The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 374 — 29 Feb 2024
Editor: João Alveswww.starformation.news

Cover image caption
RGB image of DG Tau B combining three NIRCam exposures in F164N (red) for the [Feii] 1.64µm line + continuum, F212N(green) for the H2 1-0S(1) 2.12µm line + continuum, and F323N (blue) for the 1-0O(5) 3.23µm line + continuum.
Credits: NASA, ESA, CSA, STScI, Delabrosse et al. 2024
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 whensubmitting to the arXiv. If you do, your abstract will not look great either at the arXiv or the SFN.

Abstracts
1.

A Unified Model for Bipolar Outflows from Young Stars: Kinematic and Mixing Structures in HH 30
Tsung-Han Ai, Chun-Fan Liu, Hsien Shang, Doug Johnstone, Ruben Krasnopolsky ⋆ The young stellar source

HH 30 is a textbook example of an ionic optical jet originating from a disk in an edge-on system shown by the HST. It
has a remnant envelope in 12 CO observed by ALMA. The optical jet is characterized by its narrow appearance, largeline width at the base, and high temperature inferred from line diagnostics. Three featured structures can be identified, most evident in the transverse position–velocity diagrams: an extremely–high-velocity (EHV) wide-angle windcomponent with large spectral widths in the optical, a very–low-velocity (VLV) ambient surrounding medium seen in
12
CO, and a low-velocity (LV) region traced by 12 CO nested both in velocity and location between the primary wind
and ambient environment. A layered cavity with multiple shells forms nested morphological and kinematic structures
around the optical jet. The atomic gas originating from the innermost region of the disk attains a sufficient temperature and ionization to emit brightly in forbidden lines as an optical jet. The wide-angle portion expands, forming a
low-density cavity. The filamentary 12 CO encompassing the wind cavity is mixed and advected inward through theaction of the magnetic interplay of the wide-angle wind with the molecular ambient medium. The magnetic interplay
results in the layered shells penetrating deeply into the vast cavity of tenuous atomic wind material. The HH 30
system is an ideal manifestation of the unified wind model of Shang 2020,2023, with clearly distinguishable atomic
and molecular species mixed through the atomic lightly ionized magnetized wind and the surrounding cold molecularambient material.

Evolution of the relation between the mass accretion rate and the stellar and disk mass
2. from brown dwarfs to stars
V. Almendros-Abad, C. F. Manara, L. Testi, A. Natta, R. A. B. Claes, K. Muzic, E. Sanchis, J. M. Alcalá,
A. Bayo, A. Scholz ⋆ The time evolution of the dependence of the mass accretion rate with the stellar mass andthe disk mass represents a fundamental way to understand the evolution of protoplanetary disks and the formation ofplanets. In this work, we present observations with X-Shooter of 26 Class II very low-mass stars and brown dwarfs in
the Ophiuchus, Cha-I, and Upper Scorpius star-forming regions (SFRs). These new observations extend down to SpT
M9 (∼0.02 M⊙ ) the measurement of the mass accretion rate in Ophiuchus and Cha-I and add 11 very-low-mass stars
to the sample of objects studied with broadband spectroscopy in Upper Scorpius. We obtained their SpT, extinction
and physical parameters, and we used the intensity of various emission lines to derive their accretion luminosity andmass accretion rates. Combining these new observations with data from the literature, we compare relations between
accretion and stellar and disk properties of four different SFRs with different ages: Ophiuchus (1 Myr), Lupus (2 Myr),
Cha-I (3 Myr), and Upper Scorpius (5-12 Myr). We find the slopes of the L∗ − Lacc and M∗ − Ṁ acc relationships
to steepen between Ophiuchus, Lupus, and Cha-I and that both relationships may be better described with a single
power law. We also find the relationship between the disk mass and the mass accretion rate of the stellar population
to steepen with time down to the age of Upper Scorpius. Overall, we observe hints of a faster evolution into low
accretion rates of low-mass stars and brown dwarfs. We also find that brown dwarfs present higher M disk /Ṁ acc ratios2(i.e., longer accretion depletion timescales) than stars in Ophiuchus, Lupus, and Cha-I. This apparently contradictory
result may imply that the evolution of protoplanetary disks around brown dwarfs is different from what is seen in thestellar regime.

3. JWST MIRI MRS Images Disk Winds, Water, and CO in an Edge-On Protoplanetary
Disk
Nicole Arulanantham, M. K. McClure, Klaus Pontoppidan, Tracy L. Beck, J. A. Sturm, D. Harsono, A. C.
A. Boogert, M. Cordiner, E. Dartois, M. N. Drozdovskaya, C. Espaillat, G. J. Melnick, J. A. Noble, M. E.
Palumbo, Y. J. Pendleton, H. Terada, E. F. van Dishoeck ⋆ We present JWST MIRI MRS observations of the edge-

on protoplanetary disk around the young sub-solar mass star Tau 042021, acquired as part of the Cycle 1 GO program"Mapping Inclined Disk Astrochemical Signatures (MIDAS)." These data resolve the mid-IR spatial distributions of
H2 , revealing X-shaped emission extending to 200 au above the disk midplane with a semi-opening angle of 35 ± 5degrees. We do not velocity-resolve the gas in the spectral images, but the measured semi-opening angle of the H2 isconsistent with an MHD wind origin. A collimated, bipolar jet is seen in forbidden emission lines from [Ne II], [Ne III],[Ni II], [Fe II], [Ar II], and [S III]. Extended H2 O and CO emission lines are also detected, reaching diameters between
90 and 190 au, respectively. Hot molecular emission is not expected at such radii, and we interpret its extended spatial
distribution as scattering of inner disk molecular emission by dust grains in the outer disk surface. H I recombinationlines, characteristic of inner disk accretion shocks, are similarly extended, and are likely also scattered light from theinnermost star-disk interface. Finally, we detect extended PAH emission at 11.3 microns co-spatial with the scattered
light continuum, making this the first low-mass T Tauri star around which extended PAHs have been confirmed, to
our knowledge. MIRI MRS line images of edge-on disks provide an unprecedented window into the outflow, accretion,and scattering processes within protoplanetary disks, allowing us to constrain the disk lifetimes and accretion andmass loss mechanisms.

4.

An ALMA molecular inventory of warm Herbig Ae disks: I. Molecular rings, asymmetries and complexity in the HD 100546 disk
Alice S. Booth, Margot Leemker, Ewine F. van Dishoeck, Lucy Evans, John D. Ilee, Mihkel Kama, Luke Keyte,Charles J. Law, Nienke van der Marel, Hideko Nomura, Shota Notsu, Karin Öberg, Milou Temmink, Catherine
Walsh ⋆ Observations of disks with the Atacama Large Millimeter/submillimeter Array (ALMA) allow us to map thechemical makeup of nearby protoplanetary disks with unprecedented spatial resolution and sensitivity. The typicalouter Class II disk observed with ALMA is one with an elevated C/O ratio and a lack of oxygen-bearing complex
organic molecules, but there are now some interesting exceptions: three transition disks around Herbig Ae stars allshow oxygen-rich gas traced via the unique detections of the molecules SO and CH3OH. We present the first results ofan ALMA line survey at 337 to 357 GHz of such disks and focus this paper on the first Herbig Ae disk to exhibit thischemical signature - HD 100546. In these data, we detect 19 different molecules including NO, SO and CH3OCHO(methyl formate). We also make the first tentative detections of H213CO and 34SO in protoplanetary disks. Multiple
molecular species are detected in rings, which are, surprisingly, all peaking just beyond the underlying millimeter
continuum ring at 200 au. This result demonstrates a clear connection between the large dust distribution and thechemistry in this flat outer disk. We discuss the physical and/or chemical origin of these sub-structures in relation to
ongoing planet formation in the HD 100546 disk. We also investigate how similar and/or different the molecular makeup of this disk is to other chemically well-characterised Herbig Ae disks. The line-rich data we present motivates theneed for more ALMA line surveys to probe the observable chemistry in Herbig Ae systems which offer unique insight
into the composition of disk ices, including complex organic molecules.

An ALMA molecular inventory of warm Herbig Ae disks: II. Abundant complex organ5. ics and volatile sulphur in the IRS 48 disk
Alice S. Booth, Milou Temmink, Ewine F. van Dishoeck, Lucy Evans, John D. Ilee, Mihkel Kama, Luke
Keyte, Charles J. Law, Margot Leemker, Nienke van der Marel, Hideko Nomura, Shota Notsu, Karin Öberg,
Catherine Walsh ⋆ The Atacama Large Millimeter/submillimeter Array (ALMA) can probe the molecular content

of planet-forming disks with unprecedented sensitivity. These observations allow us to build up an inventory of thevolatiles available for forming planets and comets. Herbig Ae transition disks are fruitful targets due to the thermal
sublimation of complex organic molecule (COM) and likely H2O-rich ices in these disks. The IRS 48 disk shows a3particularly rich chemistry that can be directly linked to its asymmetric dust trap. Here, we present ALMA observations of the IRS 48 disk where we detect 16 different molecules and make the first robust detections of H213CO, 34SO,
33SO and c-H2COCH2 (ethylene oxide) in a protoplanetary disk. All of the molecular emissions, aside from CO, arecolocated with the dust trap and this includes newly detected simple molecules such as HCO+, HCN and CS. Interestingly, there are spatial offsets between different molecular families, including between the COMs and sulphur-bearing
species, with the latter being more azimuthally extended and located radially further from the star. The abundancesof the newly detected COMs relative to CH3OH are higher than the expected protostellar ratios, which implies somedegree of chemical processing of the inherited ices during the disk lifetime. These data highlight IRS 48 as a uniqueastrochemical laboratory to unravel the full volatile reservoir at the epoch of planet and comet formation and the roleof the disk in (re)setting chemical complexity.
13
6. JWST observations of CO2 ice: Tracing the chemical environment and thermal historyof ices in protostellar envelopes

Nashanty G. C. Brunken, Will R. M. Rocha, Ewine F. van Dishoeck, Robert Gutermuth, Himanshu Tyagi,
Katerina Slavicinska, Pooneh Nazari, S. Thomas Megeath, Neal J. Evans II, Mayank Narang, P. Manoj, Adam
E. Rubinstein, Dan M. Watson, Leslie W. Looney, Harold Linnartz, Alessio Caratti o Garatti, Henrik Beuther,
Hendrik Linz, Pamela Klaassen, Charles A. Poteet, Samuel Federman, Guillem Anglada, Prabhani Atnagulov,
Tyler L. Bourke, William J. Fischer, Elise Furlan, Joel Green, Nolan Habel, Lee Hartmann, Nicole Karnath,
Mayra Osorio, James Muzerolle Page, Riwaj Pokhrel, Rohan Rahatgaonkar, Patrick Sheehan, Thomas Stanke,
Amelia M. Stutz, John J. Tobin, Lukasz Tychoniec, Scott Wolk, Yao-Lun Yang ⋆ The structure and compositionof simple ices can be modified during stellar evolution by protostellar heating. Key to understanding the involved
processes are thermal and chemical tracers that can diagnose the history and environment of the ice. The 15.2 µm
bending mode of 12 CO2 has proven to be a valuable tracer of ice heating events but suffers from grain shape and size
effects. A viable alternative tracer is the weaker 13 CO2 isotopologue band at 4.39 µm which has now become accessible
at high S/N with the James Webb Space Telescope (JWST). We present JWST NIRSpec observations of 13 CO2 ice
in five deeply embedded Class 0 sources spanning a wide range in luminosities (0.2 - 104 L⊙ ) taken as part of theInvestigating Protostellar Accretion Across the Mass Spectrum (IPA) program. The band profiles vary significantly,
with the most luminous sources showing a distinct narrow peak at 4.38 µm. We first apply a phenomenologicalapproach and show that a minimum of 3-4 Gaussian profiles are needed to fit the 13 CO2 absorption feature. We
then combine these findings with laboratory data and show that a 15.2 µm 12 CO2 band inspired five-component
decomposition can be applied for the isotopologue band where each component is representative of CO2 ice in a
specific molecular environment. The final solution consists of cold mixtures of CO2 with CH3 OH, H2 O and CO as well
as segregated heated pure CO2 ice. Our results are in agreement with previous studies of the 12 CO2 ice band, further
confirming that 13 CO2 is a useful alternative tracer of protostellar heating events. We also propose an alternative
solution consisting only of heated CO2 :CH3 OH and CO2 :H2 O ices and warm pure CO2 ice for decomposing the ice
profiles of the two most luminous sources in our sample.

7.

The dynamical evolution of star-forming regions measured with INDICATE
George A. Blaylock-Squibbs, Richard J. Parker ⋆ Observations of star-forming regions provide snapshots in timeof the star formation process, and can be compared with simulation data to constrain the initial conditions of starformation. In order to make robust inferences, different metrics must be used to quantify the spatial and kinematic
distributions of stars. In this paper, we assess the suitability of the INDICATE (INdex to Define Inherent Clustering
And TEndencies) method as a diagnostic to infer the initial conditions of star-forming regions that subsequently
undergo dynamical evolution. We use INDICATE to measure the degree of clustering in N-body simulations of theevolution of star-forming regions with different initial conditions. We find that the clustering of individual stars, asmeasured by INDICATE, becomes significantly higher in simulations with higher initial stellar densities, and is higher
in subvirial star-forming regions where significant amounts of dynamical mixing has occurred. We then combine
INDICATE with other methods that measure the mass segregation, relative stellar surface density ratio and themorphology (Q-parameter) of star-forming regions, and show that the diagnostic capability of INDICATE increases
when combined with these other metrics.

48. Deep Paβ Imaging of the Candidate Accreting Protoplanet AB Aur b
Lauren I. Biddle, Brendan P. Bowler, Yifan Zhou, Kyle Franson, Zhoujian Zhang ⋆ Giant planets grow byaccreting gas through circumplanetary disks, but little is known about the timescale and mechanisms involved in theplanet assembly process because few accreting protoplanets have been discovered. Recent visible and infrared (IR)imaging revealed a potential accreting protoplanet within the transition disk around the young intermediate-mass
Herbig Ae star, AB Aurigae (AB Aur). Additional imaging in Hα probed for accretion and found agreement between
the line-to-continuum flux ratio of the star and companion, raising the possibility that the emission source could be acompact disk feature seen in scattered starlight. We present new deep Keck/NIRC2 high-contrast imaging of AB Aur
to characterize emission in Paβ, another accretion tracer less subject to extinction. Our narrow band observations
reach a 5σ contrast of 9.6 mag at 0.6′′ , but we do not detect significant emission at the expected location of thecompanion, nor from other any other source in the system. Our upper limit on Paβ emission suggests that if AB Aur
b is a protoplanet, it is not heavily accreting or accretion is stochastic and was weak during the observations.

9. ALMA-IMF XI: The sample of hot core candidates A rich population of young highmass proto-stars unveiled by the emission of methyl formate
M. Bonfand, T. Csengeri, S. Bontemps, N. Brouillet, F. Motte, F. Louvet, A. Ginsburg, N. Cunningham, R.
Galván-Madrid, F. Herpin, F. Wyrowski, M. Valeille-Manet, A. M. Stutz, J. Di Francesco, A. Gusdorf, M.
Fernández-López, B. Lefloch, H-L. Liu, P. Sanhueza, R. H. Álvarez-Gutiérrez, F. Olguin, T. Nony, A. LopezSepulcre, P. Dell’Ova, Y. Pouteau, D. Jeff, H. -R. V. Chen, M. Armante, A. Towner, L. Bronfman, N. Kessler⋆ Sites associated with high-mass star and cluster formation exhibit a so-called hot core phase, characterized byhigh temperatures and column densities of complex organic molecules. We built a comprehensive census of hot core
candidates towards the ALMA-IMF protoclusters based on the detection of two CH3OCHO emission lines at 216.1
GHz. We used the source extraction algorithm GExt2D to identify peaks of methyl formate (CH3OCHO) emissionthat is a complex species commonly observed towards sites of star formation. We built up a catalog of 76 hot core
candidates with masses ranging from about 0.2 to 80 Msun , of which 56 are new detections. A large majority of theseobjects are compact, rather circular, with deconvolved FWHM sizes of about 2300 au on average. About 30% of oursample of methyl formate sources have core masses above 8 Msun within sizes ranging from about 1000 au to 13400
au, which well correspond to archetypical hot cores. The origin of the CH3OCHO emission toward the lower-masscores can be explained by a mixture of contribution from shocks, or may correspond to objects in a more evolved
state, i.e. beyond the hot core stage. We find that the fraction of hot core candidates increases with the core mass.
The large fraction of hot core candidates towards the most massive cores suggests that they rapidly enter the hot corephase and feedback effects from the forming protostar(s) impact their environment on short time-scales.

10. Protoplanet collisions: new scaling laws from SPH simulations

Samuele Crespi, Mohamad Ali-Dib, Ian Dobbs-Dixon ⋆ One common approach for solving collisions between

protoplanets in simulations of planet formation is to employ analytical scaling laws. The most widely used one wasdeveloped by Leinhardt & Stewart (2012) from a catalog of 180 N-body simulations of rubble-pile collisions. In thiswork, we use a new catalogue of more than 20,000 SPH simulations to test the validity and the prediction capabilityof Leinhardt & Stewart (2012) scaling laws. We find that these laws overestimate the fragmentation efficiency in themerging regime and they are not able to properly reproduce the collision outcomes in the super-catastrophic regime.
In the merging regime, we also notice a significant dependence between the collision outcome, in terms of the largest
remnant mass, and the relative mass of the colliding protoplanets. Here, we present a new set of scaling laws that areable to better predict the collision outcome in all regimes and it is also able to reproduce the observed dependence on
the mass ratio. We compare our new scaling laws against a machine learning approach and obtain similar prediction
efficiency.

11. Thermal processing of primordial pebbles in evolving protoplanetary disks

Maria Jose Colmenares, Michiel Lambrechts, Elishevah van Kooten, Anders Johansen ⋆ During protoplanetary
disk formation, dust grains located in the outer disk retain their pristine icy composition, while solids in the innerstellar-heated disk undergo volatile loss. This process may have left a fossil record in Solar System material showing
different nucelosynthetic imprints that have been attributed to different degrees of thermal processing. However, itremains unclear how a large mass fraction of thermally-processed inner-disk pebbles is produced and how these grains5are subsequently transported throughout the disk. In this work we numerically investigate the evolution in time ofa two-component pebble disk, consisting of pristine pebbles and those that underwent ice sublimation. We find thatstellar outbursts exceeding 1000 times the solar luminosity are efficient in thermally altering, through ice sublimation,a large mass fraction of pebbles (around 80%). After the establishment of this initial radial dust composition gradientthroughout the disk, the subsequent mixing and inward drift of pristine outer-disk pebbles alter the inner disk bulk
composition from processed to more unprocessed in time. Therefore, if processed pebbles without ice mantles have
an isotopic composition similar to ureilite meteorites from the inner Solar System, inner-disk minor bodies formingfrom the early pebble flux (<1Myr) will be isotopically ureilite-like, while later-formed bodies will be increasingly
admixed with the signature of the late incoming CI chondrite-like unprocessed pebbles. This appears to be largely
consistent with the trend seen between the accretion age of different meteoric classes and their different stable isotope
composition anomalies (in µ54Cr, µ48Ca, µ30Si, µ58Ni), but further work may be needed to explain the role ofisotopically anomalous refractory inclusions and anomaly trends in other elements.

12. FAUST XII. Accretion streamers and jets in the VLA 1623–2417 protocluster
C. Codella, L. Podio, M. De Simone, C. Ceccarelli, S. Ohashi, C. J. Chandler, N. Sakai, J. E. Pineda, D. M.
Segura-Cox, E. Bianchi, N. Cuello, A. López-Sepulcre, D. Fedele, P. Caselli, S. Charnley, D. Johnstone, Z.
E. Zhang, M. J. Maureira, Y. Zhang, G. Sabatini, B. Svoboda, I. Jiménez-Serra, L. Loinard, S. Mercimek,
N. Murillo, S. Yamamoto ⋆ The ALMA interferometer has played a key role in revealing a new component of the

Sun-like star forming process: the molecular streamers, i.e. structures up to thousands of au long funneling material
non-axisymmetrically to disks. In the context of the FAUST ALMA LP, the archetypical VLA1623-2417 protostellar
cluster has been imaged at 1.3 mm in the SO(56 –45 ), SO(66 –55 ), and SiO(5–4) line emission at the spatial resolutionof 50 au. We detect extended SO emission, peaking towards the A and B protostars. Emission blue-shifted down
to 6.6 km s−1 reveals for the first time a long (∼ 2000 au) accelerating streamer plausibly feeding the VLA1623 B
protostar. Using SO, we derive for the first time an estimate of the excitation temperature of an accreting streamer:
33±9 K. The SO column density is ∼ 1014 cm−2 , and the SO/H2 abundance ratio is ∼ 10−8 . The total mass of thestreamer is 3 × 10−3 M sun, while its accretion rate is 3–5 × 10−7 Msun yr−1 . This is close to the mass accretion rateof VLA1623 B, in the 0.6–3 × 10−7 Msun yr−1 range, showing the importance of the streamer in contributing to themass of protostellar disks. The highest blue- and red-shifted SO velocities behave as the SiO(5–4) emission, the latter
species detected for the first time in VLA1623-2417: the emission is compact (100-200 au), and associated only with
the B protostar. The SO excitation temperature is ∼ 100 K, supporting the occurrence of shocks associated with thejet, traced by SiO.

13. An Automated Chemical Exploration of NGC 6334I at 340 au Resolution
Samer J. El-Abd, Crystal L. Brogan, Todd R. Hunter, Kin Long Kelvin Lee, Ryan A. Loomis, Brett A.
McGuire ⋆ Much of the information gleaned from observations of star-forming regions comes from the analysis of

their molecular emission spectra, particularly in the radio regime. The time-consuming nature of fitting synthetic
spectra to observations interactively for such line-rich sources, however, often results in such analysis being limited
to data extracted from a single-dish observation or a handful of pixels from an interferometric observation. Yet,star-forming regions display a wide variety of physical conditions that are difficult, if not impossible, to accurately
characterize with such a limited number of spectra. We have developed an automated fitting routine that visits every
pixel in the field of view of an ALMA data cube and determines the best-fit physical parameters, including excitation
temperature and column densities, for a given list of molecules. In this proof-of-concept work, we provide an overview
of the fitting routine and apply it to 0".26, 1.1 km s−1 resolution ALMA observations of two sites of massive starformation in NGC 6334I. Parameters were found for 21 distinct molecules by generating synthetic spectra across 7.48
GHz of spectral bandwidth between 280 and 351 GHz. Spatial images of the derived parameters for each of the > 8000
pixels are presented with special attention paid to the C2 H4 O2 isomers and their relative variations. We highlightthe greater scientific utility of the column density and velocity images of individual molecules compared to traditional
moment maps of single transitions.

614. The 3D structure of disc-instability protoplanets
Adam Fenton, Dimitris Stamatellos ⋆ Context. The model of disc fragmentation due to gravitational instabilities
offers an alternate formation mechanism for gas giant planets, especially those on wide orbits. Aims. Our goal is todetermine the 3D structure of disc-instability protoplanets and to examine how this relates to the thermal physics ofthe fragmentation process. Methods. We modelled the fragmentation of gravitationally unstable discs using the SPH
code PHANTOM, and followed the evolution of the protoplanets formed through the first and second-hydrostatic corephases (up to densities 1e-3 g/cm3). Results. We find that the 3D structure of disc-instability protoplanets is affectedby the disc environment and the formation history of each protoplanet (e.g. interactions with spiral arms, mergers).
The large majority of the protoplanets that form in the simulations are oblate spheroids rather than spherical, andthey accrete faster from their poles. Conclusions. The 3D structure of disc-instability protoplanets is expected to affecttheir observed properties and should be taken into account when interpreting observations of protoplanets embeddedin their parent discs.

15. Stellar companions and Jupiter-like planets in young associations
R. Gratton, M. Bonavita, D. Mesa, S. Desidera, A. Zurlo, S. Marino, V. D’Orazi, E. Rigliaco, V. Nascimbeni,
D. Barbato, G. Columba, V. Squicciarini ⋆ Recently, combining high-contrast imaging and space astrometry wefound that Jupiter-like (JL) planets are frequent in the beta Pic moving group (BPMG) around those stars where
their orbit can be stable, prompting further analysis and discussion. We broaden our previous analysis to other young
nearby associations to determine the frequency, mass, and separation of companions in general and JL in particular andtheir dependencies on the mass and age of the associations. We collected available data about companions including
those revealed by visual observations, eclipses, spectroscopy, and astrometry. We determined search completeness andfound that it is very high for stellar companions, while completeness corrections are still large for JL companions.
Once these corrections are included, we found a high frequency of companions, both stellar (>0.52+/-0.03) and JL(0.57+/-0.11). The two populations are separated by a gap that corresponds to the brown dwarf desert. Within
the population of massive companions, we found trends in frequency, separation, and mass ratios with stellar mass.
Planetary companions pile up in the region just outside the ice line and we found them to be frequent once completenesswas considered. The frequency of JL planets decreases with the overall mass and possibly the age of the association. We
tentatively identify the two populations as due to disk fragmentation and core accretion, respectively. The distributionsof stellar companions with a semi-major axis <1000 au is well reproduced by a simple model of formation by disk
fragmentation. The observed trends with stellar mass can be explained by a shorter but much more intense phase ofaccretion onto the disk of massive stars and by a more steady and prolonged accretion on solar-type stars. Possible
explanations for the trends in the population of JL planets with association mass and age are briefly discussed.

Search for Brown Dwarfs in IC 1396 with Subaru HSC: Interpreting the Impact of
16. Environmental Factors on Sub-stellar Population
Saumya Gupta, Jessy Jose, Swagat Ranjan Das, Zhen Guo, Belinda Damian, Prem Prakash, Manash Ranjan
Samal ⋆ Young stellar clusters are predominantly the hub of star formation and hence, ideal to perform comprehensive

studies over the least explored sub-stellar regime. Various unanswered questions like the mass distribution in browndwarf regime and the effect of diverse cluster environment on brown dwarf formation efficiency still plague the scientificcommunity. The nearby young cluster, IC 1396 with its feedback-driven environment, is ideal to conduct such study. In
this paper we adopt a multi-wavelength approach, using deep Subaru HSC, Gaia DR3, Pan-STARRS, UKIDSS/2MASS
photometry and machine learning techniques to identify the cluster members complete down to ∼ 0.03 M⊙ in thecentral 22′ area of IC 1396. We identify 458 cluster members including 62 brown dwarfs which are used to determine
mass distribution in the region. We obtain a star-to-brown dwarf ratio of ∼ 6 for a stellar mass range 0.03 – 1 M⊙
in the studied cluster. The brown dwarf fraction is observed to increase across the cluster as radial distance from thecentral OB-stars increases. This study also compiles 15 young stellar clusters to check the variation of star-to-browndwarf ratio relative to stellar density and UV flux ranging within 4-2500 stars pc−2 and 0.7-7.3 G0 respectively. The
brown dwarf fraction is observed to increase with stellar density but the results about the influence of incident UVflux are inconclusive within this range. This is the deepest study of IC 1396 as of yet and it will pave the way tounderstand various aspects of brown dwarfs using spectroscopic observations in future.

7

Implications of the discovery of AF Lep b: The mass-luminosity relation for planets in
17. the β Pic Moving Group and the L-T transition for young companions and free-floating
planets
R. Gratton, M. Bonavita, D. Mesa, A. Zurlo, S. Marino, S. Desidera, V. D’Orazi, E. Rigliaco, V. Squicciarini,
P. H. Nogueira ⋆ Dynamical masses of young planets aged between 10 and 200 Myr detected in imaging play a crucialrole in shaping models of giant planet formation. Regrettably, only a few such objects possess these characteristics.
Furthermore, the evolutionary pattern of young sub-stellar companions in near-infrared colour-magnitude diagramsmight diverge from free-floating objects, possibly due to differing formation processes. The recent identification of agiant planet around AF Lep, part of the beta Pic moving group (BPMG), encouraged us to re-examine these points.
We considered updated dynamical masses and luminosities for the sub-stellar objects in the BPMG. In addition, we
compared the properties of sub-stellar companions and free-floating objects in the BPMG and other young associations
remapping the positions of the objects in the colour-magnitude diagram into a dustiness-temperature plane. We foundthat cold-start evolutionary models do not reproduce the mass-luminosity relation for sub-stellar companions in the
BPMG. This aligns rather closely with predictions from ’hot start’ scenarios and is consistent with recent planet
formation models. We obtain rather good agreement with masses from photometry and the remapping approachcompared to actual dynamical masses. We also found a strong suggestion that the near-infrared colour-magnitude
diagram for young companions is different from that of free-floating objects belonging to the same young associations.
If confirmed by further data, this last result would imply that cloud settling - which likely causes the transition between
L and T spectral type - occurs at a lower effective temperature in young companions than in free-floating objects.
This might tentatively be explained with a different chemical composition.

Constraining Planetary Formation Models Using Conditional Occurrences of Various
18. Planet Types
Sridhar Gajendran, Ing-Guey Jiang, Li-Chin Yeh, Devesh P. Sariya ⋆ We report the conditional occurrences
between three planetary types: super-Earths (m sin i < 10 M⊕ , P < 100 days), warm Jupiters (m sin i > 95 M⊕ , 10 <P < 100 days), and cold Jupiters (m sin i > 95 M⊕ , P > 400 days) for sun-like stars. We find that while the occurrence+8.3
of cold Jupiters in systems with super-Earths is 22.2−5.4%, compared to 10% for the absolute occurrence rate of cold
+18.0
Jupiters, the occurrence of super-Earths in systems with cold Jupiters is 66.0−16.0%, compared to 30% for the absolute
occurrence rate of super-Earths for sun-like stars. We find that the enhancement of super-Earths in systems with cold
Jupiters is evident for sun-like stars, in agreement with several previous studies. We also conduct occurrence studies
between warm Jupiters and super-Earths, and between warm Jupiters and cold Jupiters, to consolidate our methods.
We conduct an independent observational test to study the effects of cold Jupiters against the inner multiplicity
using the well-established giant planet host star metallicity correlation for all transiting planets found to date. The
conditional occurrences we find here can be used to constrain the validity of various planetary formation models. The
extremely interesting correlations between the super-Earths, cold Jupiters, and warm Jupiters can also be used tounderstand the formation histories of these planetary types.

19. Multi-wavelength detection of an ongoing FUOr-type outburst on a low-mass YSO

Zhen Guo, P. W. Lucas, R. G. Kurtev, J. Borissova, V. Elbakyan, C. Morris, A. Bayo, L. Smith, A. Carattio Garatti, C. Contreras Peña, D. Minniti, J. Jose, M. Ashraf, J. Alonso-García, N. Miller, H. D. S. Muthu⋆ During the pre-main-sequence evolution, Young Stellar Objects (YSOs) assemble most of their mass during theepisodic accretion process. The rarely seen FUOr-type events (FUOrs) are valuable laboratories to investigate theoutbursting nature of YSOs. Here, we present multi-wavelength detection of a high-amplitude eruptive source inthe young open cluster VdBH 221 with an ongoing outburst, including optical to mid-infrared time series and nearinfrared spectra. The initial outburst has an exceptional amplitude of >6.3 mag in Gaia and 4.6 mag in Ks , witha peak luminosity up to 16 L⊙ and a peak mass accretion rate of 1.4 × 10−5 M⊙ yr−1 . The optical to infrared
spectral energy distribution (SED) of this object is consistent with a low-mass star (0.2M⊙ ) with a modest extinction(AV < 2 mag). A 100-d delay between optical and infrared rising stages is detected, suggesting an outside-in originof the instability. The spectroscopic features of this object reveal a self-luminous accretion disc, very similar to FU
Orionis, with a low line-of-sight extinction. Most recently, there has been a gradual increase in brightness throughout
the wavelength range, possibly suggesting an enhancement of the mass accretion rate.

8

Spectroscopic confirmation of high-amplitude eruptive YSOs and dipping giants from
20. the VVV survey
Zhen Guo, P. W. Lucas, R. Kurtev, J. Borissova, C. Contreras Peña, S. N. Yurchenko, L. C. Smith, D. Minniti,
R. K. Saito, A. Bayo, M. Catelan, J. Alonso-García, A. Caratti o Garatti, C. Morris, D. Froebrich, J. Tennyson,
K. Maucó, A. Aguayo, N. Miller, H. D. S. Muthu ⋆ During the pre-main-sequence (pre-MS) evolution stage of astar, significant amounts of stellar mass are accreted during episodic accretion events, such as multi-decade FUor-type
outbursts. Here, we present a near-infrared spectroscopic follow-up study of 33 high-amplitude (most with ∆Ks >4 mag) variable sources discovered by the Vista Variables in the Via Lactea (VVV) survey. Based on the spectralfeatures, 25 sources are classified as eruptive young stellar objects (YSOs), including 15 newly identified FUors, sixwith long-lasting but EXor-like bursts of magnetospheric accretion and four displaying outflow-dominated spectra. By
examining the photometric behaviours of eruptive YSOs, we found most FUor-type outbursts have higher amplitudes(∆Ks and ∆W 2), faster eruptive timescales and bluer infrared colours than the other outburst types. In addition,
we identified seven post-main sequence variables apparently associated with deep dipping events and an eruptive starwith deep AlO absorption bands resembling those seen in the V838 Mon stellar merger.

21. Cloudlet Capture Model for the Accretion Streamer onto the disk of DG Tau

Tomoyuki Hanawa, Antonio Garufi, Linda Podio, Claudio Codella, Dominique Segura-Cox ⋆ DG Tau is a nearby

T Tauri star associated with a collimated jet, a circumstellar disk and a streamer a few hundred au long. The streamer
connects to the disk at ∼50 au from DG Tau. At this location SO emission is observed, likely due to the release ofsulphur from dust grains caused by the shock of the impact of the accretion streamer onto the disk. We investigate thepossibility that the DG Tau streamer was produced via cloudlet capture on the basis of hydrodynamic simulations,considering a cloudlet initiating infall at 600 au from DG Tau with low angular momentum so that the centrifugal
force is smaller than the gravitational force, even at 50 au. The elongation of the cloudlet into a streamer is caused by
the tidal force when its initial velocity is much less than the free-fall velocity. The elongated cloudlet reaches the disk
and forms a high density gas clump. Our hydrodynamic model reproduces the morphology and line-of-sight velocity
of CS (5 − 4) emission from the Northern streamer observed with ALMA. We discuss the conditions for forming a
streamer based on the simulations. We also show that the streamer should perturb the disk after impact for several
thousands of years.

22. On the magnetic field properties of protostellar envelopes in Orion
Bo Huang, Josep M. Girart, Ian W. Stephens, Manuel Fernandez-Lopez, Hector G. Arce, John M. Carpenter,Paulo Cortes, Erin G. Cox, Rachel Friesen, Valentin J. M. Le Gouellec, Charles L. H. Hull, Nicole Karnath,
Woojin Kwon, Zhi-Yun Li, Leslie W. Looney, Tom Megeath, Philip C. Myers, Nadia M. Murillo, Jaime E.
Pineda, Sarah Sadavoy, Alvaro Sanchez-Monge, Patricio Sanhueza, John J. Tobin, Qizhou Zhang, James M.
Jackson, Dominique Segura-Cox ⋆ We present 870 um polarimetric observations toward 61 protostars in the Orion

molecular clouds, with 400 au (1") resolution using the Atacama Large Millimeter/submillimeter Array. We successfully detect dust polarization and outflow emission in 56 protostars, in 16 of them the polarization is likely produced
by self-scattering. Self-scattering signatures are seen in several Class 0 sources, suggesting that grain growth appears
to be significant in disks at earlier protostellar phases. For the rest of the protostars, the dust polarization traces themagnetic field, whose morphology can be approximately classified into three categories: standard-hourglass, rotatedhourglass (with its axis perpendicular to outflow), and spiral-like morphology. 40.0% (+-3.0%) of the protostars exhibita mean magnetic field direction approximately perpendicular to the outflow on several 100–1000 au scales. However,in the remaining sample, this relative orientation appears to be random, probably due to the complex set of morphologies observed. Furthermore, we classify the protostars into three types based on the C17O (3–2) velocity envelope’s
gradient: perpendicular to outflow, non-perpendicular to outflow, and unresolved gradient (<1.0 km/s/arcsec). In
protostars with a velocity gradient perpendicular to outflow, the magnetic field lines are preferentially perpendicular
to outflow, most of them exhibit a rotated hourglass morphology, suggesting that the magnetic field has been overwhelmed by gravity and angular momentum. Spiral-like magnetic fields are associated with envelopes having large
velocity gradients, indicating that the rotation motions are strong enough to twist the field lines. All of the protostars
with a standard-hourglass field morphology show no significant velocity gradient due to the strong magnetic braking.

9

Chondrule Formation During Low-Speed Collisions of Planetesimals: A Hybrid Splash23. Flyby Framework
William Herbst, James P. Greenwood ⋆ Chondrules probably formed during a small window of time ∼1-4 Ma

after CAIs, when most solid matter in the asteroid belt was already in the form of km-sized planetesimals. They are
unlikely, therefore, to be “building blocks" of planets or abundant on asteroids, but more likely to be a product ofenergetic events common in the asteroid belt at that epoch. Laboratory experiments indicate that they could haveformed when solids of primitive composition were heated to temperatures of ∼1600 K and then cooled for minutes tohours. A plausible heat source for this is magma, which is likely to have been abundant in the asteroid belt at thattime, and only that time, due to the trapping of 26 Al decay energy in planetesimal interiors. Here we propose thatchondrules formed during low-speed (≲ 1 km s−1 ) collisions between large planetesimals when heat from their interiors
was released into a stream of primitive debris from their surfaces.
p Heating would have been essentially instantaneousand cooling would have been on the dynamical time scale, 1/ (Gρ) ∼ 30 minutes, where ρ is the mean density ofa planetesimal. Many of the heated fragments would have remained gravitationally bound to the merged object andcould have suffered additional heating events as they orbited and ultimately accreted to its surface. This is a hybridof the splash and flyby models: we propose that it was the energy released from a body’s molten interior, not its mass,that was responsible for chondrule formation by heating primitive debris that emerged from the collision.

24. An Episode of Occultation Events in Gaia21bcv

Klaus W. Hodapp, Eric Gaidos, Matthew A. Kenworthy, Michael Tucker, Benjamin J. Shappee, Anna V.
Payne, Aaron Do ⋆ A previously unremarkable star near the Canis Major OB1/R1 association underwent an episodeof multiple deep brightness minima. Light curves based on archival Gaia, ZTF, NEOWISE data and additional
observations from LCO and UKIRT show that the star was not variable prior to 2019 Aug 18 (MJD 58700), and onthat date started showing brightness dips of up to 3 magnitudes in the Gaia G and ZTF r bandpasses. After MJD
59500, 800 days after the onset of these dipping events, the star returned to its previous brightness, and no significant
dipping events have been recorded since. Compared to the stable phase, NEOWISE infrared photometry in the W1
and W2 bands indicates a generally redder color, and both decreases and increases in brightness at different times
during the dipping episode. The spectrum of Gaia21bcv taken after the end of the dipping episode shows several
neutral and ionized metal absorption lines, including Li, indicating a spectral type of K5. Variable emission from
[OI] was observed. The H alpha absorption in Gaia21bcv is too faint and irregular for this spectral type, indicatingthat the line is partly filled in by variable emission, a signature of weak episodic accretion. Gaia21bcv lies above thezero-age main sequence, but is much fainter than typical R CrB stars. We interpret the light curve of Gaia21bcv
as being similar to the occultation events in Epsilon Aurigae, i.e., occultation by a disk around a companion object
orbiting the primary star.

25. The outflow of the protostar in B335: I

Klaus W. Hodapp, Laurie L. Chu, Thomas Greene, Michael R. Meyer, Doug Johnstone, Marcia J. Rieke,
John Stansberry, Martha Boyer, Charles Beichman, Scott Horner, Tom Roellig, George Rieke, Eric T. Young⋆ The isolated globule B335 contains a single, low luminosity Class 0 protostar associated with a bipolar nebulaand outflow system seen nearly perpendicular to its axis. We observed the innermost regions of this outflow as partof JWST/NIRCam GTO program 1187, primarily intended for wide-field slitless spectroscopy of background stars
behind the globule. We find a system of expanding shock fronts with kinematic ages of only a few decades emerging
symmetrically from the position of the embedded protostar, which is not directly detected at NIRCam wavelengths.
The innermost and youngest of the shock fronts studied here shows strong emission from CO. The next older shock
front shows less CO and the third shock front shows only H2 emission in our data. This third and most distant ofthese inner shock fronts shows substantial evolution of its shape since it was last observed with high spatial resolution
in 1996 with Keck/NIRC. This may be evidence of a faster internal shock catching up with a slower one and of thetwo shocks merging.

1026. Cloud-cloud collision and cluster formation in the W5-NW complex
Namitha Issac, Anindya Saha, Saanika Choudhary, Aakash Chaudhary, Anandmayee Tej, Hong-Li Liu, Tie Liu,
Maheswar Gopinathan ⋆ We present a detailed structural and gas kinematic study of the star-forming complex W5-

NW. A cloud-cloud collision scenario unravels with evidences of collision induced star and cluster formation. Various
signatures of cloud-cloud collision such as "complementary distribution" and "bridging-features" are explored. At thecolliding region, the two clouds have complementary morphologies, where W5-NWb has a filamentary key-like shapewhich fits into the U-shaped cavity in W5-NWa that behaves like a keyhole. The interaction region between the two
clouds is characterised by bridging features with intermediate velocities connecting the two clouds. A skewed V-shaped
bridging feature is also detected at the site of collision. A robust picture of the molecular gas distribution highlighting
the bridges is seen in the position-position-velocity diagram obtained using the SCOUSEPY algorithm. Star cluster
formation with an over-density of Class I and Class II young stellar objects is also seen towards this cloud complex,
likely triggered by the cloud collision event.

27.

Atmospheric Retrievals of the Young Giant Planet ROXs 42B b from Low- and HighResolution Spectroscopy
Julie Inglis, Nicole L. Wallack, Jerry W. Xuan, Heather A. Knutson, Yayaati Chachan, Marta L. Bryan,
Brendan P. Bowler, Aishwarya Iyer, Tiffany Kataria, Björn Benneke ⋆ Previous attempts have been made tocharacterize the atmospheres of directly imaged planets at low-resolution (R∼10s-100s), but the presence of clouds hasoften led to degeneracies in the retrieved atmospheric abundances with cloud opacity and temperature structure thatbias retrieved compositions. In this study, we perform retrievals on the ultra-young (≲ 5 Myr) directly imaged planet
ROXs 42B b with both a downsampled low-resolution JHK-band spectrum from Gemini/NIFS and Keck/OSIRIS, anda high-resolution K-band spectrum from pre-upgrade Keck/NIRSPAO. Using the atmospheric retrieval framework ofpetitRADTRANS, we analyze both data sets individually and combined. We additionally fit for the stellar abundancesand other physical properties of the host stars, a young M spectral type binary, using the SPHINX model grid. We findthat the measured C/O, 0.50 ± 0.05, and metallicity, [Fe/H] = −0.67 ± 0.35, for ROXs 42B b from our high-resolution
spectrum agree with that of its host stars within 1σ. The retrieved parameters from the high-resolution spectrum arealso independent of our choice of cloud model. In contrast, the retrieved parameters from the low-resolution spectrum
show strong degeneracies between the clouds and the retrieved metallicity and temperature structure. When we
retrieve on both data sets together, we find that these degeneracies are reduced but not eliminated, and the final
results remain highly sensitive to cloud modeling choices. We conclude that high-resolution spectroscopy offers themost promising path for reliably determining atmospheric compositions of directly imaged companions independentof their cloud properties.

28. The Gaia-ESO Survey: Empirical estimates of stellar ages from lithium equivalent
widths (EAGLES)
R. D. Jeffries, R. J. Jackson, Nicholas J. Wright, G. Weaver, G. Gilmore, S. Randich, A. Bragaglia, A. J. Korn,
R. Smiljanic, K. Biazzo, A. R. Casey, A. Frasca, A. Gonneau, G. Guiglion, L. Morbidelli, L. Prisinzano, G. G.
Sacco, G. Tautvaišienė, C. C. Worley, S. Zaggia ⋆ We present an empirical model of age-dependent photosphericlithium depletion, calibrated using a large, homogeneously-analysed sample of 6200 stars in 52 open clusters, withages from 2–6000 Myr and −0.3 < [Fe/H] < 0.2, observed in the Gaia-ESO spectroscopic survey. The model is used
to obtain age estimates and posterior age probability distributions from measurements of the Li I 6708A equivalent
width for individual (pre) main sequence stars with 3000 < Teff /K < 6500, a domain where age determination fromthe HR diagram is either insensitive or highly model-dependent. In the best cases, precisions of 0.1 dex in log age
are achievable; even higher precision can be obtained for coeval groups and associations where the individual age
probabilities of their members can be combined. The method is validated on a sample of exoplanet-hosting youngstars, finding agreement with claimed young ages for some, but not others. We obtain better than 10 per cent precisionin age, and excellent agreement with published ages, for seven well-studied young moving groups. The derived ages
for young clusters (< 1 Gyr) in our sample are also in good agreement with their training ages, and consistent withseveral published, model-insensitive lithium depletion boundary ages. For older clusters there remain systematic age
errors that could be as large as a factor of two. There is no evidence to link these errors to any strong systematic
metallicity dependence of (pre) main sequence lithium depletion, at least in the range −0.29 < [Fe/H] < 0.18. Our
methods and model are provided as software – "Empirical AGes from Lithium Equivalent widthS" (EAGLES).

11

29.

The Radcliffe Wave is Oscillating
Ralf Konietzka, Alyssa A. Goodman, Catherine Zucker, Andreas Burkert, João Alves, Michael Foley, Cameren
Swiggum, Maria Koller, Núria Miret-Roig ⋆ Our Sun lies within 300 pc of the 2.7-kpc-long sinusoidal chain of

dense gas clouds known as the Radcliffe Wave. The structure’s wave-like shape was discovered using 3D dust mapping,but initial kinematic searches for oscillatory motion were inconclusive. Here we present evidence that the Radcliffe
Wave is oscillating through the Galactic plane while also drifting radially away from the Galactic Center. We use
measurements of line-of-sight velocity for 12CO and 3D velocities of young stellar clusters to show that the most
massive star-forming regions spatially associated with the Radcliffe Wave (including Orion, Cepheus, North America,and Cygnus X) move as if they are part of an oscillating wave driven by the gravitational acceleration of the Galactic
potential. By treating the Radcliffe Wave as a coherently oscillating structure, we can derive its motion independentlyof the local Galactic mass distribution, and directly measure local properties of the Galactic potential as well as theSun’s vertical oscillation period. In addition, the measured drift of the Radcliffe Wave radially outward from the
Galactic Center suggests that the cluster whose supernovae ultimately created today’s expanding Local Bubble may
have been born in the Radcliffe Wave.

30. Magnetic fields of protoplanetary disks

Sergey A. Khaibrakhmanov ⋆ We review the current status of studies on accretion and protoplanetary disks ofyoung stars with large-scale magnetic fields. Observational data on magnetic fields of the disks are compiled andanalysed. Modern analytical and numerical MHD models of protoplanetary disks are discussed. The mechanisms ofangular momentum transport via turbulence, magnetic tensions and outflows are outlined. We consider the influenceof Ohmic dissipation, magnetic ambipolar diffusion, magnetic buoyancy, and the Hall effect on the evolution of themagnetic flux in disks. Modern MHD models of accretion disks show that the magnetic field can influence the structureof protoplanetary disks. We argue that the available observational data on the magnetic fields in protoplanetary disks
can be interpreted within the framework of fossil magnetic field theory. We summarize the problems of the modern
theory of accretion and protoplanetary disks with magnetic fields and also outline the prospects for further research.

31. SMA detection of an extreme millimeter flare from the young class III star HD 283572

Joshua Bennett Lovell, Garrett K. Keating, David J. Wilner, Sean M. Andrews, Meredith MacGregor, Ramisa
Akther Rahman, Ramprasad Rao, Jonathan P. Williams ⋆ We present evidence of variable 1.3 millimeter emission

from the 1-3 Myr, SpT G2-G5 class III YSO, HD 283572. HD 283572 was observed on 8 dates with the Submillimeter
Array between 2021 December and 2023 May, a total on-source time of 10.2 hours, probing a range of timescales down
to 5.2 seconds. Averaging all data obtained on 2022 Jan 17 shows a 4.4 mJy (8.8σ) point source detection with anegative spectral index (α=−2.7±1.2), with peak emission rising to 13.8 mJy in one 3 minute span, and 25 mJy in one
29.7 second integration (Lν = 4.7 × 1017 erg s−1 Hz−1 ). Combining our data for the other 7 dates shows no detection,with an rms noise of 0.24 mJy beam−1 . The stochastic millimeter enhancements on time frames of seconds–minutes–
hours with negative spectral indices are most plausibly explained by synchrotron or gyro-synchrotron radiation fromstellar activity. HD 283572’s 1.3 mm light-curve has similarities with variable binaries, suggesting HD 283572’s activity
may have been triggered by interactions with an as-yet undetected companion. We additionally identify variability of
HD 283572 at 10 cm, from VLASS data. This study highlights the challenges of interpreting faint mm emission fromevolved YSOs that may host tenuous disks, and suggests that a more detailed temporal analysis of spatially unresolved
data is generally warranted. The variability of class III stars may open up new ground for understanding the physics
of flares in the context of terrestrial planet formation.

32. Forming localized dust concentrations in a dust ring: DM Tau case study
Hauyu Baobab Liu, Takayuki Muto, Mihoko Konishi, Chia-Ying Chung, Jun Hashimoto, Kiyoaki Doi, Ruobing
Dong, Tomoyuki Kudo, Yasuhiro Hasegawa, Yuka Terada, Akimasa Kataoka ⋆ The previous, high angularresolution 225 GHz (∼1.3 mm) continuum observations on the transitional disk DM Tau have resolved an outer ringat 20-120 au radii that is weakly azimuthally asymmetric. We aimed to examine dust growth and filtration in theouter ring. We performed the ∼0′′ .06 (∼8.7 au) resolution Karl G. Jansky Very Large Array (JVLA) 40-48 GHz(∼7 mm; Q band) continuum observations and the complementary observations at lower frequencies. In addition, we
analyzed the archival JVLA observations that were taken since 2010. Intriguingly, the Q band image resolved theazimuthally highly asymmetric, knotty dust emission sources close to the inner edge of the outer ring. Fitting the12

8-700 GHz spectral energy distribution (SED) with two dust components indicates that the maximum grain size inthese knotty dust emission sources is likely ≳300 µm while it is ≲50 µm in the rest of the ring. These results may
be explained by trapping of inward migrating grown dust close to the ring inner edge. The exact mechanism fordeveloping the azimuthal asymmetry has not yet been identified, which may be due to planet-disk interaction thatmight also be responsible for the creation of the dust cavity and pressure bump, or the fluid instabilities and vortex
formation due to shear motions. Finally, we remark that the asymmetries in DM Tau are hard to diagnose fromthe ≳225 GHz observations owing to a high optical depth at the ring. In other words, the apparent symmetric or
asymmetric morphology of the transitional disks may be related to the optical depths of those disks at the observing
frequency.

Spatial Variations of Dust Opacity and Grain Growth in Dark Clouds: L1689, L1709
33. and L1712
Jun Li, Biwei Jiang, He Zhao, Xi Chen, Yang Yang ⋆ The far-infrared (FIR) opacity of dust in dark clouds within

the Ophiuchus molecular cloud is investigated through multi-wavelength infrared observations from UKIDSS, Spitzer
and Herschel. Employing the infrared color excess technique with both near-infrared (NIR) and mid-infrared (MIR)
photometric data, a high-resolution extinction map in the K band (AK ) is constructed for three dark clouds: L1689,
L1709, and L1712. The derived extinction map has a resolution of 1′ and reaches a depth of AK ∼ 3 mag. The
FIR optical depths τ250 at a reference wavelength of 250 µm are obtained by fitting the Herschel PACS and SPIRE
continuum data at 100, 160, 250, 350 and 500 µm using a modified blackbody model. The average dust opacity perunit gas mass at 250µm, rκ250 is determined through a pixel-by-pixel correlation of τ250 with AK , yielding a value ofapproximately 0.09 cm2 g−1 , which is about 2-3 times higher than the typical value in the diffuse interstellar medium(ISM). Additionally, an independent analysis across 16 sub-regions within the Ophiuchus cloud indicates spatial
variations in dust opacity, with values ranging from 0.07-0.12 cm2 g−1 . Although the observed trend of increasing
dust opacity with higher extinction implies grain growth, our findings indicate that rapid grain growth clearly not yet
occurred in the dark clouds studied in this work.

34. Dust Accumulation near the Magnetospheric Truncation of Protoplanetary Discs. II.
The Effects of Opacity and Thermal Evolution
Rixin Li, Yi-Xian Chen, Douglas N. C. Lin ⋆ Dust trapping in the global pressure bump induced by magnetospherictruncation offers a promising formation mechanism for close-in super-Earths/sub-Neptunes. These planets likely formin evolved protoplanetary discs, where the gas temperature at the expanding truncation radius become amiable torefractory solids. However, dust accumulation may alter the disc opacity such that thermal evolution is inevitable.
To better understand how thermodynamics affects this planet formation pathway, we conduct a suite of local dust
evolution simulations in an idealized inner disc model. Our calculations take into account self-consistent opacitydependent temperature changes as well as dust evaporation and vapour condensation. We find that disc thermal
evolution regulates dust growth and evolution, discouraging any accumulation of small particles that drives the increaseof opacity and temperature. Significant retention of dust mass takes place when the disc environments allow runaway
growth of large solids beyond the fragmentation barrier, where small particles are then swept up and preserved. Our
results further validate dust accumulation near disc truncation as a promising mechanism to form close-in planets.

35. Observations of high-order multiplicity in a high-mass stellar protocluster
Shanghuo Li, Patricio Sanhueza, Henrik Beuther, Huei-Ru Vivien Chen, Rolf Kuiper, Fernando A. Olguin,
Ralph E. Pudritz, Ian W. Stephens, Qizhou Zhang, Fumitaka Nakamura, Xing Lu, Rajika L. Kuruwita, Takeshi
Sakai, Thomas Henning, Kotomi Taniguchi, Fei Li ⋆ The dominant mechanism forming multiple stellar systems in

the high-mass regime (M∗ ≳ 8 M⊙ ) remained unknown because direct imaging of multiple protostellar systems at earlyphases of high-mass star formation is very challenging. High-mass stars are expected to form in clustered environments
containing binaries and higher-order multiplicity systems. So far only a few high-mass protobinary systems, and no
definitive higher-order multiples, have been detected. Here we report the discovery of one quintuple, one quadruple, one
triple and four binary protostellar systems simultaneously forming in a single high-mass protocluster, G333.23–0.06,
using Atacama Large Millimeter/submillimeter Array high-resolution observations. We present a new example of agroup of gravitationally bound binary and higher-order multiples during their early formation phases in a protocluster.
This provides the clearest direct measurement of the initial configuration of primordial high-order multiple systems,

13with implications for the in situ multiplicity and its origin. We find that the binary and higher-order multiple
systems, and their parent cores, show no obvious sign of disk-like kinematic structure. We conclude that the observed
fragmentation into binary and higher-order multiple systems can be explained by core fragmentation, indicating its
crucial role in establishing the multiplicity during high-mass star cluster formation.

JWST-MIRI Spectroscopy of Warm Molecular Emission and Variability in the AS 209
36. Disk
Carlos E. Muñoz-Romero, Karin I. Öberg, Andrea Banzatti, Klaus M. Pontoppidan, Sean M. Andrews, David
J. Wilner, Edwin A. Bergin, Ian Czekala, Charles J. Law, Colette Salyk, Richard Teague, Chunhua Qi, Jennifer
B. Bergner, Jane Huang, Catherine Walsh, Viviana V. Guzmán, L. Ilsedore Cleeves, Yuri Aikawa, Jaehan Bae,
Alice S. Booth, Gianni Cataldi, John D. Ilee, Romane Le Gal, Feng Long, Ryan A. Loomis, François Menard,
Yao Liu ⋆ We present MIRI MRS observations of the large, multi-gapped protoplanetary disk around the T-Tauri

star AS 209. The observations reveal hundreds of water vapor lines from 4.9 to 25.5 µm towards the inner ∼ 1 au in
the disk, including the first detection of ro-vibrational water emission in this disk. The spectrum is dominated by hot(∼ 800 K) water vapor and OH gas, with only marginal detections of CO2 , HCN, and a possible colder water vapor
component. Using slab models with a detailed treatment of opacities and line overlap, we retrieve the column density,
emitting area, and excitation temperature of water vapor and OH, and provide upper limits for the observable massof other molecules. Compared to MIRI spectra of other T-Tauri disks, the inner disk of AS 209 does not appear to
be atypically depleted in CO2 nor HCN. Based on Spitzer IRS observations, we further find evidence for molecularemission variability over a 10-year baseline. Water, OH, and CO2 line luminosities have decreased by factors 2-4 inthe new MIRI epoch, yet there are minimal continuum emission variations. The origin of this variability is yet to beunderstood.

High-resolution ALMA observations of compact discs in the wide-binary system Sz 65
37. and Sz 66
J. M. Miley, J. Carpenter, R. Booth, J. Jennings, T. J. Haworth, M. Vioque, S. Andrews, D. Wilner, M.
Benisty, J. Huang, L. Perez, V. Guzman, L. Ricci, A. Isella ⋆ Substructures in disc density are ubiquitous in

the bright extended discs that are observed with high resolution. These substructures are intimately linked to thephysical mechanisms driving planet formation and disc evolution. Surveys of star-forming regions find that mostdiscs are in fact compact, less luminous, and do not exhibit these same substructures. It remains unclear whether
compact discs also have similar substructures or if they are featureless. This suggests that different planet formationand disc evolution mechanisms operate in these discs. We investigated evidence of substructure within two compact
discs around the stars Sz 65 and Sz 66 using high angular resolution observations with ALMA at 1.3 mm. The twostars form a wide-binary system with 6.36 arcsec separation. The continuum observations achieve a synthesised beammajor axis of 0.026 arcsec, equivalent to about 4.0 au, enabling a search for substructure on these spatial scales and acharacterisation of the gas and dust disc sizes with high precision. We analysed the data in the image plane through ananalysis of reconstructed images, as well as in the uv plane by modelling the visibilities and by an analysis of the 12CO
emission line. Comparisons were made with high-resolution observations of compact discs and radially extended discs.
We find evidence of substructure in the dust distribution of Sz 65, namely a shallow gap centred at approximately 20
au, with an emission ring exterior to it. Ninety percent of the measured continuum flux is found within 27 au, and the
distance for 12CO is 142 au. The observations show that Sz 66 is very compact: 90 per cent of the continuum flux iscontained within 16 au, and 48 au for the gas. While the overall prevalence and diversity of substructure in compact
discs relative to larger discs is yet to be determined, we find evidence that substructures can exist in compact discs.

Angular Momentum Transport in Binary Star Formation: The Enhancement of Magneto38. Rotational Instability and Role of Outflows
Tomoaki Matsumoto ⋆ The formation of binary stars is highly influenced by magnetic fields, which play a crucial rolein transporting angular momentum. We conducted three-dimensional numerical simulations of binary star accretion
via a circumbinary disk, taking into account a magnetic field perpendicular to the disk and an infalling envelope. Our
simulations reproduce the following phenomena: (1) spiral arms associated with circumstellar disks, (2) turbulence inthe circumbinary disk, induced by magneto-rotational instability (MRI), (3) a fast outflow launched from each circumstellar disk, and (4) a slow outflow from the circumbinary disk. The binary models exhibit a higher α-parameter14

than the corresponding single star models, indicating that the binary stars enhance MRI turbulence. Moreover, an
infalling envelope also enhance the turbulence, leading to a high α-parameter. While the spiral arms promotes radialflow, causing transfer of mass and angular momentum within the circumbinary disk, the MRI turbulence and outflows
are main drivers of angular momentum transfer to reduce the specific angular momentum of the system.

39. Rotation curves in protoplanetary disks with thermal stratification
Paola Martire, Cristiano Longarini, Giuseppe Lodato, Giovanni P. Rosotti, Andrew Winter, Stefano Facchini,
Caitlyn Hardiman, Myriam Benisty, Jochen Stadler, Andrés F. Izquierdo, Leonardo Testi ⋆ In recent years thegas kinematics probed by molecular lines detected with ALMA has opened a new window to study protoplanetarydisks. High spatial and spectral resolution observations have revealed the complexity of protoplanetary disk structure
and correctly interpreting these data allow us to gain a better comprehension of the planet formation process. We
investigate the impact of thermal stratification on the azimuthal velocity of protoplanetary disks. High resolution
gas observations are showing velocity differences between CO isotopologues, which cannot be adequately explainedwith vertically isothermal models. The aim of this work is to determine whether a stratified model can explain thisdiscrepancy. We analytically solve the hydrostatic equilibrium for a stratified disk and we derive the azimuthal velocity.
We test the model with SPH numerical simulations and then we use it to fit for star mass, disk mass and scale radiusof the sources in the MAPS sample. In particular, we use 12CO and 13CO datacubes.

40. Aeolian erosion in protoplanetary discs: How impactful it is on dust evolution?

Stéphane Michoulier, Jean-François Gonzalez, Evgeni Grishin, Clément Petetin ⋆ Context: Many barriers
prevent dust to form planetesimals via coagulation in protoplanetary discs, such as bouncing, collisional fragmentation
or aeolian erosion. Modelling dust and the different phenomena that can alter its evolution is therefore needed. Multiple
solutions have been proposed, but still need to be confirmed. Aims: In this paper, we explore the role aeolian erosion
plays in the evolution of dust. Methods: We use a monodisperse model to account for dust growth and fragmentation,
implemented in a 1D model to compute the evolution of single grains and a 3D SPH code to compute the global
evolution of dust and gas. We test the erosion model in our code and ensured it matches previous results. Results:
With a model of disc reproducing observations, we show with both 1D and 3D studies that erosion is not significant
during the evolution of dust when we take fragmentation into consideration. With a low-viscosity disc, fragmentationis less of a problem, but grain growth is also less important, preventing the formation of large objects anyway. In dust
traps, close to the star, erosion is also not impactful, even when fragmentation is turned off. Conclusions: We show inthis paper that aeolian erosion is negligible when radial drift, fragmentation and dust traps are taken into account anddoes not alter the dust evolution in the disc. However, it can have an impact on later stages, i.e. when the streaming
instability forms large clumps close to the star, or when planetesimals are captured.

New method for estimating molecular cloud distances based on Gaia, 2MASS, and the
41. TRILEGAL galaxy model
Juan Mei, Zhiwei Chen, Zhibo Jiang, Sheng Zheng, Haoran Feng ⋆ We propose a new method for estimating the

distances of molecular clouds traced by CO line emission. Stars from 2MASS and Gaia EDR3 are selected as on-cloudstars when they are projected on a cloud. The background on-cloud stars have redder colors on average than theforeground stars. Instead of searching for stars projected away from the cloud, we employed the TRILEGA galaxy
model to mimic the stellar population without cloud extinction along the sightline toward the cloud. Our method
does not require an exact boundary of a cloud. The boundaries are highly variable and depend on the sensitivity ofthe molecular line data. For each cloud, we compared the distributions of on-cloud stars to the TRILEGAL stellar
populations in the diagram of J − Ks color versus distance. The intrinsic J − Ks colors of main-sequence and evolvedstars from TRILEGAL were considered separately, and they were used as the baseline for subtracting the observed
J − Ks colors. The baseline-corrected J − Ks color was deployed with the Bayesian analysis and Markov chain Monte
Carlo sampling to determine the distance at which the J − Ks color jump is largest. This method was successfully
applied to measure the distances of 27 molecular clouds, which were selected from previously published cloud samples.
By replacing TRILEGAL with the GALAXIA galaxy model, we were able to measure the distances for 21 of the 27
clouds. The distances of the 21 clouds based on the GALAXIA model agree well with those based on the TRILEGAL
model. The distances of the 27 clouds estimated by this method are consistent with previous estimates. We will apply
this new method to a larger region of the gaseous galactic plane, in particular, for the inner galactic region, where a15

region free of CO emission is hard to separate from the crowded field of clouds.
13
42. ALMA view of the L1448-mm protostellar system on disk scales: CH3 OH and H CN
as new disk wind tracers

P. Nazari, B. Tabone, A. Ahmadi, S. Cabrit, E. F. van Dishoeck, C. Codella, J. Ferreira, L. Podio, Ł. Tychoniec,
M. L. van Gelder ⋆ Protostellar disks are known to accrete, however, the exact mechanism that extracts the angularmomentum and drives accretion in the low-ionization "dead" region of the disk is under debate. In recent years,
magneto-hydrodynamic (MHD) disk winds have become a popular solution. Yet, observations of these winds require
both high spatial resolution (∼10s au) and high sensitivity, which has resulted in only a handful of MHD disk windcandidates so far. In this work we present high angular resolution (∼30 au) ALMA observations of the emblematic
L1448-mm protostellar system and find suggestive evidence for an MHD disk wind. The disk seen in dust continuum(∼0.9 mm) has a radius of ∼23 au. Rotating infall signatures in H13 CO+ indicate a central mass of 0.4 ± 0.1 M⊙ anda centrifugal radius similar to the dust disk radius. Above the disk, we unveil rotation signatures in the outflow tracedby H13 CN, CH3 OH, and SO lines and find a kinematical structure consistent with theoretical predictions for MHD
disk winds. This is the first detection of an MHD disk wind candidate in H13 CN and CH3 OH. The wind launchingregion estimated from cold MHD wind theory extends out to the disk edge. The magnetic lever arm parameter wouldbe λϕ ≃ 1.7, in line with recent non-ideal MHD disk models. The estimated mass-loss rate is ∼4 times the protostellar
accretion rate (Ṁacc ≃ 2 × 10−6 M⊙ /yr) and suggests that the rotating wind could carry enough angular momentum
to drive disk accretion.

43. Gas Phase Ions in Protoplanetary Disks from Collisions of Solids
Jakob Penner, Gerhard Wurm, Jens Teiser ⋆ Ionization is important for magnetohydrodynamics and chemistry
in protoplanetary disks but known ionization sources are often weak along the midplane. We present, for the firsttime, data from a laboratory experiment, where we measure ions from colliding mm-basalt grains emitted into thesurrounding gas phase. This positive detection implies that very basic collisions in early phases of planet formation
are sources of ionization. The midplane of protoplanetary disks might be ionized despite the lack of intense radiation
sources.

44. Accretion and magnetism on young eccentric binaries: DQ Tau and AK Sco
Kim Pouilly, Axel Hahlin, Oleg Kochukhov, Julien Morin, Ágnes Kóspál ⋆ The accretion and ejection of massin pre-main sequence (PMS) stars are key processes in stellar evolution as they shape the stellar angular momentum
transport necessary for the stars’ stability. Magnetospheric accretion onto classical T Tauri stars and low-mass PMS
stars has been widely studied in the single-star case. This process can not be directly transferred to PMS binary
systems, as tidal and gravitation effects, and/or accretion from a circumbinary disc (with variable separation of thecomponents in the case of eccentric orbits) are in place. This work examines the accretion process of two PMS
eccentric binaries, DQ Tau and AK Sco, using high-resolution spectropolarimetric time series. We investigate howmagnetospheric accretion can be applied to these systems by studying the accretion-related emission lines and themagnetic field of each system. We discover that both systems are showing signs of magnetospheric accretion, despite
their slightly different configurations, and the weak magnetic field of AK Sco. Furthermore, the magnetic topology
of DQ Tau A shows a change relative to the previous orbital cycle studied: previously dominated by the poloidal
component, it is now dominated by the toroidal component. We also report an increase of the component’s accretionand the absence of an accretion burst at the apastron, suggesting that the component’s magnetic variation might be thecause of the inter-cycle variations of the system’s accretion. We conclude on the presence of magnetospheric accretionfor both systems, together with gravitational effects, especially for AK Sco, composed of more massive components.

45. On the growth and evolution of low-mass planets in pressure bumps

Arnaud Pierens, Sean N. Raymond ⋆ Observations of protoplanetary discs have revealed dust rings which are

likely due to the presence of pressure bumps in the disc. Because these structures tend to trap drifting pebbles,
it has been proposed that pressure bumps may play an important role in the planet formation process. In thispaper, we investigate the orbital evolution of a 0.1 M⊕ protoplanet embedded in a pressure bump using 2-dimensionalhydrodynamical simulations of protoplanetary discs consisting of gas and pebbles. We examine the role of thermal
forces generated by the pebble accretion-induced heat release, taking into account the feedback between luminosity
16

and eccentricity. We also study the effect of the pebble-scattered flow on the planet’s orbital evolution. Due toaccumulation of pebbles at the pressure bump, the planet’s accretion luminosity is high enough to induce significant
eccentricity growth through thermal forces. Accretion luminosity is also responsible for vortex formation at the planet
position through baroclinic effects, which cause the planet escape from the dust ring if dust feedback onto the gas isneglected. Including the effect of the dust back-reaction leads to weaker vortices, which enable the planet to remainclose to the pressure maximum on an eccentric orbit. Simulations in which the planet mass is allowed to increase as aconsequence of pebble accretion resulted in the formation of giant planet cores with mass in the range 5 − 20 M⊕ over
∼ 2 × 104 yrs. This occurs for moderate values of the Stokes number St ≈ 0.01 such that the pebble drift velocity
is not too high and the dust ring mass not too small. Our results suggest that pressure bumps mays be preferred
locations for the formation of giant planets, but this requires a moderate level of grain growth within the disc.

Probing the physics of star formation (ProPStar): I. First resolved maps of the electron
46. fraction and cosmic-ray ionization rate in NGC 1333
Jaime E. Pineda, Olli Sipilä, Dominique M. Segura-Cox, Maria Teresa Valdivia-Mena, Roberto Neri, Michael
Kuffmeier, Alexei V. Ivlev, Stella S. R. Offner, Maria Jose Maureira, Paola Caselli, Silvia Spezzano, Nichol
Cunningham, Anika Schmiedeke, Mike Chen ⋆ Electron fraction and cosmic-ray ionization rates (CRIR) in star-

forming regions are important quantities in astrochemical modeling and are critical to the degree of coupling between
neutrals, ions, and electrons, which regulates the dynamics of the magnetic field. However, these are difficult quantities
to estimate. We aim to derive the electron fraction and CRIR maps of an active star-forming region. We combined
observations of the nearby NGC 1333 star-forming region carried out with the NOEMA interferometer and IRAM
30-m single dish to generate high spatial dynamic range maps of different molecular transitions. We used the DCO+
and H13 CO+ ratio (in addition to complementary data) to estimate the electron fraction and produce cosmic-ray
ionization rate maps. We derived the first large-area electron fraction and CRIR resolved maps in a star-forming
region, with typical values of 10−6.5 and 10−16.5 s−1 , respectively. The maps present clear evidence of enhanced values
around embedded young stellar objects (YSOs). This provides strong evidence for locally accelerated cosmic rays. We
also found a strong enhancement toward the northwest region in the map that might be related either to an interaction
with a bubble or to locally generated cosmic rays by YSOs. We used the typical electron fraction and derived a MHD
turbulence dissipation scale of 0.054 pc, which could be tested with future observations. We found a higher cosmic-ray
ionization rate compared to the canonical value for N (H2 ) = 1021 − 1023 cm−2 of 10−17 s−1 in the region, and it
is likely generated by the accreting YSOs. The high value of the electron fraction suggests that new disks will form
from gas in the ideal-MHD limit. This indicates that local enhancements of ζ(H2 ), due to YSOs, should be taken into
account in the analysis of clustered star formation.

47. Spectral characterization of young LT dwarfs

L. Piscarreta, K. Mužić, V. Almendros-Abad, A. Scholz ⋆ We aim to provide a detailed characterization of nearinfrared spectra for young LT brown dwarfs, including robust spectral typing, calibrating spectral indices, identifying
possible binaries, and selecting suitable spectral standards. We processed and analyzed archival spectra from VLT/Xshooter for a sample of 56 dwarfs with ages between 10 and 600 Myr and spectral types between late-M and mid-T. We
re-determine spectral types by comparing them with a set of literature templates and assess a large range of spectral
indices, calibrated using a specifically designed literature sample. We are able to identify 15 spectral indices that are
useful for spectral typing for specific spectral ranges discussed here and provide the scaling relations with spectral
types. Moreover, we also identify 6 spectral indices which can be used to separate young L dwarfs from the field ones.
The equivalent-widths of the alkali lines show a correlation with age, increasing towards the objects with higher surface
gravity. From our sample, we confirm 3 that are likely to be binaries by their anomalous spectra that appear to bebetter fitted by a combination of spectral types. Finally, we identify 12 objects as preliminary near-infrared spectral
standards for young LT dwarfs. This paper presents a significant step toward understanding the spectral sequence andproperties of young L and T dwarfs. The relations and standards provided here will be useful for future spectroscopic
work on young brown dwarfs and giant planets.

17

Cracking the relation between mass and 1P-star fraction of globular clusters: I. Present48. day cluster masses as a first tool
Geneviève Parmentier ⋆ The phenomenon of multiple stellar populations is exacerbated in massive globular clusters,with the fraction of first-population (1P) stars a decreasing function of the cluster present-day mass. We decipher thisrelation in far greater detail than has been done so far. We assume (i) a fixed stellar mass threshold for the formation of
second-population (2P) stars, (ii) a power-law scaling F1P ∝ m−1
ecl between the mass mecl of newly-formed clusters andtheir 1P-star fraction F1P , and (iii) a constant F1P over time. The F1P (mecl ) relation is then evolved up to an age of
12Gyr for tidal field strengths representative of the entire Galactic halo. The 12Gyr-old model tracks cover extremely
well the present-day distribution of Galactic globular clusters in (mass,F1P ) space. The distribution is curtailed on
its top-right side by the scarcity of clusters at large Galactocentric distances, and on its bottom-left side by the initialscarcity of very high-mass clusters, and dynamical friction. Given their distinct dissolution rates, "inner" and "outer"model clusters are offset from each other, as observed. The locus of Magellanic Clouds clusters in (mass,F1P ) spaceis as expected for intermediate-age clusters evolving in a gentle tidal field. Given the assumed constancy of F1P ,we conclude that 2P-stars do not necessarily form centrally-concentrated. We infer a minimum mass of 4 · 105 M⊙
for multiple-populations clusters at secular evolution onset. This high-mass threshold severely limits the amount of
2P-stars lost from evolving clusters, thereby fitting the low 2P-star fraction of the Galactic halo field.

Introducing cuDisc: a 2D code for protoplanetary disc structure and evolution calcula49. tions
Alfie Robinson, Richard A. Booth, James E. Owen ⋆ We present a new 2D axisymmetric code, cuDisc, for studying protoplanetary discs, focusing on the self-consistent calculation of dust dynamics, grain size distribution and disctemperature. Self-consistently studying these physical processes is essential for many disc problems, such as structureformation and dust removal, given that the processes heavily depend on one another. To follow the evolution over substantial fractions of the disc lifetime, cuDisc uses the CUDA language and libraries to speed up the code through GPU
acceleration. cuDisc employs a second-order finite-volume Godonuv solver for dust dynamics, solves the Smoluchowski
equation for dust growth and calculates radiative transfer using a multi-frequency hybrid ray-tracing/flux-limiteddiffusion method. We benchmark our code against current state-of-the-art codes. Through studying steady-state
problems, we find that including 2D structure reveals that when collisions are important, the dust vertical structureappears to reach a diffusion-settling-coagulation equilibrium that can differ substantially from standard models that
ignore coagulation. For low fragmentation velocities, we find an enhancement of intermediate-sized dust grains atheights of 1 gas scale height due to the variation in collision rates with height, and for large fragmentation velocities,
we find an enhancement of small grains around the disc mid-plane due to collisional ”sweeping” of small grains bylarge grains. These results could be important for the analysis of disc SEDs or scattered light images, given theseobservables are sensitive to the vertical grain distribution.

DBNets: A publicly available deep learning tool to measure the masses of young planets
50. in dusty protoplanetary discs
Alessandro Ruzza, Giuseppe Lodato, Giovanni Pietro Rosotti ⋆ Current methods to characterize embedded
planets in protoplanetary disc observations are severely limited either in their ability to fully account for the observed
complex physics or in their computational and time costs. To address this shortcoming, we developed DBNets: a deeplearning tool, based on convolutional neural networks, that analyses substructures observed in the dust continuum
emission of protoplanetary discs to quickly infer the mass of allegedly embedded planets. We focussed on developing amethod to reliably quantify not only the planet mass, but also the associated uncertainty introduced by our modelling
and adopted techniques. Our tests gave promising results achieving an 87% reduction of the log Mp mean squared
error with respect to an analytical formula fitted on the same data (DBNets metrics: lmse 0.016, r2-score 97%). With
the goal of providing the final user of DBNets with all the tools needed to interpret their measurements and decide on
their significance, we extensively tested our tool on out-of-distribution data. We found that DBNets can identify inputs
strongly outside its training scope returning an uncertainty above a specific threshold and we thus provided a rejection
criterion that helps determine the significance of the results obtained. Additionally, we outlined some limitations of ourtool: it can be reliably applied only on discs observed with inclinations below approximately 60 deg, in the opticallythin regime, with a resolution 8 times better than the gap radial location and with a signal-to-noise ratio higher thanapproximately ten. Finally, we applied DBNets to 33 actual observations of protoplanetary discs measuring the massof 48 proposed planets and comparing our results with the available literature. We confirmed that most of the observed

18

gaps imply planets in the sub-Jupiter regime. DBNets is publicly available at dbnets.fisica.unimi.it.

51. Testing analytical methods to derive the cosmic-ray ionisation rate in cold regions via
synthetic observations
E. Redaelli, S. Bovino, A. Lupi, T. Grassi, D. Gaete-Espinoza, G. Sabatini, P. Caselli ⋆ Cosmic rays (CRs) heavily

impact the chemistry and physics of cold and dense star-forming regions. However, characterising their ionisation rateis still challenging from an observational point of view. In the past, a few analytical formulas have been proposed toinfer the cosmic-ray ionization rate ζ2 from molecular line observations. These have been derived from the chemical
kinetics of the involved species, but they have not been validated using synthetic data processed with a standard
observative pipeline. We aim to bridge this gap. We perform the radiative transfer on a set of three-dimensional
magneto-hydrodynamical simulations of prestellar cores, exploring different initial ζ2 , evolutionary stages, types ofradiative transfer (e.g. assuming local-thermodynamic-equilibrium conditions), and telescope responses. We thencompute the column densities of the involved tracers to determine ζ2 , using, in particular, the equation proposed by
Bovino et. al (2020) and by Caselli et al. (1998) both used nowadays. Our results confirm that the method of Bovino
et al. (2020) accurately retrieves the actual ζ2 within a factor of 2 − 3, in the physical conditions explored in our tests.
Since we also explore a non-local thermodynamic equilibrium radiative transfer, this work indirectly offers insights
into the excitation temperatures of common transitions at moderate volume densities (n ≈ 105 cm−3 ). We have also
performed a few tests using the formula proposed by Caselli et al. (1998), which overestimates the actual ζ2 by atleast two orders of magnitudes. We also consider a new derivation of this method, which, however, still leads to large
overestimates.

52. Predicting the Dominant Formation Mechanism of Multi-Planetary Systems
Cheyanne Shariat, Yasuhiro Hasegawa, Bradley M. S. Hansen, Tze Yeung Mathew Yu, Renyu Hu ⋆ Most, if

not all, sun-like stars host one or more planets, making multi-planetary systems commonplace in our galaxy. We utilize
hundreds of multi-planet simulations to explore the origin of such systems, focusing on their orbital architecture. The
first set of simulations assumes in-situ assembly of planetary embryos, while the second explores planetary migration.
After applying observational biases to the simulations, we compare them to 250+ observed multi-planetary systems,
including 13 systems with planets in the habitable zone. For all of the systems, we calculate two of the so-calledstatistical measures: the mass concentration (Sc ) and orbital spacing (Ss ). After analytic and empirical analyses, wefind that the measures are related to first-order with a power law: Sc ∼ Ssβ . The in-situ systems exhibit steeper powerlaw relations relative to the migration systems. We show that different formation scenarios cover different regions in
the Ss − Sc diagram with some overlap. Furthermore, we discover that observed systems with Ss < 30 are likely
dominated by the migration scenario, while those with Ss ≥ 30 are likely dominated by the in-situ scenario. We apply
these criteria to determine that a majority (62%) of observed multi-planetary systems formed via migration, whereas
most systems with currently observed habitable planets formed via in-situ assembly. This work provides methodsof leveraging the statistical measures (Ss and Sc ) to disentangle the formation history of observed multi-planetarysystems based on their present-day architectures.

A Statistical and Multiwavelength Photometric Analysis of a Young Embedded Open
53. Star Cluster: IC 1590
A. H. Sheikh, Biman J. Medhi ⋆ We present a statistical and multiwavelength photometric studies of young open

cluster IC 1590. We identified 91 cluster members using Gaia DR3 astrometry data using ensemble-based unsupervisedmachine learning techniques. From Gaia EDR3 data, we estimate the best-fitted parameters for IC 1590 using theAutomated Stellar Cluster Analysis package (ASteCA) yielding the distance d ∼ 2.87 ± 0.02 Kpc, age ∼ 3.54 ± 0.05
Myr, metallicity z ∼ 0.0212 ± 0.003, binarity value of ∼ 0.558, and extinction Av ∼ 1.252 ± 0.4 mag for an Rv valueof ∼ 3.322 ± 0.23. We estimate the initial mass function slope of the cluster to be α = 1.081 ± 0.112 for single stars
and α = 1.490 ± 0.051 for a binary fraction of ∼ 0.558 in the mass range 1 M⊙ ≤ m(M⊙ ) ≤ 100 M⊙ . The G-band
luminosity function slope is estimated to be ∼ 0.33 ± 0.09. We use (J − H) versus (H − Ks ) color-color diagram to
identify young stellar objects (YSOs). We found that all the identified YSOs have ages ≤ 2 Myr and masses ∼ 0.35 5.5 M⊙ . We also fit the radial surface density profile. Using the galpy we performed orbit analysis of the cluster. The
extinction map for the cluster region has been generated using the PNICER technique and it is almost similar to thedust structure obtained from the 500 µm dust continuum emissions map of Herschel SPIRE. We finally at the end

19discussed the star formation scenario in the cluster region.

54. Planetesimal and planet formation in transient dust traps

Zs. Sándor, O. M. Guilera, Zs. Regály, W. Lyra ⋆ The ring-like structures in protoplanetary discs that are

observed in the cold dust emission by ALMA, might be explained by dust aggregates trapped aerodynamically inpressure maxima. The effect of a transient pressure maximum is investigated that develops between two regimes withdifferent turbulent levels. We study how such a pressure maximum collects dust aggregates and transforms them intolarge planetesimals and Moon-mass cores that can further grow to a few Earth-mass planets by pebble accretion,and eventually to giant planets, by considering the accretion of a gaseous envelope. A numerical model is developed,
incorporating the evolution of gaseous disc, growth and transport of pebbles, N-body interactions of growing planetarycores and their backreaction to gas disc by opening a partial gap. Planetesimal formation by streaming instability isparametrized in our model. A transient pressure maximum efficiently accumulates dust particles that can grow larger
than mm-size. If this happens, dust aggregates can be transformed by the streaming instability process into such large
planetesimals, which can grow further by pebble accretion, according to our assumptions. As the gas evolves to its
steady state, the pressure maximum vanishes, and the concentrated pebbles that are not transformed to planetesimals
and accreted by the growing planet, drift inward. During this inward drift, if the conditions of the streaming instability
are met, planetesimals are formed in a wide radial range of the disc. Conclusions. A transient pressure maximum isa favourable place for planetesimal and planet formation during its lifetime and the concentration of pebbles induces
continuous formation of planetesimals even after its disappearance. Besides, the formation of a planet can trigger theformation of planetesimals over a wide area of the protoplanetary disc.

55. Luminosity Outbursts in Interacting Protoplanetary Systems

Aleksandr M. Skliarevskii, Eduard I. Vorobyov ⋆ FU Orionis type objects (fuors) are characterized by rapid(tens to hundreds years) episodic outbursts, during which the luminosity increases by orders of magnitude. One of thepossible causes of such events is a close encounter between stars and protoplanetary disks. Numerical simulations showthat the fuor-like outburst ignition requires a very close encounter ranging from a few to a few tens of au. In contrast,
the observed stellar objects in fuor binaries are usually hundreds of au apart. Simple mathematical estimates showthat if such a close approach took place, the binary stellar components would have an unrealistic relative velocity,
at least an order of magnitude greater than the observed velocity dispersion in young stellar clusters. Thus, thebursts are either triggered with a certain delay after passage of the periastron or their ignition does not necessary
require a close encounter and hence the outburst is not caused by the primordial gravitational perturbation of the
protoplanetary disk. In this work, an encounter of a star surrounded by a protoplanetary disk with a diskless external
stellar object was modeled using numerical hydrodynamics simulations. We showed that even fly-bys with a relatively
large periastron (at least 500 au) can result in fuor-like outbursts. Moreover, the delay between the periastron passage
and the burst ignition can reach several kyr. It was shown for the first time by means of numerical modeling that the
perturbation of the disk caused by the external object can trigger a cascade process, which includes the developmentof the thermal instability in the innermost disk followed by the magneto-rotational instability ignition. Because of thesequential development of these instabilities, the rapid increase in the accretion rate occurs, resulting in the luminosity
increase by more than two orders of magnitude.

PRODIGE – Planet-forming disks in Taurus with NOEMA. I. Overview and first results
56. for 12CO, 13CO, and C18O
D. Semenov, Th. Henning, S. Guilloteau, G. Smirnov-Pinchukov, A. Dutrey, E. Chapillon, V. Pietu, R.
Franceschi, K. Schwarz, S. van Terwisga, L. Bouscasse, P. Caselli, C. Ceccarelli, N. Cunningham, A. Fuente,
C. Gieser, T. -H. Hsieh, A. Lopez-Sepulcre, D. M. Segura-Cox, J. E. Pineda, M. J. Maureira, Th. Moeller,
M. Tafalla, M. T. Valdivia-Mena ⋆ We are performing a line survey of 8 planet-forming Class II disks in Taurus

with the IRAM NOrthern Extended Millimeter Array (NOEMA), as a part of the MPG-IRAM Observatory Program
PRODIGE (PROtostars and DIsks: Global Evolution; PIs: P. Caselli and Th. Henning). Compact and extended disks
around T Tauri stars CI, CY, DG, DL, DM, DN, IQ Tau, and UZ Tau E are observed in 80 lines from >20 C-, O,N-, and S-bearing species. The observations in four spectral settings at 210-280 GHz with 1σ rms sensitivity of 8-12
mJy/beam at 0.9" and 0.3 km/s resolution will be completed in 2024. The uv-visibilities are fitted with the DiskFit
model to obtain key stellar and disk properties. In this paper, the combined 12 CO, 13 CO and C18 O J = 2 − 1 data are20

presented. We find that the CO fluxes and disk masses inferred from dust continuum tentatively correlate with theCO emission sizes. We constrain dynamical stellar masses, geometries, temperatures, the CO column densities andgas masses for each disk. The best-fit temperatures at 100 au are 17-37 K, and decrease radially with the power-law
exponent q 0.05-0.76. The inferred CO column densities decrease radially with the power-law exponent p 0.2-3.1.
The gas masses estimated from 13 CO (2-1) are 0.001 − 0.2MSun . The best-fit CO column densities point to severe
CO freeze-out in the disks. The DL Tau disk is an outlier, and has either stronger CO depletion or lower gas mass
than the rest of the sample. The CO isotopologue ratios are roughly consistent with the observed values in disks andthe low-mass star-forming regions.

57. Length and Velocity Scales in Protoplanetary Disk Turbulence
Debanjan Sengupta, Jeffrey N. Cuzzi, Orkan M. Umurhan, Wladimir Lyra ⋆ In the theory of protoplanetary

disk turbulence, a widely adopted ansatz, or assumption, is that the turnover frequency of the largest turbulent eddy,ΩL , is the local Keplerian frequency ΩK . In terms of the standard dimensionless Shakura-Sunyaev α parameter thatquantifies turbulent√ or diffusivity, this assumption leads to characteristic length and velocity scales given√ viscosity
respectively by αH and αc, in which H and c are the local gas scale height and sound speed. However, thisassumption is not applicable in cases when turbulence is forced numerically or driven by some natural processes suchas Vertical Shear Instability. Here we explore the more general case whereΩL ≥ ΩKp√ and show that under these
α/R′ H and αR′ c, where R′ ≡ ΩL /ΩK isconditions, the characteristic length and velocity scales are respectively√
twice the Rossby number. It follows that α = αt/R′ , where αtc is the root-mean-square average of the turbulent
velocities. Properly allowing for this effect naturally explains the reduced particle scale heights produced in shearing
box simulations of particles in forced turbulence, and may help with interpreting recent edge-on disk observations;more general implications for observations are also presented. For R′ > 1 the effective particle Stokes numbers are
increased, which has implications for particle collision dynamics and growth, as well as for planetesimal formation.

58. Small and Large Dust Cavities in Disks around mid-M Stars in Taurus

Yangfan Shi, Feng Long, Gregory J. Herczeg, Daniel Harsono, Yao Liu, Paola Pinilla, Enrico Ragusa, Doug
Johnstone, Xue-Ning Bai, Ilaria Pascucci, Carlo F. Manara, Gijs D. Mulders, Lucas A. Cieza ⋆ High-angularresolution imaging by ALMA has revealed the near-universality and diversity of substructures in protoplanetary disks.
However, disks around M-type pre-main-sequence stars are still poorly sampled, despite the prevalence of M-dwarfs
in the galaxy. Here we present high-resolution ( 50 mas, 8 au) ALMA Band 6 observations of six disks around mid-M
stars in Taurus. We detect dust continuum emission in all six disks, 12CO in five disks, and 13CO line in two disks.
The size ratios between gas and dust disks range from 1.6 to 5.1. The ratio of about 5 for 2M0436 and 2M0450
indicates efficient dust radial drift. Four disks show rings and cavities and two disks are smooth. The cavity sizes
occupy a wide range: 60 au for 2M0412, and 10 au for 2M0434, 2M0436 and 2M0508. Detailed visibility modelingindicates that small cavities of 1.7 and 5.7 au may hide in the two smooth disks 2M0450 and CIDA 12. We perform
radiative transfer fitting of the infrared SEDs to constrain the cavity sizes, finding that micron-sized dust grains may
have smaller cavities than millimeter grains. Planet-disk interactions are the preferred explanation to produce thelarge 60 au cavity, while other physics could be responsible for the three 10 au cavities under current observations
and theories. Currently, disks around mid-to-late M stars in Taurus show a higher detection frequency of cavities thanearlier type stars, although a more complete sample is needed to evaluate any dependence of substructure on stellar
mass.

JWST Observations of Young protoStars (JOYS): Linked accretion and ejection in a
59. Class I protobinary systemŁukasz Tychoniec, Martijn L. van Gelder, Ewine F. van Dishoeck, Logan Francis, Will R. M. Rocha, Alessio
Caratti o Garatti, Henrik Beuther, Caroline Gieser, Kay Justtanont, Harold Linnartz, Valentin J. M. Le
Gouellec, Giulia Perotti, Dev Rangaswamy, Benoît Tabone, Thomas P. Ray, Nashanty G. C. Brunken, Yuan
Chen, Patrick J. Kavanagh, Pamela Klaassen, Katerina Slavicinska, Manuel Güdel, Goran Östlin ⋆ Accretionand ejection sets the outcome of the star and planet formation process. The mid-infrared wavelength range offers
key tracers of those processes that were difficult to detect and spatially resolve in protostars until now. We aim tocharacterize the interplay between accretion and ejection in the low-mass Class I protobinary system TMC1, comprising
two young stellar objects: TMC1-W and TMC1-E with 85 au separation. With the James Webb Space Telescope

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(JWST) - Mid-Infrared Instrument (MIRI) observations in 5 - 28 µm range, we measure intensities of emission lines ofH2 , atoms and ions, e.g., [Fe II] and [Ne II], and HI recombination lines. We detect H2 outflow coming from TMC1-E,
with no significant H2 emission from TMC1-W. The H2 emission from TMC1-E outflow appears narrow and extends
to wider opening angles with decreasing Eup from S(8) to S(1) rotational transitions, indicating a disk wind origin.
The outflow from TMC1-E protostar shows spatially extended emission lines of [Ne II], [Ne III], [Ar II], and [ArIII], with their line ratios consistent with UV radiation as a source of ionization. With ALMA, we detect accretion
streamer infalling from > 1000 au scales onto the TMC1-E component. TMC1-W protostar powers a collimated jet,detected with [Fe II] and [Ni II] consistent with energetic flow. A much weaker ionized jet is observed from TMC1-E.
TMC1-W is associated with strong emission from hydrogen recombination lines, tracing the accretion onto the youngstar. Observations of a binary Class I protostellar system show that the two processes are clearly intertwined, withaccretion from the envelope onto the disk influencing a wide-angle wind ejected on disk scales, while accretion fromthe protostellar disk onto the protostar is associated with the source launching a collimated high-velocity jet within
the innermost regions of the disk.

60. WTP 10aaauow: Discovery of a new FU Ori outburst towards the RCW 49 star-forming
region in NEOWISE data
Vinh Tran, Kishalay De, Lynne Hillenbrand ⋆ Large-amplitude accretion outbursts in young stars are expected
to play a central role in proto-stellar assembly. Outburst identification historically has taken place using opticaltechniques, but recent, systematic infrared searches are enabling their discovery in heavily dust-obscured regions of
the Galactic plane. Here, we present the discovery of WTP 10aaauow, a large-amplitude mid-infrared (MIR) outburst
identified in a systematic search of NEOWISE data using new image subtraction techniques. The source is locatedtowards the RCW 49 star-forming region, and estimated to be at a distance of ≈ 4 kpc via Gaia parallax measurement.
Concurrent with the MIR brightening, the source underwent a ≳ 5 mag outburst in the optical and near-infrared (NIR)
bands, reaching a peak luminosity of ≈ 260 L⊙ in 2014-2015, followed by a slow decline over the next 7 years. Analysisof the pre- and post-outburst spectral energy distributions reveal a pre-outburst stellar photosphere at a temperatureof 3600 − 4000 K, surrounded by a likely two-component dust structure similar to a flat-spectrum or Class I type YSO.
We present optical and NIR spectroscopy that show a GK-type spectrum in the optical bands exhibiting complex
line profiles in strong absorption features, and evidence for a wind reaching a terminal velocity of ≈ 400 km s−1 . The
NIR bands are characterized by a cooler M-type spectrum exhibiting a forest of atomic and molecular features. All
together, the spectra demonstrate that WTP 10aaauow is an FU Ori type outburst. Ongoing systematic infrared
searches will continue to reveal the extent of this population in the Galactic disk.

Curves of growth for transiting exocomets: Application to Fe II lines in the Beta Pictoris
61. system
T. Vrignaud, A. Lecavelier des Etangs, F. Kiefer, A. -M. Lagrange, G. Hébrard, P. A. Strøm, A. Vidal-Madjar⋆ This study introduces the exocomet curve of growth, a new method to analyse the variable absorptions observedin β Pictoris spectrum and link them to the physical properties of the transiting cometary tails. We show that theabsorption depth of a comet in a set of lines arising from similar excitation levels of a given chemical species follows a
simple curve as a function of the gf-values of the lines. This curve is the analogue of the curve of growth for interstellar
absorption lines, where equivalent widths are replaced by absorption depths. To fit this exocomet curve of growth, we
introduce a model where the cometary absorption is produced by a homogeneous cloud, covering a limited fraction of
the stellar disc. This model is defined by two parameters: α, the covering factor of the cloud, and β, related to its
typical the optical depth. This model is tested on two comets observed with the Hubble Space Telescope in December
1997 and October 2018, in a set of Fe II lines at 275 nm. The measured absorption depths are found to satisfactory
match the two-parameter curve of growth model, indicating that both comets cover roughly 40 unity. Then, weshow that if we consider a set of lines arising from a wider range of energy levels, the absorbing species seems to be
populated at thermodynamical equilibrium, causing the cometary absorption to follow a curve of growth as a functionof gf · e−El /kB T (where T is the temperature of the absorbing medium). For the comet observed on December 6,
1997, we derive a temperature of 10500 ± 500 K and a total Fe II column density of (1.11 ± 0.09) × 1015 cm−2 . By
probing the population of the highest excited energy levels (El ∼ 25000 cm−1 ), we also estimate an electronic densityof (3 ± 1) × 107 cm−3 .

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62. Magnetic fields in the Southern Coalsack and beyond

M. J. F. Versteeg, Y. Angarita, A. M. Magalhães, M. Haverkorn, C. V. Rodrigues, R. Santos-Lima, Koji S.
Kawabata ⋆ Starlight polarimetry, when combined with accurate distance measurements, allows for exploration of

the three-dimensional structure of local magnetic fields in great detail. We present optical polarimetric observationsof stars in and close to the Southern Coalsack, taken from the Interstellar Polarization Survey (IPS). Located infive fields of view approximately 0.3o by 0.3o in size, these data represent the highest density of optical polarimetricobservations in the Southern Coalsack to date. Using these data, combined with accurate distances and extinctions
based on Gaia data, we are able to characterize the magnetic field of the Coalsack and disentangle contributions to
the polarization caused by the Southern Coalsack and a background structure. For the Southern Coalsack, we findan average magnetic field orientation of θ ∼ 75o with respect to the Galactic north pole and an average plane-of-sky
magnetic field strength of approximately BP OS = 10 µG, using the Davis-Chandrasekhar-Fermi (DCF) method. These
values are in agreement with some earlier estimates of the Coalsack’s magnetic field. In order to study the distant
structure, we introduce a simple method to separate and isolate the polarization of distant stars from foregroundcontribution. For the distant structure, which we estimate to be located at a distance of approximately 1.3-1.5 kpc,
we find an average magnetic field orientation of θ ∼ 100o and we estimate a field strength of BP OS ∼ 10 µG, although
this will remain highly uncertain until the precise nature of the distant structure can be uncovered.

The interplay between forming planets and photoevaporating discs II: Wind-driven gas
63. redistribution
Michael L. Weber, Giovanni Picogna, Barbara Ercolano ⋆ Disc winds and planet-disc interactions are two crucial

mechanisms that define the structure, evolution and dispersal of protoplanetary discs. While winds are capable ofremoving material from discs, eventually leading to their dispersal, massive planets can shape their disc by creating
sub-structures such as gaps and spiral arms. We study the interplay between an X-ray photoevaporative disc wind andthe substructures generated due to planet-disc interactions to determine how their mutual interactions affect the disc’s
and the planet’s evolution. We perform three-dimensional hydrodynamic simulations of viscous (α = 6.9 · 10−4 ) discs
that host a Jupiter-like planet and undergo X-ray photoevaporation. We trace the gas flows within the disc and windand measure the accretion rate onto the planet, as well as the gravitational torque that is acting on it. Our results
show that the planetary gap takes away the wind’s pressure support, allowing wind material to fall back into the gap.
This opens new pathways for material from the inner disc (and part of the outer disc) to be redistributed throughthe wind towards the gap. Consequently, the gap becomes shallower, and the flow of mass across the gap in both
directions is significantly increased, as well as the planet’s mass-accretion rate (by factors ≈ 5 and ≈ 2, respectively).
Moreover, the wind-driven redistribution results in a denser inner disc and less dense outer disc, which, combinedwith the recycling of a significant portion of the inner wind, leads to longer lifetimes of the inner disc, contrary to the
expectation in a planet-induced photoevaporation (PIPE) scenario that has been proposed in the past.

64. Disk Wind Feedback from High-mass Protostars. III. Synthetic CO Line Emission

Duo Xu, Jonathan C. Tan, Jan E. Staff, Jon P. Ramsey, Yichen Zhang, Kei E. Tanaka ⋆ To test theoreticalmodels of massive star formation it is important to compare their predictions with observed systems. To this end,
we conduct CO molecular line radiative transfer post-processing of 3D magneto-hydrodynamic (MHD) simulations ofvarious stages in the evolutionary sequence of a massive protostellar core, including its infall envelope and disk windoutflow. Synthetic position-position-velocity (PPV) cubes of various transitions of CO, 13CO, and C18O emission are
generated. We also carry out simulated Atacama Large Millimeter/submillimeter Array (ALMA) observations of thisemission. We compare the mass, momentum and kinetic energy estimates obtained from molecular lines to the true
values, finding that the mass and momentum estimates can have uncertainties of up to a factor of four. However,
the kinetic energy estimated from molecular lines is more significantly underestimated. Additionally, we compare themass outflow rate and momentum outflow rate obtained from the synthetic spectra with the true values. Finally,
we compare the synthetic spectra with real examples of ALMA-observed protostars and determine the best fitting
protostellar masses and outflow inclination angles. We then calculate the mass outflow rate and momentum outflow
rate for these sources, finding that both rates agree with theoretical protostellar evolutionary tracks.

2365. Dense Core Collisions in Molecular Clouds: Formation of Streamers and Binary Stars
Yuta Yano, Fumitaka Nakamura, Shinichi W. Kinoshita ⋆ Dense core collisions, previously regarded as minor instar formation, are proposed to play a significant role in structure formation around protostellar envelopes and binary
formation. Using archival data of nearby star-forming regions, we determine the frequencies of core collisions. Our
calculations reveal that a typical core is likely to undergo multiple interactions with other cores throughout its lifetime.
To further investigate the core collision process, we employ adaptive mesh refinement hydrodynamic simulations withsink particles. Our simulations demonstrate that following the formation of a protostar within a gravitationallyunstable core, the merging core’s accreting gas gives rise to a rotationally-supported circumstellar disk. Meanwhile,
the region compressed by the shock between the cores develops into asymmetric arms that connect with the disk. Gas
along these arms tends to migrate inward, ultimately falling toward the protostar. One of the arms, a remnant of theshock-compressed region, dominates over the second core gas, potentially exhibiting a distinct chemical composition.
This is consistent with recent findings of large-scale streamers around protostars. Additionally, we found that collisions
with velocities of ∼ 1.5 km s−1 result in the formation of a binary system, as evidenced by the emergence of a sinkparticle within the dense section of the shocked layer. Overall, dense core collisions are highlighted as a critical process
in creating 103 au-scale streamers around protostellar systems and binary stars.

Turbulent vortex with moderate dust settling probed by scattering-induced polarization
66. in the IRS 48 system

Haifeng Yang, Manuel Fernández-López, Zhi-Yun Li, Ian W. Stephens, Leslie W. Looney, Zhe-Yu Daniel Lin,
Rachel Harrison ⋆ We investigate the crescent-shaped dust trap in the transition disk, Oph IRS 48, using well-resolved (sub)millimeter polarimetric observations at ALMA Band 7 (870 µm). The dust polarization map reveals
patterns consistent with dust scattering-induced polarization. There is a relative displacement between the polarized
flux and the total flux, which holds the key to understanding the dust scale heights in this system. We model
the polarization observations, focusing on the effects of dust scale heights. We find that the interplay between the
inclination-induced polarization and the polarization arising from radiation anisotropy in the crescent determines theobserved polarization; the anisotropy is controlled by the dust optical depth along the midplane, which is, in turn,
determined by the dust scale height in the vertical direction. We find that the dust grains can neither be completely
settled nor well mixed with the gas. The completely settled case produces little radial displacement between the total
and polarized flux, while the well-mixed case produces an azimuthal pattern in the outer (radial) edge of the crescentthat is not observed. Our best model has a gas-to-dust scale height ratio of 2, and can reproduce both the radialdisplacement and the azimuthal displacement between the total and polarized flux. We infer an effective turbulence
α parameter of approximately 0.0001 − 0.005. The scattering-induced polarization provides insight into a turbulent
vortex with a moderate level of dust settling in the IRS 48 system, which is hard to achieve otherwise.

67.

Gas content and evolution of a sample of YSO associations at d ≲ 3.5 kpc from the Sun
Ji-Xuan Zhou, Guang-Xing Li, Bing-Qiu Chen ⋆ Young Stellar Objects (YSO) are newly formed stars frommolecular clouds. They stay close to where they were born and serve as good tracers to study gas and star formation.
During cloud evolution, young massive stars can disrupt the surrounding gas through stellar feedback, changing thegas distribution. We study the distribution of the gas around a sample of YSO associations located at d ≲ 3.5 kpc
from the Sun by comparing the location and morphology between 12 CO (J = 1−0) emission, Planck 870 µm maps and
YSO associations. Based on the spatial distribution of the gas compared to that of the YSOs, we classify the YSO
associations into six types: direct, close, bubble, complex, diffuse, and clean associations. The complex associations
are large structures consisting of both gas-rich and gas-poor segments. We study the velocity dispersion-size relation
toward different association types. From the ratio between different types, we estimate a feedback time of ≈ 1.7 Myrin the solar neighborhood. The sample sets a solid foundation to explore the relationship between interstellar medium
evolution, star formation, and Galaxy structure.

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Effects of physical conditions on the stellar initial mass function: The low-metallicity
68. star-forming region Sh 2-209
Marie Zinnkann, Henriette Wirth, Pavel Kroupa ⋆ Recent work suggested that the variation of the initial massfunction (IMF) of stars depends on the physical conditions, notably, the metallicity and gas density. We investigatedthe properties of two clusters, namely the main cluster (MC) and the subcluster (SC), in the low-metallicity HII
region Sh 2-209 (S209) based on recently derived IMFs. We tested three previously published correlations using
previous observations: the top-heaviness of the IMF in dependence on metallicity, the half-mass radius, and the most
massive star in dependence on the stellar mass of the embedded clusters. For this region, two different galactocentric
distances, namely 10.5 kpc and 18 kpc, were considered, where an age-distance-degeneracy was found for the previously
determined IMF to be consistent with other formulated metallicity and density dependent IMFs. The determined halfmass radius (0.080 +/- 0.005) pc and the embedded cluster density (0.2 +/- 0.1) 106 Msun pc−3 for the MC with anage of 0.5 Myr in S209 assuming a galactocentric distance of 18 kpc support the assumption that a low-metallicity
environment results in a denser cluster, which leads to a top-heavy IMF. Thus, all three tests are consistent with thepreviously published correlations. The results for S209 are placed in the context with the IMF determination within
the metal-poor cluster in the star-forming region NGC 346 in the Small Magellanic Cloud.

69.

Multi-band reflectance and shadowing of RX J1604.3-2130 protoplanetary disk in scattered light
Huisheng Zhong, Bin B. Ren, Bo Ma, Chen Xie, Jie Ma, Nicole L. Wallack, Dimitri Mawet, Garreth Ruane⋆ Context.Spatially-resoved cicrumstellar disk spectrum and composition can provide valuable insights into the bulk
composition of forming planets, as well as the mineralogical signatures that emerge during and after planet formation.
Aims. We aim to systemically extract the RX J1604.3-213010 (J1604 hereafter) protoplanetary disk in high-contrast
imaging observations, and obtain its multi-band reflectance in visible to near-infrared wavelengths. Methods. We
obtained coronagraphic observations of J1604 from the Keck Observatory’s NIRC2 instrument, and archival datafrom the Very Large Telescope’s SPHERE instrument. Using archival images to remove star light and speckles, werecovered the J1604 disk and obtained its surface brightness using forward modeling. Together with polarization data,
we obtained the relative reflectance of the disk in R, J, H (H2 and H3), K (K1 and K2), and L′ bands spanning
two years. Results. Relative to the J1604 star, the resolved disk has a reflectance of ∼10−1 arcsec−2 in R through Hbands and ∼10−2 arcsec−2 in K and L′ bands, showing a blue color. Together with other systems, we summarized
the multi-band reflectance for 9 systems. We also identified varying disk geometry structure, and a shadow thatvanished between June and August in 2015. Conclusions. Motivated by broad-band observations, the deployment of
cutting-edge technologies could yield higher-resolution reflection spectra, thereby informing the dust composition ofdisks in scattered light in the future. With multi-epoch observations, variable shadows have the potential to deepen
insights into the dynamic characteristics of inner disk regions.

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