The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 370 — 31 October 2023
Editor: João Alveswww.starformation.news

Cover image caption
Detail of the dark cloud in front of the Gum 15 Nebula, a star-forming region part of the Vela Molecular Ridge at about a kpc
from Earth. The nebula is illuminated by the bright star in the image (Pettersson & Reipurth 1994, Enokiya et al. 2018).
Credits: WFI camera at MPG/ESO 2.2-meter telescope at La Silla Observatory, Chile.
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. 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 the arXiv or the SFN.

Abstracts
1.

The birth and early evolution of a low mass protostar
Adnan Ali Ahmad, Matthias González, Patrick Hennebelle, Benoît Commerçon F Understanding the collapse of
dense molecular cloud cores to stellar densities and the subsequent evolution of the protostar is of importance to model the
feedback effects such an object has on its surrounding environment, as well as describing the conditions with which it enters thestellar evolutionary track. This process is fundamentally multi-scale and necessitates the use of robust numerical simulations.
We aim to model the birth and early evolution of a low-mass protostar. We also seek to describe the interior structure of the
protostar and the radiative behavior of its accretion shock front. We carry out a high resolution numerical simulation of thecollapse of a gravitationally unstable 1 M dense molecular cloud core to stellar densities using three-dimensional radiationhydrodynamics under the gray flux-limited diffusion approximation. We follow the initial isothermal phase, the first adiabatic
contraction, the second gravitational collapse triggered by the dissociation of H2 molecules, and ≈ 247 days of the subsequent
main accretion phase. We find that the sub-critical radiative behavior of the protostar’s shock front causes it to swell as it
accretes matter. We also find that the protostar is turbulent from the moment of its inception despite its radiative stability.
This turbulence causes significant entropy mixing inside the protostar, which regulates the swelling. Furthermore, we find thatthe protostar is not fully ionized at birth, but the relative amount of ionized material within it increases as it accretes matterfrom its surroundings. Finally, we report in the appendix the results of the first 3D calculations involving a frequency-dependent
treatment of radiative transfer, which has not produced any major differences with its gray counterpart.

2.

Growth of Massive Molecular Cloud Filament by Accretion Flows I: Slow Shock Instability v.s. Ambipolar Diffusion
Daisei Abe, Tsuyoshi Inoue, Shu-ichiro Inutsuka F The Herschel Gould Belt Survey showed that stars form in dense
filaments in nearby molecular clouds. Recent studies suggest that massive filaments are bound by the slow shocks caused byaccretion flows onto the filaments. The slow shock is known to be unstable to the corrugation deformation of the shock front.
The corrugation instability could convert the accretion flow’s ram pressure into turbulent pressure that influences the widthof the filament, which, according to theory, determines the self-gravitational fragmentation scale and core mass. In spite ofits importance, the effect of slow shock instability on star-forming filaments has not been investigated. In addition, the linear
dispersion relation obtained from the ideal magnetohydrodynamics (MHD) analysis shows that the most unstable wavelength ofshock corrugation is infinitesimally small (or mean free path). In the scale of dense filaments, the effect of ambipolar diffusion can
suppress the instability at small scales. This study investigates the influence of ambipolar diffusion on the instability of the slow
shock. We perform two-dimensional MHD simulations to examine the linear growth of the slow shock instability, considering
the effect of ambipolar diffusion. The results demonstrate that the most unstable scale of slow shock instability is approximately
five times the length scale of ambipolar diffusion lAD calculated using post-shock variables, where, lAD corresponds to the scale
where the magnetic Reynolds number for ambipolar diffusivity is unity.

3.

Fragmentation and dynamics of dense gas structures in the proximity of massive youngstellar object W42-MME
N. K. Bhadari, L. K. Dewangan, L. E. Pirogov, A. G. Pazukhin, I. I. Zinchenko, A. K. Maity, Saurabh Sharma
F We present an analysis of the dense gas structures in the immediate surroundings of the massive young stellar object(MYSO) W42-MME, using the high-resolution (000 .31×000 .25) ALMA dust continuum and molecular line data. We performed
a dendrogram analysis of H13 CO+ (4-3) line data to study multi-scale structures and their spatio-kinematic properties, and2analyzed the fragmentation and dynamics of dense structures down to ∼2000 AU scale. Our results reveal 19 dense gas structures,out of which 12 are leaves and 7 are branches in dendrogram terminology. These structures exhibit transonic-supersonic gas
motions (1< M < 5) with overvirial states (αvir ≥ 2). The non-thermal velocity dispersion-size relation (σnt −L) of dendrogram
structures shows a weak negative correlation, while the velocity dispersion across the sky (δVlsr ) correlates positively withstructure size (L). Velocity structure function (S2 (l)1/2 ) analysis of H13 CO+ data reveals strong power-law dependencies
with lag (l) up to a scale length of . 6000 AU. The mass-size (M − R) relation of dendrogram structures shows a positive
correlation with power-law index of 1.73±0.23, and the leaf L17 hosting W42-MME meets the mass-size conditions for massive
star formation. Blue asymmetry is observed in the H12 CO+ (4-3) line profiles of most of the leaves, indicating infall. Overall,our results observationally support the hierarchical and chaotic collapse scenario in the proximity of the MYSO W42-MME.

4.

The Comprehensive Archive of Substellar and Planetary Accretion Rates
S. K. Betti, K. B. Follette, K. Ward-Duong, A. E. Peck, Y. Aoyama, J. Bary, B. Dacus, S. Edwards, G. -D.
Marleau, K. Mohamed, J. Palmo, C. Plunkett, C. Robinson, H. Wang F Accretion rates (Ṁ ) of young stars show astrong correlation with object mass (M ); however, extension of the Ṁ −M relation into the substellar regime is less certain. Here,
we present the Comprehensive Archive of Substellar and Planetary Accretion Rates (CASPAR), the largest to-date compilationof substellar accretion diagnostics. CASPAR includes: 658 stars, 130 brown dwarfs, and 10 bound planetary mass companions.
In this work, we investigate the contribution of methodological systematics to scatter in the Ṁ − M relation, and comparebrown dwarfs to stars. In our analysis, we rederive all quantities using self-consistent models, distances, and empirical line
flux to accretion luminosity scaling relations to reduce methodological systematics. This treatment decreases the original 1σ
scatter in the log Ṁ − log M relation by ∼ 17%, suggesting that it makes only a small contribution to the dispersion. CASPAR
rederived values are best fit by Ṁ ∝ M 2.02±0.06 from 10 MJ to 2 M , confirming previous results. However, we argue that thebrown dwarf and stellar populations are better described separately and by accounting for both mass and age. Therefore, we
derive separate age-dependent Ṁ − M relations for these regions, and find a steepening in the brown dwarf Ṁ − M slope withage. Within this mass regime, the scatter decreases from 1.36 dex to 0.94 dex, a change of ∼44%. This result highlights thesignificant role that evolution plays in the overall spread of accretion rates, and suggests that brown dwarfs evolve faster thanstars, potentially as a result of different accretion mechanisms.

5. Growing Planet Envelopes in Spite of Recycling Flows

Avery Bailey, Zhaohuan Zhu F The hydrodynamic exchange of a protoplanet’s envelope material with the backgroundprotoplanetary disk has been proposed as one mechanism to account for the diversity of observed planet envelopes whichrange in mass fractions of 1% for super-Earths to 90% for giants. Here we present and analyze 3D radiation-hydrodynamics
models of protoplanet envelopes to understand how the exchange of mass and energy between the protoplanet and backgrounddisk influences the formation process. Our protoplanet envelope simulations show an exchange of material bringing the outer<0.4Rbondi envelope to steady state. This exchange provides a continuous source of energy, which acts to increase the observed
luminosity beyond that inferred from the binding energy liberated from Kelvin-Helmholtz contraction alone – a finding importantfor potential protoplanet observations. The inner <0.4Rbondi, on the other hand, appears insulated – growing in accordancewith 1D quasi-static theory. We incorporate these 3D hydrodynamic effects into an extensible 1D framework with a physicallymotivated three-layer recycling parameterization. Specializing to the case of Jupiter, recycling produces minimal changes to thegrowth rate with the planet still entering runaway accretion and becoming a gas giant in 1 Myr. Even in the inner disk (0.1
AU), our 1D models suggest that recycling is not so robust and ubiquitous as to stop all cores from becoming giants. At thesame time however, this recycling can delay a runaway phase by an order-of-magnitude depending on the inner disk conditions
and core mass.

6. Shocking Sgr B2(N1) with its own outflow: A new perspective on segregation between
O- and N-bearing molecules
Laura A. Busch, Arnaud Belloche, Robin T. Garrod, Holger S. P. Mueller, Karl M. Menten F We want toinvestigate the influence of the powerful outflow driven by the hot core Sgr B2(N1) on the gas molecular inventory of thesurrounding medium. We used the data taken as part of the 3 mm imaging spectral-line survey ReMoCA (Re-exploring
Molecular Complexity with ALMA). Integrated intensity maps of SO and SiO emission reveal a bipolar structure with blueshifted emission dominantly extending to the SE from the centre of the hot core and red-shifted emission to the NW. Thisis also prominently observed in emission of other S-bearing molecules and species that only contain N as a heavy element,
including COMs, but also CH3OH, CH3CHO, HNCO, and NH2CHO. For a selection of COMs and simpler species, spectra
were modelled under the assumption of LTE and population diagrams were derived at two positions, one in each outflow lobe.
From this analysis, we obtained rotational temperatures, which are in a range of 100-200K, and column densities. Abundanceswere subsequently compared to predictions of astrochemical models and to observations of L1157-B1, a position located in thewell-studied outflow of the low-mass protostar L1157, and the source G+0.693-0.027, located in the Sgr B2 molecular cloudcomplex. Given the short distance of the analysed outflow positions to the centre of Sgr B2(N1), we propose a scenario in which3a phase of hot-core chemistry (i.e. thermal desorption of ice species and high-temperature gas-phase chemistry) preceded a
shock wave. The subsequent compression and further heating of the material resulted in the accelerated destruction of (mainly
O-bearing) molecules. Gas-phase formation of cyanides seems to be able to compete with their destruction in the post-shockgas. Abundances of HCnN (n=3,5) are enhanced in the outflow component pointing to (additional) gas-phase formation. To
confirm such a scenario, appropriate chemical shock models need to be run.

7.

Constraining the formation history of the TOI-1338/BEBOP-1 circumbinary planetarysystemGavin A. L. Coleman, Richard P. Nelson, Amaury H. M. J. Triaud, Matthew R. Standing F The recent discovery
of multiple planets in the circumbinary system TOI-1338/BEBOP-1 raises questions about how such a system formed. The
formation of the system was briefly explored in the discovery paper, but only to answer the question do current pebble accretion
models have the potential to explain the origin of the system? We use a global model of circumbinary planet formation thatutilises N-body simulations, including prescriptions for planet migration, gas and pebble accretion, and interactions with acircumbinary disc, to explore the disc parameters that could have led to the formation of the TOI-1338/BEBOP-1 system.
With the disc lifetime being the main factor in determining how planets form, we limit our parameter space to those that
determine the disc lifetime. These are: the strength of turbulence in the disc, the initial disc mass, and the strength of theexternal radiation field that launches photoevaporative winds. When comparing the simulated systems to TOI-1338/BEBOP-1,
we find that only discs with low levels of turbulence are able to produce similar systems. The radiation environment has a large
effect on the types of planetary systems that form, whilst the initial disc mass only has limited impact since the majority ofplanetary growth occurs early in the disc lifetime. With the most TOI-1338/BEBOP-1 like systems all occupying similar regionsof parameter space, our study shows that observed circumbinary planetary systems can potentially constrain the properties ofplanet forming discs.

8.

Planet Gap-opening Feedback on Disk Thermal Structure and Composition

9.

Uncovering a new group of T Tauri stars in the Taurus-Auriga molecular complex from
Gaia and GALEX data

Kan Chen, Mihkel Kama, Paola Pinilla, Luke Keyte F (Exo-)planets inherit their budget of chemical elements from a
protoplanetary disk. The disk temperature determines the phase of each chemical species, which sets the composition of solids
and gas available for planet formation. We investigate how gap structures, which are widely seen by recent disk observations,alter the thermal and chemical structure of a disk. Planet-disk interaction is a leading hypothesis of gap formation and so suchchanges could present a feedback that planets have on planet-forming material. Both the planet gap-opening process and thedisk thermal structure are well studied individually, but how the gap-opening process affects disk thermal structure evolution
remains an open question. We develop a new modelling method by iterating hydrodynamical and radiative transfer simulations
to explore the gap-opening feedback on disk thermal structure. We carry out parameter studies by considering different planet
locations rp and planet masses Mp. We find that for the same rp and Mp, our iteration method predicts a wider and deeper
gap than the non-iteration method. We also find that the inner disk and gap temperature from the iteration method can varystrongly from the non-iteration or disk without planets, which can further influence dust-trap conditions, iceline locations, anddistribution of various ices, such as H2O, CO2, and CO on large dust grains ("pebbles"). Through that, a gap-opening planetcan complicate the canonical picture of the non-planet disk C/O ratio and influence the composition of the next generation ofplanetesimals and planets.

Ana Inés Gómez de Castro, Raúl de la Fuente Marcos, Ada Canet, Leire Beitia-Antero, Javier Yañez-Gestoso,
Juan Carlos Vallejo F In this work, we examine the list of 63 candidates to T Tauri star (TTS) in the TAMC identified bytheir ultraviolet (UV) and infrared colours (IR) measured from data obtained by the Galaxy Evolution Explorer all sky survey(GALEX-AIS) and the Two Microns All Sky Survey (2MASS), respectively. The objective of this work is twofold: evaluate
whether they are pre-main sequence (PMS) stars and evaluate the goodness of the UV-IR colour-colour diagram to detect PMS
stars in wide-fields. The astrometric properties of these sources have been retrieved from the Gaia DR3 catalogue and used toevaluate their membership probability. Several classification algorithms have been tested to search for the kinematical groups
but the final classification has been made with k-means++ algorithms. Membership probability has been evaluated by applying
Logistic Regression. In addition, spectroscopic information available in the archive of the Large Sky Area Multi Object Fiber
Spectroscopic Telescope has been used to ascertain their PMS nature when available. About 20% of the candidates share thekinematics of the TAMC members. Among them, HD 281691 is a G8-type field star located in front of the cloud and HO Aur
is likely a halo star given the very low metallicity provided by Gaia. The rest are three known PMS stars (HD 30171, V600 Aur
and J04590305+3003004), two previously unknown accreting M-type stars (J04510713+1708468 and J05240794+2542438) and,five additional sources, which are very likely PMS stars. Most of these new sources are concentrated at low galactic latitudes
over the Auriga-Perseus region.

410. Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): HD 34700
A unveils an inner ring
G. Columba, E. Rigliaco, R. Gratton, D. Mesa, V. D’Orazi, C. Ginski, N. Engler, J. P. Williams, J. Bae,M. Benisty, T. Birnstiel, P. Delorme, C. Dominik, S. Facchini, F. Menard, P. Pinilla, C. Rab, Á. Ribas, V.
Squicciarini, R. G. van Holstein, A. Zurlo F Context. The study of protoplanetary disks is fundamental to understandtheir evolution and interaction with the surrounding environment, and to constrain planet formation mechanisms. Aims. We
aim at characterising the young binary system HD 34700 A, which shows a wealth of structures. Methods. Taking advantage ofthe high-contrast imaging instruments SPHERE at the VLT, LMIRCam at the LBT, and of ALMA observations, we analyse thissystem at multiple wavelengths. We study the rings and spiral arms morphology and the scattering properties of the dust. We
discuss the possible causes of all the observed features. Results. We detect for the first time, in the Hα band, a ring extending
from ∼65 au to ∼120 au, inside the ring already known from recent studies. These two have different physical and geometricalproperties. Based on the scattering properties, the outer ring may consist of grains of typical size aout > 4µm, while the innerring of smaller grains (ain <= 0.4µm). Two extended logarithmic spiral arms stem from opposite sides of the disk. The outerring appears as a spiral arm itself, with a variable radial distance from the centre and extended substructures. ALMA data
confirm the presence of a millimetric dust substructure centred just outside the outer ring, and detect misaligned gas rotation
patterns for HD 34700 A and B. Conclusions. The complexity of HD 34700 A, revealed by the variety of observed features,
suggests the existence of one or more disk-shaping physical mechanisms. Possible scenarios, compatible with our findings,
involve the presence inside the disk of a yet undetected planet of several Jupiter masses and the system interaction with thesurroundings by means of gas cloudlet capture or flybys. Further observations with JWST/MIRI or ALMA (gas kinematics)
could shed more light on these.

11. Composition of giant planets: the roles of pebbles and planetesimals

Claudia Danti, Bertram Bitsch, Jingyi Mah F One of the current challenges of planet formation theory is to explain theenrichment of observed exoplanetary atmospheres. Past studies have focused on scenarios where either pebbles or planetesimals
were the heavy element enrichment’s drivers, we combine here both approaches to understand whether the composition of aplanet can constrain its formation pathway. We study three different formation scenarios: pebble accretion, pebble accretion
with planetesimal formation, combined pebble and planetesimal accretion. We use the chemcomp code to perform semianalytical 1D simulations of protoplanetary discs, including viscous evolution, pebble drift, and simple chemistry to simulate
the growth of planets from planetary embryos to gas giants as they migrate through the disc, while tracking their composition.
Our simulations confirm that the composition of the planetary atmosphere is dominated by the accretion of gas enriched byinward drifting and evaporating pebbles. Including planetesimal formation hinders the enrichment, because the pebbles locked
into planetesimals cannot evaporate and enrich the disc. This results in a big drop of the accreted heavy elements both in theplanetesimal formation and accretion case, proving that planetesimal formation needs to be inefficient in order to explain planetswith high heavy element content. Accretion of planetesimals enhances the refractory component of the atmosphere, leading to
low volatile to refractory ratios, contrary to the pure pebble scenario. Such low volatile to refractory ratios can also be achievedby planets migrating in the inner disc in pure pebble scenario. Distinguishing these two scenarios requires knowledge about theplanet’s atmospheric C/H and O/H ratios, which are higher for pure pebble accretion. Therefore, a detailed knowledge of thecomposition of planetary atmospheres could help to constrain the planet’s formation pathway.

12. Spectroscopic variability of massive pre-main-sequence stars in M17

A. R. Derkink, M. C. Ramírez-Tannus, L. Kaper, A. de Koter, F. Backs, J. Poorta, M. L. van Gelder F It is achallenge to study the formation process of massive stars: their formation time is short, they are few, often deeply embedded,
and at relatively large distances. Our strategy is to study the outcome of the star formation process and to look for signatures
remnant of the formation. We have access to a unique sample of (massive) pre-main-sequence (PMS) stars in the giant HII
region M17, showing a photosphere and circumstellar disk. The aim is to determine the variability properties of the hot gaseousdisks to understand the physical origin of the emission lines and identify dominant physical processes in these disks. We haveobtained multiple-epoch (4-5 epochs) VLT/X-shooter spectra of six young stars in M17 covering about a decade. Using stacked
spectra we update the spectral classification and identify circumstellar features. With the temporal variance method (TVS) we
determine the extent and amplitude of the spectral line variations. The double-peaked emission lines in the PMS stars withgaseous disks are used to determine peak-to-peak velocities, V/R-ratios and the radial velocity of the systems. We identify
many disk features, under which a new detection of CO bandhead and CI emission. In three of the stars we detect spectral
variability, mainly in lines originating in the circumstellar disk, in a velocity range up to 320 km/s. In two PMS stars the ratio
between the blue and red peaks shows a correlation with the peak-to-peak velocity, possibly explained by a spiral-arm structurein the disk. The PMS stars with variability are at similar positions in the HRD but show significant differences in disk lines
and variability. The extent and timescale of the variability differs for each star and per line (sets). We find indications for an
accretion flow, slow disk winds and/or disk structures in the hot gaseous inner disk as the cause of the variability in these PMS
stars.

5

13. Can Uranus and Neptune form concurrently via pebble, gas and planetesimal accretion?
Linn E. J. Eriksson, Marit A. S. Mol Lous, Sho Shibata, Ravit Helled F The origin of Uranus and Neptune has long
been challenging to explain, due to the large orbital distances from the Sun. After a planetary embryo has been formed, themain accretion processes are likely pebble, gas and planetesimal accretion. Previous studies of Uranus and Neptune formation
typically don’t consider all three processes; and furthermore, do not investigate how the formation of the outer planet impacts
the inner planet. In this paper we study the concurrent formation of Uranus and Neptune via both pebble, gas and planetesimalaccretion. We use a dust-evolution model to predict the size and mass flux of pebbles, and derive our own fit for gas accretion.
We do not include migration, but consider a wide range of formation locations between 12 and 40au. If the planetary embryos
form at the same time and with the same mass, our formation model with an evolving dust population is unable to produce
Uranus and Neptune analogues. This is because the mass difference between the planets and the H-He mass fractions become
too high. However, if the outer planetary embryo forms earlier and/or more massive than the inner embryo, the two planets
do form in a few instances when the disk is metal-rich and dissipates after a few Myr. Furthermore, our study suggests thatin-situ formation is rather unlikely. Nethertheless, giant impacts and/or migration could potentially aid in the formation, andfuture studies including these processes could bring us one step closer to understanding how Uranus and Neptune formed.

14. Monitoring the young planet host V1298 Tau with SPIRou: planetary system andevolving large-scale magnetic field
B. Finociety, J. -F. Donati, P. I. Cristofari, C. Moutou, C. Cadieux, N. J. Cook, E. Artigau, C. Baruteau, F.
Debras, P. Fouqué, J. Bouvier, S. H. P Alencar, X. Delfosse, K. Grankin, A. Carmona, P. Petit, Á. Kóspál,
the SLS/SPICE consortium F We report results of a spectropolarimetric monitoring of the young Sun-like star V1298 Taubased on data collected with the near-infrared spectropolarimeter SPIRou at the Canada-France-Hawaii Telescope between
late 2019 and early 2023. Using Zeeman-Doppler Imaging and the Time-dependent Imaging of Magnetic Stars methods on
circularly polarized spectra, we reconstructed the large-scale magnetic topology of the star (and its temporal evolution), foundto be mainly poloidal and axisymmetric with an average strength varying from 90 to 170 G over the 3.5 years of monitoring.
The magnetic field features a dipole whose strength evolves from 85 to 245 G, and whose inclination with respect to the stellar
rotation axis remains stable until 2023 where we observe a sudden change, suggesting that the field may undergo a polarity
reversal, potentially similar to those periodically experienced by the Sun. Our data suggest that the differential rotation shearing
the surface of V1298 Tau is about 1.5 times stronger than that of the Sun. When coupling our data with previous photometricresults from K2 and TESS and assuming circular orbits for all four planets, we report a 3.9σ detection of the radial velocity
signature of the outermost planet (e), associated with a most probable mass, density and orbital period of Me = 0.95+0.33−0.24 Mjup ,−3
ρe = 1.66+0.61
g
cm
and
P
=
53.0039±0.0001d,respectively.
For
the
3
inner
planets,
we
only
derive99%
confidence
upper
e
−0.48
limits on their mass of 0.44 Mjup , 0.22 Mjup and 0.25 Mjup , for b, c and d, respectively.

15. Investigating Protostellar Accretion-Driven Outflows Across the Mass Spectrum: JWSTNIRSpec IFU 3-5 µm Spectral Mapping of Five Young Protostars
Samuel Federman, S. Thomas Megeath, Adam E. Rubinstein, Robert Gutermuth, Mayank Narang, Himanshu
Tyagi, P. Manoj, Guillem Anglada, Prabhani Atnagulov, Henrik Beuther, Tyler L. Bourke, Nashanty Brunken,
Alessio Caratti o Garatti, Neal J. Evans II, William J. Fischer, Elise Furlan, Joel Green, Nolan Habel, Lee
Hartmann, Nicole Karnath, Pamela Klaassen, Hendrik Linz, Leslie W. Looney, Mayra Osorio, James Muzerolle
Page, Riwaj Pokhrel, Rohan Rahatgaonkar, Will R. M. Rocha, Patrick Sheehan, Katerina Slavicinska, Thomas
Stanke, Amelia M. Stutz, John J. Tobin, Lukasz Tychoniec, Ewine F. Van Dishoeck, Dan M. Watson, Scott
Wolk, Yao-Lun Yang F Investigating Protostellar Accretion (IPA) is a Cycle 1 JWST program using the NIRSpec+MIRI
IFUs to obtain 2.9–28 µm spectral cubes of five young protostars with luminosities of 0.2 to 10,000 L in their primary accretion
phase. This paper introduces the NIRSpec 2.9–5.3 µm data of the inner 840-9000 au with spatial resolutions from 28-300 au.
The spectra show rising continuum emission, deep ice absorption, emission from H2 , H I, and [Fe II], and the CO fundamental
series in emission and absorption. Maps of the continuum emission show scattered light cavities for all five protostars. In thecavities, collimated jets are detected in [Fe II] for the four < 320 L protostars, two of which are additionally traced in Br-α.
Knots of [Fe II] emission are detected toward the most luminous protostar, and knots of [FeII] emission with dynamical timesof < 30 yrs are found in the jets of the others. While only one jet is traced in H2 , knots of H2 and CO are detected in the jetsof four protostars. H2 is seen extending through the cavities showing they are filled by warm molecular gas. Bright H2 emission
is seen along the walls of a single cavity, while in three cavities, narrow shells of H2 emission are found, one of which has an[Fe II] knot at its apex. These data show cavities containing collimated jets traced in atomic/ionic gas surrounded by warm
molecular gas in a wide-angle wind and/or gas accelerated by bow shocks in the jets.

616. The evolution of sulphur-bearing molecules in high-mass star-forming cores
F. Fontani, E. Roueff, L. Colzi, P. Caselli F To understand the chemistry of sulphur (S) in the interstellar medium, models
need to be tested by observations of S-bearing molecules in different physical conditions. We analyse observations obtainedwith the IRAM 30m telescope towards 15 well-known cores classified in the three main evolutionary stages of the high-massstar-formation process: high-mass starless cores,high-mass protostellar objects, and ultracompact HII regions. We detectedrotational lines of SO, SO+, NS, C34S, 13CS, SO2, CCS, H2S, HCS+, OCS, H2CS, and CCCS. We also analyse for the firsttime lines of the NO molecule to complement the analysis. From a local thermodynamic equilibrium approach, we have derived
column densities of each species and excitation temperatures. Based on a statistical analysis on the line widths and the excitation
temperatures, we find that: NS, C34S, 13CS, CCS, and HCS+ trace cold, quiescent, and likely extended material; OCS, andSO2 trace warmer, more turbulent, and likely denser and more compact material; SO and perhaps SO+ trace both quiescentand turbulent material depending on the target. The abundances of SO, SO2, and H2S show the strongest positive correlations
with the kinetic temperature, believed to be an evolutionary indicator. Moreover, the sum of all molecular abundances show
an enhancement of gaseous S from the less evolved to the more evolved stages. These trends could be due to the increasing
amount of S sputtered from dust grains owing to the increasing protostellar activity with evolution. The average abundancesin each evolutionary group increase especially in the oxygen-bearing molecules, perhaps due to the increasing abundance of
atomic oxygen with evolution owing to photodissociation of water in gas phase. Our observational work represents a test-bed
for theoretical studies aimed at modelling the chemistry of sulphur during the evolution of high-mass star-forming cores

17. Early Planet Formation in Embedded Disks (eDisk) XII: Accretion streamers, protoplanetary disk, and outflow in the Class I source Oph IRS63
Christian Flores, Nagayoshi Ohashi, John J. Tobin, Jes K. Jørgensen, Shigehisa Takakuwa, Zhi-Yun Li, Zhe-Yu
Daniel Lin, Merel L. R. van ’t Hoff, Adele L. Plunkett, Yoshihide Yamato, Jinshi Sai, Patrick M. Koch, Hsi-Wei
Yen, Yuri Aikawa, Yusuke Aso, Itziar de Gregorio-Monsalvo, Miyu Kido, Woojin Kwon, Jeong-Eun Lee, Chang
Won Lee, Leslie W. Looney, Alejandro Santamaría-Miranda, Rajeeb Sharma, Travis J. Thieme, Jonathan P.
Williams, Ilseung Han, Suchitra Narayanan, Shih-Ping Lai F We present ALMA observations of the Class I source
Oph IRS63 in the context of the Early Planet Formation in Embedded Disks (eDisk) large program. Our ALMA observations of
Oph IRS63 show a myriad of protostellar features, such as a shell-like bipolar outflow (in 12 CO), an extended rotating envelope
structure (in 13 CO), a streamer connecting the envelope to the disk (in C18 O), and several small-scale spiral structures seen
towards the edge of the dust continuum (in SO). By analyzing the velocity pattern of 13 CO and C18 O, we measure a protostellar
mass of M? = 0.5 ± 0.2 M and confirm the presence of a disk rotating at almost Keplerian velocity that extends up to ∼ 260
au. These calculations also show that the gaseous disk is about four times larger than the dust disk, which could indicate dust
evolution and radial drift. Furthermore, we model the C18 O streamer and SO spiral structures as features originating from an
infalling rotating structure that continuously feeds the young protostellar disk. We compute an envelope-to-disk mass infall
rate of ∼ 10−6 M yr−1 and compare it to the disk-to-star mass accretion rate of ∼ 10−8 M yr−1 , from which we infer thatthe protostellar disk is in a mass build-up phase. At the current mass infall rate, we speculate that soon the disk will become
too massive to be gravitationally stable.

theoretical approach to the complex chemical evolution of phosphorus in the inter18. A
stellar medium
Marina Fernández-Ruz, Izaskun Jiménez-Serra, Jacobo Aguirre F The study of phosphorus chemistry in the interstellar medium has become a topic of growing interest in astrobiology, because it is plausible that a wide range of P-bearing
molecules were introduced in the early Earth by the impact of asteroids and comets on its surface, enriching prebiotic chemistry.
Thanks to extensive searches in recent years, it has become clear that P mainly appears in the form of PO and PN in molecular
clouds and star-forming regions. Interestingly, PO is systematically more abundant than PN by factors typically of ∼ 1.4 − 3,independently of the physical properties of the observed source. In order to unveil the formation routes of PO and PN, in thiswork we introduce a mathematical model for the time evolution of the chemistry of P in an interstellar molecular cloud andanalyze its associated chemical network as a complex dynamical system. By making reasonable assumptions, we reduce the
network to obtain explicit mathematical expressions that describe the abundance evolution of P-bearing species and study thedependences of the abundance of PO and PN on the system’s kinetic parameters with much faster computation times thanavailable numerical methods. As a result, our model reveals that the formation of PO and PN is governed by just a few critical
reactions, and fully explains the relationship between PO and PN abundances throughout the evolution of molecular clouds.
Finally, the application of Bayesian methods constrains the real values of the most influential reaction rate coefficients making
use of available observational data.

719. Shaping the CO snowline in protoplanetary disks
S. Gavino, J. Kobus, A. Dutrey, S. Guilloteau, S. Wolf, J. K. Jørgensen, R. Sharma F Characterizing the dust
thermal structure in protoplanetary disks is a fundamental task as the dust surface temperature can affect both the planetary
formation and the chemical evolution. Since the temperature is dependent on many parameters, including the grain size, properly
modeling the grain temperature structure can be challenging. Many chemistry disk models usually employ a sophisticated single
dust structure designed to reproduce the effect of a realistic population presumably composed of a large diversity of sizes. This
generally represents a good approximation in most cases. Nonetheless, this dilutes the effects of the complex radiative interactions
between the different grain populations on the resulting dust temperature, and thus the chemistry. We seek to show that theradiative interactions between dust grains of different sizes can induce a non-trivial dust temperature structure that cannot be
reproduced by a single dust population and that can significantly affect the chemical outcome. The disk thermal structures
are computed using the Monte-Carlo radiative transfer code RADMC-3D. The thermal structures are post-processed using thegas-grain code NAUTILUS to calculate the evolution of the chemical abundance. We find that simultaneously using at least two
independent dust grain populations in disk models produces a complex temperature structure due to the starlight interceptedby the upper layers of the disk. In particular, we find that micron-sized dust grains are warmer than larger grains and can evenshow a radial temperature bump in some conditions. This dust temperature spread between the grains populations results inthe segregation of the CO snowline and the presence of an unexpected CO gas hole along the midplane. We compare the resultswith observed close to edge-on class I/II disks.

20. IRAS4A1: Multi-wavelength continuum analysis of a very flared Class 0 disk
O. M. Guerra-Alvarado, N. van der Marel, J. Di Francesco, L. W. Looney, J. J. Tobin, E. G. Cox, P. D. Sheehan, D. J. Wilner, E. Macías, C. Carrasco-González F Understanding the formation of substructures in protoplanetarydisks is vital for gaining insights into dust growth and the process of planet formation. Studying these substructures in highly
embedded Class 0 objects using the Atacama Large Millimeter/submillimeter Array (ALMA), however, poses significant challenges. Nonetheless, it is imperative to do so to unravel the mechanisms and timing behind the formation of these substructures.
In this study, we present high-resolution ALMA data at Bands 6 and 4 of the NGC1333 IRAS4A Class 0 protobinary system.
This system consists of two components, A1 and A2, separated by 1.8" and located in the Perseus molecular cloud at ∼293 pc
distance. To gain a comprehensive understanding of the dust properties and formation of substructures in the early stages, we
conducted a multi-wavelength analysis of IRAS4A1. Additionally, we sought to address whether the lack of observed substructures in very young disks, could be attributed to factors such as high degrees of disk flaring and large scale heights. To explore
this phenomenon, we employed radiative transfer models using RADMC-3D. Our multi-wavelength analysis of A1 discovered
characteristics such as high dust surface density, substantial dust mass within the disk, and elevated dust temperatures. Thesefindings suggest the presence of large dust grains compared to the ones in the interstellar medium (ISM), greater than 100
microns in size within the region. Furthermore, while there’s no direct detection of any substructure, our models indicate that
some, such as a small gap, must be present. In summary, this result implies that disk substructures may be masked or obscured
by a large scale height in combination with a high degree of flaring in Class 0 disks. [Abridged]

21. X-ray, Near-Ultraviolet, and Optical Flares Produced By Colliding Magnetospheres in
The Young High-Eccentricity Binary DQ Tau
Konstantin V. Getman, Ágnes Kóspál, Nicole Arulanantham, Dmitry A. Semenov, Grigorii V. SmirnovPinchukov, Sierk E. van Terwisga F DQ Tau is a unique young high-eccentricity binary system that exhibits regularmagnetic reconnection flares and pulsed accretion near periastron. We conducted NuSTAR, Swift, and Chandra observations
during the July 30, 2022 periastron to characterize X-ray, near-ultraviolet (NUV), and optical flaring emissions. Our findings
confirm the presence of X-ray super-flares accompanied by substantial NUV and optical flares, consistent with previous discoveries of periastron flares in 2010 and 2021. These observations, supported by new evidence, strongly establish the magnetospherecollision mechanism as the primary driver of magnetic energy release during DQ Tau’s periastron flares. The energetics ofthe observed X-ray super-flares remain consistent across the three periastrons, indicating recurring energy sources during eachpassage, surpassing the capabilities of single stars. The observed flaring across multiple bands supports the Adams et al. model
for magnetosphere interaction in eccentric binaries. Evidence from modeling and past and current observations suggests thatboth the mm/X-ray periastron flares and tentatively, the magnetic reconnection-related components of the optical/NUV emissions, conform to the classical solar/stellar non-thermal thick-target model, except for the distinctive magnetic energy source.
However, our NuSTAR observations suffered from high background levels, hindering the detection of anticipated non-thermal
hard X-rays. Furthermore, we report serendipitous discovery of X-ray super-flares occurring away from periastron, potentiallyassociated with interacting magnetospheres. The current study is part of a broader multi-wavelength campaign, which is planned
to investigate the influence of DQ Tau’s stellar radiation on gas-phase ion chemistry within its circumbinary disk.

822. An SiO Toroid and Wide-angle Outflow associated with the Massive Protostar W75N(B)VLA2
Jose F. Gomez, Jose M. Torrelles, Josep M. Girart, Gabriele Surcis, Jeong-Sook Kim, Jorge Canto, Guillem
Anglada, Salvador Curiel, Wouter H. T. Vlemmings, Carlos Carrasco-Gonzalez, Adriana R. Rodriguez-Kamenetzky,
Soon-Wook Kim, Ciriaco Goddi, Huib J. van Langevelde, Alvaro Sanchez-Monge F We have carried out ALMA
observations of the massive star-forming region W75N(B), which contains the massive protostars VLA1, VLA2, and VLA3.
Particularly, VLA2 is an enigmatic protostar associated with a wind-driven H2 O maser shell, which has evolved from an almost
isotropic outflow to a collimated one in just 20 years. The shell expansion seemed to be halted by an obstacle located to thenortheast of VLA2. Here we present our findings from observing the 1.3 mm continuum and H2 CO and SiO emission lines.
Within a region of ∼ 30” (∼ 39, 000 au) diameter, we have detected 40 compact mm-continuum sources, three of them coinciding
with VLA1, VLA2, and VLA3. While the H2 CO emission is mainly distributed in a fragmented structure around the threemassive protostars, but without any of the main H2 CO clumps spatially coinciding with them, the SiO is highly concentrated
on VLA2, indicating the presence of very strong shocks generated near this protostar. The SiO emission is clearly resolved into
an elongated structure (∼ 0.6” × 0.3”; ∼ 780 au×390 au) perpendicular to the major axis of the wind-driven maser shell. The
structure and kinematics of the SiO emission are consistent with a toroid and a wide-angle outflow surrounding a central massof ∼ 10 M , thus supporting previous theoretical predictions regarding the evolution of the outflow. Additionally, we haveidentified the expected location and estimated the gas density of the obstacle that is hindering the expansion of the maser shell.

23. Sulfur isotope ratios in the Large Magellanic Cloud
Y. Gong, C. Henkel, K. M. Menten, C. -H. R. Chen, Z. Y. Zhang, Y. T. Yan, A. Weiss, N. Langer, J. Z.
Wang, R. Q. Mao, X. D. Tang, W. Yang, Y. P. Ao, M. Wang F Sulfur isotope ratios have emerged as a promising tool
for tracing stellar nucleosynthesis, quantifying stellar populations, and investigating the chemical evolution of galaxies. While
extensively studied in the Milky Way, in extragalactic environments they remain largely unexplored. We focus on investigating
the sulfur isotope ratios in the Large Magellanic Cloud (LMC) to gain insights into sulfur enrichment in this nearby system andto establish benchmarks for such ratios in metal-poor galaxies. We conducted pointed observations of CS and its isotopologues
toward N113, one of the most prominent star-formation regions in the LMC, utilizing the Atacama Pathfinder EXperiment
12 m telescope. We present the first robust detection of C33 S in the LMC by successfully identifying two C33 S transitions ona large scale of ∼5 pc. Our measurements result in an accurate determination of the 34 S/33 S isotope ratio, which is 2.0±0.2.
Our comparative analysis indicates that the 32 S/33 S and 34 S/33 S isotope ratios are about a factor of 2 lower in the LMC thanin the Milky Way. Our findings suggest that the low 34 S/33 S isotope ratio in the LMC can be attributed to a combination of
the age effect, low metallicity, and star formation history.

24. RNO 54: A Previously Unappreciated FU Ori Star

Lynne A. Hillenbrand, Adolfo Carvalho, Jan van Roestel, Kishalay De F We present evidence in support of the
hypothesis that the young stellar object RNO 54 is a mature-stage FU Ori type source. The star was first cataloged as a “rednebulous object" in the 1980s but appears to have undergone its outburst prior to the 1890s. Present-day optical and nearinfrared spectra are consistent with those of other FU Ori type stars, both in the details of spectral line presence and shape, andin the overall change in spectral type from an FGK-type in the optical, to the M-type presented in the near-infrared. In addition,
the spectral energy distribution of RNO 54 is well-fit by a pure-accretion disk model with parameters: Ṁ = 10−3.45±0.06 M
yr−1 , M∗ = 0.23 ± 0.06 M , and Rinner = 3.68 ± 0.76 R , though we believe Rinner is likely close to its upper range of 4.5R inorder to produce a Tmax = 7000 K that is consistent with the optical to near-infrared spectra. The resulting Lacc is ∼ 265 L .
To find these values, we adopted a source distance d = 1400 pc and extinction AV = 3.9 mag, along with disk inclination i = 50
deg based on consideration of confidence intervals from our initial disk model, and in agreement with observational constraints.
The new appreciation of a well-known source as an FU Ori type object suggests that other such examples may be lurking in
extant samples.

25. Observational signatures of forming young massive clusters: continuum emission fromdense HII regions
Mutsuko Inoguchi, Takashi Hosokawa, Hajime Fukushima, Kei E. I. Tanaka, Hidenobu Yajima, Shin Mineshige
F Young massive clusters (YMCs) are the most massive star clusters forming in nearby galaxies and are thought to be ayoung analogue to the globular clusters. Understanding the formation process of YMCs leads to looking into very efficient starformation in high-redshift galaxies suggested by recent JWST observations. We investigate possible observational signatures of
their formation stage, particularly when the mass of a cluster is increasing via accretion from a natal molecular cloud. To thisend, we study the broad-band continuum emission from ionized gas and dust enshrouding YMCs, whose formation is followed byrecent radiation-hydrodynamics simulations. We perform post-process radiative transfer calculations using simulation snapshots
and find characteristic spectral features at radio and far-infrared frequencies. We show that a striking feature is long-lasting,strong free-free emission from a ∼ 10pc-scale HII region with a large emission measure of & 107 cm−6 pc, corresponding to the9mean electron density of & 103 cm−3 . There is a turnover feature below ∼ 10 GHz, a signature of the optically-thick free-freeemission, often found in Galactic ultra-compact HII regions. These features come from the peculiar YMC formation process,where the cluster’s gravity effectively traps photoionized gas for a long duration and enables continuous star formation within
the cluster. Such large and dense HII regions show distinct distribution on the density-size diagram, apart from the standard
sequence of Galactic HII regions. This is consistent with the observational trend inferred for extragalactic HII regions associatedwith YMCs.

26. TODDLERS: A new UV-mm emission library for star-forming regions. 1. Integration
with SKIRT and public release
Anand Utsav Kapoor, Maarten Baes, Arjen van der Wel, Andrea Gebek, Peter Camps, Angelos Nersesian,
Sharon E. Meidt, Aaron Smith, Sebastien Vicens, Francesco D’Eugenio, Marco Martorano, Daniela Barrientos,
Nina Sanches Sartorio F We present and publicly release a new star-forming regions emission library TODDLERS (Timeevolution of Observables including Dust Diagnostics and Line Emission from Regions containing young Stars) for the publicly
available radiative transfer code SKIRT. The library generation involves the spherical evolution of a homogeneous gas cloudaround a young stellar cluster that accounts for stellar feedback processes including stellar winds, supernovae, and radiationpressure, as well as the gravitational forces on the gas. The semi-analytical evolution model is coupled with the photoionization
code Cloudy to calculate time-dependent UV-mm spectral energy distributions (SEDs) from star-forming regions of varying
metallicity, star-formation efficiency, birth-cloud density, and mass. The calculated SEDs include the stellar, nebular, and dust
continuum emission along with a wide range of emission lines originating from H ii, photo-dissociation, and molecular gas
regimes tabulated at high resolution. The SEDs incorporated in SKIRT are generated by calculating a stellar-mass normalized
luminosity, which assumes that each emission source is composed of a power-law population of star-forming clouds. When
compared to the previous treatment of star-forming regions in SKIRT, TODDLERS shows a better agreement with low-redshiftobservational data in the IR wavelength range while offering a more comprehensive line-emission support. This paves the way
for a variety of applications using simulated galaxies at low and high redshift.

27. Spectral Survey of the Star Formation Region DR21OH in the 4 mm Wavelength Range

S. V. Kalenskii, E. A. Mikheeva F The results of a spectral survey of the region of massive star formation DR21OH in the
4-mm wavelength range are presented. Sixty-nine molecules and their isotopologues have been detected, ranging from simple
diatomic or triatomic species such as SO, SiO and CCH, to complex organic molecules such as CH3 OCHO or CH3 OCH3 . The
obtained results qualitatively repeat the results of the survey of the same source at 3 mm. The inventories of molecules found at
3mm and 4mm overlap to a great extent. However, at 4 mm we found a number of species that have no allowed transitions in
the 3-mm wavelength range, e.g. DCN, DNC, or SO+ . The bulk of the molecules detected at 4 mm are those that are common
for dense cores, e.g., HC3 N or CH3 CCH, but some of the detected species are typical for hot cores. The latter include complex
organic molecules CH3 OCHO, CH3 CH2 OH, CH3 OCH3 , etc. However, the detected emission of these molecules probably arises
in a gas heated to 30 K only. Nine molecules, including complex species CH3 C3 N, CH3 CH2 CN, CH3 COCH3 , were found byspectral line stacking. This demonstrates the prospects of the method in the study of molecular clouds.

28. Hydrocarbon chemistry in inner regions of planet forming disks

Jayatee Kanwar, Inga Kamp, Peter Woitke, Christian Rab, Wing-Fai Thi, Michiel Min F The analysis of the midinfrared spectra helps understanding the composition of the gas in the inner, dense and warm terrestrial planet forming region ofdisks around young stars. ALMA has detected hydrocarbons in the outer regions of the planet forming disk and Spitzer detected
C2H2 in the inner regions. JWST- MIRI provides high spectral resolution observations of C2H2 and a suite of more complexhydrocarbons are now reported. Interpreting the fluxes observed in the spectra is challenging and radiation thermo-chemical
codes are needed to properly take into account the disk structure, radiative transfer, chemistry and thermal balance. Various
disk physical parameters like the gas-to-dust ratio, dust evolution including radial drift, dust growth and settling can affect thefluxes observed in the mid-IR. Still, thermo-chemical disk models were not always successful in matching all observed molecularemission bands simultaneously. The goal of this project is two-fold. We analyse the warm carbon chemistry in the inner regionsof the disk, i.e. within 10 au to find pathways forming C2H2 potentially missing from the existing chemical networks. Second, weanalyse the effect of the new chemistry on the line fluxes of acetylene. We use radiative thermo-chemical disk code PRODIMO
to expand the hydrocarbon chemistry that occurs in a typical standard T Tauri disks. We used the UMIST and the KIDA
rate databases for collecting reactions for the species. We include a number of three-body and thermal decomposition reactions
from STAND2020 network. We included isotopomers for the species that were present in the databases. The chemistry is thenanalysed in the regions that produce observable features in the mid-infrared spectra. The effect of expanding the hydrocarbon
chemistry on the mid-infrared spectra is studied.

1029. A survey of SiO J = 1 – 0 emission toward massive star-forming regions
W. -J. Kim, J. S. Urquhart, V. S. Veena, G. A. Fuller, P. Schilke, K-T Kim F The application of silicon monoxide(SiO) as a shock tracer arises from its propensity to occur in the gas phase as a result of shock-induced phenomena, including
outflow activity and interactions between molecular clouds and expanding HII regions or supernova remnants. We searched
for indications of shocks toward 366 massive star-forming regions by observing the ground rotational transition of SiO (v = 0,
J = 1 − 0) at 43 GHz with the Korean VLBI Network (KVN) 21 m telescopes to extend our understanding on the origins of SiO
in star-forming regions. We detected SiO emission toward 104 regions that consist of 57 IRDCs, 21 HMPOs, and 26 UCHIIs.
The determined median SiO column density, N (SiO), and abundance, X(SiO), relative to N (H2 ) are 8.12 × 1012 cm−2 and1.28 × 10−10 , respectively. These values are similar to those obtained toward other star-forming regions and also consistent withpredicted values from shock models with low-velocity shocks (.10 - 15 km s−1 ). While the X(SiO) does not exhibit any strong
correlation with the evolutionary stages of their host clumps, LSiO is highly correlated with dust clump mass, and LSiO /Lbol
also has a strong negative correlation with Tdust . This shows that colder and younger clumps have high LSiO /Lbol suggestiveof an evolutionary trend. This trend is not due to excess emission at higher velocities, such as SiO wing features, as the colder
sources with high LSiO /Lbol ratios lack wing features. Comparing SiO emission with H2 O and Class I CH3 OH masers, we finda significant correlation between LSiO /Lbol and LCH3 OH /Lbol ratios, whereas no similar correlation is seen for the H2 O maser
emission. This suggests a similar origin for the SiO and Class I CH3 OH emission in these sources.

30. 3D structure of HII regions in the star-forming complex S254-S258

Maria S. Kirsanova, Alexei V. Moiseev, Paul A. Boley F The S254-258 star-forming complex is a place of massive starformation where five OB-stars have created HII regions, visible as optical nebulae, and disrupted the parental molecular gas.
In this work, we study the 3D structure of these HII regions using optical spectroscopy and tunable-filter photometry with the
6-m and 1-m telescopes of the Special Astrophysical Observatory of the Russian Academy of Sciences. We construct maps ofthe optical extinction, and find that the HII emission is attenuated by neutral material with 2 ≤ AV ≤ 5 mag. The typicalelectron density in S255, and S257 is ≈ 100 cm−3 , with enhancements up to 200 cm−3 in their borders, and up to 400 cm−3
toward the dense molecular cloud between them, where active star formation is taking place. We show that either a model of aclumpy dense neutral shell, where UV photons penetrate through and ionize the gas, or a stellar wind, can explain the shell-likestructure of the ionized gas. S255 is surrounded by neutral material from all sides, but S257 is situated on the border of amolecular cloud and does not have dense front and rear walls. The compact HII regions S256 and S258 are deeply embeddedin the molecular clouds.

3D Global Simulations of Accretion onto Gap-opening Planets: Implications for Cir31. cumplanetary Disc Structures and Accretion Rates
Ya-Ping Li, Yi-Xian Chen, Douglas N. C. Lin F We perform a series of 3D simulations to study the accretion of giant
planet embedded in protoplanetary discs (PPDs) over gap-opening timescales. We find that the accretion mass flux mainly
comes from the intermediate latitude above the disc midplane. The circumplanetary disc (CPD) for a super-thermal planet isrotation-supported up to ∼20-30% of the planet Hill radius. While both mass inflow and outflow exists in the CPD midplane,
the overall trend is an outflow that forms a meridional circulation with high-latitude inflows. We confirm the absence of accretion outburst from disc eccentricity excited by massive planets in our 3D simulations, contrary to the consensus of previous 2D
simulations. This suggests the necessity of 3D simulations of accretion even for super-Jupiters. The accretion rates of planetsmeasured in steady-state can be decomposed into the “geometric" and “density depletion" factors. Through extensive parameter
2/3
survey, we identify a power-law scaling for the geometric factor ∝ qth for super-thermal planets (qth being the thermal mass
2
ratio), which transforms to ∝ qth for less massive cases. The density depletion factor is limited by the disc accretion rate for
mildly super-thermal planets, and by gap-opening for highly super-thermal ones. Moderate planetary eccentricities can enhance
the accretion rates by a factor of 2 − 3 through making the gap shallower, but does not impact the flow geometry. We haveapplied our simulations results to accreting protoplanet system PDS 70 and can satisfactorily explain the accretion rate and
CPD size in observations.

32. A low-mass line-rich core found in Massive Star-forming Region IRAS 16351-4722

Meizhu Liu, Sheng-Li Qin, Tie Liu, Mengyao Tang, Sheng-Yuan Liu, Li Chen, ChuanShou Li, HongQiong
Shi, Xiaohu Li, Tianwei Zhang, Ken’ichi Tatematsu, Fengwei Xu, Yuefang Wu F We present ALMA sub-arcsecondresolution observations of both continuum and molecular lines at 345 GHz towards the massive star-forming region IRAS 163514722 (hereafter I16351). A total of 12 dust cores were detected based on high spatial resolution observations of the continuum.
Among them, a high-mass core (11.6 Msun) and a low-mass core (1.7 Msun) show abundant molecular line emissions. 164
molecular transitions from 29 species and 104 molecular transitions from 25 species are identified in the high-mass and low-masscores, respectively. Complex organic molecules (COMs) such as CH3OH, CH3OCHO, CH3OCH3, C2H5OH, and C2H5CN
are detected in the two cores. Under the assumption of local thermodynamic equilibrium (LTE), rotational temperatures andcolumn densities of the COMs are derived with the XCLASS software. The maximum rotation temperature values in the low-11

mass core and the high-mass core were found to be approximately 130 K and 198 K, respectively. Additionally, the line widths
in the high-mass core are larger than those in the low-mass one. Abundant complex organic molecular line transitions, high gas
temperatures, and smaller line widths indicate the presence of a low-mass line-rich core in the massive star formation region
for the first time, while the high-mass line-rich core shows hot core property. When comparing the molecular abundances of
CH3OH, CH3OCHO, CH3OCH3 and C2H5OH of the two cores with other hot cores and hot corinos reported in the literature,
we further confirm that both a hot core and a low-mass line-rich core are simultaneously detected in I16351.

33. A JWST survey of the Trapezium Cluster & inner Orion Nebula. I. Observations &overview
M. J. McCaughrean, S. G. Pearson F We present a near-IR survey of the Trapezium Cluster and inner Orion Nebula using
the NASA/ESA/CSA James Webb Space Telescope. The survey with the NIRCam instrument covers 10.9 x 7.5 arcminutes( 1.25 x 0.85 pc) in twelve wide-, medium-, and narrow-band filters from 1-5 microns and is diffraction-limited at all wavelengths,
providing a maximum spatial resolution of 0.063 arcsec at 2 microns, corresponding to 25 au at Orion. The suite of filterschosen was designed to address a number of scientific questions including the form of the extreme low-mass end of the IMF
into the planetary-mass range to 1 Jupiter mass and below; the nature of ionised and non-ionised circumstellar disks andassociated proplyds in the near-IR with a similar resolution to prior HST studies; to examine the large fragmented outflow fromthe embedded BN-KL region at very high resolution and fidelity; and to search for new jets and outflows from young stars in
the Trapezium Cluster and the Orion Molecular Cloud 1 behind. In this paper, we present a description of the design of theobservational programme, explaining the rationale for the filter set chosen and the telescope and detector modes used to makethe survey; the reduction of the data using the JWST pipeline and other tools; the creation of large colour mosaics covering
the region; and an overview of the discoveries made in the colour images and in the individual filter mosaics. Highlights include
the discovery of large numbers of free-floating planetary-mass candidates as low as 0.6 Jupiter masses, a significant fractionof which are in wide binaries; new emission phenomena associated with the explosive outflow from the BN-KL region; and amysterious "dark absorber" associated with a number of disparate features in the region, but which is seen exclusively in the
F115W filter. Further papers will examine those discoveries and others in more detail.

34. Early phases of star formation: testing chemical tools
N. C. Martinez, S. Paron F The star forming processes strongly influence the ISM chemistry. Nowadays, there are available
many high-quality databases at millimeter wavelengths. Using them, it is possible to carry out studies that review and deepen
previous results. If these studies involve large samples of sources, it is preferred to use direct tools to study the moleculargas. With the aim of testing these tools such as the use of the HCN/HNC ratio as a thermometer, and the use of H13 CO+ ,HC3 N, N2 H+ , and C2 H as "chemical clocks", we present a molecular line study towards 55 sources representing massive youngstellar objects (MYSOs) at different evolutive stages: infrared dark clouds (IRDCs), high-mass protostellar objects (HMPOs),
hot molecular cores (HMCs) and ultracompact HII regions (UCHII). We found that the use of HCN/HNC ratio as an universal
thermometer in the ISM should be taken with care because the HCN optical depth is a big issue that can affect the method.
Hence, this tool should be used only after a careful analysis of the HCN spectrum, checking that no line, neither the main
nor the hyperfine ones, present absorption features. We point out that the analysis of the emission of H13 CO+ , HC3 N, N2 H+ ,and C2 H could be useful to trace and distinguish regions among IRDCs, HMPOs and HMCs. The molecular line widths ofthese four species increase from the IRDC to the HMC stage, which can be a consequence of the gas dynamics related to thestar-forming processes taking place in the molecular clumps. Our results do not only contribute with more statistics regarding
to probe such chemical tools, useful to obtain information in large samples of sources, but also complement previous works
through the analysis on other types of sources.

35. An improved dynamical Poisson equation solver for self-gravity
Ryunosuke Maeda, Tsuyoshi Inoue, Shu-ichiro Inutsuka F Since self-gravity is crucial in the structure formation of
the universe, many hydrodynamics simulations with the effect of self-gravity have been conducted. The multigrid method
is widely used as a solver for the Poisson equation of the self-gravity; however, the parallelization efficiency of the multigrid
method becomes worse when we use a massively parallel computer, and it becomes inefficient with more than 104 cores, evenfor highly tuned codes. To perform large-scale parallel simulations (> 104 cores), developing a new gravity solver with goodparallelization efficiency is beneficial. In this article, we develop a new self-gravity solver using the telegraph equation with adamping coefficient, κ. Parallelization is much easier than the case of the elliptic Poisson equation since the telegraph equation
is a hyperbolic partial differential equation. We analyze convergence tests of our telegraph equations solver and determine thatthe best non-dimensional damping coefficient of the telegraph equations is κ̃ ' 2.5. We also show that our method can maintainhigh parallelization efficiency even for massively parallel computations due to the hyperbolic nature of the telegraphic equation
by weak-scaling tests. If the time step of the calculation is determined by heating/cooling or chemical reactions, rather than the
CFL condition, our method may provide the method for calculating self-gravity faster than other previously known methods
such as the fast Fourier transform and multigrid iteration solvers because gravitational phase velocity determined by the CFL

12

condition using these timescales is much larger than the fluid velocity plus sound speed.

36. Co-Evolution of Stars and Gas: Using Analysis of Synthetic Observations to Investigate
the Star-Gas Correlation in STARFORGE
Samuel Millstone, Robert Gutermuth, Stella S. R. Offner, Riwaj Pokhrel, Michael Y. Grudić F We explore therelationship between stellar surface density and gas surface density (the star-gas or S-G correlation) in a 20,000 M simulationfrom the STAR FORmation in Gaseous Environments (STARFORGE) Project. We create synthetic observations based on
the Spitzer and Herschel telescopes by modeling active galactic nuclei contamination, smoothing based on angular resolution,
cropping the field-of-view, and removing close neighbors and low-mass sources. We extract star-gas properties such as thedense gas mass fraction, the Class II:I ratio, and the S-G correlation (ΣYSO /Σgas ) from the simulation and compare them toobservations of giant molecular clouds, young clusters, and star-forming regions, as well as to analytical models. We find thatthe simulation reproduces trends in the counts of young stellar objects and the median slope of the S-G correlation. This implies
that the S-G correlation is not simply the result of observational biases but is in fact a real effect. However, other statistics, suchas the Class II:I ratio and dense gas mass fraction, do not always match observed equivalents in nearby clouds. This motivates
further observations covering the full simulation age range and more realistic modeling of cloud formation.

A kinematic study of the disc-outflow system around a high-mass protostar G59.783+0.065
37. probed by methanol and water masers
M. Nakamura, K. Motogi, H. Nakamura, Y. Yonekura, K. Fujisawa F Class II CH3OH masers are used as a convenient tracer of disc-like structures in high-mass star formation. However, more than half of them show a complex distribution
in Very Long Baseline Interferometry (VLBI) maps. The origin of such a complex distribution is still unknown. We conducted
VLBI monitoring observations to unveil the origin of a complex class II CH3OH maser in the high-mass star-forming region
G59.783+0.065. We observed the CH3OH maser at 6.7 GHz and the H2O maser at 22 GHz to probe detailed circumstellar
kinematics and structures by the Japanese VLBI network and the VLBI Exploration of Radio Astrometry. We found similarbipolar distributions in both masers, specifically two clusters located 2000 au apart along the East-West direction. We detecteda linear distribution of CH3OH masers in the Western cluster. A position-velocity diagram shows that the Western CH3OH
masers trace a rotating disc-wind or infalling component inside an edge-on disc-like structure. In contrast to the simple bipolar
expanding motions of the H2O masers, the CH3OH masers exhibited complex motions despite their spatial coincidence. Someof the Eastern CH3OH masers showed bipolar expansions similar to the H2O masers, while others displayed random or eveninward motions. Such complex kinematics and their close association with the H2O maser could occur at the boundary between
outflow and inflow. We suggest that the complex distribution of class II CH3OH masers, like G59.783+0.065 arises from several
distinct circumstellar structures that simultaneously achieve maser excitation.

38. Early Planet Formation in Embedded Disks (eDisk) X: Compact Disks, Extended Infall,
and a Fossil Outburst in the Class I Oph IRS43 Binary
Suchitra Narayanan, Jonathan P. Williams, John J. Tobin, Jes K. Jorgensen, Nagayoshi Ohashi, Zhe-Yu Daniel
Lin, Merel L. R. van’t Hoff, Zhi-Yun Li, Adele L. Plunkett, Leslie W. Looney, Shigehisa Takakuwa, Hsi-Wei
Yen, Yusuke Aso, Christian Flores, Jeong-Eun Lee, Shih-Ping Lai, Woojin Kwon, Itziar de Gregorio-Monsalvo,
Rajeeb Sharma, Chang Won Lee F We present the first results from the Early Planet Formation in Embedded Disks(eDisk) ALMA Large Program toward Oph IRS43, a binary system of solar mass protostars. The 1.3 mm dust continuum
observations resolve a compact disk, 6au radius, around the northern component and show that the disk around the southerncomponent is even smaller, < 3 au. CO, 13CO, and C18O maps reveal a large cavity in a low mass envelope that shows
kinematic signatures of rotation and infall extending out to 2000au. An expanding CO bubble centered on the extrapolated
location of the source 130 years ago suggests a recent outburst. Despite the small size of the disks, the overall picture is of aremarkably large and dynamically active region.
+
39. Variations of the HCO+, HCN, HNC, N2 H and NH3 deuterium fractionation in highmass star-forming regions

A. G. Pazukhin, I. I. Zinchenko, E. A. Trofimova, C. Henkel, D. A. Semenov F We use spectra and maps of theJ = 1 − 0 and J = 2 − 1 DCO+ , DCN, DNC, N2 D+ lines and 111 − 101 ortho- and para-NH2 D lines, obtained with the IRAM30m telescope, as well as observations of their hydrogenated isotopologues to study deuteration processes in five high-massstar-forming regions. The temperature was estimated from CH3 CCH lines, also observed with the IRAM-30m telescope, andfrom NH3 lines, observed with the 100-m radio telescope in Effelsberg, as well as using the integrated intensity ratios of theJ = 1 − 0 H13 CN and HN13 C lines and their main isotopologues. Applying a non-LTE radiative transfer model with RADEX,
the gas density and the molecular column densities were estimated. D/H ratios are 0.001 − 0.05 for DCO+ , 0.001 − 0.02 for
DCN, 0.001 − 0.05 for DNC and 0.02 − 0.4 for NH2 D. The D/H ratios decrease with increasing temperature in the range of13

20 − 40 K and slightly vary at densities n(H2 ) ∼ 104 − 106 cm−3 . The deuterium fraction of N2 H+ is 0.008 − 0.1 at temperaturesin the range of 20 − 25 K and at a density of ∼ 105 cm−3 . We also estimate relative abundances and find ∼ 10−11 − 10−9 for
DCO+ and DNC, ∼ 10−11 − 10−10 for N2 D+ and ∼ 10−10 − 10−8 for NH2 D. The relative abundances of these species decrease
with increasing temperature. However, the DCN/H2 ratio is almost constant (∼ 10−10 ). The observational results agree withthe predictions of chemical models (although in some cases there are significant differences).

40. Jupiter Mass Binary Objects in the Trapezium Cluster
Samuel G Pearson, Mark J McCaughrean F A key outstanding question in star and planet formation is how far the
initial mass function of stars and sub-stellar objects extends, and whether or not there is a cut-off at the very lowest masses.
Isolated objects in the planetary-mass domain below 13 Jupiter masses, where not even deuterium can fuse, are very challenging
to observe as these objects are inherently faint. Nearby star-forming regions provide the best opportunity to search for themthough: while they are young, they are still relatively warm and luminous at infrared wavelengths. Previous surveys havediscovered a handful of such sources down to 3–5 Jupiter masses, around the minimum mass limit established for formation
via the fragmentation of molecular clouds, but does the mass function extend further? In a new James Webb Space Telescopenear-infrared survey of the inner Orion Nebula and Trapezium Cluster, we have discovered and characterised a sample of 540
planetary-mass candidates with masses down to 0.6 Jupiter masses, demonstrating that there is indeed no sharp cut-off in
the mass function. Furthermore, we find that 9% of the planetary-mass objects are in wide binaries, a result that is highly
unexpected and which challenges current theories of both star and planet formation.

41. Sandwiched planet formation: restricting the mass of a middle planet
Matthew Pritchard, Farzana Meru, Sahl Rowther, David Armstrong, Kaleb Randall F We conduct gas and dusthydrodynamical simulations of protoplanetary discs with one and two embedded planets to determine the impact that a second
planet located further out in the disc has on the potential for subsequent planet formation in the region locally exterior to
the inner planet. We show how the presence of a second planet has a strong influence on the collection of solid material near
the inner planet, particularly when the outer planet is massive enough to generate a maximum in the disc’s pressure profile.
This effect in general acts to reduce the amount of material that can collect in a pressure bump generated by the inner planet.
When viewing the inner pressure bump as a location for potential subsequent planet formation of a third planet, we therefore
expect that the mass of such a planet will be smaller than it would be in the case without the outer planet, resulting in asmall planet being sandwiched between its neighbours - this is in contrast to the expected trend of increasing planet mass withradial distance from the host star. We show that several planetary systems have been observed that do not show this trend but
instead have a smaller planet sandwiched in between two more massive planets. We present the idea that such an architecture
could be the result of the subsequent formation of a middle planet after its two neighbours formed at some earlier stage.

Coagulation Reconciles Protoplanetary Disk Observations with the Vertical Shear
42. Dust
Instability – Part I: Dust Coagulation and the VSI Dead Zone
Thomas Pfeil, Til Birnstiel, Hubert Klahr F Protoplanetary disks exhibit a vertical gradient in angular momentum,
rendering them susceptible to the Vertical Shear Instability (VSI). The most important condition for the onset of this mechanism
is a short timescale of thermal relaxation (. 0.1 orbital timescales). Simulations of fully VSI active disks are characterizedby turbulent, vertically extended dust layers. This is in contradiction with recent observations of the outer regions of some
protoplanetary disks, which appear highly settled. In this work, we demonstrate that the process of dust coagulation candiminish the cooling rate of the gas in the outer disk and extinct the VSI activity. Our findings indicate that the turbulence
strength is especially susceptible to variations in the fragmentation velocity of the grains. A small fragmentation velocity of≈ 100 cm s−1 results in a fully turbulent simulation, whereas a value of ≈ 400 cm s−1 results in a laminar outer disk, being
consistent with observations. We show that VSI turbulence remains relatively unaffected by variations in the maximum particle
size in the inner disk regions. However, we find that dust coagulation can significantly suppress the occurrence of VSI turbulenceat larger distances from the central star.

43. The Corona Australis complex is accelerating away from the Galactic plane
L. Posch, N. Miret-Roig, J. Alves, S. Ratzenböck, J. Großschedl, S. Meingast, C. Zucker, A. Burkert F We
study the kinematics of the recently discovered Corona Australis (CrA) chain of clusters by examining the 3D space motion of its
young stars using Gaia DR3 and APOGEE-2 data. While we observe linear expansion between the clusters in the Cartesian XY
directions, the expansion along Z exhibits a curved pattern. To our knowledge, this is the first time such a nonlinear velocityposition relation has been observed for stellar clusters. We propose a scenario to explain our findings, in which the observed
gradient is caused by stellar feedback, accelerating the gas away from the Galactic plane. A traceback analysis confirms that
the CrA star formation complex was located near the central clusters of the Scorpius Centaurus (Sco-Cen) OB association 10-15
Myr ago. It contains massive stars and thus offers a natural source of feedback. Based on the velocity of the youngest unbound

14

CrA cluster, we estimate that a median number of about two supernovae would have been sufficient to inject the present-day
kinetic energy of the CrA molecular cloud. This number agrees with that of recent studies. The head-tail morphology of the
CrA molecular cloud further supports the proposed feedback scenario, in which a feedback force pushed the primordial cloudfrom the Galactic north, leading to the current separation of 100 pc from the center of Sco-Cen. The formation of spatiallyand temporally well-defined star formation patterns, such as the CrA chain of clusters, is likely a common process in massive
star-forming regions.
+44. NEATH II: N2 H as a tracer of imminent star formation in quiescent high-density gas

F. D. Priestley, P. C. Clark, S. C. O. Glover, S. E. Ragan, O. Fehér, L. R. Prole, R. S. Klessen F Star
formation activity in molecular clouds is often found to be correlated with the amount of material above a column density
threshold of ∼ 1022 cm−2 . Attempts to connect this column density threshold to a volume density above which star formation
can occur are limited by the fact that the volume density of gas is difficult to reliably measure from observations. We postprocess hydrodynamical simulations of molecular clouds with a time-dependent chemical network, and investigate the connection
between commonly-observed molecular species and star formation activity. We find that many molecules widely assumed to
specifically trace the dense, star-forming component of molecular clouds (e.g. HCN, HCO+ , CS) actually also exist in substantial
quantities in material only transiently enhanced in density, which will eventually return to a more diffuse state without forming
any stars. By contrast, N2 H+ only exists in detectable quantities above a volume density of 104 cm−3 , the point at which CO,
which reacts destructively with N2 H+ , begins to deplete out of the gas phase onto grain surfaces. This density threshold for
detectable quantities of N2 H+ corresponds very closely to the volume density at which gas becomes irreversibly gravitationallybound in the simulations: the material traced by N2 H+ never reverts to lower densities, and quiescent regions of molecular
clouds with visible N2 H+ emission are destined to eventually form stars. The N2 H+ line intensity is likely to directly correlatewith the star formation rate averaged over timescales of around a Myr.

45. Neural network-based emulation of interstellar medium models
Pierre Palud, Lucas Einig, Franck Le Petit, Emeric Bron, Pierre Chainais, Jocelyn Chanussot, Jérôme Pety,
Pierre-Antoine Thouvenin, David Languignon, Ivana Bešlić, Miriam G. Santa-Maria, Jan H. Orkisz, Léontine
E. Ségal, Antoine Zakardjian, Sébastien Bardeau, Maryvonne Gerin, Javier R. Goicoechea, Pierre Gratier,Viviana V. Guzman, Annie Hughes, François Levrier, Harvey S. Liszt, Jacques Le Bourlot, Antoine Roueff,
Albrecht Sievers F The interpretation of observations of atomic and molecular tracers in the galactic and extragalacticinterstellar medium (ISM) requires comparisons with state-of-the-art astrophysical models to infer some physical conditions.
Usually, ISM models are too time-consuming for such inference procedures, as they call for numerous model evaluations. As aresult, they are often replaced by an interpolation of a grid of precomputed models. We propose a new general method to derive
faster, lighter, and more accurate approximations of the model from a grid of precomputed models. These emulators are definedwith artificial neural networks (ANNs) designed and trained to address the specificities inherent in ISM models. Indeed, suchmodels often predict many observables (e.g., line intensities) from just a few input physical parameters and can yield outliers
due to numerical instabilities or physical bistabilities. We propose applying five strategies to address these characteristics: 1)
an outlier removal procedure; 2) a clustering method that yields homogeneous subsets of lines that are simpler to predict withdifferent ANNs; 3) a dimension reduction technique that enables to adequately size the network architecture; 4) the physicalinputs are augmented with a polynomial transform to ease the learning of nonlinearities; and 5) a dense architecture to easethe learning of simple relations. We compare the proposed ANNs with standard classes of interpolation methods to emulate the
Meudon PDR code, a representative ISM numerical model. Combinations of the proposed strategies outperform all interpolation
methods by a factor of 2 on the average error, reaching 4.5% on the Meudon PDR code. These networks are also 1000 times
faster than accurate interpolation methods and require ten to forty times less memory. This work will enable efficient inferences
on wide-field multiline observations of the ISM.

46. Wind erosion and transport on planetesimals

A. C. Quillen, Stephen Luniewski, Adam E. Rubinstein, Jeremy Couturier, Rachel Glade F We consider the
possibility that aeolian (wind blown) processes occur on small, 10 to 100 km diameter, planetesimals when they were embeddedin the protosolar nebula. Drag from a headwind within a protostellar disk is sufficiently large to loft cm and smaller sizedparticles off the surface of a 10 km diameter asteroid in the inner solar system (at a few AU), and micron sized particles off
the surface of a 10 km diameter object in the Transneptunian region. The headwind is sufficiently strong to overcome surface
cohesion in the inner solar system, but not in the outer solar system. However, in the outer solar system, surface particles canbe redistributed or escape due to impacts from particles that are in the protosolar disk’s wind. Based on scaling crater ejecta,
we estimate that impacts from particles in the headwind will lead to erosion of mass rather than accretion for planetesimals
below about 10 km in diameter. The erosion limit is independent of material strength but proportional to the wind velocity.
We explore the sensitivity of splash particle trajectories to particle size, headwind velocity and Reynolds number. Winds froma protostellar disk could account for Kuiper Belt Object (486958) Arrokoth’s smooth undulating terrain but only during an

15

epoch of high particle flux and low wind velocity. These conditions could have been present during and just after coalescenceof Arrokoth’s building blocks.

Protoplanetary and debris disks in the η Chamaeleontis Association: A sub-millimeter
47. survey obtained with APEX/LABOCA
V. Roccatagliata, A. Sicilia-Aguilar, M. Kim, J. Campbell-White, M. Fang, S. J. Murphy, S. Wolf, W. A.
Lawson, Th. Henning, J. Bouwman F Nearby associations are ideal regions to study coeval samples of protoplanetary anddebris disks down to late M-type stars. Those aged 5-10,Myrs, where most of the disk should have already dissipated forming
planets, are of particular interest. We present the first complete study of both protoplanetary and debris disks in a young
region, using the η Chamaeleontis association as a test bench to study the cold disk content. We obtained sub-millimeter data
for the entire core population down to late M-type stars, plus a few halo members. We performed a continuum sub-millimeter
survey with APEX/LABOCA of all the core populations of η Cha association. Disk properties have been derived by modelingprotoplanetary and debris disks using RADMC 2D and DMS, respectively. We find that protoplanetary disks in η Cha typicallyhave holes with radii of the order of 0.01 to 0.03 AU, while ring-like emission from the debris disks is located between 20 au
and 650 au from the central star. The parallaxes and Gaia eDR3 photometry, in combination with the PARSEC and COLIBRI
isochrones, enable us to confirm an age of η Cha between 7 and 9 Myrs. In general, the disk mass seems insufficient to support
accretion over a long time, even for the lowest mass accretors, a clear difference compared with other regions and also a signthat the mass budget is further underestimated. We do not find a correlation between the stellar masses, accretion rates, anddisk masses, although this could be due to sample issues. We confirm that the presence of inner holes is not enough to stop
accretion unless accompanied by dramatic changes to the total disk mass content. Comparing η Cha with other regions at
different ages, we find that the physical processes responsible for debris disks (e.g., dust growth, dust trapping) efficiently act
in less than 5 Myrs.

48. A High-Mass Young Star-forming Core Escaping from Its Parental Filament

Zhiyuan Ren, Xi Chen, Tie Liu, Emma Mannfors, Leonardo Bronfman, Fengwei Xu, Siyi Feng, Hongli Liu,
Fanyi Meng, Amelia. M. Stutz, Shanghuo Li, Chang Won Lee, Ke Wang, Jianwen Zhou, Di Li, Chen Wang,
Chakali Eswaraiah, Anandmayee Tej, Long-Fei Chen, Hui Shi F We studied the unique kinematic properties inmassive filament G352.63-1.07 at 103 -AU spatial scale with the dense molecular tracers observed with the Atacama Large
Millimeter/submillimeter Array (ALMA). We find the central massive core M1 (12 M ) being separated from the surrounding
filament with a velocity difference of v − vsys = −2 km/s and a transverse separation within 3 arcsec. Meanwhile, as shown in
multiple dense-gas tracers, M1 has a spatial extension closely aligned with the main filament and is connected to the filament
towards its both ends. M1 thus represents a very beginning state for a massive young star-forming core escaping from theparental filament, within a time scale of ∼ 4000 years. Based on its kinetic energy (3.5 × 1044 erg), the core escape is unlikely
solely due to the original filament motion or magnetic field, but requires more energetic events such as a rapid intense anisotropic
collapse. The released energy also seems to noticeably increase the environmental turbulence. This may help the filament tobecome stabilized again.

49. Modelling Deuterated Isotopologues of Methanol toward the Pre-Stellar Core L1544

W. Riedel, O. Sipilä, E. Redaelli, P. Caselli, A. I. Vasyunin, F. Dulieu, N. Watanabe F Aims. We aim to improve a
previous model for the prediction of column densities and deuterium fractions of non- and singly deuterated methanol. Thereby,
we try to identify crucial chemical and physical parameters, for which the study of deuteration could provide valuable additional
constraints. Methods. We employed a gas-grain chemical code to devise a model that is in agreement with the observed column
density and deuterium fraction profiles of the innermost region of the pre-stellar core L1544. For that purpose, we developed a
new treatment of reactive desorption, deriving an individual reactive desorption efficiency for every product species in a chemical
reaction, that depends on the reaction enthalpy and type of underlying surface. Furthermore, we explored several options topromote the diffusion of hydrogen and deuterium atoms over the surface of interstellar dust grains, in order to increase methanol
formation. Results. Our fiducial model employs diffusion by quantum tunneling of hydrogen and deuterium atoms, resulting in
CH3 OH and CH2 DOH column densities that are approximately an order of magnitude lower than the observed values, which
improves the results compared to the previous model by a factor 10. The N (CH2 DOH)/N (CH3 OH) ratio is reproduced withina factor of 1.2 for the centre and 1.8 for the position of the methanol peak. Given the large uncertainties that chemical models
typically have, we consider our predictions to be in agreement with the observations. In general, we conclude that a diffusion
process with a high diffusion rate needs to be employed to obtain methanol column densities that are in accordance with theobserved values. Also, we find that the introduction of abstraction reactions into the methanol formation scheme suppresses
deuteration, when used in combination with a high diffusion rate.

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50. Protoplanetary disks in Ks -band total intensity and polarized light

Bin B. Ren, Myriam Benisty, Christian Ginski, Ryo Tazaki, Nicole L. Wallack, Julien Milli, Antonio Garufi,
Jaehan Bae, Stefano Facchini, François Ménard, Paola Pinilla, C. Swastik, Richard Teague, Zahed Wahhaj
F Diverse protoplanetary disk morphology can result from planet-disk interaction, suggesting planetary presence. To date,most scattered light imaging campaigns have probed polarized light, which is only a fraction of the total light and not very
sensitive to planets. To observe and characterize protoplanetary disk systems in the near-infrared in both polarized and total
intensity light, we carried out an unprecedented study of scattering properties of disks, as well as of any planetary companions.
Using SPHERE with star-hopping at the Very Large Telescope, we observed 29 disk hosts and their reference stars in Ks -bandpolarized light. We extracted disks in total intensity by adopting the data imputation concept with sequential non-negative
matrix factorization (DI-sNMF). We obtained high-quality disk images in total intensity for 15 systems and in polarized lightfor 23. For well-recovered disks in polarized light and total intensity, we parameterized the polarization fraction phase functions
using scaled beta distribution: the peak of polarization fraction tentatively correlates with the peak scattering angle, which
could be reproduced using certain compact dust, yet more detailed modeling studies are needed. We investigated the empirical
DI-sNMF detectability of disks using logistic regression: total intensity detectability of disks primarily depends on host starbrightness. For disks with SPHERE data in Y -/J-/H-band, we summarized their polarized color at 90 deg scattering angle:
most of disks are blue in polarized J − Ks color, and they are relatively redder as stellar luminosity increases, indicatinglarger scatterers. High-quality disk imagery in both total intensity and polarized light thus allows for disk characterization inpolarization fraction, and reduces the confusion between disk and planetary signals.

XUE. Molecular inventory in the inner region of an extremely irradiated Protoplanetary
51. Disk
María Claudia Ramirez-Tannus, Arjan Bik, Lars Cuijpers, Rens Waters, Christiane Goppl, Thomas Henning,
Inga Kamp, Thomas Preibisch, Konstantin V. Getman, Germán Chaparro, Pablo Cuartas-Restrepo, Alex deKoter, Eric D. Feigelson, Sierra L. Grant, Thomas J. Haworth, Sebastián Hernández, Michael A. Kuhn, Giulia
Perotti, Matthew S. Povich, Megan Reiter, Veronica Roccatagliata, Elena Sabbi, Benoît Tabone, Andrew J.
Winter, Anna F. McLeod, Roy van Boekel, Sierk E. van Terwisga F We present the first results of the eXtreme UV
Environments (XUE) James Webb Space Telescope (JWST) program, that focuses on the characterization of planet forming
disks in massive star forming regions. These regions are likely representative of the environment in which most planetary systems
formed. Understanding the impact of environment on planet formation is critical in order to gain insights into the diversityof the observed exoplanet populations. XUE targets 15 disks in three areas of NGC 6357, which hosts numerous massive OBstars, among which some of the most massive stars in our Galaxy. Thanks to JWST we can, for the first time, study the effectof external irradiation on the inner (< 10 au), terrestrial-planet forming regions of proto-planetary disks. In this study, we
report on the detection of abundant water, CO, CO2 , HCN and C2 H2 in the inner few au of XUE 1, a highly irradiated diskin NGC 6357. In addition, small, partially crystalline silicate dust is present at the disk surface. The derived column densities,
the oxygen-dominated gas-phase chemistry, and the presence of silicate dust are surprisingly similar to those found in inner
disks located in nearby, relatively isolated low-mass star-forming regions. Our findings imply that the inner regions of highly
irradiated disks can retain similar physical and chemical conditions as disks in low-mass star-forming regions, thus broadening
the range of environments with similar conditions for inner disk rocky planet formation to the most extreme star-forming regions
in our Galaxy.

Illuminating evaporating protostellar outflows: ERIS/SPIFFIER reveals the dissocia52. tion and ionization of HH 900
Megan Reiter, Thomas J. Haworth, Carlo F. Manara, Suzanne Ramsay, Pamela D. Klaassen, Dominika Itrich,Anna F. McLeod F Protostellar jets and outflows are signposts of active star formation. In H II regions, molecular tracers
like CO only reveal embedded portions of the outflow. Outside the natal cloud, outflows are dissociated, ionized, and eventuallycompletely ablated, leaving behind only the high-density jet core. Before this process is complete, there should be a phase
where the outflow is partially molecular and partially ionized. In this paper, we capture the HH 900 outflow while this process
is in action. New observations from the ERIS/SPIFFIER near-IR integral field unit (IFU) spectrograph using the K-middle
filter (λ=2.06-2.34 µm) reveal H2 emission from the dissociating outflow and Br-γ tracing its ionized skin. Both lines trace thewide-angle outflow morphology but H2 only extends ∼5000 au into the H II region while Br-γ extends the full length of theoutflow (∼12,650 au), indicating rapid dissociation of the molecules. H2 has higher velocities further from the driving source,
consistent with a jet-driven outflow. Diagnostic line ratios indicate that photoexcitation, not just shocks, contributes to theexcitation in the outflow. We argue that HH 900 is the first clear example of an evaporating molecular outflow and predict thata large column of neutral material that may be detectable with ALMA accompanies the dissociating molecules. Results fromthis study will help guide the interpretation of near-IR images of externally irradiated jets and outflows such as those obtainedwith the James Webb Space Telescope (JWST) in high-mass star-forming regions where these conditions may be common.

17

53. Stable accretion in young stars: The cases of EX Lupi and TW Hya

A. Sicilia-Aguilar, J. Campbell-White, V. Roccatagliata, J. Desira, S. G. Gregory, A. Scholz, M. Fang, F. CruzSaenz de Miera, Á. Kóspál, S. Matsumura, P. Ábrahám F We examine the long-term spectroscopic and photometricvariability of EX Lupi and TW Hya, studying the presence of stable accretion and the role it plays in the observed variability.
Analysing the velocity modulations of the emission lines with STAR-MELT, we obtain information on the structure of theaccretion columns and the disk-star connection. The emission line radial velocities reveal that TW Hya, like EX Lupi, has aremarkably stable or slow-varying accretion column footprint, locked to the star for several years. The line-emitting regions
are non-polar for both EX Lupi and TW Hya, and species with different energies differ in position. In contrast, the continuum
emission as observed in the photometry is very variable and can be modelled by hot spot(s) that change over time in phase,shape, temperature, size, and location with respect to the emission line region. The continuum emission region may not belimited to the stellar surface, especially during episodes of high accretion. The broad line emission observed in EX Lupi during
episodes of increased accretion reveals a further structure, which can be fitted by non-axisymmetric disk in Keplerian rotation
inwards of the corotation radius. Since the radial velocity modulation due to accretion footprints is so stable, we used it tosearch for further velocity modulations. While no residual modulation (other than caused by stellar rotation) is found in theseobjects, a similar analysis could help to identify young planets/companions. Therefore, determining whether stable accretion
footprints are common among young stars is a key to detect young planets.

54. Formation of misaligned second-generation discs through flyby encounters

Jeremy L. Smallwood, Rebecca Nealon, Nicolás Cuello, Ruobing Dong, Richard A. Booth F Observations reveal
protoplanetary discs being perturbed by flyby candidates. We simulate a scenario where an unbound perturber, i.e., a flyby,
undergoes an inclined grazing encounter, capturing material and forming a second-generation protoplanetary disc. We run N –body and three-dimensional hydrodynamical simulations of a parabolic flyby grazing a particle disc and a gas-rich protoplanetary
disc, respectively. In both our N –body and hydrodynamic simulations, we find that the captured, second-generation disc forms
at a tilt twice the initial flyby tilt. This relationship is robust to variations in the flyby’s tilt, position angle, periastron, andmass. We extend this concept by also simulating the case where the flyby has a disc of material prior to the encounter but
we do not find the same trend. An inclined disc with respect to the primary disc around a misaligned flyby is tilted by a few
degrees, remaining close to its initial disc tilt. Therefore, if a disc is present around the flyby before the encounter, the disc may
not tilt up to twice the perturber tilt depending on the balance between the angular momentum of the circumsecondary discand captured particles. In the case where the perturber has no initial disc, analyzing the orientation of these second-generation
discs can give information about the orbital properties of the flyby encounter.

55. Secondary outflow driven by the protostar Ser-emb 15 in Serpens

Asako Sato, Kazuki Tokuda, Masahiro N. Machida, Kengo Tachihara, Naoto Harada, Hayao Yamasaki, Shingo
Hirano, Toshikazu Onishi, Yuko Matsushita F We present the detection of a secondary outflow associated with a ClassI source, Ser-emb 15, in the Serpens Molecular Cloud. We reveal two pairs of molecular outflows consisting of three lobes,
namely primary and secondary outflows, using ALMA 12CO and SiO line observations at a resolution of 318 au. The secondary
outflow is elongated approximately perpendicular to the axis of the primary outflow in the plane of the sky. We also identify
two compact structures, Sources A and B, within an extended structure associated with Ser-emb 15 in the 1.3 mm continuum
emission at a resolution of 40 au. The projected sizes of Sources A and B are 137 au and 60 au, respectively. Assuming a
dust temperature of 20 K, we estimate the dust mass to be 0.0024 Msun for Source A and 0.00033 Msun for Source B. C18O
line data imply the existence of rotational motion around the extended structure, however, cannot resolve rotational motion
in Source A and/or B, due to insufficient angular and frequency resolutions. Therefore, we cannot conclude whether Ser-emb
15 is a single or binary system. Thus, either Source A or B could drive the secondary outflow. We discuss two scenarios toexplain the driving mechanism of the primary and secondary outflows: the Ser-emb 15 system is (1) a binary system composedof Source A and B or (2) a single star system composed of only Source A. In either case, the system could be a suitable target
for investigating the disk and/or binary formation processes in complicated environments. Detecting these outflows should
contribute to understanding complex star-forming environments, which may be common in the star-formation processes.

56. A rotating accretion disk around MWC297, a young B1.5 Ve star

Goran Sandell, William Vacca F High resolution spectra with iSHELL on IRTF in the K and M band of the young, heavily
accreting B 1.5e star MWC297 show numerous double-peaked CO lines. These CO lines originate in an inclined gaseous disk
in Keplerian rotation. MWC297 is the only early B star known to show a Keplerian disk in CO. Analysis of the spectra showthat 12CO 1 - 0 is optically thick for the low excitation lines. Even the 13CO 1 - 0 and 12CO 2 - 1 have somewhat opticallythick lines at low J levels. We find that the CO emission in the disk can be fitted with CO being in a narrow ring at a radius of
12 AU, with a temperature of 1500 K, and a CO column density of 1.6 e18 cm-2. This model underestimates the line strengthof high J lines, indicating that they are excited by fluorescence. The CO overtone lines have a similar temperature, The 13CO
lines are much brighter than expected from interstellar isotope ratios. The 13CO lines are wider than the 12CO ones suggesting18

different excitation conditions. The same is true for 12CO 2 - 1. We see strong absorption in 12CO and 13CO 1 - 0 at low J
levels, which is due to two two cold foreground clouds. These clouds, one with a temperature of 8.3 K and a column densityof 6.7 e17 cm-2, and the other one colder and with lower column density, can fully account for the observed extinction toward
MWC297.

57. RZ Piscium Hosts a Compact and Highly Perturbed Debris Disk

Kate Y. L. Su, Grant M. Kennedy, George H. Rieke, A. Meredith Hughes, Yu-Chia Lin, Jamar Kittling, Alan
P. Jackson, Ramya M. Anche, Hauyu Baobab Liu F RZ Piscium (RZ Psc) is well-known in the variable star field
because of its numerous, irregular optical dips in the past five decades, but the nature of the system is heavily debated in theliterature. We present multiyear infrared monitoring data from Spitzer and WISE to track the activities of the inner debris
production, revealing stochastic infrared variability as short as weekly timescales that is consistent with destroying a 90-km-size
asteroid every year. ALMA 1.3 mm data combined with spectral energy distribution modeling show that the disk is compact(∼0.1–13 au radially) and lacks cold gas. The disk is found to be highly inclined and has a significant vertical scale height.
These observations confirm that RZ Psc hosts a close to edge-on, highly perturbed debris disk possibly due to migration ofrecently formed giant planets which might be triggered by the low-mass companion RZ Psc B if the planets formed well beyond
the snowlines.

HCN emission from translucent gas and UV-illuminated cloud edges revealed by wide58. field IRAM 30m maps of Orion B GMC: Revisiting its role as tracer of the dense gas
reservoir for star formation
M. G. Santa-Maria, J. R. Goicoechea, J. Pety, M. Gerin, J. H. Orkisz, F. Le Petit, L. Einig, P. Palud, V.
de Souza Magalhaes, I. Bešlić, L. Segal, S. Bardeau, E. Bron, P. Chainais, J. Chanussot, P. Gratier, V. V.
Guzmán, A. Hughes, D. Languignon, F. Levrier, D. C. Lis, H. S. Liszt, J. Le Bourlot, Y. Oya, K. Öberg, N.
Peretto, E. Roueff, A. Roueff, A. Sievers, P. -A. Thouvenin, S. Yamamoto F We present 5 deg2 ( 250 pc2 ) HCN,
HNC, HCO+, and CO J=1−0 maps of the Orion B GMC, complemented with existing wide-field [CI] 492 GHz maps, as well
as new pointed observations of rotationally excited HCN, HNC, H13CN, and HN13C lines. We detect anomalous HCN J=1-0
hyperfine structure line emission almost everywhere in the cloud. About 70% of the total HCN J=1-0 luminosity arises from gas
at AV < 8 mag. The HCN/CO J=1−0 line intensity ratio shows a bimodal behavior with an inflection point at AV < 3 mag
typical of translucent gas and UV-illuminated cloud edges. We find that most of the HCN J=1-0 emission arises from extended
gas with n(H2) < 104 cm−3 , even lower density gas if the ionization fraction is > 10−5 and electron excitation dominates. This
result explains the low-AV branch of the HCN/CO J=1-0 intensity ratio distribution. Indeed, the highest HCN/CO ratios ( 0.1)
at AV < 3 mag correspond to regions of high [CI] 492 GHz/CO J=1-0 intensity ratios (>1) characteristic of low-density PDRs.
Enhanced FUV radiation favors the formation and excitation of HCN on large scales, not only in dense star-forming clumps.
The low surface brightness HCN and HCO+ J=1-0 emission scale with IF IR (a proxy of the stellar FUV radiation field) ina similar way. Together with CO J=1-0, these lines respond to increasing IF IR up to G0 20. On the other hand, the bright
HCN J=1-0 emission from dense gas in star-forming clumps weakly responds to IF IR once the FUV radiation field becomes too
intense (G0>1500). The different power law scalings (produced by different chemistries, densities, and line excitation regimes)
in a single but spatially resolved GMC resemble the variety of Kennicutt-Schmidt law indexes found in galaxy averages. As acorollary for extragalactic studies, we conclude that high HCN/CO J=1-0 line intensity ratios do not always imply the presenceof dense gas.

59. How much large dust could be present in hot exozodiacal dust systems?

T. A. Stuber, F. Kirchschlager, T. D. Pearce, S. Ertel, A. V. Krivov, S. Wolf F An infrared excess over thestellar photospheric emission of main-sequence stars has been found in interferometric surveys, commonly attributed to thepresence of hot exozodiacal dust (HEZD). While submicrometer-sized grains in close vicinity to their host star have beeninferred to be responsible for the found near-infrared excesses, the presence and amount of larger grains as part of the dust
distributions are weakly constrained. We quantify how many larger grains (above-micrometer-sized) could be present in addition
to submicrometer-sized grains, while being consistent with observational constraints. This is important in order to distinguishbetween various scenarios for the origin of HEZD and to better estimate its observational appearance when observed with
future instruments. We extended a model suitable to reproduce current observations of HEZD to investigate a bimodal size
distribution. By deriving the characteristics of dust distributions whose observables are consistent with observational limits
from interferometric measurements in the K and N bands we constrained the radii of sub- and above-micrometer-sized grains
as well as their mass, number, and flux density ratios. In the most extreme cases of some of the investigated systems, large
grains & 10 µm might dominate the mass budget of HEZD while contributing up to 25 % of the total flux density originatingfrom the dust at a wavelength of 2.13 µm and up to 50 % at a wavelength of 4.1 µm; at a wavelength of 11.1 µm their emission
might clearly dominate over the emission of small grains. While it is not possible to detect such hot-dust distributions using
ALMA, the ngVLA might allow us to detect HEZD at millimeter wavelengths. Large dust grains might have a more important19

impact on the observational appearance of HEZD than previously assumed, especially at longer wavelengths.

60. Rapid Dust Growth During Hydrodynamic Clumping Due to Streaming Instability

Ryosuke T. Tominaga, Hidekazu Tanaka F Streaming instability is considered to be one of the dominant processes topromote planetesimal formation by gravitational collapse of dust clumps. The development of streaming instability is expected
to form dust clumps in which the local dust density is strongly enhanced and even greater than the Roche density. The resulting
clumps can collapse to form planetesimals. Recent simulations conducted long-term simulations and showed that such strong
clumping occurs in a wider parameter space than previously expected. However, the indicated timescale for strong clumping
can be on the order of tens to hundreds Keplerian periods. In this paper, we estimate the growth time of dust grains during thepre-clumping phase. We find that the dust growth considerably proceeds before the strong clumping because even the moderate
clumping due to streaming instability increases the local dust-to-gas ratio & 10. Depending on the gas sound speed, the dust
collision velocity can be kept below ∼ 1 m/s once sufficiently strong dust clumping occurs. Thus, even silicate grains might
have the potential to grow safely toward the size whose Stokes number is unity during the clumping. Our results demonstrate
the importance of local dust coagulation during the dust clumping due to streaming instability.

61. Planet migration in massive circumbinary discs
Matthew Teasdale, Dimitris Stamatellos F Most stars are in multiple systems, with the majority of those being binaries.
A large number of planets have been confirmed in binary stars and therefore it is important to understand their formationand dynamical evolution. We perform simulations to investigate the migration of wide-orbit giant planets (semi-major axis 100AU) in massive circumbinary discs (mass 0.1 M ) that are marginally gravitationally unstable, using the three-dimensional
Smooth Particle Hydrodynamic code SEREN. We vary the binary parameters to explore their effect on planet migration. We
find that a planet in a massive circumbinary disc initially undergoes a period of rapid inward migration before switching to aslow outward migration, as it does in a circumstellar disc. However, the presence of the binary enhances planet migration andmass growth. We find that a high binary mass ratio (binary with equal mass stars) results in more enhanced outward planet
migration. Additionally, larger binary separation and/or higher binary eccentricity results to a faster outward planet migrationand stronger planet growth. We conclude that wide-orbit giant planets attain wider final orbits due to migration around binarystars than around single stars.

Early Planet Formation in Embedded Disks (eDisk). VIII. A Small Protostellar Disk
62. around the Extremely Low-Mass and Young Class 0 Protostar, IRAS 15398-3359
Travis J. Thieme, Shih-Ping Lai, Nagayoshi Ohashi, John J. Tobin, Jes K. Jørgensen, Jinshi Sai, Yusuke Aso,
Jonathan P. Williams, Yoshihide Yamato, Yuri Aikawa, Itziar de Gregorio-Monsalvo, Ilseung Han, Woojin
Kwon, Chang Won Lee, Jeong-Eun Lee, Zhi-Yun Li, Zhe-Yu Daniel Lin, Leslie W. Looney, Suchitra Narayanan,
Nguyen Thi Phuong, Adele L. Plunkett, Alejandro Santamaría-Miranda, Rajeeb Sharma, Shigehisa Takakuwa,
Hsi-Wei Yen F Protostellar disks are a ubiquitous part of the star formation process and the future sites of planet formation.
As part of the Early Planet Formation in Embedded Disks (eDisk) large program, we present high-angular resolution dust
continuum (∼ 40 mas) and molecular line (∼ 150 mas) observations of the Class 0 protostar, IRAS 15398-3359. The dust
continuum is small, compact, and centrally peaked, while more extended dust structures are found in the outflow directions.
We perform a 2D Gaussian fitting to find the deconvolved size and 2σ radius of the dust disk to be 4.5 × 2.8 au and 3.8 au,
respectively. We estimate the gas+dust disk mass assuming optically thin continuum emission to be 0.6 − 1.8 Mjup , indicatinga very low-mass disk. The CO isotopologues trace components of the outflows and inner envelope, while SO traces a compact,
rotating disk-like component. Using several rotation curve fittings on the PV diagram of the SO emission, the lower limits ofthe protostellar mass and gas disk radius are 0.022 M and 31.2 au from our Modified 2 single power-law fitting. A conservative
upper limit of the protostellar mass is inferred to be 0.1 M . The protostellar mass-accretion rate and the specific angularmomentum at the protostellar disk edge are found to be between 1.3 − 6.1 × 10−6 M yr−1 and 1.2 − 3.8 × 10−4 km s−1 pc,
respectively, with an age estimated between 0.4 − 7.5 × 104 yr. At this young age with no clear substructures in the disk,
planet formation would likely not yet have started. This study highlights the importance of high-resolution observations andsystematic fitting procedures when deriving dynamical properties of deeply embedded Class 0 protostars.

63.

ALMA-IMF IX: Catalog and Physical Properties of 315 SiO Outflow Candidates in 15
Massive Protoclusters
A. P. M. Towner, A. Ginsburg, P. Dell’Ova, A. Gusdorf, S. Bontemps, T. Csengeri, R. Galván-Madrid, F. K.
Louvet, F. Motte, P. Sanhueza, A. M. Stutz, J. Bally, T. Baug, H. R. V. Chen, N. Cunningham, M. FernándezLópez, H. -L. Liu, X. Lu, T. Nony, M. Valeille-Manet, B. Wu, R. H. Álvarez-Gutiérrez, M. Bonfand, J.
Di Francesco, Q. Nguyen-Luong, F. Olguin, A. P. Whitworth F We present a catalog of 315 protostellar outflow
candidates detected in SiO J=5-4 in the ALMA-IMF Large Program, observed with 2000 au spatial resolution, 0.339 km/s

20

velocity resolution, and 2-12 mJy/beam (0.18-0.8 K) sensitivity. We find median outflow masses, momenta, and kinetic energies
of 0.3 M , 4 M km/s, and 1045 erg, respectively. Median outflow lifetimes are 6,000 years, yielding median mass, momentum,
and energy rates of Ṁ = 10−4.4 M yr−1 , Ṗ = 10−3.2 M km/s yr−1 , and Ė = 1 L . We analyze these outflow properties
in the aggregate in each field. We find correlations between field-aggregated SiO outflow properties and total mass in cores( 3−5σ), and no correlations above 3σ with clump mass, clump luminosity, or clump luminosity-to-mass ratio. We performa linear regression analysis and find that the correlation between field-aggregated outflow mass and total clump mass - which
has been previously described in the literature - may actually be mediated by the relationship between outflow mass and total
mass in cores. We also find that the most massive SiO outflow in each field is typically responsible for only 15-30% of the total
outflow mass (60% upper limit). Our data agree well with the established mechanical force-bolometric luminosity relationshipin the literature, and our data extend this relationship up to L ≥ 106 L and Ṗ ≥ 1 M km/s yr−1 . Our lack of correlation
with clump L/M is inconsistent with models of protocluster formation in which all protostars start forming at the same time.

Characterizing the line emission from molecular clouds. II. A comparative study of
64. California, Perseus, and Orion A
M. Tafalla, A. Usero, A. Hacar F Aims. We characterize the molecular-line emission of three clouds whose star-formation
rates span one order of magnitude: California, Perseus, and Orion A. M ethods. We use stratified random sampling to selectpositions representing the different column density regimes of each cloud and observe them with the IRAM-30m telescope. We
cover the 3 mm wavelength band and focus our analysis on CO, HCN, CS, HCO+, HNC, and N2H+. Results. We find that theline intensities depend most strongly on the H2 column density. A secondary effect, especially visible in Orion A, is a dependenceof the line intensities on the gas temperature. We explored a method that corrects for temperature variations and show that,when it is applied, the emission from the three clouds behaves very similarly. CO intensities vary weakly with column density,
while the intensity of traditional dense-gas tracers such as HCN, CS, and HCO+ varies almost linearly with column density.
N2H+ differs from all other species in that it traces only cold dense gas. The intensity of the rare HCN and CS isotopologs
reveals additional temperature-dependent abundance variations. Overall, the clouds have similar chemical compositions that,as the depth increases, are sequentially dominated by photodissociation, gas-phase reactions, molecular freeze-out, and stellar
feedback in the densest parts of Orion A. Our observations also allowed us to calculate line luminosities for each cloud, and acomparison with literature values shows good agreement. We used our HCN data to explore the behavior of the HCN conversion
factor, finding that it is dominated by the emission from the outermost cloud layers. It also depends strongly on the gas kinetic
temperature. Finally, we show that the HCN/CO ratio provides a gas volume density estimate, and that its correlation withthe column density resembles that found in extragalactic observations.

Angular Resolution Imaging of the V892 Tau Binary System: A New Circumpri65. Highmary Disk Detection and Updated Orbital Constraints
Christina Vides, Steph Sallum, Josh Eisner, Andy Skemer, Ruth Murray-Clay F We present a direct imaging studyof V892 Tau, a young Herbig Ae/Be star with a close-in stellar companion and circumbinary disk. Our observations consist ofimages acquired via Keck 2/NIRC2 with non-redundant masking and the pyramid wavefront sensor at K0 band (2.12µm) and L0
band (3.78µm). Sensitivity to low-mass accreting companions and cool disk material is high at L0 band, while complimentary
observations at K0 band probe hotter material with higher angular resolution. These multi-wavelength, multi-epoch data allow
us to differentiate the secondary stellar emission from disk emission and deeply probe the structure of the circumbinary disk
at small angular separations. We constrain architectural properties of the system by fitting geometric disk and companion
models to the K0 and L0 band data. From these models, we constrain the astrometric and photometric properties of the stellar
binary and update the orbit, placing the tightest estimates to date on the V892 Tau orbital parameters. We also constrain thegeometric structure of the circumbinary disk, and resolve a circumprimary disk for the first time.

66. Exploring the Formation of Resistive Pseudodisks with the GPU Code Astaroth

Miikka S. Väisälä, Hsien Shang, Daniele Galli, Susana Lizano, Ruben Krasnopolsky F Pseudodisks are dense
structures formed perpendicular to the direction of the magnetic field during the gravitational collapse of a molecular cloudcore. Numerical simulations of the formation of pseudodisks are usually computationally expensive with conventional CPU
codes. To demonstrate the proof-of-concept of a fast computing method for this numerically costly problem, we explore theGPU-powered MHD code Astaroth, a 6th-order finite difference method with low adjustable finite resistivity implemented withsink particles. The formation of pseudodisks is physically and numerically robust and can be achieved with a simple and clean
setup for this newly adopted numerical approach for science verification. The method’s potential is illustrated by evidencing
the dependence on the initial magnetic field strength of specific physical features accompanying the formation of pseudodisks,e.g. the occurrence of infall shocks and the variable behavior of the mass and magnetic flux accreted on the central object. As
a performance test, we measure both weak and strong scaling of our implementation to find most efficient way to use the code
on a multi-GPU system. Once suitable physics and problem-specific implementations are realized, the GPU-accelerated code isan efficient option for 3-D magnetized collapse problems.

2167. A Lithium Depletion Age for the Carina Association

Mackenna L. Wood, Andrew W. Mann, Madyson G. Barber, Jonathan L. Bush, Reilly P. Milburn, Pa Chia
Thao, Stephen P. Schmidt, Benjamin M. Tofflemire, Adam L. Kraus F The dispersed remnants of stellar nurseries,
stellar associations provide unparalleled samples of coeval stars critical for studies of stellar and planetary formation andevolution. The Carina Stellar Association is one of the closest stellar associations to Earth, and yet measurements of its age
have varied from 13 to 45 Myr. We aim to update the age of Carina using the Lithium Depletion Boundary method. We obtainnew measurements of the Li 6708 Angstrom, absorption feature in likely members using optical spectra from the Goodman
HTS on SOAR and NRES on LCO. We detect the depletion boundary at MK = 6.8 (M5), which corresponds to an age of41(+3,-5) Myr. The age is consistent within uncertainties across six different models, including those that account for magnetic
fields and spots. We also estimate the age through analysis of the group’s overall variability, and by comparing the association
members’ CMD to stellar evolutionary models using a Gaussian Mixture Model, recovering ages consistent with the LDB. The
resulting age agrees with the older end of previous age measurements and is consistent with the lithium depletion age for theneighboring Tucana-Horologium Moving Group.

68. The dependence of the structure of planet-opened gaps in protoplanetary disks on radiative cooling
Minghao Zhang, Pinghui Huang, Ruobing Dong F Planets can excite density waves and open annular gas gaps inprotoplanetary disks. The depth of gaps is influenced by the evolving angular momentum carried by density waves. While theimpact of radiative cooling on the evolution of density waves has been studied, a quantitative correlation to connect gap depthwith the cooling timescale is lacking. To address this gap in knowledge, we employ the grid-based code Athena++ to simulate
disk-planet interactions, treating cooling as a thermal relaxation process. We establish quantitative dependences of steady-state
gap depth (Eq. 36) and width (Eq. 41) on planetary mass, Shakura-Sunyaev viscosity, disk scale height, and thermal relaxation
timescale (β). We confirm previous results that gap opening is the weakest when thermal relaxation timescale is comparable tolocal dynamical timescale. Significant variations in gap depth, up to an order of magnitude, are found with different β. In termsof width, a gap is at its narrowest around β = 1, approximately 10% to 20% narrower compared to the isothermal case. Whenβ ∼ 100, it can be ∼ 20% wider, and higher viscosity enhances this effect. We derive possible masses of the gas gap-opening
planets in AS 209, HD 163296, MWC 480, and HL Tau, accounting for the uncertainties in local thermal relaxation timescale.

22