR-excesses of the sample, finding 92 previously unidentified stars with IR-excess. We
classified this sample into ’protoplanetary’, ’hybrid candidates’ and ’debris’ discs based on their observed fractional
excess at 12microns, finding a new population of 17 hybrid disc candidates. We studied inner disc dispersal timescalesfor λ < 10µm and found very different trends for IMSs and low mass stars (LMSs). IMSs show excesses dropping
fast during the first 6 Myrs independently of the wavelength, while LMSs show consistently lower fractions of excess
at the shortest wavelengths and increasingly higher fractions for longer wavelengths, with slower dispersal rates. In
conclusion, this study demonstrates empirically that IMSs dissipate their inner discs very differently than LMSs,
providing a possible explanation for the lack of short period planets around IMSs.

A rich molecular chemistry in the gas of the IC 348 star cluster of the Perseus Molecular

32. CloudSusana Iglesias-Groth, Martina Marin-Dobrincic F We present Spitzer 10-34 µm spectroscopic observations of the

diffuse gas in the inner region of the star-forming region IC 348 of the Perseus Molecular Cloud. We find evidence
for the strongest mid-IR bands of common molecules as H2 , OH, H2 O,CO2 and NH3 and of several carbonaceous
molecules which may play an important role in the production of more complex hydrocarbons: HCN, C2 H2 , C4 H2 ,HC3 N, HC5 N, C2 H6 , C6 H2 , C6 H6 . The excitation diagram of H2 reveals the presence of warm gas (270 +- 30 K) at
the observed locations. Assuming this temperature, the derived abundances of CO2 and NH3 relative to H2 are 10-8
and 10-7 , respectively. From the water lines we obtain an abundance of order 10-6 and higher gas temperatures. The
abundances derived for HCN and C2 H2 , key molecules in the development of prebiotic building blocks, are of order
10-7 and 10-9 , respectively. More complex molecules such as PAHs and the fullerenes C60 and C70 are also present.
IC 348 appears to be very rich and diverse in molecular content. The JWST spectroscopic capabilities may provide
details on the spatial distribution of all these molecules and extend the present search to more complex hydrocarbons.

12Anatomy of rocky planets formed by rapid pebble accretion I. How icy pebbles deter-

33. mine the core fraction and FeO contents

Anders Johansen, Thomas Ronnet, Martin Schiller, Zhengbin Deng, Martin Bizzarro F We present a series of

papers dedicated to modelling the accretion and differentiation of rocky planets that form by pebble accretion within
the lifetime of the protoplanetary disc. In this first paper, we focus on how the accreted ice determines the distributionof iron between the mantle (oxidized FeO and FeO1.5 ) and the core (metallic Fe and FeS). We find that an initialprimitive composition of ice-rich material leads, upon heating by the decay of 26 Al, to extensive water flow and theformation of clay minerals inside planetesimals. Metallic iron dissolves in liquid water and precipitates as oxidized
magnetite Fe3 O4 . Further heating by 26 Al destabilizes the clay at a temperature of around 900 K. The released supercritical water ejects the entire water content from the planetesimal. Upon reaching the silicate melting temperatureof 1,700 K, planetesimals further differentiate into a core (made mainly of iron sulfide FeS) and a mantle with a highfraction of oxidized iron. We propose that the asteroid Vesta’s significant FeO fraction in the mantle is a testimony
of its original ice content. We consider Vesta to be a surviving member of the population of protoplanets from whichMars, Earth, and Venus grew by pebble accretion. We show that the increase in the core mass fraction and decreasein FeO contents with increasing planetary mass (in the sequence Vesta – Mars – Earth) is naturally explained by
the growth of terrestrial planets outside of the water ice line through accretion of pebbles containing iron that was
dominantly in metallic form with an intrinsically low oxidation degree.

Anatomy of rocky planets formed by rapid pebble accretion II. Differentiation by ac-

34. cretion energy and thermal blanketing

Anders Johansen, Thomas Ronnet, Martin Schiller, Zhengbin Deng, Martin Bizzarro F We explore the heating

and differentiation of rocky planets that grow by rapid pebble accretion. Our terrestrial planets grow outside of theice line and initially accrete 28% water ice by mass. The accretion of water stops after the protoplanet reaches a massof 0.01 ME where the gas envelope becomes hot enough to sublimate the ice and transport the vapour back to theprotoplanetary disc by recycling flows. The energy released by the decay of 26 Al melts the accreted ice to form clay
(phyllosilicates), oxidized iron (FeO), and a water surface layer with ten times the mass of Earth’s modern oceans. The
ocean–atmosphere system undergoes a run-away greenhouse effect after the effective accretion temperature crosses athreshold of around 300 K. The run-away greenhouse process vaporizes the water layer, thereby trapping the accretion
heat and heating the surface to more than 6,000 K. This causes the upper part of the mantle to melt and form a global
magma ocean. Metal melt separates from silicate melt and sediments towards the bottom of the magma ocean; thegravitational energy released by the sedimentation leads to positive feedback where the beginning differentiation of theplanet causes the whole mantle to melt and differentiate. All rocky planets thus naturally experience a magma ocean
stage. We demonstrate that Earth’s small excess of 182 W (the decay product of 182 Hf) relative to the chondrites is
consistent with such rapid core formation within 5 Myr followed by equilibration of the W reservoir in Earth’s mantle
with 182 W-poor material from the core of a planetary-mass impactor, provided that the equilibration degree is at least
25%-50%, depending on the initial Hf/W ratio. The planetary collision must have occurred at least 35 Myr after themain accretion phase of the terrestrial planets.

Anatomy of rocky planets formed by rapid pebble accretion III. Partitioning of volatiles

35. between planetary core, mantle, and atmosphere

Anders Johansen, Thomas Ronnet, Martin Schiller, Zhengbin Deng, Martin Bizzarro F Volatile molecules
containing hydrogen, carbon, and nitrogen are key components of planetary atmospheres. In the pebble accretion
model for rocky planet formation, these volatile species are accreted during the main planetary formation phase.
For this study, we modelled the partitioning of volatiles within a growing planet and the outgassing to the surface.
The core stores more than 90% of the hydrogen and carbon budgets of Earth for realistic values of the partition
coefficients of H and C between metal and silicate melts. The magma oceans of Earth and Venus are sufficiently
deep to undergo oxidation of ferrous Fe2+ to ferric Fe3+ . This increased oxidation state leads to the outgassing ofprimarily CO2 and H2 O from the magma ocean of Earth. In contrast, the oxidation state of Mars’ mantle remains low
and the main outgassed hydrogen carrier is H2 . This hydrogen easily escapes the atmosphere due to the irradiationfrom the young Sun in XUV wavelengths, dragging with it the majority of the CO, CO2 , H2 O, and N2 contents of
the atmosphere. A small amount of surface water is maintained on Mars, in agreement with proposed ancient ocean
shorelines, for moderately low values of the mantle oxidation. Nitrogen partitions relatively evenly between the core
and the atmosphere due to its extremely low solubility in magma; the burial of large reservoirs of nitrogen in the core13

is thus not possible. The overall low N contents of Earth disagree with the high abundance of N in all chondrite classes
and favours a volatile delivery by pebble snow. Our model of rapid rocky planet formation by pebble accretion displays
broad consistency with the volatile contents of the Sun’s terrestrial planets. The diversity of the terrestrial planets
can therefore be used as benchmark cases to calibrate models of extrasolar rocky planets and their atmospheres.

of the High-mass "Starless” Core G10.21-0.31: a Coherent Evolutionary
36. Fragmentation
Picture for Star Formation
Wenyu Jiao, Ke Wang, Thushara G. S. Pillai, Tapas Baug, Siju Zhang, Fengwei Xu F G10.21-0.31 is a 70
µm-dark high-mass starless core (M > 300 M within r < 0.15 pc) identified in Spitzer, Herschel, and APEX
continuum surveys, and is believed to harbor the initial stages of high-mass star formation. We present ALMA andSMA observations to resolve the internal structure of this promising high-mass starless core. Sensitive high-resolution
ALMA 1.3 mm dust continuum emission reveals three cores of mass ranging 11-18 M , characterized by a turbulent
fragmentation. Core 1, 2, and 3 represent a coherent evolution at three different evolutionary stages, characterizedby outflows (CO, SiO), gas temperature (H2 CO), and deuteration (N2 D+ /N2 H+ ). We confirm the potential to formhigh-mass stars in G10.21 and explore the evolution path of high-mass star formation. Yet, no high-mass prestellar
core is present in G10.21. This suggests a dynamical star formation where cores grow in mass over time.

37. Discovery of dusty sub-solar mass young stellar objects in NGC 346 with JWST/NIRCam
Olivia C. Jones, Conor Nally, Nolan Habel, Laura Lenkić, Katja Fahrion, Alec S. Hirschauer, Laurie E. U.
Chu, Margaret Meixner, Guido De Marchi, Omnarayani Nayak, Massimo Robberto, Elena Sabbi, Peter Zeidler,
Catarina Alves de Oliveira, Tracy Beck, Katia Biazzo, Bernhard Brandl, Giovanna Giardino, Teresa Jerabkova,
Charles Keyes, James Muzerolle, Nino Panagia, Klaus M. Pontoppidan, Ciaran Rogers, B. A. Sargent, David
R. Soderblom F JWST observations of NGC 346, a star-forming region in the metal-poor Small Magellanic Cloud,

reveal a substantial population of sub-solar mass young stellar objects (YSOs) with IR excess. We have detected morethan 33,000 sources across six NIRCam filters with deep, high-resolution imaging, where ongoing low-mass star formation is concentrated along dust filaments. From these observations, we construct detailed near-IR colour-magnitude
diagrams with which preliminary classifications of different YSO classes are made. For the youngest, most deeply embedded objects, JWST/NIRCam reaches over 10 magnitudes below Spitzer observations at comparable wavelengths,
and two magnitudes fainter than HST for more evolved pre main sequence sources, corresponding to ∼0.1 Msun. For
the first time in an extragalactic environment, we detect the full sequence of low-mass YSOs at all evolutionary phases.
Furthermore, evidence of IR excess and accretion suggests that the dust required for rocky planet formation is present
at low metallicities.

38. Filaments in the OMC-3 cloud and uncertainties in estimates of filament profiles
M. Juvela, E. Mannfors F Filaments are an important part of star-forming interstellar clouds. Theie properties holdclues to their formation mechanisms and role in the star-formation process. We compare the properties of filaments in
the Orion Molecular Cloud 3 (OMC-3), as seen in mid-infrared (MIR) absorption and far-infrared (FIR) dust emission.
We calculated optical depth maps of the OMC-3 filaments based on the MIR absorption seen in Spitzer data and FIR
dust emission observed with Herschel and the ArTéMiS instrument. The widths of the selected OMC-3 filament
segments are in the range 0.03-0.1 pc, with similar average values seen in both MIR and FIR analyses. Comparedto the widths, the individual parameters of the fitted Plummer functions are much more uncertain. The asymptotic
power-law index has typically values p 3 but with a large scatter. Modelling shows that the FIR observations cansystematically overestimate the filament widths. The effect is potentially tens of per cent at column densities above
N(H2 ) 1022 cm−2 but is reduced in more intense radiation fields, such as the Orion region. Spatial variations indust properties could cause errors of similar magnitude. In the MIR analysis, dust scattering should generally not
be a significant factor, unless there are high-mass stars nearby or the dust MIR scattering efficiency is higher thanin the tested dust models. Thermal MIR dust emission can be a more significant source of error, especially close toembedded sources. The analysis of interstellar filaments can be affected by several sources of systematic error, butmainly at high column densities and, in the case of FIR observations, in weak radiation fields. The widths of the
OMC-3 filaments were consistent between the MIR and FIR analyses and did not reveal systematic dependence on
the angular resolution of the observations.

1439. A low-mass hub-filament with double centre revealed in NGC2071-North

Vera Könyves, Derek Ward-Thompson, Yoshito Shimajiri, Pedro Palmeirim, Philippe André F We present thefirst analysis in NGC2071-North as a resolved hub-filament featuring a double centre. This ∼ 1.5 × 1.5 parsec-scalefilament hub contains ∼500 M . Seen from Planck, magnetic field lines may have facilitated the gathering of material
at this isolated location. The energy balance analysis, supported by infalling gas signatures, reveal that these filaments
are currently forming stars. Herschel 100 µm emission concentrates in the hub, at IRAS 05451+0037 and LkHα 316,
and presents diffuse lobes and loops around them. We suggest that such a double centre could be formed, because
the converging locations of filament pairs are offset, by 2.30 (0.27 pc). This distance also matches the diameter ofa hub-ring, seen in column density and molecular tracers, such as HCO+ (1−0) and HCN(1−0), that may indicate atransition and the connection between the hub and the radiating filaments. We argue that all of the three componentsof the emission star LkHα 316 are in physical association. We find that a ∼0.06 pc-sized gas loop, attached to IRAS
05451+0037, can be seen at wavelengths all the way from Pan-STARRS-i to Herschel-100 µm. These observations
suggest that both protostars at the double hub centre are interacting with the cloud material. In our 13 CO data, we
do not seem to find the outflow of this region that was identified in the 80s with much lower resolution.

Size-selective accretion of dust onto CPDs: Low CPD masses and filtration of larger

40. grains

Samuel M. Karlin, Olja Panić, Sven van Loo F The major satellites of Jupiter and Saturn are believed to haveformed in circumplanetary discs, which orbit forming giant protoplanets. Gas and dust in CPDs have different
distributions and affect each other by drag, which varies with grain size. Yet simulations of multiple dust grain sizes
with separate dynamics have not been done before. We seek to assess how much dust of each grain size there is incircumplanetary discs. We run multifluid 3D hydrodynamical simulations including gas and four discrete grain sizesof dust from 1µm to 1mm, representing a continuous distribution. We consider a 1 MJup protoplanet embedded in a
protoplanetary disc around a 1 M star. Our results show a truncated MRN distribution at smaller grain sizes, whichstarts to tail off by a = 100µm and is near zero at 1mm. Large dust grains, which hold most of the dust mass, havevery inefficient accretion to the CPD, due to dust filtration. Therefore CPDs’ dust masses must be small, with mass
ratio a few ×10−6 to the protoplanet. These masses and the corresponding millimetre opacities are in line with CPD
fluxes observed to date.

Ammonia mapping observations of the Galactic infrared bubble N49: Three NH3 clumps

41. along the molecular filament

Mikito Kohno, James O. Chibueze, Ross A. Burns, Toshihiro Omodaka, Toshihiro Handa, Takeru Murase,
Rin I. Yamada, Takumi Nagayama, Makoto Nakano, Kazuyoshi Sunada, Kengo Tachihara, Yasuo Fukui F We

have carried out the NH3 (J, K) = (1, 1), (2, 2), and (3, 3) mapping observations toward the Galactic infrared bubble
N49 (G28.83-0.25) using the Nobeyama 45 m telescope. Three NH3 clumps (A, B, and C) were discovered along themolecular filament with the radial velocities of ∼ 96, 87, and 89 km s−1 , respectively. The kinetic temperature derived
from the NH3 (2,2)/NH3 (1,1) shows Tkin = 27.0 ± 0.6 K enhanced at Clump B in the eastern edge of the bubble,
where position coincides with massive young stellar objects (MYSOs) associated with the 6.7 GHz class II methanol
maser source. This result shows the dense clump is locally heated by stellar feedback from the embedded MYSOs.
The NH3 Clump B also exists at the 88 km s−1 and 95 km s−1 molecular filament intersection. We therefore suggestthat the NH3 dense gas formation in Clump B can be explained by a filament-filament interaction scenario. On theother hand, NH3 Clump A and C at the northern and southern side of the molecular filament might be the sites of
spontaneous star formation because these clumps are located ∼5−10 pc away from the edge of the bubble.

42. JWST/MIRI Spectroscopy of the Disk of the Young Eruptive Star EX Lup in QuiescenceÁgnes Kóspál, Péter Ábrahám, Lindsey Diehl, Andrea Banzatti, Jeroen Bouwman, Lei Chen, Fernando CruzSáenz de Miera, Joel D. Green, Thomas Henning, Christian Rab F EX Lup is a low-mass pre-main sequence starthat occasionally shows accretion-related outbursts. Here, we present JWST/MIRI medium resolution spectroscopy
obtained for EX Lup fourteen years after its powerful outburst. EX Lup is now in quiescence and displays a Class II
spectrum. We detect a forest of emission lines from molecules previously identified in infrared spectra of classical T
Tauri disks: H2O, OH, H2, HCN, C2H2, and CO2. The detection of organic molecules demonstrates that they areback after disappearing during the large outburst. Spectral lines from water and OH are for the first time de-blended15and will provide a much improved characterization of their distribution and density in the inner disk. The spectrum
also shows broad emission bands from warm, sub-micron size amorphous silicate grains at 10 and 18 um. During theoutburst, in 2008, crystalline forsterite grains were annealed in the inner disk within 1 au, but their spectral signaturesin the 10 um silicate band later disappeared. With JWST we re-discovered these crystals via their 19.0, 20.0, and 23.5
um emission, whose strength implies that the particles are at 3 au from the star. This suggests that crystalline grains
formed in 2008 were transported outwards and now approach the water snowline, where they may be incorporated intoplanetesimals. Containing several key tracers of planetesimal and planet formation, EX Lup is an ideal laboratory to
study the effects of variable luminosity on the planet-forming material and may provide explanation for the observedhigh crystalline fraction in solar system comets.

43. Polar circumtriple planets and disks can only form close to a triple star

Stephen Lepp, Rebecca G. Martin, Stephen H. Lubow F Observations of protoplanetary disks around binary

and triple star systems suggest that misalignments between the orbital plane of the stars and the disks are common.
Motivated by recent observations of polar circumbinary disks, we explore the possibility for polar circumtriple disks
and therefore polar circumtriple planets that could form in such a disk. With n-body simulations and analytic methods
we find that the inclusion of the third star, and the associated apsidal precession, significantly reduces the radial rangeof polar orbits so that circumtriple polar disks and planets can only be found close to the stellar system. Outside ofa critical radius, that is typically in the range of 3-10 times the outer binary separation depending upon the binaryparameters, the orbits behave the same as they do around a circular orbit binary. For some observed systems thathave shorter period inner binaries, the critical radius is considerably larger. If polar circumtriple planets can form, wesuggest that it is likely that they form in a disk that was subject to breaking.

Evidence of high-mass star formation through multi-scale mass accretion in hub-filament-

44. system clouds

Hong-Li Liu, Anandmayee Tej, Tie Liu, Patricio Sanhueza, Shengli Qin, Jinhua He, Paul F. Goldsmith, Guido
Garay, Sirong Pan, Kaho Morii, Shanghuo Li, Amelia Stutz, Keníchi Tatematsu, Feng-Wei Xu, Leonardo
Bronfman, Anindya Saha, Namitha Issac, Tapas Baug, L. Viktor Toth, Lokesh Dewangan, Ke Wang, Jianwen
Zhou, Chang Won Lee, Dongting Yang, Anxu Luo, Xianjin Shen, Yong Zhang, Yue-Fang Wu, Zhiyuan Ren,
Xun-Chuan Liu, Archana Soam, Siju Zhang, Qiu-Yi Luo F We present a statistical study of a sample of 17

hub-filament-system (HFS) clouds of high-mass star formation using high-angular resolution (∼1-2 arcsecond) ALMA
1.3mm and 3mm continuum data. The sample includes 8 infrared (IR)-dark and 9 IR-bright types, which correspondto an evolutionary sequence from the IR-dark to IR-bright stage. The central massive clumps and their associatedmost massive cores are observed to follow a trend of increasing mass (M ) and mass surface density (Σ) with evolution
from IR-dark to IR-bright stage. In addition, a mass-segregated cluster of young stellar objects (YSOs) are revealed
in both IR-dark and IR-bright HFSs with massive YSOs located in the hub and the population of low-mass YSOs
distributed over larger areas. Moreover, outflow feedback in all HFSs are found to escape preferentially through theinter-filamentary diffuse cavities, suggesting that outflows would render a limited effect on the disruption of the HFSs
and ongoing high-mass star formation therein. From the above observations, we suggest that high-mass star formationin the HFSs can be described by a multi-scale mass accretion/transfer scenario, from hub-composing filaments throughclumps down to cores, that can naturally lead to a mass-segregated cluster of stars.

45. Atomic oxygen abundance toward Sagittarius B2

Dariusz C. Lis, Paul F. Goldsmith, Rolf Güsten, Peter Schilke, Helmut Wiesemeyer, Youngmin Seo, Michael
W. Werner F A substantial fraction of oxygen in diffuse clouds is unaccounted for by observations and is postulated

to be in an unknown refractory form, referred to as unidentified depleted oxygen (UDO), which, depending on thelocal gas density, may contribute up to 50% of the total oxygen content. Previous Infrared Space Observatory (ISO)observations suggest that a significant fraction of oxygen in even denser, translucent clouds may be in atomic form.
We have analyzed velocity-resolved archival SOFIA observations of the 63 µm fine-structure [O I] transition toward
the high-mass star-forming region Sgr B2(M) in the Central Molecular Zone. The foreground spiral-arm clouds aswell as the extended Sgr B2 envelope between the Sun and the background dust continuum source produce multiple[O i] absorption components, spectrally separated in velocity space. The gas-phase atomic oxygen column density inforeground clouds toward Sgr B2 is well correlated with the total hydrogen column density, with an average atomic

16

oxygen abundance of (2.51 ± 0.69) × 10−4 with respect to hydrogen nuclei. This value is in good agreement with theearlier ISO measurements on the same line of sight, and is about 35% lower than the total interstellar medium oxygen
abundance in the low-density warm gas, as measured in the UV. We find no evidence that a significant fraction of theoxygen on the line of sight toward Sagittarius B2 is in the form of UDO.

Analytical Theory for the Growth from Planetesimals to Planets by Polydisperse
46. AnPebble Accretion
Wladimir Lyra, Anders Johansen, Manuel H. Cañas, Chao-Chin Yang F Pebble accretion is recognized as asignificant accelerator of planet formation. Yet, only formulae for single-sized (monodisperse) distribution have been
derived in the literature. These can lead to significant underestimates for Bondi accretion, for which the best accreted
pebble size may not be the one that dominates the mass distribution. We derive in this paper the polydisperse theoryof pebble accretion. We consider a power-law distribution in pebble radius, and we find the resulting surface andvolume number density distribution functions. We derive also the exact monodisperse analytical pebble accretion rate
for which 3D and 2D accretion are limits. In addition, we find analytical solutions to the polydisperse 2D Hill and 3D
Bondi limits. We integrate the polydisperse pebble accretion numerically for the MRN distribution, finding a slightdecrease (by an exact factor 3/7) in the Hill regime compared to the monodisperse case. In contrast, in the Bondi
regime, we find 1-2 orders of magnitude higher accretion rates compared to monodisperse, also extending the onsetof pebble accretion to 1-2 order of magnitude lower in mass. We find Myr-timescales, within the disk lifetime, for
Bondi accretion on top of planetary seeds of masses 10−6 − 10−4 M⊕ , over a significant range of the parameter space.
This mass range overlaps with the high mass end of the planetesimal initial mass function, and thus pebble accretionis possible directly following formation by streaming instability. This alleviates the need for mutual planetesimalcollisions as a major contribution to planetary growth.

47. A disk-wind driving the rotating molecular outflow in CB 26

J. A. López-Vázquez, Luis A. Zapata, Chin-Fei Lee F We present 12CO (J=2-1) sensitive molecular line and1.3 mm continuum observations made with the Submillimeter Array (SMA) of the bipolar outflow associated withthe young star located in the Bok globule known as CB 26. The SMA observations were carried out in its extended
configuration allowing us to study the kinematics and structure of the outflow with about 1 arcsec or 140 au resolution.
We find that the dusty and edge-on circumstellar disk related with the outflow has an projected spatial (deconvolved)
size of 196 au x 42 au with a total (gas and dust) mass of 0.031 Msun. We estimated a dynamical mass for thecentral object of 0.66 Msun, and the mass of the molecular outflow of 5x10-5 Msun. The observations confirm thatthe outflow rotation has a similar orientation to that of the edge-on disk. For the outflow, we find that the following
quantities: the rotation velocity, the specific angular momentum, and the launching radius, decrease with the height
above mid-plane, as observed in other molecular rotating outflows. The radius, and expansion velocity also increase
with the height above the disk midplane. Estimations for the outflow linear momentum rate, the outflow angularmomentum rate, and the accretion luminosity seem to be well explained by a disk wind present in CB26.

48. SOLIS XVII: Jet candidate unveiled in OMC-2 and its possible link to the enhanced
cosmic-ray ionisation rate

V. Lattanzi, F. O. Alves, M. Padovani, F. Fontani, P. Caselli, C. Ceccarelli, A. López-Sepulcre, C. Favre, R.
Neri, L. Chahine, C. Vastel, L. Evans F The study of the early phases of star and planet formation is importantto understand the physical and chemical history of stellar systems such as our own. In particular, protostars bornin rich clusters are prototypes of the young Solar System. In the framework of the Seeds Of Life In Space (SOLIS)
large observational project, the aim of the present work is to investigate the origin of the previously inferred high fluxof energetic particles in the protocluster FIR4 of the Orion Molecular Cloud 2 (OMC-2), which appears asymmetricwithin the protocluster itself. Interferometric observations carried out with the IRAM NOEMA interferometer wereused to map the silicon monoxide (SiO) emission around the FIR4 protocluster. Complementary archival data fromthe ALMA interferometer were also employed to help constrain excitation conditions. A physical-chemical model
was implemented to characterise the particle acceleration along the protostellar jet candidate, along with a non-LTE
analysis of the SiO emission along the jet. The emission morphology of the SiO rotational transitions hints for the
first time at the presence of a collimated jet originating very close to the brightest protostar in the cluster, HOPS-108.
The NOEMA observations unveiled a possible jet in the OMC-2 FIR4 protocluster propagating towards a previously

17measured enhanced cosmic-ray ionisation rate. This suggests that energetic particle acceleration by the jet shock close
to the protostar might be at the origin of the enhanced cosmic-ray ionisation rate, as confirmed by modelling theprotostellar jet.

Mid-infrared spectra of differentiated meteorites (achondrites): Comparison with as-

49. tronomical observations of dust in protoplanetary and debris disks

A. Morlok, C. Koike, K. Tomeoka, A. B. Mason, C. M. Lisse, M. Anand, M. M. Grady F Mid-infrared (5 mi-cron to 25 micron) transmission/absorption spectra of differentiated meteorites (achondrites) were measured to permit
comparison with astronomical observations of dust in different stages of evolution of young stellar objects. In contrast
to primitive chondrites, achondrites underwent heavy metamorphism and/or extensive melting and represent moreadvanced stages of planetesimal evolution. Spectra were obtained from primitive achondrites (acapulcoite, winonaite,ureilite, and brachinite) and differentiated achondrites (eucrite, diogenite, aubrite, and mesosiderite silicates). The
ureilite and brachinite show spectra dominated by olivine features, and the diogenite and aubrite by pyroxene features. The acapulcoite, winonaite, eucrite, and mesosiderite silicates exhibit more complex spectra, reflecting theirmulti-phase bulk mineralogy. Mixtures of spectra of the primitive achondrites and differentiated achondrites in various proportions show good similarities to the spectra of the few Myr old protoplanetary disks HD104237A and V410
Anon 13. A spectrum of the differentiated mesosiderite silicates is similar to the spectra of the mature debris disks
HD172555 and HD165014. A mixture of spectra of the primitive ureilite and brachinite is similar to the spectrum of
the debris disk HD113766. The results raise the possibility that materials produced in the early stage of planetesimaldifferentiation occur in the protoplanetary and debris disks.

50. 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.

51. An APEX study of molecular outflows in FUor-type stars

Fernando Cruz-Sáenz de Miera, Ágnes Kóspál, Péter Ábrahám, Timea Csengeri, Orsolya Féher, Rolf Güsten,
Thomas Henning F FU Orionis-type objects (FUors) are low-mass pre-main-sequence objects which go through ashort-lived phase ( 100 years) of increased mass accretion rate (from 10−8 to 10−4 MSun yr−1 ). These eruptive youngstars are in the early stages of stellar evolution and, thus, still deeply embedded in a massive envelope that feeds
material to the circumstellar disk that is then accreted onto the star. Some FUors drive molecular outflows, i.e.
low-velocity wide-angle magneto-hydrodynamical winds, that inject energy and momentum back to the surrounding
envelopes, and help clear the material surrounding the young star. Here we present a 12CO (3–2), 13CO (3–2) and
12CO (4–3) survey of 20 FUor-type eruptive young stars observed with APEX. We use our 13CO (3–2) observations
to measure the masses of the envelopes surrounding each FUor and find an agreement with the FUor evolutionary
trend found from the 10um silicate feature. We find outflows in 11 FUors, calculate their masses and other kinematic
properties, and compare these with those of outflows found around quiescent young stellar objects gathered from theliterature. This comparison indicates that outflows in FUors are more massive than outflows in quiescent sources, andthat FUor outflows have a higher ratio outflow mass with respect to the envelope than the quiescent sample, indicatingthat the eruptive young stars have lower star-forming efficiencies. Finally, we found that the outflow forces in FUors
are similar to those of quiescent young stellar objects, indicating that their accretion histories are similar or that the18

FUor outflows have lower velocities.

New members of the Lupus I cloud based on Gaia astrometry Physical and accretion

52. properties from X-Shooter spectra

F. Z. Majidi, J. M. Alcala’, A. Frasca, S. Desidera, C. F. Manara, G. Beccari, V. D’Orazi, A. Bayo, K. Biazzo,
R. Claudi, E. Covino, G. Mantovan, M. Montalto, D. Nardiello, G. Piotto, E. Rigliaco F We characterize twelve

young stellar objects (YSOs) located in the Lupus I region, spatially overlapping with the Upper Centaurus Lupus(UCL) sub-stellar association. The aim of this study is to understand whether the Lupus I cloud has more members
than what has been claimed so far in the literature and gain a deeper insight into the global properties of the region.
We selected our targets using Gaia DR2 catalog, based on their consistent kinematic properties with the Lupus I bonafide members. In our sample of twelve YSOs observed by X-Shooter, we identified ten Lupus I members. We could
not determine the membership status of two of our targets, namely Gaia DR2 6014269268967059840 and 2MASSJ15361110-3444473 due to technical issues. We found out that four of our targets are accretors, among them 2MASSJ15551027-3455045, with a mass of 0.03 M , is one of the least massive accretors in the Lupus complex to date.
Several of our targets (including accretors) are formed in-situ and off-cloud with respect to the main filaments ofLupus I, hence, our study may hint that there are diffused populations of M-dwarfs around Lupus I main filaments. In
this context, we would like to emphasize that our kinematic analysis with Gaia catalogs played a key role in identifying
the new members of the Lupus I cloud.

53. The mixing of dust and gas in the high latitude translucent cloud MBM 40

Marco Monaci, Loris Magnani, Steven N. Shore F Context. High latitude molecular clouds (hereafter HLMCs)
permit the study of interstellar gas dynamics and astrochemistry with good accuracy due to their proximity, generally
clear lines of sight, and lack of internal star-forming activity which can heavily modify the physical context. MBM 40,
one of the nearest HLMCs, has been extensively studied, making it a superb target to infer and study the dust-to-gas
mixing ratio (DGMR). Aims. The mixing of dust and gas in the interstellar medium remains a fundamental issue tokeep track of astrochemistry evolution and molecular abundances. Accounting for both molecular and atomic gas isdifficult because H2 is not directly observable and HI spectra always show different dynamical profiles blended together
which are not directly correlated with the cloud. We used two independent strategies to infer the molecular and atomic
gas column densities and compute the dust-to-gas mixing ratio. Methods. We combined HI 21 cm and 12 CO line
observations with the IRAS 100 µm image to infer the dust-to-gas mixing ratio within the cloud. The cloud 21 cm
profile was extracted using a hybrid Gaussian decomposition where 12 CO was used to deduce the total molecularhydrogen column density. Infrared images were used to calculate the dust emission. Results. The dust-to-gas mixing
ratio is nearly uniform within the cloud as outlined by the hairpin structure. The total hydrogen column density and100 µm emissivity are linearly correlated over a range in N (Htot ) of one order of magnitude.

SOUL view of IRAS20126+4104. Kinematics and variability of the H2 jet from a
54. Themassive protostar
F. Massi, A. Caratti o Garatti, R. Cesaroni, T. K. Sridharan, E. Ghose, E. Pinna, M. T. Beltrán, S. Leurini,
L. Moscadelli, A. Sanna, G. Agapito, R. Briguglio, J. Christou, S. Esposito, T. Mazzoni, D. Miller, C. Plantet,
J. Power, A. Puglisi, F. Rossi, B. Rothberg, G. Taylor, C. Veillet F We exploit the increased sensitivity of

the recently installed AO SOUL at the LBT to obtain new high-spatial-resolution NIR images of the massive youngstellar object IRAS20126+4104 and its outflow. We aim to derive the jet proper motions and kinematics, as wellas to study its photometric variability by combining the novel performances of SOUL together with previous NIR
images. We used both broad-band (Ks , K 0 ) and narrow-band (Brγ, H2) observations from a number of NIR cameras(UKIRT/UFTI,SUBARU/CIAO,TNG/NICS,LBT/PISCES,and LBT/LUCI1) to derive maps of the continuum andthe H2 emission in the 2.12 µm line. Three sets of images, obtained with AO systems (CIAO,2003; FLAO,2012;
SOUL,2020), allowed us to derive the proper motions of a large number of H2 knots along the jet. Photometry fromall images was used to study the jet variability. We derived knot proper motions in the range of 1.7-20.3 mas yr−1 (i.e.
13-158 km s−1 at 1.64 kpc, avg. outflow tangential velocity ∼ 80 km s−1 ). The derived knot dynamical age spans a ∼200-4000 yr interval. A ring-like H2 feature near the protostar location exhibits peculiar kinematics and may represent
the outcome of a wide-angle wind impinging on the outflow cavity. Both H2 geometry and velocities agree with thoseinferred from proper motions of the H2 O masers, located at a smaller distance from the protostar. Although the total

19

e 0.3 mag level, we have found a clear continuum
H2 line emission from the knots does not exhibit time variations at a >flux variation (radiation scattered by the dust in the cavity opened by the jet) which is anti-correlated between theblue-shifted and red-shifted lobes and may be periodic (with a period of ∼ 12-18 yr). We suggest that the continuum
variability might be related to inner-disc oscillations which have also caused the jet precession.

55. An Ice Age JWST inventory of dense molecular cloud ices

M. K. McClure, W. R. M. Rocha, K. M. Pontoppidan, N. Crouzet, L. E. U. Chu, E. Dartois, T. Lamberts, J.
A. Noble, Y. J. Pendleton, G. Perotti, D. Qasim, M. G. Rachid, Z. L. Smith, Fengwu Sun, Tracy L Beck, A. C.
A. Boogert, W. A. Brown, P. Caselli, S. B. Charnley, Herma M. Cuppen, H. Dickinson, M. N. Drozdovskaya,
E. Egami, J. Erkal, H. Fraser, R. T. Garrod, D. Harsono, S. Ioppolo, I. Jimenez-Serra, M. Jin, J. K. Jørgensen,
L. E. Kristensen, D. C. Lis, M. R. S. McCoustra, Brett A. McGuire, G. J. Melnick, Karin I. Oberg, M. E.
Palumbo, T. Shimonishi, J. A. Sturm, E. F. van Dishoeck, H. Linnartz F Icy grain mantles are the main reservoirof the volatile elements that link chemical processes in dark, interstellar clouds with the formation of planets andcomposition of their atmospheres. The initial ice composition is set in the cold, dense parts of molecular clouds,
prior to the onset of star formation. With the exquisite sensitivity of JWST, this critical stage of ice evolution is
now accessible for detailed study. Here we show the first results of the Early Release Science program "Ice Age" thatreveal the rich composition of these dense cloud ices. Weak ices, including, 13 CO2 , OCN− , 13 CO, OCS, and COMs
functional groups are now detected along two pre-stellar lines of sight. The 12 CO2 ice profile indicates modest growthof the icy grains. Column densities of the major and minor ice species indicate that ices contribute between 2 and
19% of the bulk budgets of the key C, O, N, and S elements. Our results suggest that the formation of simple andcomplex molecules could begin early in a water-ice rich environment.

56. 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.

of the outer disk of DK Tau and a first look at its magnetic field using
57. Misalignment
spectropolarimetry
M. Nelissen, P. McGinnis, C. P. Folsom, T. Ray, A. A. Vidotto, E. Alecian, J. Bouvier, J. Morin, J. -F. Donati,
R. Devaraj F Misalignments between a forming star’s rotation axis and its outer disk axis, although not predicted bystandard theories of stellar formation, have been observed in several classical T Tauri stars (cTTs). The low-mass cTTs
DK Tau is suspected of being among them. It is also an excellent subject to investigate the interaction between stellar
magnetic fields and material accreting from the circumstellar disk, as it presents clear signatures of accretion. The
goal of this paper is to study DK Tau’s average line-of-sight magnetic field (Blos) in both photospheric absorption lines
and emission lines linked to accretion, using spectropolarimetric observations, as well as to examine inconsistencies
regarding its rotation axis. We used data collected with the ESPaDOnS and NARVAL spectropolarimeters, probing
two distinct epochs (2010 and 2012). We first determined the stellar parameters, such as effective temperature and v
sin i. Next, we removed the effect of veiling from the spectra, then obtained least-squares deconvolution profiles of theabsorption lines, before determining the Blos. We also investigated emission lines, the 587.6 nm HeI line and the CaII

20

infrared triplet, as tracers of the magnetic fields present in the accretion shocks. We find that DK Tau experiences
accretion onto a magnetic pole at an angle of about 30 degrees from the pole of its rotation axis, with a positive fieldat the base of the accretion funnels. In 2010 we find a magnetic field of up to 1.77kG, and in 2012 up to 1.99kG.
Additionally, using our derived values of period, v sin i and stellar radius, we find a value of 58 degrees (+18)(-11)
for the inclination of the stellar rotation axis, which is significantly different from the outer disk axis inclination of 21
degrees given in the literature. We find that DK Tau’s outer disk axis is likely misaligned compared to its rotation
axis by 37 degrees.

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

59. ALMA-IMF. VI. Prestellar and protostellar core populations in the W43 cloud complex
T. Nony, R. Galvan-Madrid, F. Motte, Y. Pouteau, N. Cunningham, F. Louvet, A. M. Stutz, B. Lefloch, S.
Bontemps, N. Brouillet, A. Ginsburg, I. Joncour, F. Herpin, P. Sanhueza, T. Csengeri, A. P. M. Towner,
M. Bonfand, M. Fernández-López, T. Baug, L. Bronfman, G. Busquet, J. Di Francesco, A. Gusdorf, X. Lu,
F. Olguin, M. Valeille-Manet, A. P. Whitworth F The origin of the stellar initial mass function (IMF) and its

relation with the core mass function (CMF) are actively debated issues with important implications in astrophysics.
Recent observations in the W43 molecular complex of top-heavy CMFs, with an excess of high-mass cores comparedto the canonical mass distribution, raise questions about our understanding of the star formation processes and theirevolution in space and time. We aim to compare populations of protostellar and prestellar cores in three regions
imaged in the ALMA-IMF Large Program. We created an homogeneous core catalogue in W43, combining a new coreextraction in W43-MM1 with the catalogue of W43-MM2 & MM3 presented in a previous work. Our detailed searchfor protostellar outflows enabled us to identify between 23 and 30 protostellar cores out of 127 cores in W43-MM1
and between 42 and 51 protostellar cores out of 205 cores in W43-MM2 & MM3. Cores with neither outflows nor
hot core emission are classified as prestellar candidates. We found a similar fraction of cores which are protostellar in
the two regions, about 35%. This fraction strongly varies in mass, from 15-20% at low mass, between 0.8 and 3M
up to about 80% above 16M . Protostellar cores are found to be, on average, more massive and smaller in size thanprestellar cores. Our analysis also revealed that the high-mass slope of the prestellar CMF in W43, α = −1.46+0.12−0.19 ,
is consistent with the Salpeter slope, and thus the top-heavy form measured for the global CMF, α = −0.96, is dueto the protostellar core population. Our results could be explained by clump-fed models in which cores grow in mass,
especially during the protostellar phase, through inflow from their environment. The difference between the slopes ofthe prestellar and protostellar CMFs moreover implies that high-mass cores grow more in mass than low-mass cores.

60. Do simulated molecular clouds look like real ones?

F. D. Priestley, P. C. Clark, A. P Whitworth F Simulations of molecular clouds often begin from highly idealised
initial conditions, such as a uniform-density sphere with an artificially imposed turbulent velocity field. While theresulting structures may appear qualitatively similar to those detected in continuum and line observations, it is unclear
whether they are genuinely representative of real molecular clouds. Recent observational work has discovered a tight,
often close-to-linear relationship between the integrated intensity of molecular lines and the total column density of the21cloud material. We combine magnetohydrodynamical simulations, time-dependent chemistry, and radiative transfer
to produce synthetic molecular line observations of model clouds. We find similarly tight correlations between line
intensity and column density to those observed, although the linear behaviour is only seen in isolated (as opposed
to colliding) model clouds. This linear relationship is not due to optically thin emission; all lines investigated havehigh optical depths, and the increase in integrated intensity with column density is due to higher velocity dispersion
along the line of sight. Overall, the idealised models commonly used in the literature appear to be reasonably accurate
representations of real molecular clouds.

61. BD+30◦ 549: young helium-weak silicon star in NGC 1333 star-forming region
I. Potravnov, L. Mashonkina, T. Ryabchikova F We present results of the spectroscopic study of the chemicallypeculiar star BD+30◦ 549 which is bona-fide member of young NGC 1333 star forming region. We found that thestar possesses negligible rotation and helium-weak spectroscopic pattern with strongly enhanced Si II and Si III lines.
The fundamental parameters of the star Tef f =13100 K and log(L/L )=2.1 indicate its age of about 2.7 Myr andposition on the Hertzsprung-Russell diagram at the end of the Pre-Main Sequence evolutionary track, close to theZero Age Main Sequence. Abundance analysis reveals the modest deficit of almost all elements with exception of Si,
Fe, Ca and P which are overabundant. We performed the non-LTE calculations for Si II/Si III, Mg II and Ca II inorder to check the influence of departures from LTE on line formation. Non-LTE calculations lead to much better
reproduction of individual silicon line profiles, but does not completely remove the abundance discrepancy between Si
II and Si III lines. We also investigate the effects of possible chemical stratification in BD+30◦ 549. We suspect thatthe "Si II/Si III anomaly", observed in BD+30◦ 549 spectrum arises under the combined action of the vertical andhorizontal abundance gradients and non-LTE effects. We suppose that evolutionary status and phenomena observedin BD+30◦ 549 indicate that conditions favorable for the selective diffusion and formation of the surface chemicalcomposition peculiarities (slow rotation and stabilization of the atmosphere) can be built up already at the Pre-Main
Sequence phase.

62. Analysis of the first infrared spectrum of quasi-bound H2 line emission in Herbig-Haro7

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

Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Charac-

63. terization of the young star T CrA and its circumstellar environment

E. Rigliaco, R. Gratton, S. Ceppi, C. Ginski, M. Hogerheijde, M. Benisty, T. Birnstiel, M. Dima, S. Facchini,
A. Garufi, J. Bae, M. Langlois, G. Lodato, E. Mamajek, C. F. Manara, F. Ménard, Á. Ribas, A. Zurlo F Birthenvironments of young stars have strong imprints on the star itself and their surroundings. We present a detailed analysis of the wealthy circumstellar environment around the young Herbig Ae/Be star TCrA. Our aim is to understandthe nature of the stellar system and the extended circumstellar structures as seen in scattered light images. We conduct
our analysis combining archival data, and new adaptive optics high-contrast and high-resolution images. The scattered
light images reveal the presence of a complex environment composed of a bright forward scattering rim of the disk’s

22surface that is seen at very high inclination, a dark lane of the disk midplane, bipolar outflows, and streamer features
likely tracing infalling material from the surrounding birth cloud onto the disk. The analysis of the light curve suggests
the star is a binary with a period of 29.6yrs. The comparison of the scattered light images with ALMA continuum and
12CO line emission shows the disk is in keplerian rotation, with the northern side of the outflowing material receding,while the southern side approaching the observer. The disk is itself seen edge-on. The direction of the outflows seenin scattered light is in agreement with the direction of the more distant molecular hydrogen emission-line objects(MHOs) associated to the star. Modeling of the SED using a radiative transfer scheme well agrees with the proposed
configuration, as well as the hydrodynamical simulation performed using a Smoothed Particle Hydrodynamics code.
We find evidence of streamers of accreting material around TCrA. These streamers connect the filament along which
TCrA is forming with the outer parts of the disk, suggesting that the strong misalignment between the inner andouter disk is due to a change in the direction of the angular momentum of the material accreting on the disk during
the late phase of star formation.

64. Vortex weighing and dating of planets in protoplanetary discs

Roman R. Rafikov, Nicolas P. Cimerman F High-resolution sub-mm observations of some protoplanetary discs
reveal non-asixymmetric features, which can often be interpreted as dust concentrations in vortices that form at theedges of gaps carved out by the embedded planets. We use recent results on the timescale for the planet-driven
vortex development in low-viscosity discs to set constraints on the mass and age of a planet producing the vortex.
Knowledge of the age of the central star in a vortex-bearing protoplanetary disc system allows one to set a lower limiton the planetary mass at the level of several tens of M⊕ . Also, an independent upper limit on the planetary mass
would constrain the planetary age, although given the current direct imaging detection limits this constraint is not
yet very stringent (it is also sensitively dependent on the disc scale height). These results can be extended to accountfor the history of planetary mass accretion if it is known. We apply our calculations to several protoplanetary discs
harbouring vortex-like features as revealed by ALMA and set limits of (30 − 50)M⊕ (for disc aspect ratio of 0.1) on theminimum masses of putative planets that could be responsible for these vortices. Our vortex-based method provides
an independent way of constraining the properties of embedded planets, complementary to other approaches.

65. The HH 24 Complex: Jets, Multiple Star Formation, and Orphaned Protostars
Bo Reipurth, J. Bally, Hsi-Wei Yen, H. G. Arce, L. -F. Rodriguez, A. C. Raga, T. R. Geballe, R. Rao, F.
Comeron, S. Mikkola, C. A. Aspin, J. Walawender F The HH 24 complex harbors five collimated jets emanatingfrom a small protostellar multiple system. We have carried out a multi-wavelength study of the jets, their driving
sources, and the cloud core hosting the embedded stellar system, based on data from the HST, Gemini, Subaru,
APO 3.5m, VLA, and ALMA telescopes. The data show that the multiple system, SSV 63, contains at least 7
sources, ranging in mass from the hydrogen-burning limit to proto-Herbig Ae stars. The stars are in an unstable nonhierarchical configuration, and one member, a borderline brown dwarf, is moving away from the protostellar systemwith 25 km/s, after being ejected about 5,800 yr ago as an orphaned protostar. Five of the embedded sources are
surrounded by small, possibly truncated, disks resolved at 1.3 mm with ALMA. Proper motions and radial velocities
imply jet speeds of 200-300 km/s. The two main HH 24 jets, E and C, form a bipolar jet system which traces theinnermost portions of parsec-scale chains of Herbig-Haro and H2 shocks with a total extent of at least 3 parsec. H2COand C18O observations show that the core has been churned and continuously fed by an infalling streamer. 13CO
and 12CO trace compact, low-velocity, cavity walls carved by the jets and an ultra-compact molecular outflow fromthe most embedded object. Chaotic N-body dynamics likely will eject several more of these objects. The ejection ofstars from their feeding zones sets their masses. Dynamical decay of non-hierarchical systems can thus be a major
contributor to establishing the initial mass function.

for Molecular Jets from High-Mass Protostars
66. Searching
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 what23

is 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.

the early mass-ejection in jet driven protostellar outflows. Lessons from
67. Modelling
Cep E
P. R. Rivera-Ortiz, A. de A. Schutzer, B. Lefloch, A. Gusdorf F We have used the axisymmetric chemo-hydrodynamical code WALKIMYA-2D to numerically model and reproduce the physical and CO emission propertiesof the jet-driven outflow from the intermediate-mass protostar Cep E, which was observed at ∼ 800au resolution in the
CO J = 2 → 1 line with the IRAM interferometer. Our simulations take into account the observational constraints
available on the physical structure of the protostellar envelope to provide constraints on the dynamics of the innerprotostellar environment from the study of the outflow/jet propagation away from the launch region. WALKIMYA-2D
successfully reproduces the main qualitative and quantitative features of the Cep E outflow and the jet kinematics,
naturally accounting for their time variability. Signatures of internal shocks are detected as knots along the jet. In theearly times of the ejection process, the young emitted knots interact with the dense circumstellar envelope throughhigh-velocity, dissociative shocks, which strongly decrease the CO gas abundance in the jet. As time proceeds, theknots propagate more smoothly through the envelope and dissociative shocks disappear after ∼ 103 yr. The distribution of CO abundance along the jet shows that the latter bears memory of the early dissociative phase in the courseof its propagation. Analysis of the velocity field shows that the jet material mainly consists of gas entrained from thecircumstellar envelope and accelerated away from the protostar at 700 au scale. As a result, the overall jet mass loss
rate appears higher than the actual mass ejection rate by a factor ∼ 3. Numerical modelling of the Cep E jet-driven
outflow and comparison with the CO observations have allowed us to peer into the outflow formation mechanism with
unprecedented detail and to retrieve the history of the mass-loss events that have shaped the outflow.

Simulations of Polar Circumbinary Disks: Polar Alignment and Vortex
68. Grid-Based
Formation
Ian Rabago, Zhaohuan Zhu, Rebecca G. Martin, Stephen H. Lubow F We describe the first grid-based simulationsof the polar alignment of a circumbinary disk. We simulate the evolution of an inclined disk around an eccentricbinary using the grid-based code ATHENA++. The use of a grid-based numerical code allows us to explore lower
disk viscosities than have been examined in previous studies. We find that the disk aligns to a polar orientation whenthe α viscosity is high, while disks with lower viscosity nodally precess with little alignment over 1000 binary orbital
periods. The timescales for polar alignment and disk precession are compared as a function of disk viscosity, and arefound to be in agreement with previous studies. At very low disk viscosities (e.g. α = 10−5 ), anticyclonic vortices
are observed along the inner edge of the disk. These vortices can persist for thousands of binary orbits, creating
azimuthally localized overdensities as well as multiple pairs of spiral arms. The vortex is formed at ∼ 3 − 4 times
the binary semi-major axis, close to the inner edge of the disk, and orbits at roughly the local Keplerian speed. The
presence of a vortex in the disk may play an important role in the evolution of circumbinary systems, such as driving
episodic accretion and accelerating the formation of polar circumbinary planets.

A kinematically detected planet candidate in a transition disk

69. Jochen Stadler, Myriam Benisty, Andrés F. Izquierdo, Stefano Facchini, Richard Teague, Nicolas Kurtovic,
Paola Pinilla, Jaehan Bae, Megan Ansdell, Ryan Loomis, Satoshi Mayama, Laura M. Pérez, Leonardo Testi

F Transition disks are protoplanetary disks with inner cavities possibly cleared by massive companions, which makes
them prime targets to observe at high resolution to map their velocity structure. We present ALMA Band 6 dust
and gas observations of the transition disk around RXJ1604.3-2130 A, known to feature nearly symmetric shadowsin scattered light. We studied the 12 CO line channel maps and moment maps of the line of sight velocity andpeak intensity. We fitted a Keplerian model of the channel-by-channel emission to study line profile differences andproduced deprojected radial profiles for all velocity components. The 12 CO emission shows a cavity inwards of ∼56
au and within the dust continuum ring at 81 au. The azimuthal brightness variations in the 12 CO line and dust
continuum are broadly aligned with the shadows detected in scattered-light observations. We find a strong localized
non-Keplerian feature toward the west within the continuum ring (at R = 41 ± 10 au and P A = 280 ± 2◦ ). A tightly
wound spiral is also detected which extends over 300◦ in azimuth, possibly connected to the localized non-Keplerian24feature. Finally, a bending of the iso-velocity contours within the gas cavity indicates a highly perturbed inner region,
possibly related to the presence of a misaligned inner disk. While broadly aligned with the scattered-light shadows, thelocalized non-Keplerian feature cannot be solely due to changes in temperature. Instead, we interpret the kinematicalfeature as tracing a massive companion located at the edge of the dust continuum ring. We speculate that the spiralis caused by buoyancy resonances driven by planet-disk interactions. However, this potential planet at ∼41 au cannot
explain the gas-depleted cavity, the low accretion rate, and the misaligned inner disk, which suggests the presence ofanother companion closer in.

70. The Gaia view of the Cepheus OB2 association

Máté Szilágyi, Mária Kun, Péter Ábrahám, Gábor Marton F OB associations, birthplaces of the most luminousstars, are key objects for understanding the formation of high-mass stars and their effects on their environments. The
aim of this work is to explore the structure and kinematics of the Cepheus OB2 association and characterize the historyof star formation in the region – in particular, the role of the Cepheus Bubble, surrounding Cepheus OB2. Basedon Gaia DR3 data we study the spatial and age distribution and kinematics of young stars in the region. We selectcandidate pre-main-sequence stars in the MG vs. bp−rp colour-magnitude diagram, and using a clustering algorithm,
we identify 13 stellar groups belonging to Cep OB2. Four groups, consisting of 10-13 Myr old low- and intermediatemass stars, are located in the interior of the bubble, and are part of the oldest subsystem of the association Cep OB2a.
Younger groups are found on the periphery. The tangential velocities suggest that some groups on the periphery wereborn in an expanding system of star-forming clouds, whereas others have been formed due to the collision of theirparent cloud with the expanding bubble.

71. Evolution of the reservoirs of volatiles in the protosolar nebula

Antoine Schneeberger, Olivier Mousis, Artyom Aguichine, Jonathan I. Lunine F The supersolar abundances ofvolatiles observed in giant planets suggest that a compositional gradient was present at the time of their formationin the protosolar nebula. To explain this gradient, several studies have investigated the radial transport of trace
species and the effect of icelines on the abundance profiles of solids and vapors formed in the disk. However, thesemodels only consider the presence of solids in the forms of pure condensates or amorphous ice during the evolution of
the protosolar nebula. They usually neglect the possible crystallization and destabilization of clathrates, along withthe resulting interplay between the abundance of water and those of these crystalline forms. This study is aimed atpushing this kind of investigation further by considering all possible solid phases together in the protosolar nebula:
pure condensates, amorphous ice, and clathrates. To this end, we used a one-dimensional (1D) protoplanetary disk
model coupled with modules describing the evolution of trace species in the vapor phase, as well as the dynamics ofdust and pebbles. Eleven key species are considered here, including H2 O, CO, CO2 , CH4 , H2 S, N2 , NH3 , Ar, Kr, Xe,and PH3 . Two sets of initial conditions are explored for the protosolar nebula. In a first scenario, the disk is initiallyfilled with icy grains in the forms of pure condensates. In this case, we show that clathrates can crystallize and form
enrichment peaks up to about ten times the initial abundances at their crystallization lines. In a second scenario,
the volatiles were delivered to the protosolar nebula in the forms of amorphous grains. In this case, the presence ofclathrates is not possible because there is no available crystalline water ice in their formation region. Enrichment
peaks of pure condensates also form beyond the snowline up to about seven times the initial abundances.

72. Leaky dust traps: How fragmentation impacts dust filtering by planets

Sebastian Markus Stammler, Tim Lichtenberg, Joanna Drążkowska, Tilman Birnstiel F The nucleosynthetic
isotope dichotomy between carbonaceous (CC) and non-carbonaceous (NC) meteorites has been interpreted as evidence
for spatial separation and the coexistence of two distinct planet-forming reservoirs for several million years in the solar
protoplanetary disk. The rapid formation of Jupiter’s core within one million years after the formation of calciumaluminium-rich inclusions (CAIs) has been suggested as a potential mechanism for spatial and temporal separation.
In this scenario, Jupiter’s core would open a gap in the disk and trap inward-drifting dust grains in the pressure bumpat the outer edge of the gap, separating the inner and outer disk materials from each other. We performed simulationsof dust particles in a protoplanetary disk with a gap opened by an early-formed Jupiter core, including dust growthand fragmentation as well as dust transport, using the dust evolution software DustPy. Our numerical experiments
indicate that particles trapped in the outer edge of the gap rapidly fragment and are transported through the gap,
contaminating the inner disk with outer disk material on a timescale that is inconsistent with the meteoritic record.

25This suggests that other processes must have initiated or at least contributed to the isotopic separation between the
inner and outer Solar System.

grain-size distributions in C-type shocks using a discrete power-law model
73. Modelling
Rosie Sumpter, Sven Van Loo F In this paper we discuss the implementation of a discrete, piecewise power-law grainsize distribution method into a numerical multifluid MHD code as described in Sumpter (2020). Such a description
allows to capture the full size range of dust grains and their dynamical effects. The only assumptions are that grains
within a single discrete bin have the same velocity and charge. We test the implementation by modelling plane-parallel
C-type shocks and compare the results with shock models of multispecies grain models. We find that both the discreteand multispecies grain models converge to the same shock profile. However, the convergence for the discrete models isfaster than for the multispecies grain models. For the pure advection models a single discrete bin is sufficient, while themultispecies grain models need a minimum of 8 grain species. When including grain sputtering the necessary numberof discrete bins increases to 4, as the grain distribution cannot be described by a single power-law as in the advection
models. The multispecies grain models still need more grain species to model the distribution, but the number does
not increase compared to the pure advection models. Our results show that modelling the grain distribution function
using a discrete distribution reduces the computational cost needed to capture the grain physics significantly.

74. Probing Velocity Structures of Protostellar Envelopes: Infalling and Rotating Envelopes
within Turbulent Dense Cores

Jinshi Sai, Nagayoshi Ohashi, Hsi-Wei Yen, Anaëlle J. Maury, Sébastien Maret F We have observed the threelow-mass protostars, IRAS 15398−3359, L1527 IRS and TMC-1A, with the ALMA 12-m array, the ACA 7-m array,and the IRAM-30m and APEX telescopes in the C18 O J = 2-1 emission. Overall, the C18 O emission shows clear
velocity gradients at radii of ∼100-1000 au, which likely originate from rotation of envelopes, while velocity gradientsare less clear and velocity structures are more perturbed on scales of ∼1000-10,000 au. IRAS 15398−3359 and L1527
IRS show a break at radii of ∼1200 and ∼1700 au in the radial profile of the peak velocity, respectively. The peakvelocity is proportional to r−1.38 or r−1.7 within the break radius, which can be interpreted as indicating a rotationalmotion of the envelope with a degree of contamination of gas motions on larger spatial scales. The peak velocity
follows vpeak ∝ r0.68 or vpeak ∝ r0.46 outside the break radius, which is similar to the J/M -R relation of dense cores.
TMC-1A exhibits the radial profile of the peak velocity not consistent with the rotational motion of the envelope nor
the J/M -R relation. The origin of the relation of vpeak ∝ r0.46 - 0.68 is investigated by examining correlations of thevelocity deviation (δv) and the spatial scale (τ ) in the two sources. Obtained spatial correlations, δv ∝ τ ∼0.6 , areconsistent with the scaling law predicted by turbulence models, which may suggest the large-scale velocity structures
originate from turbulence.

A Unified Model for Bipolar Outflows from Young Stars: Kinematic Signatures of Jets,

75. Winds, and Their Magnetic Interplay with the Ambient Toroids

Hsien Shang, Chun-Fan Liu, Ruben Krasnopolsky, Liang-Yao Wang F Kinematic signatures of the jet, winds,

multicavities, and episodic shells arising in the unified model of bipolar outflows developed in Shang et al. (2020),
in which an outflow forms by radially directed, wide-angle toroidally magnetized winds interacting with magnetized
isothermal toroids, are extracted in the form of position–velocity diagrams. Elongated outflow lobes, driven bymagnetized winds and their interplay with the environment, are dominated by extended bubble structures with mixing
layers beyond the conventional thin-shell models. The axial cylindrically stratified density jet carries a broad profilenear the base, across the projected velocity of the wide-angle wind, and narrows down along the axis with thecollimated flow. The reverse shock encloses the magnetized free wind, forms an innermost cavity, and deflects theflow pattern. Shear, Kelvin–Helmholtz instabilities, and pseudopulses add fine and distinctive features between thejet–shell components, and the fluctuating jet velocities. The broad webbed velocity features connect the extremely
high and the low velocities across the multicavities, mimicking nested outflowing slower-wind components. Rings andovals in the perpendicular cuts trace multicavities at different heights, and the compressed ambient gap regions enrich
the low-velocity features with protruding spikes. Our kinematic signatures capture the observed systematics of thehigh-, intermediate-, and low-velocity components from Class 0 to II jet–outflow systems in molecular and atomic
lines. The nested shells observed in HH 212, HH 30, and DG Tau B are naturally explained. Outflows as bubbles are
ubiquitous and form an inevitable integrative outcome of the interaction between wind and ambient media.

26

A Unified Model for Bipolar Outflows from Young Stars: Apparent Magnetic Jet Ac-

76. celeration

Hsien Shang, Ruben Krasnopolsky, Chun-Fan Liu F We explore a new, efficient mechanism that can power

toroidally magnetized jets up to two to three times their original terminal velocity after they enter a self-similar phaseof magnetic acceleration. Underneath the elongated outflow lobe formed by a magnetized bubble, a wide-angle freewind, through the interplay with its ambient toroid, is compressed and accelerated around its axial jet. The extremely
magnetic bubble can inflate over its original size, depending on the initial Alfvén Mach number MA of the launched
flow. The shape-independent slope ∂vr /∂r = 2/3t is a salient feature of the self-similarity in the acceleration phase.
Peculiar kinematic signatures are observable in the position–velocity (PV) diagrams and can combine with other morphological signatures as probes for the density-collimated jets arising in toroidally dominated magnetized winds. The
apparent second acceleration is powered by the decrease of the toroidal magnetic field but operates far beyond thescales of the primary magnetocentrifugal launch region and the free asymptotic terminal state. Rich implications mayconnect the jets arising from the youngest protostellar outflows such as HH 211 and HH 212 and similar systems withparsec-scale jets across the mass and evolutionary spectra.

77. 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.

QUIJOTE scientific results – V. The microwave intensity and polarisation spectra of

78. the Galactic regions W49, W51 and IC443

D. Tramonte, R. T. Génova-Santos, J. A. Rubiño-Martín, P. Vielva, F. Poidevin, C. H. López-Caraballo, M.
W. Peel, M. Ashdown, E. Artal, R. B. Barreiro, F. J. Casas, E. de la Hoz, M. Fernández-Torreiro, F. Guidi,
D. Herranz, R. J. Hoyland, A. N. Lasenby, E. Martinez-Gonzalez, L. Piccirillo, R. Rebolo, B. Ruiz-Granados,
F. Vansyngel, R. A. Watson F We present new intensity and polarisation maps obtained with the QUIJOTE

experiment towards the Galactic regions W49, W51 and IC443, covering the frequency range from 10 to 20 GHz at∼ 1 deg angular resolution, with a sensitivity in the range 35-79 µK/beam for total intensity and 13-23 µK/beam forpolarisation. For each region, we combine QUIJOTE maps with ancillary data at frequencies ranging from 0.4 to 3000
GHz, reconstruct the spectral energy distribution and model it with a combination of known foregrounds. We detect
anomalous microwave emission (AME) in total intensity towards W49 at 4.7σ and W51 at 4.0σ with peak frequencies
νAM E = (20.0 ± 1.4) GHz and νAM E = (17.7 ± 3.6) GHz respectively; this is the first detection of AME towards W51.
The contamination from ultra-compact HII regions to the residual AME flux density is estimated at 10% in W49 and
5% in W51, and does not rule out the AME detection. The polarised SEDs reveal a synchrotron contribution with
spectral indices αs = -0.67 ± 0.10 in W49 and αs = -0.51 ± 0.07 in W51, ascribed to the diffuse Galactic emission
and to the local supernova remnant respectively. Towards IC443 in total intensity we measure a broken power-law
synchrotron spectrum with cut-off frequency ν0,s = (114 ± 73) GHz, in agreement with previous studies; our analysis,
however, rules out any AME contribution which had been previously claimed towards IC443. No evidence of polarised
AME emission is detected in this study.

27

79. Magnetic fields do not suppress global star formation in low metallicity dwarf galaxies

David J. Whitworth, Rowan J. Smith, Ralf S. Klessen, Mordecai-Mark Mac Low, Simon C. O. Glover, Robin
Tress, Rudiger Pakmor, Juan D. Soler F Many studies concluded that magnetic fields suppress star formation inmolecular clouds and Milky Way like galaxies. However, most of these studies are based on fully developed fields
that have reached the saturation level, with little work on investigating how an initial weak primordial field affects
star formation in low metallicity environments. In this paper, we investigate the impact of a weak initial field on
low metallicity dwarf galaxies. We perform high-resolution AREPO simulations of five isolated dwarf galaxies. Twomodels are hydrodynamical, two start with a primordial magnetic field of 10−6 µG and different sub-solar metallicities,
and one starts with a saturated field of 10−2 µG. All models include a non-equilibrium, time-dependent chemical
network that includes the effects of gas shielding from the ambient ultraviolet field. Sink particles form directly fromthe gravitational collapse of gas and are treated as star-forming clumps that can accrete gas. We vary the ambientuniform far ultraviolet field, and cosmic ray ionization rate between 1% and 10% of solar values. We find that themagnetic field has little impact on the global star formation rate, which is in tension with some previously publishedresults. We further find that the initial field strength has little impact on the global star formation rate. We show thatan increase in the mass fractions of both molecular hydrogen and cold gas, along with changes in the perpendicular
gas velocity dispersion and the magnetic field acting in the weak-field model, overcome the expected suppression instar formation.

80. A Naive Bayes Classifier for identifying Class II YSOs

Andrew J. Wilson, Ben S. Lakeland, Tom J. Wilson, Tim Naylor F A naive Bayes classifier for identifying ClassII YSOs has been constructed and applied to a region of the Northern Galactic Plane containing 8 million sources withgood quality Gaia EDR3 parallaxes. The classifier uses the five features: Gaia G-band variability, WISE mid-infraredexcess, UKIDSS and 2MASS near-infrared excess, IGAPS Hα excess and overluminosity with respect to the main
sequence. A list of candidate Class II YSOs is obtained by choosing a posterior threshold appropriate to the task at
hand, balancing the competing demands of completeness and purity. At a threshold posterior greater than 0.5 ourclassifier identifies 6504 candidate Class II YSOs. At this threshold we find a false positive rate around 0.02 per centand a true positive rate of approximately 87 per cent for identifying Class II YSOs. The ROC curve rises rapidly
to almost one with an area under the curve around 0.998 or better, indicating the classifier is efficient at identifying
candidate Class II YSOs. Our map of these candidates shows what are potentially three previously undiscoveredclusters or associations. When comparing our results to published catalogues from other young star classifiers, we findbetween one quarter and three quarters of high probability candidates are unique to each classifier, telling us no single
classifier is finding all young stars.

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -XIII.

81. Ongoing triggered star formation within clump-fed scenario found in the massive (∼ 1500
M ) clump
S. Zhang, K. Wang, T. Liu, A. Zavagno, M. Juvela, H. Liu, A. Tej, A. M. Stutz, S. Li, L. Bronfman, Q.
Zhang, P. F. Goldsmith, C. W. Lee, E. Vázquez-Semadeni, K. Tatematsu, W. Jiao, F. Xu, C. Wang, J. -W.
Zhou F Whether ionization feedback triggers the formation of massive stars is highly debated. Using ALMA 3 mm

observations with a spatial resolution of ∼ 0.05 pc and a mass sensitivity of 1.1 M beam−1 at 20 K, we investigate thestar formation and gas flow structures within the ionizing feedback-driven structure, a clump-scale massive (& 1500
M ) bright-rimmed cloud (BRC) associated with IRAS 18290-0924. This BRC is bound only if external compression
from ionized gas is considered. A small-scale (. 1 pc) age sequence along the direction of ionizing radiation is revealed
for the embedded cores and protostars, which suggests triggered star formation via radiation-driven implosion (RDI).
Furthermore, filamentary gas structures converge towards the cores located in the BRC’s center, indicating that thesefilaments are fueling mass towards cores. The local core-scale mass infall rate derived from H13 CO+ J = 1 − 0blue profile is of the same order of magnitude as the filamentary mass inflow rate, approximately 1 M kyr−1 . A
photodissociation region (PDR) covering the irradiated clump surface is detected in several molecules, such as CCH,
HCO+ , and CS whereas the spatial distribution stratification of these molecules is indistinct. CCH spectra of the
PDR possibly indicate a photoevaporation flow leaving the clump surface with a projected velocity of ∼ 2 km s−1 .
Our new observations show that RDI accompanied by a clump-fed process is operating in this massive BRC. Whether
this combined process works in other massive BRCs is worth exploring with dedicated surveys.

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