The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 368 — 31 August 2023
Editor: João Alveswww.starformation.news

Cover image caption
A three-colour JWST NIRCam composite of the bipolar HH 211 outflow, in the Perseus molecular, not far from the youngstellar cluster IC348. The composite consists of images made in the F335M (blue), F460M (green) and F470N (red) filters.
The data shows a surprising absence of atomic or ionized emission, suggesting that the jet’s core is primarily molecular. The
orientation and projected scale in astronomical units (au) assuming a distance of 321 pc are shown in the lower right corner.
Credits: NASA, ESA, CSA - Ray et al. 2023.
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
Spectral survey of a Hot core with an Eruptive Accretion in S255IR NIRS3 (SHEA):
1. The discovery of class I and class II millimeter methanol maser transitions
Giseon Baek, Jeong-Eun Lee, Neal J. Evans II, Tomoya Hirota, Yuri Aikawa, Ji-hyun Kang, Jungha Kim,
Jes K. Jørgensen ⋆ We report the detection of the millimeter CH3 OH masers including a new detection of class I (110,11 101,10 A) and class II (61,5 -52,4 E) maser transitions toward the high-mass protostar S255IR NIRS3 in post-burst phase. The
CH3 OH emissions were detected as a mixture of maser and thermal characteristics. We examine the detected transitions
using an excitation diagram and LTE model spectra and compare the observed properties with those of thermal lines. ClassII CH3 OH maser transitions showed distinctive intensity and velocity distributions from those of thermal transitions. Bright
distinct emission components in addition to the fragmented and arc-shaped emissions are only detected in class I CH3 OH masertransitions toward southern and western directions from the protostellar position, implying the presence of the slow outflow
shocks.

Dust and Free-Free Emission in ONC Proplyds with ALMA Band 3 Observa2. Isolatingtions
Nicholas P. Ballering, L. Ilsedore Cleeves, Thomas J. Haworth, John Bally, Josh A. Eisner, Adam Ginsburg,
Ryan D. Boyden, Min Fang, Jinyoung Serena Kim ⋆ The Orion Nebula Cluster (ONC) hosts protoplanetary disks experiencing external photoevaporation by the cluster’s intense UV field. These “proplyds" are comprised of a disk surrounded by anionization front. We present ALMA Band 3 (3.1 mm) continuum observations of 12 proplyds. Thermal emission from the dust
disks and free-free emission from the ionization fronts are both detected, and the high-resolution (0.057") of the observations
allows us to spatially isolate these two components. The morphology is unique compared to images at shorter (sub)millimeter
wavelengths, which only detect the disks, and images at longer centimeter wavelengths, which only detect the ionization fronts.
The disks are small (rd = 6.4–38 au), likely due to truncation by ongoing photoevaporation. They have low spectral indices(α ≲ 2.1) measured between Bands 7 and 3, suggesting the dust emission is optically thick. They harbor tens of Earth massesof dust as computed from the millimeter flux using the standard method, although their true masses may be larger due to thehigh optical depth. We derive their photoevaporative mass-loss rates in two ways: first, by invoking ionization equilibrium, andsecond using the brightness of the free-free emission to compute the density of the outflow. We find decent agreement between
these measurements and Ṁ = 0.6–18.4 × 10−7 M⊙ yr−1 . The photoevaporation timescales are generally shorter than the ∼1
Myr age of the ONC, underscoring the known “proplyd lifetime problem." Disk masses that are underestimated due to being
optically thick remains one explanation to ease this discrepancy.

Tracing snowlines and C/O ratio in a planet-hosting disk: ALMA molecular line obser3. vations towards the HD169142 disk
Alice S. Booth, Charles J. Law, Milou Temmink, Margot Leemker, Enrique Macias ⋆ The composition of a forming
planet is set by the material it accretes from its parent protoplanetary disk. Therefore, it is crucial to map the chemical make-upof the gas in disks to understand the chemical environment of planet formation. This paper presents molecular line observations
taken with the Atacama Large Millimeter/submillimeter Array of the planet-hosting disk around the young star HD 169142.

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We detect N2H+, CH3OH, [CI], DCN, CS, C34S, 13CS, H2CS, H2CO, HC3N and c-C3H2 in this system for the first time.
Combining these data with the recent detection of SO and previously published DCO+ data, we estimate the location of H2O
and CO snowlines and investigate radial variations in the gas phase C/O ratio. We find that the HD 169142 disk has a relatively
low N2H+ flux compared to the disks around Herbig stars HD 163296 and MWC 480 indicating less CO freeze-out and place
the CO snowline beyond the millimetre disk at 150 au. The detection of CH3OH from the inner disk is consistent with the H2O
snowline being located at the edge of the central dust cavity at 20 au. The radially varying CS/SO ratio across the proposed
H2O snowline location is consistent with this interpretation. Additionally, the detection of CH3OH in such a warm disk adds
to the growing evidence supporting the inheritance of complex ices in disks from the earlier, colder stages of star formation.
Finally, we propose that the giant HD 169142 b located at 37 au is forming between the CO2 and H2O snowlines where thelocal elemental make of the gas is expected to have C/O=1.0.

4. Chemical evolution of some selected complex organic molecules in low-mass star-forming
regions
Bratati Bhat, Rumela Kar, Suman Kumar Mondal, Rana Ghosh, Prasanta Gorai, Takashi Shimonishi, Kei
E. I. Tanaka, Kenji Furuya, Ankan Das ⋆ The destiny of complex organic molecules (COMs) in star-forming regionsis interlinked with various evolutionary phases. Therefore, identifying these species in diversified environments of identicalstar-forming regions would help to comprehend their physical and chemical heritage. We identified multiple COMs utilizing theLarge Program ‘Astrochemical Surveys At IRAM’ (ASAI) data, dedicated to chemical surveys in Sun-like star-forming regionswith the IRAM 30 m telescope. It was an unbiased survey in the millimetre regime, covering the prestellar core, protostar,outflow region, and protoplanetary disk phase. Here, we have reported some transitions of seven COMs, namely, methanol(CH3OH), acetaldehyde (CH3CHO), methyl formate (CH3OCHO), ethanol (C2H5OH), propynal (HCCCHO), dimethyl ether(CH3OCH3), and methyl cyanide (CH3CN) in some sources L1544, B1-b, IRAS4A, and SVS13A. We found a trend among these
species from the derived abundances using the rotational diagram method and MCMC fit. We have found that the abundancesof all of the COMs, except for HCCCHO, increase from the L1544 (prestellar core) and peaks at IRAS16293-2422 (class 0phase). It is noticed that the abundance of these molecules correlate with the luminosity of the sources. The obtained trend isalso visible from the previous interferometric observations and considering the beam dilution effect.

5.

The potential of VLTI observations for the study of circumstellar disk variability
A. Bensberg, J. Kobus, S. Wolf ⋆ Context. A characteristic feature of young stellar objects is their variability, which is
caused by a variety of different physical processes. High-resolution interferometric observations in the near- and mid-infrared
wavelength ranges spanning multiple epochs allow the detailed study of these processes. Aims. We aim at investigating the
expected variations of the interferometric observables connected to changes in the measured photometric fluxes of a typicalvariable accreting central young stellar object with a circumstellar disk. Methods. We calculated visibilities and closure phases
as well as the photometric flux of brightness distributions obtained using 3D Monte Carlo radiative transfer simulations fora model of a circumstellar disk with an accreting central star. Results. Changes in the accretion luminosity of the central
object, that is, an accreting pre-main-sequence star, can lead to significant variations in the visibility and closure phase of thestar-disk system measured with instruments at the Very Large Telescope Interferometer (VLTI) that can be related to changes
in the photometric flux. Taking into account additional effects due to baseline variation, interferometric observations canprovide valuable contributions to the understanding of the underlying processes. Additionally, we provide the web application
VLTI B-VAR that allows the impact of the hour angle on the visibility and closure phase for customized intensity maps to be
estimated.

Forming Gas Giants Around a Range of Protostellar M-dwarfs by Gas Disk Gravita6. tional Instability
Alan P. Boss, Shubham Kanodia ⋆ Recent discoveries of gas giant exoplanets around M-dwarfs (GEMS) from transiting
and radial velocity (RV) surveys are difficult to explain with core-accretion models. We present here a homogeneous suite of
162 models of gravitationally unstable gaseous disks. These models represent an existence proof for gas giants more massive
than 0.1 Jupiter masses to form by the gas disk gravitational instability (GDGI) mechanism around M-dwarfs for comparison
with observed exoplanet demographics and protoplanetary disk mass estimates for M-dwarf stars. We use the Enzo 2.6 adaptive
mesh refinement (AMR) 3D hydrodynamics code to follow the formation and initial orbital evolution of gas giant protoplanetsin gravitationally unstable gaseous disks in orbit around M-dwarfs with stellar masses ranging from 0.1 M⊙ to 0.5 M⊙ . The gas
disk masses are varied over a range from disks that are too low in mass to form gas giants rapidly to those where numerous gas
giants are formed, therefore revealing the critical disk mass necessary for gas giants to form by the GDGI mechanism aroundM-dwarfs. The disk masses vary from 0.01 M⊙ to 0.05 M⊙ while the disk to star mass ratios explored range from 0.04 to
0.3. The models have varied initial outer disk temperatures (10 K to 60 K) and varied levels of AMR grid spatial resolution,
producing a sample of expected gas giant protoplanets for each star mass. Broadly speaking, disk masses of at least 0.02 M⊙
are needed for the GDGI mechanism to form gas giant protoplanets around M-dwarfs.

3

7. HH 80/81: Structure and Kinematics of the Fastest Protostellar Outflow

John Bally, Bo Reipurth ⋆ Hubble Space Telescope images obtained in 2018 are combined with archival HST data taken in
1995 to detect changes and measure proper motions in the HH 80/81 shock complex which is powered by the fastest known jet
driven by a forming star, the massive object IRAS 18162-2048. Some persistent features close to the radio jet axis have propermotions grater than 1,000 km/s away from IRAS 18162-2048. About 3 to 5 parsecs downstream from the IRAS source andbeyond HH 80/81, H-alpha emission traces the rim of a parsec-scale bubble blown by the jet. Lower speed motions are seen in[Sii] away from the jet axis; these features have a large component of motion at right-angles to the jet. We identify new HH
objects and H2 shocks in the counterflow opposite HH 80/81. The northeastern counterflow to HH 80/81 exhibits an extended
but faint complex of 2.12 um H2 shocks. The inner portion of the outflow is traced by dim 1.64 um [Feii] emission. The full
extent of this outflow is at least 1,500" (about 10 pc in projection at a distance of 1.4 kpc). We speculate about the conditions
responsible for the production of the ultra-fast jet and the absence of prominent large-scale molecular outflow lobes.

8.

A Keplerian disk with a four-arm spiral birthing an episodically accreting high-mass
protostar
R. A. Burns, Y. Uno, N. Sakai, J. Blanchard, Z. Rosli, G. Orosz, Y. Yonekura, Y. Tanabe, K. Sugiyama, T.
Hirota, Kee-Tae Kim, A. Aberfelds, A. E. Volvach, A. Bartkiewicz, A. Caratti o Garatti, A. M. Sobolev, B.
Stecklum, C. Brogan, C. Phillips, D. A. Ladeyschikov, D. Johnstone, G. Surcis, G. C. MacLeod, H. Linz, J.
O. Chibueze, J. Brand, J. Eislöffel, L. Hyland, L. Uscanga, M. Olech, M. Durjasz, O. Bayandina, S. Breen,
S. P. Ellingsen, S. P. van den Heever, T. R. Hunter, X. Chen ⋆ High-mass protostars (M⋆ > 8 M⊙ ) are thought
to gain the majority of their mass via short, intense bursts of growth. This episodic accretion is thought to be facilitatedby gravitationally unstable and subsequently inhomogeneous accretion disks. Limitations of observational capabilities, pairedwith a lack of observed accretion burst events has withheld affirmative confirmation of the association between disk accretion,
instability and the accretion burst phenomenon in high-mass protostars. Following its 2019 accretion burst, a heat-wave driven
by a burst of radiation propagated outward from the high-mass protostar G358.93-0.03-MM1. Six VLBI (very long baseline
interferometry) observations of the raditively pumped 6.7 GHz methanol maser were conducted during this period, tracing
ever increasing disk radii as the heat-wave propagated outward. Concatenating the VLBI maps provided a sparsely sampled,
milliarcsecond view of the spatio-kinematics of the accretion disk covering a physical range of ∼ 50 - 900 AU. We term thisobservational approach ‘heat-wave mapping’. We report the discovery of a Keplerian accretion disk with a spatially resolved
four-arm spiral pattern around G358.93-0.03-MM1. This result positively implicates disk accretion and spiral arm instabilities
into the episodic accretion high-mass star formation paradigm.

The Orion-Taurus ridge: a synchrotron radio loop at the edge of the Orion-Eridanus
9. superbubble
Andrea Bracco, Marco Padovani, Juan D. Soler ⋆ Large-scale synchrotron loops are recognized as the main source ofdiffuse radio-continuum emission in the Galaxy at intermediate and high Galactic latitudes. Their origin, however, remains
rather unexplained. Using a combination of multi-frequency data in the radio band of total and polarized intensities, for the
first time in this letter, we associate one arc – hereafter, the Orion-Taurus ridge – with the wall of the most prominent stellarfeedback blown shell in the Solar neighborhood, namely the Orion-Eridanus superbubble. We traced the Orion-Taurus ridge
using 3D maps of interstellar dust extinction and column-density maps of molecular gas, NH2 . We found the Orion-Taurus ridge
21
at a distance of 400 pc, with a plane-of-the-sky extent of 180 pc. Its median NH2 value is (1.4+2.6
cm−2 . Thanks to the−0.6 ) × 10
broadband observations below 100 MHz of the Long Wavelength Array, we also computed the low-frequency spectral-index mapof synchrotron emissivity, β, in the Orion-Taurus ridge. We found a flat distribution of β with a median value of −2.24+0.03−0.02
that we interpreted in terms of depletion of low-energy (< GeV) cosmic-ray electrons in recent supernova remnants (105 - 106yrs). Our results are consistent with plane-of-the-sky magnetic-field strengths in the Orion-Taurus ridge larger than a few tensof µG (> 30 − 40 µG). We report the first detection of diffuse synchrotron emission from cold-neutral, partly molecular, gas in
the surroundings of the Orion-Eridanus superbubble. This observation opens a new perspective to study the multiphase andmagnetized interstellar medium with the advent of future high-sensitivity radio facilities, such as the C-Band All-Sky Survey
and the Square Kilometre Array.

JWST reveals excess cool water near the snowline in compact disks, consistent with
10. pebble drift
Andrea Banzatti, Klaus M. Pontoppidan, John Carr, Evan Jellison, Ilaria Pascucci, Joan Najita, Carlos E.
Munoz-Romero, Karin I. Oberg, Anusha Kalyaan, Paola Pinilla, Sebastiaan Krijt, Feng Long, Michiel Lambrechts, Giovanni Rosotti, Gregory J. Herczeg, Colette Salyk, Ke Zhang, Edwin Bergin, Nick Ballering, Michael
R. Meyer, Simon Bruderer, the JDISCS collaboration ⋆ Previous analyses of mid-infrared water spectra from young
protoplanetary disks observed with the Spitzer-IRS found an anti-correlation between water luminosity and the millimeter dust
disk radius observed with ALMA. This trend was suggested to be evidence for a fundamental process of inner disk water en-

4richment, used to explain properties of the Solar System 40 years ago, in which icy pebbles drift inward from the outer disk andsublimate after crossing the snowline. Previous analyses of IRS water spectra, however, were uncertain due to the low spectral
resolution that blended lines together. We present new JWST-MIRI spectra of four disks, two compact and two large withmultiple radial gaps, selected to test the scenario that water vapor inside the snowline is regulated by pebble drift. The higher
spectral resolving power of MIRI-MRS now yields water spectra that separate individual lines, tracing upper level energies from900 K to 10,000 K. These spectra clearly reveal excess emission in the low-energy lines in compact disks, compared to the large
disks, demonstrating an enhanced cool component with T ≈ 170-400 K and equivalent emitting radius Req ≈ 1-10 au. Weinterpret the cool water emission as ice sublimation and vapor diffusion near the snowline, suggesting that there is indeed ahigher inwards mass flux of icy pebbles in compact disks. Observation of this process opens up multiple exciting prospects tostudy planet formation chemistry in inner disks with JWST.

11. CoCCoA: Complex Chemistry in hot Cores with ALMA. Selected oxygen-bearing species
Y. Chen, M. L. van Gelder, P. Nazari, C. L. Brogan, E. F. van Dishoeck, H. Linnartz, J. K. Jørgensen, T. R.
Hunter, O. H. Wilkins, G. A. Blake, P. Caselli, K. -J. Chuang, C. Codella, I. Cooke, M. N. Drozdovskaya, R.
T. Garrod, S. Ioppolo, M. Jin, B. M. Kulterer, N. F. W. Ligterink, A. Lipnicky, R. Loomis, M. G. Rachid, S.
Spezzano, B. A. McGuire ⋆ Complex organic molecules (COMs) have been observed to be abundant in the gas phase toward
protostars. Deep line surveys have been carried out only for a limited number of well-known high-mass star forming regions using
the Atacama Large Millimeter/submillimeter Array (ALMA), which has unprecedented resolution and sensitivity. Statisticalstudies on oxygen-bearing COMs (O-COMs) in high-mass protostars using ALMA are still lacking. With the recent CoCCoA
survey, we are able to determine the column density ratios of six O-COMs with respect to methanol (CH3 OH) in a sample
of 14 high-mass protostellar sources to investigate their origin through ice and/or gas-phase chemistry. The selected species
are: acetaldehyde (CH3 CHO), ethanol (C2 H5 OH), dimethyl ether (DME, CH3 OCH3 ), methyl formate (MF, CH3 OCHO), glycolaldehyde (GA, CH2 OHCHO), and ethylene glycol (EG, (CH2 OH)2 ). DME and MF have the highest and most constantratios within one order of magnitude, while the other four species have lower ratios and exhibit larger scatter by 1-2 ordersof magnitude. We compare the O-COM ratios of high-mass CoCCoA sources with those of 5 low-mass protostars available
from the literature, along with the results from experiments and simulations. We find that the O-COM ratios with respect tomethanol are on the same level in both the high- and low-mass samples, which suggests that these species are mainly formedin similar environments during star formation, probably in ice mantles on dust grains during early pre-stellar stages. Current
simulations and experiments can reproduce most observational trends with a few exceptions, and hypotheses exist to explain
the differences between observations and simulations/experiments, such as the involvement of gas-phase chemistry and different
emitting areas of molecules.

12.

New radio lobes at parsec scale from the East-West protostellar jet RAFGL2591
A. G. Cheriyan, S. Vig, Sreelekshmi Mohan ⋆ RAFGL2591 is a massive star-forming complex in the Cygnus-X region
comprising of a cluster of embedded protostars and young stellar objects located at a distance of 3.33 kpc. We investigate
low-frequency radio emission from the protostellar jet associated with RAFGL2591 using the Giant Metrewave Radio Telescope(GMRT) at 325, 610 and 1280 MHz. For the first time, we have detected radio jet lobes in the E-W direction, labelled as
GMRT-1 and GMRT-2. While GMRT-1 displays a flat radio spectral index of α = -0.10 , GMRT-2 shows a steeply negativevalue α = -0.62 suggestive of non-thermal emission. H2 emission maps show the presence of numerous knots, arcs and extended
emission towards the East-West jet, excited by the protostar VLA 3. In addition, we report a few H2 knots in the North-East
and South-West for the first time. The radio lobes (GMRT-1, GMRT-2) and H2 emission towards this region are understood in
the context of the prominent East-West jet as well as its lesser-known sibling jet in the North-East and South-West direction.
To model the radio emission from the lobes, we have employed a numerical model including both thermal and non-thermal
emission and found number densities towards these lobes in the range 100 - 1000 cm−3 . The misalignment of the East-West jet
lobes exhibits a reflection symmetry with a bending of ∼ 20◦ . We attempt to understand this misalignment through precession
caused by a binary partner and/or a supersonic side wind from source(s) in the vicinity.

magnetically driven disc wind in the inner disc of PDS 70
13. A
Justyn Campbell-White, Carlo F. Manara, Myriam Benisty, Antonella Natta, Rik A. B. Claes, Antonio Frasca,
Jaehan Bae, Stefano Facchini, Andrea Isella, Laura Pérez, Paola Pinilla, Aurora Sicilia-Aguilar, Richard Teague⋆ PDS 70 is so far the only young disc where multiple planets have been detected by direct imaging. The disc has a large
cavity when seen at sub-mm and NIR wavelengths, which hosts two massive planets. This makes PDS 70 the ideal target to
study the physical conditions in a strongly depleted inner disc shaped by two giant planets, and in particular to test whether
disc winds can play a significant role in its evolution. Using X-Shooter and HARPS spectra, we detected for the first time thewind-tracing [O I] 6300AA line, and confirm the low-moderate value of mass-accretion rate in the literature. The [O I] line
luminosity is high with respect to the accretion luminosity when compared to a large sample of discs with cavities in nearby
star-forming regions. The FWHM and blue-shifted peak of the [O I] line suggest an emission in a region very close to the star,5

favouring a magnetically driven wind as the origin. We also detect wind emission and high variability in the He I 10830AA line,
which is unusual for low-accretors. We discuss that, although the cavity of PDS 70 was clearly carved out by the giant planets,
the substantial inner disc wind could also have had a significant contribution to clearing the inner-disc.

14. MagAO-X and HST high-contrast imaging of the AS209 disk at HαGabriele Cugno, Yifan Zhou, Thanawuth Thanathibodee, Per Calissendorff, Michael R. Meyer, Suzan Edwards,
Jaehan Bae, Myriam Benisty, Edwin Bergin, Matthew De Furio, Stefano Facchini, Jared R. Males, Laird M.
Close, Richard D. Teague, Olivier Guyon, Sebastiaan Y. Haffert, Alexander D. Hedglen, Maggie Kautz, Andrés
Izquierdo, Joseph D. Long, Jennifer Lumbres, Avalon L. McLeod, Logan A. Pearce, Lauren Schatz, Kyle Van
Gorkom ⋆ The detection of emission lines associated with accretion processes is a direct method for studying how and wheregas giant planets form, how young planets interact with their natal protoplanetary disk and how volatile delivery to theiratmosphere takes place. Hα (λ = 0.656 µm) is expected to be the strongest accretion line observable from the ground withadaptive optics systems, and is therefore the target of specific high-contrast imaging campaigns. We present MagAO-X andHST data obtained to search for Hα emission from the previously detected protoplanet candidate orbiting AS209, identified
through ALMA observations. No signal was detected at the location of the candidate, and we provide limits on its accretion.
Our data would have detected an Hα emission with FHα > 2.5 ± 0.3 × 10−16 erg s−1 cm−2 , a factor 6.5 lower than the HST
flux measured for PDS70b (Zhou et al., 2021). The flux limit indicates that if the protoplanet is currently accreting it is likelythat local extinction from circumstellar and circumplanetary material strongly attenuates its emission at optical wavelengths.
In addition, the data reveal the first image of the jet north of the star as expected from previous detections of forbidden lines.
Finally, this work demonstrates that current ground-based observations with extreme adaptive optics systems can be moresensitive than space-based observations, paving the way to the hunt for small planets in reflected light with extremely large
telescopes.

ALMA-IMF VII – First release of the full spectral line cubes:Core kinematics traced
15. by DCN J=(3-2)
N. Cunningham, A. Ginsburg, R. Galván-Madrid, F. Motte, T. Csengeri, A. M. Stutz, M. Fernández-López, R.
H. Álvarez-Gutiérrez, M. Armante, T. Baug, M. Bonfand, S. Bontemps, J. Braine, N. Brouillet, G. Busquet,
D. J. Díaz-González, J. Di Francesco, A. Gusdorf, F. Herpin, H. Liu, A. López-Sepulcre, F. Louvet, X. Lu, L.
Maud, T. Nony, F. A. Olguin, Y. Pouteau, R. Rivera-Soto, N. A. Sandoval-Garrido, P. Sanhueza, K. Tatematsu,
A. P. M. Towner, M. Valeille-Manet ⋆ ALMA-IMF is an Atacama Large Millimeter/submillimeter Array (ALMA) Large
Program designed to measure the core mass function (CMF) of 15 protoclusters chosen to span their early evolutionary stages.
It further aims to understand their kinematics, chemistry, and the impact of gas inflow, accretion, and dynamics on the CMF.
We present here the first release of the ALMA-IMF line data cubes (DR1), produced from the combination of two ALMA
12m-array configurations. The data include 12 spectral windows, with eight at 1.3mm and four at 3mm. The broad spectral
coverage of ALMA-IMF ( 6.7 GHz bandwidth coverage per field) hosts a wealth of simple atomic, molecular, ionised, andcomplex organic molecular lines. We describe the line cube calibration done by ALMA and the subsequent calibration andimaging we performed. We discuss our choice of calibration parameters and optimisation of the cleaning parameters, and we
demonstrate the utility and necessity of additional processing compared to the ALMA archive pipeline. As a demonstration of
the scientific potential of these data, we present a first analysis of the DCN (3-2) line. We find that DCN traces a diversity ofmorphologies and complex velocity structures, which tend to be more filamentary and widespread in evolved regions and are
more compact in the young and intermediate-stage protoclusters. Furthermore, we used the DCN (3-2) emission as a tracerof the gas associated with 595 continuum cores across the 15 protoclusters, providing the first estimates of the core systemic
velocities and linewidths within the sample. We find that DCN (3-2) is detected towards a higher percentage of cores in evolved
regions than the young and intermediate-stage protoclusters and is likely a more complete tracer of the core population in more
evolved protoclusters. The full ALMA 12m-array cubes for the ALMA-IMF Large Program are provided with this DR1 release.

The Role of Magnetic Fields in the Formation of the Filamentary Infrared Dark Cloud
16. G11.11-0.12
Zhiwei Chen, Ramotholo Sefako, Yang Yang, Zhibo Jiang, Yang Su, Shaobo Zhang, Xin Zhou ⋆ We report on thenear-infrared polarimetric observations of G11.11-0.12 (hereafter G11) obtained with SIRPOL on the 1.4 m IRSF telescope. The
starlight polarisation of the background stars reveals the on-sky component of magnetic fields in G11, and these are consistent
with the field orientation observed from polarised dust emission at 850 µm. The magnetic fields in G11 are perpendicular to
the filament, and are independent of the filament’s orientation relative to the Galactic plane. The field strength in the envelopeof G11 is in the range 50 − 100 µG, derived from two methods. The analyses of the magnetic fields and gas velocity dispersion
indicate that the envelope of G11 is supersonic but sub-Alfvénic. The critical mass-to-flux ratio in the envelope of G11 is close
to 1 and increases to ≳ 1 on the spine of G11. The relative weights on the importance of magnetic fields, turbulence and gravity
indicate that gravity dominates the dynamical state of G11, but with significant contribution from magnetic fields. The field6

strength, |B|, increases slower than the gas density, n, from the envelope to the spine of G11, characterized by |B| ∝ n0.3 .
The observed strength and orientation of magnetic fields in G11 imply that supersonic and sub-Alfvénic gas flow is channelledby the strong magnetic fields and is assembled into filaments perpendicular to the magnetic fields. The formation of low-massstars is enhanced in the filaments with high column density, in agreement with the excess of low-mass protostars detected in
the densest regions of G11.

A Parsec-Scale Catalog of Molecular Clouds in the Solar Neighborhood Based on 3D
17. Dust Mapping: Implications for the Mass-Size Relation
Shlomo Cahlon, Catherine Zucker, Alyssa Goodman, Charles Lada, João Alves ⋆ We dendrogram the Leike etal. 2020 3D dust map, leveraging its ∼ 1 pc spatial resolution to produce a uniform catalog of molecular clouds in the solar
neighborhood. Using accurate distances, we measure the properties of 65 clouds in true 3D space, eliminating much of theuncertainty in mass, size, and density. Clouds in the catalog contain a total of 1.1 × 105 M⊙ , span distances of 116 − 440
pc, and include a dozen well-studied clouds in the literature. In addition to deriving cloud properties in 3D volume density
space, we create 2D dust extinction maps from the 3D data by projecting the 3D clouds onto a 2D "Sky" view. We measure
the properties of the 2D clouds separately from those of the 3D clouds. Using the 2D and 3D derived results, we compare
the scaling relation between the masses and sizes of clouds following Larson 1981. We find that our 2D projected mass-size
relation, M ∝ r2.1 , agrees with Larson’s Third Relation, but our 3D derived properties lead to a scaling relation of about oneorder larger: M ∝ r2.9 . Validating predictions from numerical simulations and analytic theory, our results indicate that the
mass-size relation is sensitive to whether column or volume density is used to define clouds, since mass scales with area in 2D
space (M ∝ r2 ) and with volume in 3D space (M ∝ r3 ). Our results imply a roughly constant column and volume density formolecular clouds, as would be expected for clouds where the lower density, larger volume-filling gas dominates the cloud mass
budget.

orbits18. On the survivability of a population of gas giant planets on wide>

Ethan Carter, Dimitris Stamatellos ⋆ The existence of giant planets on wide orbits (∼ 100AU) challenge planet formation
theories; the core accretion scenario has difficulty in forming them, whereas the disc instability model forms an overabundanceof them that is not seen observations. We perform N -body simulations investigating the effect of close stellar encounters(≤ 1200AU) on systems hosting wide-orbit giant planets and the extent at which such interactions may disrupt the initial wideorbit planet population. We find that the effect of an interaction on the orbit of a planet is stronger for high-mass, low-velocity
perturbers, as expected. We find that due to just a single encounter there is a ∼ 17% chance that the wide-orbit giant planet
is liberated in the field, a ∼ 10% chance it is scattered significantly outwards, and a ∼ 6% chance it is significantly scatteredinwards. Moreover, there is a ∼ 21% chance that its eccentricity is excited to e>0.1, making it more prone to disruption insubsequent encounters. The results strongly suggest that the effect of even a single stellar encounter is significant in disrupting
the primordial wide-orbit giant planet population; in reality the effect will be even more prominent, as in a young star-forming
region more such interactions are expected to occur. We conclude that the low occurrence rate of wide-orbit planets revealed
by observational surveys does not exclude the possibility that such planetary systems are initially abundant, and therefore thedisc-instability model may be a plausible scenario for their formation.

19. The diverse chemistry of protoplanetary disks as revealed by JWST

Ewine F. van Dishoeck, S. Grant, B. Tabone, M. van Gelder, L. Francis, L. Tychoniec, G. Bettoni, A. M.
Arabhavi, D. Gasman, P. Nazari, M. Vlasblom, P. Kavanagh, V. Christiaens, P. Klaassen, H. Beuther, Th.
Henning, I. Kamp ⋆ Early results from the JWST-MIRI guaranteed time programs on protostars (JOYS) and disks (MINDS)
are presented. Thanks to the increased sensitivity, spectral and spatial resolution of the MIRI spectrometer, the chemical
inventory of the planet-forming zones in disks can be investigated with unprecedented detail across stellar mass range andage. Here data are presented for five disks, four around low-mass stars and one around a very young high-mass star. The
mid-infrared spectra show some similarities but also significant diversity: some sources are rich in CO2, others in H2O or C2H2.
In one disk around a very low-mass star, booming C2H2 emission provides evidence for a “soot” line at which carbon grains are
eroded and sublimated, leading to a rich hydrocarbon chemistry in which even di-acetylene (C4H2) and benzene (C6H6) aredetected (Tabone et al. 2023). Together, the data point to an active inner disk gas-phase chemistry that is closely linked tothe physical structure (temperature, snowlines, presence of cavities and dust traps) of the entire disk and which may result invarying CO2/H2O abundances and high C/O ratios >1 in some cases. Ultimately, this diversity in disk chemistry will also bereflected in the diversity of the chemical composition of exoplanets.

720. 3-D SPH simulations of the FUOR flares in the clumpy accretion model

Tatiana V. Demidova, Vladimir P. Grinin ⋆ One of the early hypotheses about the origin of FUOR outbursts explainsthem by the fall of gas clumps from the remnants of protostellar clouds onto protoplanetary disks surrounding young stars(Hartmann and Kenyon 1985). To calculate the consequences of such an event we make 3D hydrodynamic simulations by SPH
method. It is shown that the fall of the clump on the disk in the vicinity of the star actually causes a burst of the star’s accretion
activity, resembling in its characteristics the flares of known FUORs. In the region of incidence, an inhomogeneous gas ringis formed, which is inclined relative to the outer disk. During several revolutions around the star, this ring combines with theinner disk and forms a tilted disk. In the process of evolution, the inner disk expands, and its inclination relative to the outerdisk decreases. After 100 revolutions, the angle of inclination is a few degrees. This result is of interest in connection with thediscovery in recent years of protoplanetary disks, the inner region of which is inclined relative to the outer one. Such structures
are usually associated with the existence in the vicinity of a star of a massive body (planet or brown dwarf), whose orbit isinclined relative to the plane of the disk. The results of our modeling indicate the possibility of an alternative explanation forthis phenomenon.

Constraints on the dust size distributions in the HD 163296 disk from the difference of
21. the apparent dust ring widths between two ALMA Bands
Kiyoaki Doi, Akimasa Kataoka ⋆ The dust size in protoplanetary disks is a crucial parameter for understanding planet
formation, while the observational constraints on dust size distribution have large uncertainties. In this study, we present a
new method to constrain the dust size distribution from the dust spatial distribution, utilizing the fact that larger dust grains
are more spatially localized. We analyze the ALMA Band 6 (1.25 mm) and Band 4 (2.14 mm) high-resolution images andconstrain the dust size distribution in the two rings of the HD 163296 disk. We find that the outer ring at 100 au appears
narrower at the longer wavelengths, while the inner ring at 67 au appears to have similar widths across the two wavelengths.
We model dust rings trapped at gas pressure maxima, where the dust grains follow a power-law size distribution, and the dust
grains of a specific size follow a Gaussian spatial distribution with the width depending on the grain size. By comparing theobservations with the models, we constrain the maximum dust size amax and the exponent of the dust size distribution p. We
constrain that 0.9 mm < amax < 5 mm and p < 3.3 in the inner ring, and amax > 3 × 101 mm and 3.4 < p < 3.7 in the outerring. The larger maximum dust size in the outer ring implies a spatial dependency in dust growth, potentially influencing theformation location of the planetesimals. We further discuss the turbulence strength α derived from the constrained dust spatial
distribution, assuming equilibrium between turbulent diffusion and accumulation of dust grains.

Lowest accreting protoplanetary discs consistent with X-ray photoevaporation driving
22. their final dispersal
Barbara Ercolano, Giovanni Picogna, Kristina Monsch ⋆ Photoevaporation from high energy stellar radiation has beenthought to drive the dispersal of protoplanetary discs. Different theoretical models have been proposed, but their predictions
diverge in terms of the rate and modality at which discs lose their mass, with significant implications for the formation andevolution of planets. In this paper we use disc population synthesis models to interpret recent observations of the lowest accreting
protoplanetary discs, comparing predictions from EUV-driven, FUV-driven and X-ray driven photoevaporation models. We
show that the recent observational data of stars with low accretion rates (low accretors) point to X-ray photoevaporation as thepreferred mechanism driving the final stages of protoplanetary disc dispersal. We also show that the distribution of accretion
rates predicted by the X-ray photoevaporation model is consistent with observations, while other dispersal models tested here
are clearly ruled out.

Parsec scales of carbon chain and complex organic molecules in AFGL 2591 and IRAS
23. 20126
P. Freeman, S. Bottinelli, R. Plume, E. Caux, C. Monaghan, B. Mookerjea ⋆ (Abridged) There is a diverse chemical
inventory in protostellar regions leading to the classification of extreme types of systems. Warm carbon chain chemistrysources, for one, are the warm and dense regions near a protostar containing unsaturated carbon chain molecules. Since thepresentation of this definition in 2008, there is a growing field to detect and characterise these sources. The details are lesser
known in relation to hot cores and in high-mass star-forming regions – regions of great importance in galactic evolution. To
investigate the prevalence of carbon chain species and their environment in high-mass star-forming regions, we have conducted
targeted spectral surveys of two sources in the direction of Cygnus X – AFGL 2591 and IRAS 20126+4104 – with the GreenBank Telescope and the IRAM 30m Telescope. We have constructed a Local Thermodynamic Equilibrium (LTE) model using
the observed molecular spectra to determine the physical environment in which these molecules originate. We map both theobserved spatial distribution and the physical parameters found from the LTE model. We also determine the formation routesof these molecules in each source using the three-phase NAUTILUS chemical evolution code. We detect several lines of propyne,
CH3 CCH, and cyclopropenylidene, c-C3 H2 as tracers of carbon chain chemistry, as well as several lines of formaldehyde, H2 CO,
and methanol, CH3 OH, as a precursor and a tracer of complex organic molecule chemistry, respectively. We find excitation8

temperatures of 20-30 K for the carbon chains and 8-85 K for the complex organics. The CH3 CCH abundances are reproduced
by a warm-up model, consistent with warm carbon chain chemistry, while the observed CH3 OH abundances require a shockmechanism sputtering the molecules into the gas phase.

γ-ray detection from occasional flares in T Tauri stars of NGC 2071. I. Observational
24. connection

A. Filócomo, J. F. Albacete Colombo, E. Mestre, L. J. Pellizza, J. A. Combi ⋆ NGC 2071 is a star-forming region
that overlaps with three γ-ray sources detected by the Fermi Space Telescope. We propose that strong flare activity in T Tauristars could produce γ-ray emission in a way that makes them a counterpart to some unidentified sources detected by the Large
Area Telescope aboard the Fermi satellite. We have performed a spectral and temporal analysis for two Fermi data sets: thefirst 2 yr and the entire 14 yr of observations. We have found that the γ-ray source is detectable at 3.2σ above the backgroundat energies above 100 GeV during the first 2 yr of observation. The analysis of the expected frequency of the highest energy
flares occurring in T Tauri stars is consistent with our estimate. In addition, we have determined the minimum energy of theflare that would produce γ-ray emission, which is ∼ 5 × 1037 erg. This agreement becomes a hard observational constraint
supporting previous hypotheses about rare flares as the origin of unidentified γ-ray sources in star-forming regions.

Modelling UX Ori Star Eclipses based on Spectral Observations with the Nordic Optical
25. Telescope. I. RR Tau
V. P. Grinin, L. V. Tambovtseva, A. A. Djupvik, G. Gahm, T. Grenman, H. Weber, H. Bengtsson, H. De
Angelis, G. Duszanowicz, D. Heinonen, G. Holmberg, T. Karlsson, M. Larsson, J. Warell, T. Wikander ⋆Based on observations obtained with the Nordic Optical Telescope we investigate the spectral variability of the Herbig Ae star
RR Tau. This star belongs to the UX Ori family, characterized by very deep fadings caused by the screening of the star with
opaque fragments (clouds) of the protoplanetary discs. At the moments of such minima one observes strong spectral variability
due to the fact that the dust cloud occults, for an observer, not only the star but also a part of the region where the emission
spectrum originates. We calculated a series of obscuration models to interpret the observed variability of the H-alpha line
parameters. We consider two main obscuration scenarios: (1) the dust screen rises vertically above the circumstellar disc, and(2) the screen intersects the line-of-sight moving azimuthally with the disc. In both cases the model of the emission region
consists of a compact magnetosphere and a magneto-centrifugal disc wind. Comparison with observations shows that the firstscenario explains well the variability of the radiation flux, the equivalent width, as well as the asymmetry of the H-alpha line
during eclipses, while the second scenario explains them only partly. This permits us to suggest that in the case of RR Tau,the main causes of the eclipses are either a structured disc wind, or the charged dust lifted along the field lines of the poloidal
component of the magnetic field of the circumstellar disc.

among B stars in the Scorpius-Centaurus association
26. Multiples
R. Gratton, V. Squicciarini, V. Nascimbeni, M. Janson, S. Reffert, M. Meyer, P. Delorme, E. E. Mamajek,
M. Bonavita, S. Desidera, D. Mesa, E. Rigliaco, V. D’Orazi, C. Lazzoni, G. Chauvin, M. Langlois ⋆ We
discuss the properties of companions to B stars in the Scorpius-Centaurus association (age 15 Myr, 181 B-stars). We gatheredavailable data combining high contrast imaging samples with evidence of companions from Gaia, from eclipsing binaries, andfrom spectroscopy. We evaluated the completeness of the binary search and estimated the mass and semi-major axis for all
detected companions. These data provide a complete sample of stellar secondaries for separation >3 au, and they are highly
informative as to closer companions. We found evidence for 200 companions around 181 stars. The fraction of single star is
15.2 ± 4.1% for stars with MA 3.5 Msun while it is 31.5± 5.9% for lower-mass stars. The median semi-major axis of the orbits ofthe companions is smaller for B than in A stars, confirming a turn-over previously found for OB stars. The mass distributionof the very wide (a>1000 au) and closer companions is different. Very few companions of massive stars MA >5.0 Msun have amass below solar and even fewer are M stars with a semi-major axis <1000 au. The scarcity of low-mass companions extends
throughout the whole sample. Most early B stars are in compact systems with massive secondaries, while lower-mass stars aremainly in wider systems with a larger spread in mass ratios. We interpret our results as the formation of secondaries with asemi-major axis <1000 au (about 80% of the total) by fragmentation of the disk of the primary and selective mass accretion on
the secondaries. The observed trends with primary mass may be explained by a more prolonged phase of accretion episodes on
the disk and by a more effective inward migration. We detected twelve new stellar companions from the BEAST survey andof a new BD companion at 9.6 arcsec from HIP74752 using Gaia data, and we discuss the cases of possible BD and low-massstellar companions to HIP59173, HIP62058, and HIP64053.

9

The Ṁ –Mdisk relationship for Herbig Ae/Be stars: a lifetime problem for disks with low
27. masses?
Sierra L. Grant, Lucas M. Stapper, Michiel R. Hogerheijde, Ewine F. van Dishoeck, Sean Brittain, MiguelVioque ⋆ The accretion of material from protoplanetary disks onto their central stars is a fundamental process in the evolutionof these systems and a key diagnostic in constraining the disk lifetime. We analyze the relationship between the stellar accretion
rate and the disk mass in 32 intermediate-mass Herbig Ae/Be systems and compare them to their lower-mass counterparts, T
Tauri stars. We find that the Ṁ –Mdisk relationship for Herbig Ae/Be stars is largely flat at ∼10−7 M⊙ yr−1 across over threeorders of magnitude in dust mass. While most of the sample follows the T Tauri trend, a subset of objects with high accretion
rates and low dust masses are identified. These outliers (12 out of 32 sources) have an inferred disk lifetime of less than 0.01 Myr
and are dominated by objects with low infrared excess. This outlier sample is likely identified in part by the bias in classifying
Herbig Ae/Be stars, which requires evidence of accretion that can only be reliably measured above a rate of ∼10−9 M⊙ yr−1
for these spectral types. If the disk masses are not underestimated and the accretion rates are not overestimated, this implies
that these disks may be on the verge of dispersal, which may be due to efficient radial drift of material or outer disk depletionby photoevaporation and/or truncation by companions. This outlier sample likely represents a small subset of the larger young,intermediate-mass stellar population, the majority of which would have already stopped accreting and cleared their disks.

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): The Warm-Envelope
28. Origin of Hot Corinos
Shih-Ying Hsu, Sheng-Yuan Liu, Doug Johnstone, Tie Liu, Leonardo Bronfman, Huei-Ru Vivien Chen, Somnath Dutta, David J. Eden, Neal J. Evans II, Naomi Hirano, Mika Juvela, Yi-Jehng Kuan, Woojin Kwon,
Chin-Fei Lee, Chang Won Lee, Jeong-Eun Lee, Shanghuo Li, Chun-Fan Liu, Xunchuan Liu, Qiuyi Luo, ShengLi Qin, Mark G. Rawlings, Dipen Sahu, Patricio Sanhueza, Hsien Shang, Kenichi Tatematsu, Yao-Lun Yang
⋆ Hot corinos are of great interest due to their richness in interstellar complex organic molecules (COMs) and the consequentpotential prebiotic connection to solar-like planetary systems. Recent surveys have reported an increasing number of hot corino
detections in Class 0/I protostars; however, the relationships between their physical properties and the hot-corino signatures
remain elusive. In this study, our objective is to establish a general picture of the detectability of the hot corinos by identifying the origin of the hot-corino signatures in the sample of young stellar objects (YSOs) obtained from the Atacama Large
Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP) project. We apply spectral energy
distribution (SED) modeling to our sample and identify the physical parameters of the modeled YSOs directly, linking thedetection of hot-corino signatures to the envelope properties of the YSOs. Imaging simulations of the methanol emission further
support this scenario. We, therefore, posit that the observed COM emission originates from the warm inner envelopes of thesample YSOs, based on both the warm region size and the envelope density profile. The former is governed by the source
luminosity and is additionally affected by the disk and cavity properties, while the latter is related to the evolutionary stages.
This scenario provides a framework for detecting hot-corino signatures toward luminous Class 0 YSOs, with fewer detections
observed toward similarly luminous Class I sources.

Forming rocky exoplanets around K-dwarf stars
29. P. Hatalova, R. Brasser, E. Mamonova, S. C. Werner ⋆ How multiple close-in super-Earths form around stars with
masses lower than that of the Sun is still an open issue. Several recent modeling studies have focused on planet formation
around M-dwarf stars, but so far no studies have focused specifically on K dwarfs, which are of particular interest in the searchfor extraterrestrial life. We aim to reproduce the currently known population of close-in super-Earths observed around K-dwarf
stars and their system characteristics. We performed 48 high-resolution N-body simulations of planet formation via planetesimalaccretion using the existing GENGA software running on GPUs. In the simulations we varied the initial disk mass and the solidand gas surface density profiles. Each simulation began with 12000 bodies with radii of between 200 and 2000 km around two
different stars, with masses of 0.6 and 0.8 M⊙ . Most simulations ran for 20 Myr, with several simulations extended to 40 or
100 Myr. The mass distributions for the planets with masses between 2 and 12 M⊕ show a strong preference for planets with
masses Mp < 6 M⊕ and a lesser preference for planets with larger masses, whereas the mass distribution for the observed sample
increases almost linearly. However, we managed to reproduce the main characteristics and architectures of the known planetarysystems and produce mostly long-term angular-momentum-deficit-stable, nonresonant systems, but we require an initial disk
mass of 15 M⊕ or higher and a gas surface density value at 1 AU of 1500 g cm−2 or higher. Our simulations also produce
many low-mass planets with M < 2 M⊕ , which are not yet found in the observed population, probably due to the observationalbiases. The final systems contain only a small number of planets, which could possibly accrete substantial amounts of gas, andthese formed after the gas had mostly dissipated.

10

The VLT MUSE NFM view of outflows and externally photoevaporating discs near the
30. Orion Bar
Thomas J. Haworth, Megan Reiter, C. Robert O’Dell, Peter Zeidler, Olivier Berne, Carlo F. Manara, Giulia
Ballabio, Jinyoung S. Kim, John Bally, Javier R. Goicoechea, Mari-Liis Aru, Aashish Gupta, Anna Miotello⋆ We present VLT/MUSE Narrow Field Mode (NFM) observations of a pair of disc-bearing young stellar objects towards theOrion Bar: 203-504 and 203-506. Both of these discs are subject to external photoevaporation, where winds are launched fromtheir outer regions due to environmental irradiation. Intriguingly, despite having projected separation from one another of only
1.65 arcsec (660au at 400pc), 203-504 has a classic teardrop shaped “proplyd” morphology pointing towards θ2 Ori A (indicating
irradiation by the EUV of that star, rather than θ1 Ori C) but 203-506 has no ionisation front, indicating it is not irradiated bystellar EUV at all. However, 203-506 does show [CI] 8727Å and [OI] 6300Å in emission, indicating irradiation by stellar FUV.
This explicitly demonstrates the importance of FUV irradiation in driving mass loss from discs. We conclude that shieldingof 203-506 from EUV is most likely due to its position on the observers side of an ionized layer lying in the foreground of the
Huygens Region. We demonstrate that the outflow HH 519, previously thought to be emanating from 203-504 is actually anirradiated cloud edge and identify a new compact outflow from that object approximately along our line of sight with a velocity∼ 130 km s−1 .

31. Twenty-Five Years of Accretion onto the Classical T Tauri Star TW Hya
Gregory J. Herczeg, Yuguang Chen, Jean-Francois Donati, Andrea K. Dupree, Frederick M. Walter, Lynne A.
Hillenbrand, Christopher M. Johns-Krull, Carlo F. Manara, Hans Moritz Guenther, Min Fang, P. Christian
Schneider, Jeff A. Valenti, Silvia H. P. Alencar, Laura Venuti, Juan Manuel Alcala, Antonio Frasca, Nicole
Arulanantham, Jeffrey L. Linsky, Jerome Bouvier, Nancy S. Brickhouse, Nuria Calvet, Catherine C. Espaillat,
Justyn Campbell-White, John M. Carpenter, Seok-Jun Chang, Kelle L. Cruz, S. E. Dahm, Jochen Eisloeffel,
Suzan Edwards, William J. Fischer, Zhen Guo, Thomas Henning, Tao Ji, Jesse Jose, Joel H. Kastner, Ralf
Launhardt, David A. Principe, Conner E. Robinson, Javier Serna, Michal Siwak, Michael F. Sterzik, Shinsuke
Takasao ⋆ Accretion plays a central role in the physics that governs the evolution and dispersal of protoplanetary disks.
The primary goal of this paper is to analyze the stability over time of the mass accretion rate onto TW Hya, the nearest
accreting solar-mass young star. We measure veiling across the optical spectrum in 1169 archival high-resolution spectra of
TW Hya, obtained from 1998–2022. The veiling is then converted to accretion rate using 26 flux-calibrated spectra that cover
the Balmer jump. The accretion rate measured from the excess continuum has an average of 2.51 × 10−9 M⊙ yr−1 and a
Gaussian distribution with a FWHM of 0.22 dex. This accretion rate may be underestimated by a factor of up to 1.5 becauseof uncertainty in the bolometric correction and another factor of 1.7 because of excluding the fraction of accretion energy thatescapes in lines, especially Lyα. The accretion luminosities are well correlated with He line luminosities but poorly correlatedwith Hα and Hβ luminosity. The accretion rate is always flickering over hours but on longer timescales has been stable over 25
years. This level of variability is consistent with previous measurements for most, but not all, accreting young stars.

32. Filament fragmentation: Density gradients suppress end dominated collapse
Elena Hoemann, Stefan Heigl, Andreas Burkert ⋆ The onset of star formation is set by the collapse of filaments in theinterstellar medium. From a theoretical point of view, an isolated cylindrical filament forms cores via the edge effect. Due to theself-gravity of a filament, the strong increase in acceleration at both ends leads to a pile-up of matter which collapses into cores.
However, this effect is rarely observed. Most theoretical models consider a sharp density cut-off at the edge of the filament,
whereas a smoother transition is more realistic and would also decrease the acceleration at the ends of the filament. We showthat the edge effect can be significantly slowed down by a density gradient, although not completely avoided. However, thisallows perturbations inside the filament to grow faster than the edge. We determine the critical density gradient for which thetimescales are equal and find it to be of the order of several times the filament radius. Hence, the density gradient at the ends
of a filament is an essential parameter for fragmentation and the low rate of observed cases of the edge effect could be naturally
explained by shallow gradients.

Measuring the Numerical Viscosity in Simulations of Protoplanetary Disks in Cartesian
33. Grids – The Viscously Spreading Ring Revisited
Jibin Joseph, Alexandros Ziampras, Lucas Jordan, George A. Turpin, Richard P. Nelson ⋆ Hydrodynamical
simulations solve the governing equations on a discrete grid of space and time. This discretization causes numerical diffusion
similar to a physical viscous diffusion, whose magnitude is often unknown or poorly constrained. With the current trend of
simulating accretion disks with no or very low prescribed physical viscosity, it becomes essential to understand and quantify
this inherent numerical diffusion, in the form of a numerical viscosity. We study the behavior of the viscous spreading ring andthe spiral instability that develops in it. We then use this setup to quantify the numerical viscosity in Cartesian grids and study
its properties. We simulate the viscous spreading ring and the related instability on a two-dimensional polar grid using PLUTO
as well as FARGO, and ensure convergence of our results with a resolution study. We then repeat our models on a Cartesian11

grid and measure the numerical viscosity by comparing results to the known analytical solution, using PLUTO and Athena++.
We find that the numerical viscosity in a Cartesian grid scales with resolution as approximately νnum ∝ ∆x2 and is equivalent
to an effective α ∼ 10−4 for a common numerical setup. We also show that the spiral instability manifests as a single leading
spiral throughout the whole domain on polar grids. This is contrary to previous results and indicates that sufficient resolution isnecessary in order to correctly resolve the instability. Our results are relevant in the context of models where the origin should
be included in the computational domain, or when polar grids cannot be used. Examples of such cases include models of disk
accretion onto a central binary and inherently Cartesian codes.

N -body simulation of planetary formation through pebble accretion in a radially struc34. tured protoplanetary disk
Tenri Jinno, Takayuki R. Saitoh, Yota Ishigaki, Junichiro Makino ⋆ In the conventional theory of planet formation,
it is assumed that protoplanetary disks are axisymmetric and have a smooth radial profile. However, recent radio observationsof protoplanetary disks have revealed that many of them have complex radial structures. In this study, we perform a series of
N -body simulations to investigate how planets are formed in protoplanetary disks with radial structures. For this purpose, we
consider the effect of continuous pebble accretion onto the discontinuity boundary within the terrestrial planet-forming region(∼ 0.6 AU). We found that protoplanets grow efficiently at the discontinuity boundary, reaching the Earth mass within ∼ 104
years. We confirmed that giant collisions of protoplanets occur universally in our model. Moreover, we found that multiple
planet-sized bodies form at regular intervals in the vicinity of the discontinuity boundary. These results indicate the possibilityof the formation of solar system-like planetary systems in radially structured protoplanetary disks.

the Dynamics of Dense Cores in Cluster-Forming Clumps: A 3D MHD Sim35. Unveiling
ulation Study of Angular Momentum and Magnetic Field Properties
Shinichi. W. Kinoshita, Fumitaka Nakamura ⋆ We conducted isothermal MHD simulations with self-gravity to investigate the properties of dense cores in cluster-forming clumps. Two different setups were explored: a single rotating clump andcolliding clumps. We focused on determining the extent to which the formed dense cores inherit the rotation and magnetic
field of the parental clump. Our statistical analysis revealed that the alignment between the angular momentum of dense cores,
Lcore , and the rotational axis of the clump is influenced by the strength of turbulence and the simulation setup. In single
rotating clumps, we found that Lcore tends to align with the clump’s rotational axis if the initial turbulence is weak. However,in colliding clumps, this alignment does not occur, regardless of the initial turbulence strength. This misalignment in colliding
clumps is due to the induced turbulence from the collision and the isotropic gas inflow into dense cores. Our analysis of colliding
clumps also revealed that the magnetic field globally bends along the shock-compressed layer, and the mean magnetic field ofdense cores, Bcore , aligns with it. Both in single rotating clumps and colliding clumps, we found that the angle between Bcore
and Lcore is generally random, regardless of the clump properties. We also analyzed the dynamical states of the formed coresand found a higher proportion of unbound cores in colliding clumps. In addition, the contribution of rotational energy was only
approximately 5% of the gravitational energy, regardless of the model parameters for both single and colliding cases.

Kinematic signatures of a low-mass planet with a moderately inclined orbit in a proto36. planetary disk

Kazuhiro D. Kanagawa, Tomohiro Ono, Munetake Momose ⋆ A planet embedded in a protoplanetary disk produces
a gap by disk-planet interaction. It also generates velocity perturbation of gas, which can also be observed as deviations fromthe Keplerian rotation in the channel map of molecular line emission, called kinematic planetary features. These observed signatures provide clues to determine the mass of the planet. We investigated the features induced by the planet with an inclined
orbit through three-dimensional hydrodynamic simulations. We found that a smaller planet, with the inclination being ∼ 10◦– 20◦ , can produce kinematic features as prominent as those induced by the massive coplanar planet. Despite the kinematicfeatures being similar, the gap is shallower and narrower as compared with the case in which the kinematic features are formedby the coplanar planet. We also found that the kinematic features induced by the inclined planet were fainter for rarer CO
isotopologues because the velocity perturbation is weaker at the position closer to the midplane, which was different in the casewith a coplanar massive planet. This dependence on the isotopologues is distinguished if the planet has the inclined orbit. We
discussed two observed kinematic features in the disk of HD 163296. We concluded that the kink observed at 220 au can be
induced by the inclined planet, while the kink at 67 au is consistent to that induced by the coplanar planet.

Modelling Star Cluster Formation: Gas Accretion
37. Jeremy Karam, Alison Sills ⋆ The formation of star clusters involves the growth of smaller, gas-rich subclusters throughaccretion of gas from the giant molecular cloud within which the subclusters are embedded. The two main accretion mechanisms
responsible for this are accretion of gas from dense filaments, and from the ambient background of the cloud. We perform
simulations of both of these accretion processes onto gas-rich star clusters using coupled smoothed particle hydrodynamics to12

model the gas, and N-body dynamics to model the stars. We find that, for both accretion processes, the accreting star cluster
loses some of its original mass while gaining mass from either the ambient background or the dense filament. The amount ofmass lost from both these processes is small compared to the total mass of the cluster. However, in the case of accretion froma background medium, the net effect can be a decrease in the total mass of the cluster if it is travelling fast enough throughthe ambient medium (> 4kms−1 ). We find that the amount of mass lost from the cluster through filamentary accretion is
independent of the density, width, or number of filaments funneling gas into the cluster and is always such that the mass ofthe cluster is constantly increasing with time. We compare our results to idealized prescriptions used to model star cluster
formation in larger scale GMC simulations and find that such prescriptions act as an upper limit when describing the mass ofthe star cluster they represent.

Initial conditions of star formation at ≲2000 au: physical structure and NH3 depletion
38. of three early-stage cores
Yuxin Lin, Silvia Spezzano, Jaime E. Pineda, Jorma Harju, Anika Schmiedeke, Sihan Jiao, Hauyu Baobab Liu,
Paola Caselli ⋆ Pre-stellar cores represent a critical evolutionary phase in low-mass star formation. We aim to unveil thedetailed thermal structure and density distribution of three early-stage cores, starless core L1517B, and prestellar core L694-2
and L429, with the high angular resolution observations of the NH3 (1,1) and (2,2) inversion transitions obtained with VLA
and GBT. In addition, we explore where/if NH3 depletes in the central regions. Applying the mid-infrared extinction method
to the Spitzer 8 µm map we obtain a high angular resolution hydrogen column density map, and derive the gas density profile
to assess the variation of NH3 abundance as a function of gas volume density. The measured temperature profiles of L429 andL1517B show a minor decrease towards the core center, dropping from ∼9K̃ to below 8K̃, and ∼11 K to 10 K, while L694-2
has a rather uniform temperature distribution around ∼9 K. Among the three cores, L429 has the highest central gas density,
close to sonic velocity line-width, and largest localised velocity gradient, all indicative of an advanced evolutionary stage. We
resolve that the abundance of NH3 becomes two times lower in the central region of L429, occurring around a gas density of
4.4×104 cm−3 . Compared to Ophiuchus/H-MM1 which shows an even stronger drop of the NH3 abundance at 2×105 cm−3 ,the abundance variations of the three cores plus Ophiuchus/H-MM1 suggest a progressive NH3 depletion with increasing central
density of the core.

The Dusty Rossby Wave Instability (DRWI): Linear Analysis and Simulations of Tur39. bulent Dust-Trapping Rings in Protoplanetary Discs
Hanpu Liu, Xue-Ning Bai ⋆ Recent numerical simulations have revealed that dust clumping and planetesimal formation
likely proceed in ring-like disc substructures, where dust gets trapped in weakly turbulent pressure maxima. The streaming
instability has difficulty operating in such rings with external turbulence and no pressure gradient. To explore potential paths
to planetesimal formation in this context, we analyse the stability of turbulent dust-trapping ring under the shearing sheet
framework. We self-consistently establish the pressure maximum and the dust ring in equilibrium, the former via a balanceof external forcing versus viscosity and the latter via dust drift versus turbulent diffusion. We find two types of ≳ H-scaleinstabilities (H being the pressure scale height), which we term the dusty Rossby wave instability (DRWI). Type I is generalised
from the standard RWI, which is stationary at the pressure maximum and dominates in relatively sharp pressure bumps. TypeII is a newly identified travelling mode that requires the presence of dust. It can operate in relatively mild bumps, including
many that are stable to the standard RWI, and its growth rate is largely determined by the equilibrium gas and dust density
gradients. We further conduct two-fluid simulations that verify the two types of the DRWI. While Type I leads strong to dust
concentration into a large gas vortex similar to the standard RWI, the dust ring is preserved in Type II, and meanwhile exhibiting additional clumping within the ring. The DRWI suggests a promising path towards formation of planetesimals/planetary
embryos and azimuthally asymmetric dust structure from turbulent dust-trapping rings.

40. Triple spiral arms of a triple protostar system imaged in molecular lines

Jeong-Eun Lee, Tomoaki Matsumoto, Hyun-Jeong Kim, Seokho Lee, Daniel Harsono, Jaehan Bae, Neal J.
Evans II, Shu-ichiro Inutsuka, Minho Choi, Ken’ichi Tatematsu, Jae-Joon Lee, Dan Jaffe ⋆ Most stars formin multiple star systems. For a better understanding of their formation processes, it is important to resolve the individual
protostellar components and the surrounding envelope and disk material at the earliest possible formation epoch because theformation history can be lost in a few orbital timescales. Here we present the ALMA observational results of a young multiple
protostellar system, IRAS 04239+2436, where three well-developed large spiral arms were detected in the shocked SO emission.
Along the most conspicuous arm, the accretion streamer was also detected in the SO2 emission. The observational results arecomplemented by numerical magneto-hydrodynamic simulations, where those large arms only appear in magnetically weakened
clouds. The numerical simulations also suggest that the large triple spiral arms are the result of gravitational interactions
between compact triple protostars and the turbulent infalling envelope.

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41. Complex Organic Molecules in a Very Young Hot Corino, HOPS 373SW

Jeong-Eun Lee, Giseon Baek, Seokho Lee, Jae-Hong Jeong, Chul-Hwan Kim, Yuri Aikawa, Gregory J. Herczeg,
Doug Johnstone, John J. Tobin ⋆ We present the spectra of Complex Organic Molecules (COMs) detected in HOPS 373SW
with the Atacama Large Millimeter/submillimeter Array (ALMA). HOPS 373SW, which is a component of a protostellar binary
with a separation of 1500 au, has been discovered as a variable protostar by the JCMT Transient monitoring survey with amodest 30% brightness increase at submillimeter wavelengths. Our ALMA Target of Opportunity (ToO) observation at 345
GHz for HOPS 373SW revealed extremely young chemical characteristics with strong deuteration of methanol. The dust
continuum opacity is very high toward the source center, obscuring line emission from within 0.03 arcsec. The other binary
component, HOPS 373NE, was detected only in C17O in our observation, implying a cold and quiescent environment. We
compare the COMs abundances relative to CH3OH in HOPS 373SW with those of V883 Ori, which is an eruptive disk object,
as well as other hot corinos, to demonstrate the chemical evolution from envelope to disk. High abundances of singly, doubly,
and triply deuterated methanol (CH2DOH, CHD2OH, and CD3OH) and a low CH3CN abundance in HOPS 373SW comparedto other hot corinos suggest a very early evolutionary stage of HOPS 373SW in the hot corino phase. Since the COMs detectedin HOPS 373SW would have been sublimated very recently from grain surfaces, HOPS 373SW is a promising place to study
the surface chemistry of COMs in the cold prestellar phase, before sublimation.

and mass accretion rate evolution during the 2022 burst of EX Lupi
42. Brightness
F. Cruz-Sáenz de Miera, Á. Kóspál, P. Ábrahám, R. A. B. Claes, C. F. Manara, J. Wendeborn, E. Fiorellino, T.
Giannini, B. Nisini, A. Sicilia-Aguilar, J. Campbell-White, J. M. Alcalá, A. Banzatti, Zs. M. Szabó, F. Lykou,
S. Antoniucci, J. Varga, M. Siwak, S. Park, Zs. Nagy, M. Kun ⋆ EX Lupi is the prototype by which EXor-type
outbursts were defined. It has experienced multiple accretion-related bursts and outbursts throughout the last decades, whose
study have greatly extended our knowledge about the effects of these types of events. This star experienced a new burst in
2022. We used multi-band photometry to create color-color and color-magnitude diagrams to exclude the possibility that thebrightening could be explained by a decrease in extinction. We obtained VLT/X-shooter spectra to determine the Lacc andMacc during the peak of the burst and after its return to quiescence using 2 methods: empirical relationships between line
luminosity and Lacc, and a slab model of the whole spectrum. We examined the 130 year light curve of EX Lupi to provide
statistics on the number of outbursts experienced during this period of time. Our analysis of the data taken during the 2022
burst confirmed that a change in extinction is not responsible for the brightening. Our two approaches in calculating the Macc
were in agreement, and resulted in values that are 2 orders of magnitude above what had previously been estimated, thus
suggesting that EX Lupi is a strong accretor even when in quiescence. We determined that in 2022 March the Macc increased
by a factor of 7 with respect to the quiescent level. We also found hints that even though the Macc had returned to almost
its pre-outburst levels, certain physical properties of the gas had not returned to the quiescent values. We found that the massaccreted during this three month event was 0.8 lunar masses, which is approximately half of what is accreted during a yearof quiescence. We calculated that if EX Lupi remains as active as it has been for the past 130 years, during which it has
experienced at least 3 outbursts and 10 bursts, then it will deplete the mass of its circumstellar material in less than 160000 yr.

Identification of the simplest sugar-like molecule glycolaldehyde towards the hot molec43. ular core G358.93-0.03 MM1
Arijit Manna, Sabyasachi Pal, Serena Viti, Sekhar Sinha ⋆ Glycolaldehyde (CH2 OHCHO) is the simplest monosaccharide sugar in the interstellar medium, and it is directly involved in the origin of life via the ’RNA world’ hypothesis. We present
the first detection of glycolaldehyde (CH2 OHCHO) towards the hot molecular core G358.93-0.03 MM1 using the Atacama
Large Millimeter/Submillimeter Array (ALMA). The calculated column density of CH2 OHCHO towards G358.93-0.03 MM1 is(1.52±0.9)×1016 cm−2 with an excitation temperature of 300±68.5 K. The derived fractional abundance of CH2 OHCHO withrespect to H2 is (4.90±2.92)×10−9 , which is consistent with that estimated by existing two-phase warm-up chemical models.
We discuss the possible formation pathways of CH2 OHCHO within the context of hot molecular cores and hot corinos and findthat CH2 OHCHO is likely formed via the reactions of radical HCO and radical CH2 OH on the grain surface of G358.93-0.03
MM1.

44. Star-disk interactions in the strongly accreting T Tauri Star S CrA N

H. Nowacki, E. Alecian, K. Perraut, B. Zaire, C. P. Folsom, K. Pouilly, J. Bouvier, R. Manick, G. Pantolmos,
A. P. Sousa, C. Dougados, G. A. J. Hussain, S. H. P. Alencar, J. B. Le Bouquin ⋆ Aims : We aimed at constraining
the accretion-ejection phenomena around the strongly-accreting Northern component of the S CrA young binary system (SCrA N) by deriving its magnetic field topology and its magnetospheric properties, and by detecting ejection signatures, ifany. Methods : We led a two-week observing campaign on S CrA N with the ESPaDOnS optical spectropolarimeter at the
Canada-France-Hawaii Telescope. We recorded 12 Stokes I and V spectra over 14 nights. We computed the corresponding LeastSquare Deconvolution (LSD) profiles of the photospheric lines and performed Zeeman-Doppler Imaging (ZDI). We analysed thekinematics of noticeable emission lines, namely He I λ5876 and the four first lines of the Balmer series, known to trace the14accretion process. Conclusions : The findings from spectropolarimetry are complementary to those provided by optical longbaseline interferometry, allowing us to construct a coherent view of the innermost regions of a young, strongly accreting star.
Yet, the strong and complex magnetic field reconstructed for S CrA N is inconsistent with the observed magnetic signaturesof the emission lines associated to the post-shock region. We recommend a multi-technique, synchronized campaign of several
days to put more constrains on a system that varies on a ∼ 1 day timescale.

On the importance of disc chemistry in the formation of protoplanetary disc rings
45. C. A. Nolan, B. Zhao, P. Caselli, Z. Y. Li ⋆ Radial substructures have now been observed in a wide range of protoplanetary
discs (PPDs), from young to old systems, however their formation is still an area of vigorous debate. Recent magnetohydrodynamic (MHD) simulations have shown that rings and gaps can form naturally in PPDs when non-ideal MHD effects are included.
However these simulations employ ad-hoc approximations to the magnitudes of the magnetic diffusivities in order to facilitatering growth. We replace the parametrisation of these terms with a simple chemical network and grain distribution model tocalculate the non-ideal effects in a more self-consistent way. We use a range of grain distributions to simulate grain formation
for different disc conditions. Including ambipolar diffusion, we find that large grain populations (> 1µm), and those including
a population of very small polyaromatic hydrocarbons (PAHs) facilitate the growth of periodic, stable rings, while intermediate
sized grains suppress ring formation. Including Ohmic diffusion removes the positive influence of PAHs, with only large grain
populations still producing periodic ring and gap structures. These results relate closely to the degree of coupling between themagnetic field and the neutral disc material, quantified by the non-dimensional Elsasser number Λ (the ratio of magnetic forces
to Coriolis force). For both the ambipolar-only and ambipolar-ohmic cases, if the total Elsasser number is initially of orderunity along the disc mid-plane, ring and gap structures may develop.

Planet formation throughout the Milky Way: Planet populations in the context of
46. Galactic chemical evolution
Jesper Nielsen, Matthew Raymond Gent, Maria Bergemann, Philipp Eitner, Anders Johansen ⋆ As stellar
compositions evolve over time in the Milky Way, so will the resulting planet populations. In order to place planet formationin the context of Galactic chemical evolution, we make use of a large (N = 5 325) stellar sample representing the thin andthick discs, defined chemically, and the halo, and we simulate planet formation by pebble accretion around these stars. We
build a chemical model of their protoplanetary discs, taking into account the relevant chemical transitions between vapour andrefractory minerals, in order to track the resulting compositions of formed planets. We find that the masses of our synthetic
planets increase on average with increasing stellar metallicity [Fe/H] and that giant planets and super-Earths are most common
around thin-disc (α-poor) stars since these stars have an overall higher budget of solid particles. Giant planets are found tobe very rare (≲1%) around thick-disc (α-rich) stars and nearly non-existent around halo stars. This indicates that the planet
population is more diverse for more metal-rich stars in the thin disc. Water-rich planets are less common around low-metallicity
stars since their low metallicity prohibits efficient growth beyond the water ice line. If we allow water to oxidise iron in the
protoplanetary disc, this results in decreasing core mass fractions with increasing [Fe/H]. Excluding iron oxidation from ourcondensation model instead results in higher core mass fractions, in better agreement with the core-mass fraction of Earth, that
increase with increasing [Fe/H]. Our work demonstrates how the Galactic chemical evolution and stellar parameters, such as
stellar mass and chemical composition, can shape the resulting planet population.

Dust enrichment and grain growth in a smooth disk around the DG Tau protostar
47. revealed by ALMA triple bands frequency observations

Satoshi Ohashi, Munetake Momose, Akimasa Kataoka, Aya E Higuchi, Takashi Tsukagoshi, Takahiro Ueda,
Claudio Codella, Linda Podio, Tomoyuki Hanawa, Nami Sakai, Hiroshi Kobayashi, Satoshi Okuzumi, Hidekazu
Tanaka ⋆ Characterizing the physical properties of dust grains in a protoplanetary disk is critical to comprehending the planet
formation process. Our study presents ALMA high-resolution observations of the young protoplanetary disk around DG Tau at
a 1.3 mm dust continuum. The observations, with a spatial resolution of ≈ 0.04′′ , or ≈ 5 au, revealed a geometrically thin andsmooth disk without substantial substructures, suggesting that the disk retains the initial conditions of the planet formation.
To further analyze the distributions of dust surface density, temperature, and grain size, we conducted a multi-band analysis
with several dust models, incorporating ALMA archival data of the 0.87 mm and 3.1 mm dust polarization. The results showedthat the Toomre Q parameter is ≲ 2 at a 20 au radius, assuming a dust-to-gas mass ratio of 0.01. This implies that a higher
dust-to-gas mass ratio is necessary to stabilize the disk. The grain sizes depend on the dust models, and for the DSHARP
compact dust, they were found to be smaller than ∼ 400 µm in the inner region (r ≲ 20 au), while exceeding larger than 3 mmin the outer part. Radiative transfer calculations show that the dust scale height is lower than at least one-third of the gas scaleheight. These distributions of dust enrichment, grain sizes, and weak turbulence strength may have significant implications forthe formation of planetesimals through mechanisms such as streaming instability. We also discuss the CO snowline effect andcollisional fragmentation in dust coagulation for the origin of the dust size distribution.

15

A dependence of binary and planetary system destruction on subtle variations in the
48. substructure in young star-forming regions
Richard J. Parker ⋆ Simulations of the effects of stellar fly-bys on planetary systems in star-forming regions show a strong
dependence on subtle variations in the initial spatial and kinematic substructure of the regions. For similar stellar densities, themore substructured star-forming regions disrupt up to a factor of two more planetary systems. We extend this work to look at theeffects of substructure on stellar binary populations. We present N -body simulations of substructured, and non-substructured(smooth) star-forming regions in which we place different populations of stellar binaries. We find that for binary populations
that are dominated by close (<100au) systems, a higher proportion are destroyed in substructured regions. However, for wider
systems (>100au), a higher proportion are destroyed in smooth regions. The difference is likely due to the hard-soft, or fastslow boundary for binary destruction. Hard (fast/close) binaries are more likely to be destroyed in environments with a small
velocity dispersion (kinematically substructured regions), whereas soft (slow/wide) binaries are more likely to be destroyed inenvironments with higher velocity dispersions (non-kinematically substructured regions). Due to the vast range of stellar binary
semimajor axes in star-forming regions (10−2 − 104 au) these differences are small and hence unlikely to be observable. However,planetary systems have a much smaller initial semimajor axis range (likely ∼1 – 100au for gas giants) and here the differencein the fraction of companions due to substructure could be observed if the star-forming regions that disrupt planetary systems
formed with similar stellar densities.

49. Density streams in the disc winds of Classical T Tauri stars

P. P. Petrov, K. N. Grankin, E. V. Babina, S. A. Artemenko, M. M. Romanova, S. Yu. Gorda, A. A. Djupvik,
J. F. Gameiro ⋆ Spectral and photometric variability of the Classical T Tauri stars RY Tau and SU Aur from 2013 to 2022
is analyzed. We find that in SU Aur the H-alpha line’s flux at radial velocity RV = -50 +- 7 km/s varies with a period P =255 +- 5 days. A similar effect previously discovered in RY Tau is confirmed with these new data: P = 21.6 days at RV = -95+- 5 km/s. In both stars, the radial velocity of these variations, the period, and the mass of the star turn out to be relatedby Kepler’s law, suggesting structural features on the disc plane orbiting at radii of 0.2 AU in RY Tau and 0.9 AU in SU Aur,respectively. Both stars have a large inclination of the accretion disc to the line of sight - so that the line of sight passes throughthe region of the disc wind. We propose there is an azimuthal asymmetry in the disc wind, presumably in the form of ’density
streams’, caused by substructures of the accretion disc surface. These streams cannot dissipate until they go beyond the Alfven
surface in the disc’s magnetic field. These findings open up the possibility to learn about the structure of the inner accretion
disc of CTTS on scales less than 1 AU and to reveal the orbital distances related to the planet’s formation.

cluster progenitors are dynamically decoupled from their parent molecular clouds
50. Star
Nicolas Peretto, Andrew J. Rigby, Fabien Louvet, Gary A. Fuller, Alessio Traficante, Mathilde Gaudel ⋆The formation of stellar clusters dictates the pace at which galaxies evolve, and solving the question of their formation willundoubtedly lead to a better understanding of the Universe as a whole. While it is well known that star clusters form withinparsec-scale over-densities of interstellar molecular gas called clumps, it is, however, unclear whether these clumps represent thehigh-density tip of a continuous gaseous flow that gradually leads towards the formation of stars, or a transition within the gas
physical properties. Here, we present a unique analysis of a sample of 27 infrared dark clouds embedded within 24 individual
molecular clouds that combine a large set of observations, allowing us to compute the mass and velocity dispersion profiles of
each, from the scale of tens of parsecs down to the scale of tenths of a parsec. These profiles reveal that the vast majority of
the clouds, if not all, are consistent with being self-gravitating on all scales, and that the clumps, on parsec-scale, are often
dynamically decoupled from their surrounding molecular clouds, exhibiting steeper density profiles (ρ ∝ r−2 ) and flat velocity
dispersion profiles (σ ∝ r0 ), clearly departing from Larson’s relations. These findings suggest that the formation of star clusters
correspond to a transition regime within the properties of the self-gravitating molecular gas. We propose that this transition
regime is one that corresponds to the gravitational collapse of parsec-scale clumps within otherwise stable molecular clouds.

51. Isotopic enrichment of planetary systems from Asymptotic Giant Branch stars

Richard J. Parker, Christina Schoettler ⋆ Short-lived radioisotopes, in particular 26-Al and 60-Fe, are thought to contribute to the internal heating of the Earth, but are significantly more abundant in the Solar System compared to the Interstellar
Medium. The presence of their decay products in the oldest Solar System objects argues for their inclusion in the Sun’s protoplanetary disc almost immediately after the star formation event that formed the Sun. Various scenarios have been proposed
for their delivery to the Solar System, usually involving one or more core-collapse supernovae of massive stars. An alternative
scenario involves the young Sun encountering an evolved Asymptotic Giant Branch (AGB) star. AGBs were previously discounted as a viable enrichment scenario for the Solar System due to the presumed low probability of an encounter between anold, evolved star and a young pre-main sequence star. We report the discovery in Gaia data of an interloping AGB star in thestar-forming region NGC2264, demonstrating that old, evolved stars can encounter young forming planetary systems. We use
simulations to calculate the yields of 26-Al and 60-Fe from AGBs and their contribution to the long-term geophysical heatingof a planet, and find that these are comfortably within the range previously calculated for the Solar System.

16

52. On the origin of planetary-mass objects in NGC1333
Richard J. Parker, Catarina Alves de Oliveira ⋆ The dominant formation mechanism of brown dwarfs and planetary
mass objects in star-forming regions is presently uncertain. Do they form like stars, via the collapse and fragmentation of coresin Giant Molecular clouds, or do they form like planets in the discs around stars and are ejected via dynamical interactions?
In this paper, we quantify the spatial distribution of substellar objects in NGC1333, in particular focusing on planetary-mass
objects that have been the target of recent deep imaging observations. We find that these objects have a spatial distributionthat is indistinguishable from the stars, and more massive brown dwarfs. We also analyse N-body simulations and find that a
population of ejected planets would have a significantly different spatial and kinematic distribution to stars, and brown dwarfs
that also formed through gravitational collapse and fragmentation. We therefore conclude that the low-mass substellar objects
in NGC1333 formed more like stars than planets, although we predict that a population of hitherto undetected ejected planetary
mass objects may be lurking in this, and other star-forming regions.

Photoevaporation versus enrichment in the cradle of the Sun
53. Miti Patel, Cheyenne K. M. Polius, Matthew Ridsdill-Smith, Tim Lichtenberg, Richard Parker ⋆ The presenceof short-lived radioisotopes (SLRs) 26-Al and 60-Fe in the Solar system places constraints on the initial conditions of ourplanetary system. Most theories posit that the origin of 26-Al and 60-Fe is in the interiors of massive stars, and they are eitherdelivered directly to the protosolar disc from the winds and supernovae of the massive stars, or indirectly via a sequential starformation event. However, massive stars that produce SLRs also emit photoionising far and extreme ultraviolet radiation, which
can destroy the gas component of protoplanetary discs, possibly precluding the formation of gas giant planets like Jupiter andSaturn. Here, we perfom N-body simulations of star-forming regions and determine whether discs that are enriched in SLRs canretain enough gas to form Jovian planets. We find that discs are enriched and survive the photoionising radiation only when
the dust radius of the disc is fixed and not allowed to move inwards due to the photoevaporation, or outwards due to viscous
spreading. Even in this optimal scenario, not enough discs survive until the supernovae of the massive stars and so have zeroor very little enrichment in 60-Fe. We therefore suggest that the delivery of SLRs to the Solar system may not come from thewinds and supernovae of massive stars.

54. Linking ice and gas in the Coronet cluster in Corona Australis

G. Perotti, J. K. Jørgensen, W. R. M. Rocha, A. Plunkett, E. Artur de la Villarmois, L. E. Kristensen,
M. Sewiło, P. Bjerkeli, H. J. Fraser, S. B. Charnley ⋆ During the journey from the cloud to the disc, the chemicalcomposition of the protostellar envelope material can be either preserved or processed to varying degrees depending on thesurrounding physical environment. This works aims to constrain the interplay of solid (ice) and gaseous methanol (CH3 OH) in
the outer regions of protostellar envelopes located in the Coronet cluster in Corona Australis (CrA), and assess the importanceof irradiation by the Herbig Ae/Be star R CrA. CH3 OH is a prime test-case as it predominantly forms as a consequence ofthe solid-gas interplay (hydrogenation of condensed CO molecules onto the grain surfaces) and it plays an important role infuture complex molecular processing. We present 1.3 mm Submillimeter Array (SMA) and Atacama Pathfinder Experiment(APEX) observations towards the envelopes of four low-mass protostars in the Coronet. Eighteen molecular transitions of sevenspecies are identified. We calculate CH3 OH gas-to-ice ratios in this strongly irradiated cluster and compare them with ratios
determined towards protostars located in less irradiated regions such as the Serpens SVS 4 cluster in Serpens Main and the
Barnard 35A cloud in the λ Orionis region. The CH3 OH gas-to-ice ratios in the Coronet vary by one order of magnitude(from 1.2×10−4 to 3.1×10−3 ) which is similar to less irradiated regions as found in previous studies. We find that the CH3 OH
gas-to-ice ratios estimated in these three regions are remarkably similar despite the different UV radiation field intensities
and formation histories. This result suggests that the overall CH3 OH chemistry in the outer regions of low-mass envelopes isrelatively independent of variations in the physical conditions and hence that it is set during the prestellar stage.

An inner warp discovered in the disk around HD 110058 using VLT/SPHERE and
55. HST/STIS
S. Stasevic, J. Milli, J. Mazoyer, A. -M. Lagrange, M. Bonnefoy, V. Faramaz-Gorka, F. Ménard, A. Boccaletti,
E. Choquet, L. Shuai, J. Olofsson, A. Chomez, B. Ren, P. Rubini, C. Desgrange, R. Gratton, G. Chauvin, A.
Vigan, E. Matthews ⋆ An edge-on debris disk was detected in 2015 around the young, nearby A0V star HD 110058. The disk
showed features resembling those seen in the disk of beta Pictoris that could indicate the presence of a perturbing planetarymass companion in the system. We investigated new and archival scattered light images of the disk in order to characterise
its morphology and spectrum. In particular, we analysed the disk’s warp to constrain the properties of possible planetaryperturbers. Our work uses data from two VLT/SPHERE observations and archival data from HST/STIS. We measured themorphology of the disk by analysing vertical profiles along the length of the disk to extract the centroid spine position andvertical height. We extracted the surface brightness and reflectance spectrum of the disk. We detect the disk between 20 au(with SPHERE) and 150 au (with STIS), at a position angle of 159.6◦ ±0.6◦ . Analysis of the spine shows an asymmetry between

17the two sides of the disk, with a 3.4◦ ±0.9◦ warp between 20 au and 60 au. The disk is marginally vertically resolved in scattered
light, with a vertical aspect ratio of 9.3±0.7% at 45 au. The extracted reflectance spectrum is featureless, flat between 0.95
micron and 1.1 micron, and red from 1.1 micron to 1.65 micron. The outer parts of the disk are also asymmetric with a tilt
between the two sides compatible with a disk made of forward-scattering particles and seen not perfectly edge-on, suggesting
an inclination of <84◦ . The presence of an undetected planetary-mass companion on an inclined orbit with respect to the disk
could explain the warp. The misalignment of the inner parts of the disk with respect to the outer disk suggests a warp that has
not yet propagated to the outer parts of the disk, favouring the scenario of an inner perturber as the origin of the warp.

56. Sublimation of refractory minerals in the gas envelopes of accreting rocky planets

Marie-Luise Steinmeyer, Peter Woitke, Anders Johansen ⋆ Protoplanets growing within the protoplanetary disk bypebble accretion acquire hydrostatic gas envelopes. Due to accretion heating, the temperature in these envelopes can become
high enough to sublimate refractory minerals which are the major components of the accreted pebbles. Here we study the
sublimation of different mineral species and determine whether sublimation plays a role during the growth by pebble accretion.
For each snapshot in the growth process, we calculate the envelope structure and sublimation temperature of a set of mineral
species representing different levels of volatility. Sublimation lines are determined using and equilibrium scheme for the chemical
reactions responsible for destruction and formation of the relevant minerals. We find that the envelope of the growing planet
reaches temperatures high enough to sublimate all considered mineral species when the mass is larger than 0.4 Earth masses.
The sublimation lines are located within the gravitionally bound envelope of the planet. We make a detailed analysis of thesublimation of FeS at around 720 K, beyond which the mineral is attacked by H2 to form gaseous H2S and solid Fe. We calculate
the sulfur concentration in the planet under the assumption that all sulfur released as H2S is lost from the planet by diffusion
back to the protoplanetary disk. Our calculated values are in good agreement with the slightly depleted sulfur abundance ofMars, while the model overpredicts the extensive sulfur depletion of Earth by a factor of approximately 2. We show that acollision with a sulfur-rich body akin to Mars in the moon-forming impact lifts the Earth’s sulfur abundance to approximately
10% of the solar value for all impactor masses above 0.05 Earth masses.

emission from pre-main sequence stars with multipolar magnetic fields
57. X-rayKieran A. Stuart, Scott G. Gregory ⋆ The large-scale magnetic fields of several pre-main sequence (PMS) stars have been
observed to be simple and axisymmetric, dominated by tilted dipole and octupole components. The magnetic fields of other
PMS stars are highly multipolar and dominantly non-axisymmetric. Observations suggest that the magnetic field complexity
increases as PMS stars evolve from Hayashi to Henyey tracks in the Hertzsprung–Russell diagram. Independent observations
have revealed that X-ray luminosity decreases with age during PMS evolution, with Henyey track PMS stars having lower
fractional X-ray luminosities (LX /L∗ ) compared to Hayashi track stars. We investigate how changes in the large-scale magnetic
field topology of PMS stars influences coronal X-ray emission. We construct coronal models assuming pure axisymmetricmultipole magnetic fields, and magnetic fields consisting of a dipole plus an octupole component only. We determine the closed
coronal emitting volume, over which X-ray emitting plasma is confined, using a pressure balance argument. From the coronalvolumes we determine X-ray luminosities. We find that LX decreases as the degree ℓ of the multipole field increases. For dipole
plus octupole magnetic fields we find that LX tends to decrease as the octupole component becomes more dominant. By fixing
the stellar parameters at values appropriate for a solar mass PMS star, varying the magnetic field topology results in two ordersof magnitude variation in LX . Our results support the idea that the decrease in LX as PMS stars age can be driven by anincrease in the complexity of the large-scale magnetic field.

An ALMA Glimpse of Dense Molecular Filaments Associated with High-mass Proto58. stellar Systems in the Large Magellanic Cloud
Kazuki Tokuda, Naoto Harada, Kei E. I. Tanaka, Tsuyoshi Inoue, Takashi Shimonishi, Yichen Zhang, Marta
Sewiło, Yuri Kunitoshi, Ayu Konishi, Yasuo Fukui, Akiko Kawamura, Toshikazu Onishi, Masahiro N. Machida⋆ Recent millimeter/sub-millimeter facilities have revealed the physical properties of filamentary molecular clouds in relation
to high-mass star formation. A uniform survey of the nearest, face-on star-forming galaxy, the Large Magellanic Cloud (LMC),
complements the Galactic knowledge. We present ALMA survey data with a spatial resolution of ∼0.1 pc in the 0.87 mm
continuum and HCO+ (4-3) emission toward 30 protostellar objects with luminosities of 104 -105.5 L⊙ in the LMC. The spatial
distributions of the HCO+ (4-3) line and thermal dust emission are well correlated, indicating that the line effectively traces
dense, filamentary gas with an H2 volume density of ≳105 cm−3 and a line mass of ∼103 -104 M⊙ pc−1 . Furthermore, we obtainan increase in the velocity linewidths of filamentary clouds, which follows a power-law dependence on their H2 column densities
with an exponent of ∼0.5. This trend is consistent with observations toward filamentary clouds in nearby star-forming regions
withiin ≲1 kpc from us and suggests enhanced internal turbulence within the filaments owing to surrounding gas accretion.
Among the 30 sources, we find that 14 are associated with hub-filamentary structures, and these complex structures predominantly appear in protostellar luminosities exceeding ∼5 ×104 L⊙ . The hub-filament systems tend to appear in the latest stagesof their natal cloud evolution, often linked to prominent H ii regions and numerous stellar clusters. Our preliminary statistics

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suggest that the massive filaments accompanied by hub-type complex features may be a necessary intermediate product informing extremely luminous high-mass stellar systems capable of ultimately dispersing the parent cloud.

Photometric determination of the mass accretion rates of pre-main sequence stars. VII.
59. The low-density cluster NGC 376 in the Small Magellanic Cloud
Styliani Tsilia, Guido De Marchi, Nino Panagia ⋆ Aims. We study the properties of low-mass stars recently formed in
the field of the NGC 376 cluster in the Small Magellanic Cloud (SMC). Methods. Using photometric observations acquired with
the Hubble Space Telescope (HST) in the V, I and Halpha bands, we identify 244 candidate pre-main sequence (PMS) stars
showing Halpha excess emission at the 5 sigma level and with Halpha equivalent width of 20 Å or more. We derive physicalparameters for all PMS stars, including masses, ages, and mass accretion rates. We compare the effective mass accretion rateof stars in NGC 376 to that of objects in the NGC 346 cluster, which features similar metallicity but higher total mass andgas density. Results. We find a median age of 28 Myr for this population (with 25 and 75 percentiles at about 20 and 40
Myr, respectively), in excellent agreement with previous studies of massive stars in the same field. The PMS stars are rather
uniformly distributed across the field, whereas massive stars are more clustered. The spatial distribution of PMS objects iscompatible with them having formed in the centre of the cluster and then migrated outwards. We find that in NGC 376 themass accretion rate is systematically lower than in NGC 346 for stars of the same mass and age. This indicates that, besides
metallicity, there are other environmental factors affecting the rate of mass accretion onto PMS stars. Our observations suggestthat the gas density in the star-forming region might play a role.

Photometric determination of the mass accretion rates of pre-main-sequence stars. VIII.
60. Recent star formation in NGC 299
Marissa Vlasblom, Guido De Marchi ⋆ We studied the properties of the young stellar populations in the NGC 299 clusterin the Small Magellanic Cloud using observations obtained with the Hubble Space Telescope in the V, I, and Hα bands. We
identified 250 stars with Hα excess exceeding 5 σ and an equivalent width of the Hα emission line of at least 20 Å, indicatingthat these stars are still undergoing accretion and therefore represent bona fide pre-main-sequence (PMS) objects. For 240 ofthese stars, we derived the mass, age, and mass accretion rate by comparing the observed photometry with theoretical models.
We find evidence for the existence of two populations of PMS stars, with median ages of 25 and 50 Myr respectively. The
average mass accretion rate for these PMS stars is ∼ 5 × 10−9 M⊙ yr−1 , which is comparable to the values found in otherlow-metallicity, low-density clusters in the Magellanic Clouds, but is about a factor of three lower than those measured for starsof similar mass and age in denser Magellanic Cloud stellar regions. Our findings support the hypothesis that both the metallicity
and density of the forming environment can affect the mass accretion rate and thus the star formation process in a region. A
study of the spatial distribution of both massive stars and (low-mass) PMS objects reveals that the former are clustered near
the nominal centre of NGC 299, whereas the PMS stars are rather uniformly distributed over the field. To explore whether thestars formed in an initially more diffuse or compact structure, we studied the cluster’s stellar density profile. We find a coreradius rc ≃ 0.6 pc and a tidal radius rt ≃ 5.5 pc, with an implied concentration parameter c ≃ 1, suggesting that the cluster
could be dispersing into the field.

Protostellar Interferometric Line Survey of the Cygnus-X region (PILS-Cygnus) – The
61. role of the external environment in setting the chemistry of protostars
S. J. van der Walt, L. E. Kristensen, H. Calcutt, J. K. Jørgensen, R. T. Garrod ⋆ (Abridged) Molecular lines arecommonly detected towards protostellar sources. However, to get a better understanding of the chemistry of these sources weneed unbiased molecular surveys over a wide frequency range for as many sources as possible to shed light on the origin of thischemistry, particularly any influence from the external environment. We present results from the PILS-Cygnus survey of ten
intermediate- to high-mass protostellar sources in the nearby Cygnus-X complex, through high angular resolution interferometricobservations over a wide frequency range. Using the Submillimeter Array (SMA), a spectral line survey of ten sources was
performed in the frequency range 329-361 GHz, with an angular resolution of ∼1.5 arcsec, (∼2000 AU, source distance of
1.3 kpc). Spectral modelling was performed to identify molecular emission and determine column densities and excitation
temperatures for each source. We detect CH3 OH towards nine of the ten sources, CH3 OCH3 and CH3 OCHO towards threesources, and CH3 CN towards four sources. Towards five sources the chemistry is spatially differentiated (different species peakat different positions and are offset from the peak continuum emission). The chemical properties of each source do not correlatewith their position in the Cygnus-X complex, nor do the distance or direction to the nearest OB associations. However, the fivesources located in the DR21 filament do appear to show less line emission compared to the five sources outside the filament.
This work shows how important wide frequency coverage observations are combined with high angular resolution observations
for studying the protostellar environment. Based on the ten sources observed here, the external environment appears to only
play a minor role in setting the chemical environment on these small scales (< 2000 AU).

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The molecular clouds in a section of the third Galactic quadrant: observational prop62. erties and chemical abundance ratio between CO and its isotopologues
Chen Wang, Haoran Feng, Ji Yang, Xuepeng Chen, Yang Su, Qing-Zeng Yan, Fujun Du, Yuehui Ma, Jiajun
Cai ⋆ We compare the observational properties between 12 CO, 13 CO, and C18 O and summarize the observational parameters
based on 7069 clouds sample from the Milky Way Imaging Scroll Painting (MWISP) CO survey in a section of the third Galactic
quadrant. We find that the 13 CO angular area (A13 CO ) generally increases with that of 12 CO (A12 CO ), and the ratio of A13 CO
to A12 CO is 0.38 by linear fitting. We find that the 12 CO and 13 CO flux are tightly correlated as F13 CO = 0.17 F12 CO with both
−7
fluxes calculated within the 13 CO-bright region. This indicates that the abundance X13 CO is a constant to be 6.5+0.1−0.5 ×10
for all samples under assumption of local thermodynamic equilibrium (LTE). Additionally, we observed that the X-factor isapproximately constant in large sample molecular clouds. Similarly, we find FC18 O = 0.11 F13 CO with both fluxes calculated
within C18 O-bright region, which indicates that the abundance ratios X13 CO /XC18 O stays the same value 9.7+0.6−0.8 across themolecular clouds under LTE assumption. The linear relationships of F12 CO vs. F13 CO and F13 CO vs. FC18 O hold not only for the13
CO-bright region or C18 O-bright region, but also for the entire molecular cloud scale with lower flux ratio. The abundance
ratio X13 CO /XC18 O inside clouds shows a strong correlation with column density and temperature. This indicates that the
X13 CO /XC18 O is dominated by a combination of chemical fractionation, selectively dissociation, and self-shielding effect inside
clouds.

MAPS: Constraining Serendipitous Time Variability in Protoplanetary Disk Molecular
63. Ion Emission
Abygail R. Waggoner, L. Ilsedore Cleeves, Ryan A. Loomis, Yuri Aikawa, Jaehan Bae, Jennifer B. Bergner,
Alice S. Booth, Jenny K. Calahan, Gianni Cataldi, Charles J. Law, Romane Le Gal, Feng Long, Karin I. Öberg,
Richard Teague, David J. Wilner ⋆ Theoretical models and observations suggest that the abundances of molecular ions in
protoplanetary disks should be highly sensitive to the variable ionization conditions set by the young central star. We present
a search for temporal flux variability of HCO+ J=1-0, which was observed as a part of the Molecules with ALMA at Planetforming Scales (MAPS) ALMA Large Program. We split out and imaged the line and continuum data for each individual
day the five sources were observed (HD 163296, AS 209, GM Aur, MWC 480, and IM Lup, with between 3 to 6 unique visits
per source). Significant enhancement (>3σ) was not observed, but we find variations in the spectral profiles in all five disks.
Variations in AS 209, GM Aur, and HD 163296 are tentatively attributed to variations in HCO+ flux, while variations in IM Lup
and MWC 480 are most likely introduced by differences in the uv coverage, which impact the amount of recovered flux during
imaging. The tentative detections and low degree of variability are consistent with expectations of X-ray flare driven HCO+
variability, which requires relatively large flares to enhance the HCO+ rotational emission at significant (>20%) levels. Thesefindings also demonstrate the need for dedicated monitoring campaigns with high signal to noise ratios to fully characterize
X-ray flare driven chemistry.

64. The Accretion History of EX Lup: A Century of Bursts, Outbursts, and Quiescence

Mu-Tian Wang, Gregory J. Herczeg, Hui-Gen Liu, Min Fang, Doug Johnstone, Ho-Gyu Lee, Frederick M.
Walter, Franz-Josef Hambsch, Carlos Contreras Pena, Jeong-Eun Lee, Mervyn Millward, Andrew Pearce,
Berto Monard, Lihang Zhou ⋆ EX Lup is the archetype for the class of young stars that undergoes repeated accretion
outbursts of ∼ 5 mag at optical wavelengths and that last for months. Despite extensive monitoring that dates back 130 years,
the accretion history of EX Lup remains mostly qualitative and has large uncertainties. We assess historical accretion ratesof EX Lup by applying correlations between optical brightness and accretion, developed on multi-band magnitude photometryof the ∼ 2 mag optical burst in 2022. Two distinct classes of bursts occur: major outbursts (∆V ∼ 5 mag) have year-longdurations, are rare, reach accretion rates of Ṁacc ∼ 10−7 M⊙ yr−1 at peak, and have a total accreted mass of around 0.1 Earthmasses. The characteristic bursts (∆V ∼ 2 mag) have durations of ∼ 2 − 3 months, are more common, reach accretion ratesof Ṁacc ∼ 10−8 M⊙ yr−1 at peak, and have a total accreted mass of around 10−3 Earth masses. The distribution of total
accreted mass in the full set of bursts is poorly described by a power law, which suggests different driving causes behind the
major outburst and characteristic bursts. The total mass accreted during two classes of bursts is around two times the masses
accreted during quiescence. Our analysis of the light curves reveals a color-dependent time lag in the 2022 post-burst light
curve, attributed to the presence of both hot and cool spots on the stellar surface.

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ALMA observations of the Extended Green Object G19.01−0.03: II. A massive pro65. tostar with typical chemical abundances surrounded by four low-mass prestellar core
candidates
Gwenllian M. Williams, Claudia J. Cyganowski, Crystal L. Brogan, Todd R. Hunter, Pooneh Nazari, Rowan
J. Smith ⋆ We present a study of the physical and chemical properties of the Extended Green Object (EGO) G19.01−0.03
using sub-arcsecond angular resolution Atacama Large Millimeter/submillimeter Array (ALMA) 1.05mm and Karl G. Jansky
Very Large Array (VLA) 1.21cm data. G19.01−0.03 MM1, the millimetre source associated with the central massive youngstellar object (MYSO), appeared isolated and potentially chemically young in previous Submillimeter Array observations. In
our ∼ 0.4′′ -resolution ALMA data, MM1 has four low-mass millimetre companions within 0.12pc, all lacking maser or outflow
emission, indicating they may be prestellar cores. With a rich ALMA spectrum full of complex organic molecules, MM1 does
not appear chemically young, but has molecular abundances typical of high-mass hot cores in the literature. At the 1.05mm+0.3continuum peak of MM1, N(CH3 OH) = (2.22 ± 0.01) × 1018 cm−2 and Tex = 162.7−0.5
K based on pixel-by-pixel Bayesiananalysis of LTE synthetic methanol spectra across MM1. Intriguingly, the peak CH3 OH Tex = 165.5 ± 0.6 K is offset from
MM1’s millimetre continuum peak by 0.22′′ ∼ 880au, and a region of elevated CH3 OH Tex coincides with free-free VLA 5.01cm
continuum, adding to the tentative evidence for a possible unresolved high-mass binary in MM1. In our VLA 1.21cm data, wereport the first NH3 (3,3) maser detections towards G19.01−0.03, along with candidate 25GHz CH3 OH 5(2, 3) − 5(1, 4) maser
emission; both are spatially and kinematically coincident with 44GHz Class I CH3 OH masers in the MM1 outflow. We also
report the ALMA detection of candidate 278.3GHz Class I CH3 OH maser emission towards this outflow, strengthening theconnection of these three maser types to MYSO outflows.

66. CMR exploration II – filament identification with machine learning

Duo Xu, Shuo Kong, Avichal Kaul, Hector G. Arce, Volker Ossenkopf-Okada ⋆ We adopt magnetohydrodynamics(MHD) simulations that model the formation of filamentary molecular clouds via the collision-induced magnetic reconnection(CMR) mechanism under varying physical conditions. We conduct radiative transfer using RADMC-3D to generate synthetic
dust emission of CMR filaments. We use the previously developed machine learning technique CASI-2D along with the diffusion
model to identify the location of CMR filaments in dust emission. Both models showed a high level of accuracy in identifying
CMR filaments in the test dataset, with detection rates of over 80% and 70%, respectively, at a false detection rate of 5%. We
then apply the models to real Herschel dust observations of different molecular clouds, successfully identifying several highconfidence CMR filament candidates. Notably, the models are able to detect high-confidence CMR filament candidates in Orion
A from dust emission, which have previously been identified using molecular line emission.

67. On the conditions for warping and breaking protoplanetary discs

Alison K. Young, Struan Stevenson, C. J. Nixon, Ken Rice ⋆ Recent observations demonstrate that misalignments
and other out-of-plane structures are common in protoplanetary discs. Many of these have been linked to a central host binary
with an orbit that is inclined with respect to the disc. We present simulations of misaligned circumbinary discs with a rangeof parameters to gain a better understanding of the link between those parameters and the disc morphology in the wave-likeregime of warp propagation that is appropriate to protoplanetary discs. The simulations confirm that disc tearing is possible
in protoplanetary discs as long as the mass ratio, µ, and disc-binary inclination angle, i, are not too small. For the simulations
presented here this corresponds to µ > 0.1 and i ≳ 40◦ . For highly eccentric binaries, tearing can occur for discs with smaller
misalignment. Existing theoretical predictions provide an estimate of the radial extent of the disc in which we can expect
breaking to occur. However, there does not seem to be a simple relationship between the disc properties and the radius within
the circumbinary disc at which the breaks appear, and furthermore the radius at which the disc breaks can change as a functionof time in each case. We discuss the implications of our results for interpreting observations and suggest some considerations
for modelling misaligned discs in the future.

68.

ATLASGAL: 3-mm class I methanol masers in high-mass star formation regions
W. Yang, Y. Gong, K. M. Menten, J. S. Urquhart, C. Henkel, F. Wyrowski, T. Csengeri, S. P. Ellingsen, A.
R. Bemis, J. Jang ⋆ We analyzed the 3-mm wavelength spectral line survey of 408 ATLASGAL clumps observed with the
IRAM 30m-telescope, focusing on the class I methanol masers with frequencies near 84, 95 and 104.3 GHz. We detect narrow,maser-like features towards 54, 100 and 4 sources in the maser lines near 84, 95 and 104.3 GHz, respectively. Among them,
fifty 84 GHz masers, twenty nine 95 GHz masers and four rare 104.3 GHz masers are new discoveries. The new detections
increase the number of known 104.3 GHz masers from 5 to 9. The 95 GHz class I methanol maser is generally stronger than
the 84 GHz maser counterpart. We find 9 sources showing class I methanol masers but no SiO emission, indicating that class
I methanol masers might be the only signpost of protostellar outflow activity in extremely embedded objects at the earliest
evolutionary stage. Class I methanol masers that are associated with sources that show SiO line wings are more numerous andstronger than those without such wings. The total integrated intensity of class I methanol masers is well correlated with the
integrated intensity and velocity coverage of the SiO (2–1) emission. The properties of class I methanol masers are positively

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correlated with the bolometric luminosity, clump mass, peak H2 column density of their associated clumps but uncorrelatedwith the luminosity-to-mass ratio, dust temperature, and mean H2 volume density. We suggest that the properties of class I
masers are related to shocks traced by SiO. Based on our observations, we conclude that class I methanol masers at 84 and 95
GHz can trace a similar evolutionary stage as H2 O maser, and appear prior to 6.7 and 12.2 GHz methanol and OH masers.
Despite their small number, the 104.3 GHz class I masers appear to trace a short and more evolved stage compared to the otherclass I masers. [abridged]

Buoyancy response of a disk to an embedded planet: a cross-code comparison at high69. resolution
Alexandros Ziampras, Sijme-Jan Paardekooper, Richard P. Nelson ⋆ In radiatively inefficient, laminar protoplanetarydisks, embedded planets can excite a buoyancy response as gas gets deflected vertically near the planet. This results in verticaloscillations that drive a vortensity growth in the planet’s corotating region, speeding up inward migration in the type-I regime.
We present a comparison between PLUTO/IDEFIX and FARGO3D using 3D, inviscid, adiabatic numerical simulations ofplanet-disk interaction that feature the buoyancy response of the disk, and show that PLUTO/IDEFIX struggle to resolve
higher-order modes of the buoyancy-related oscillations, weakening vortensity growth and the associated torque. We interpret
this as a drawback of total-energy-conserving, finite-volume schemes. Our results indicate that a very high resolution or highorder scheme is required in shock-capturing codes in order to adequately capture this effect.

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