The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 369 — 30 September 2023
Editor: João Alveswww.starformation.news

Cover image caption
The Orion Nebula with JWST. Color composite covering the inner Orion Nebula and Trapezium Cluster, comprising a combination of six LW channel filters (F277W, F300M, F335M, F360M, F444W, F470N). The image covers 0.85 pc × 0.85 pc assuming
a distance to the Nebula of 390 pc.
Credits: NASA, ESA, CSA / McCaughrean & Pearson 2023, CC BY-SA 3.0 IGO
Note from the Editor
The Star Formation Newsletter is now on the web at www.starformation.news. This PDF file contains the monthly Abstracts
and links. Red text in this PDF is a url link. Submitting an abstract to the SFN is as simple as entering the arXiv ID (e.g.,
2006.10139) in a web form on the SFN web site. Do not remove the LATEX formatting when submitting to the arXiv.
If you do, your abstract will not look great either at the arXiv or the SFN.

Abstracts
1. A high HDO/H2 O ratio in the Class I protostar L1551 IRS5

Audrey Andreu, Audrey Coutens, Fernando Cruz-Sáenz de Miera, Nicolas Houry, Jes K. Jørgensen, Ágnes
Kóspál, Daniel Harsono F Water is a very abundant molecule in star-forming regions. Its deuterium fractionation is
an important tool for understanding its formation and evolution during the star and planet formation processes. While the
HDO/H2 O ratio has been determined toward several Class 0 protostars and comets, the number of studies toward Class I
protostars is limited. We aim to study the water deuteration toward the Class I binary protostar L1551 IRS5 and to investigate
the effect of evolutionary stage and environment on variations in the water D/H ratio. Observations were made using the
NOEMA interferometer. The HDO 31,2 -22,1 transition at 225.9 GHz and the H18
2 O 31,3 -22,0 transition at 203.4 GHz werecovered with a spatial resolution of 0.5” × 0.8”, while the HDO 42,2 -42,3 transition at 143.7 GHz was observed with a resolutionof 2.0” × 2.5”. We used both LTE and non-LTE models. The three transitions are detected. The line profiles display two
peaks, one at ∼6 km s−1 and one at ∼9 km s−1 . We derive an HDO/H2 O ratio of (2.1 ± 0.8) × 10−3 for the redshiftedcomponent and a lower limit of > 0.3 × 10−3 for the blueshifted component due to the blending with the redshifted CH3 OCH3
emission. The HDO/H2 O in L1551 IRS5 is similar to the ratios in isolated Class 0 sources and to the Class I V883 Ori, while
it is significantly higher than in the clustered Class 0 sources and the comets. This suggests that the chemistry of protostars in
low source densities clouds share more similarities with the isolated sources than the protostars of very dense clusters. If Class
0 protostars with few sources around and isolated Class 0 objects are comparable in the HDO/H2 O ratio, it would mean that
there is little water reprocessing from the Class 0 to Class I protostellar stage.

2. Early Planet Formation in Embedded Disks (eDisk) VI: Kinematic Structures aroundthe Very Low Mass Protostar IRAS 16253-2429
Yusuke Aso, Woojin Kwon, Nagayoshi Ohashi, Jes K. Jorgensen, John J. Tobin, Yuri Aikawa, Itziar deGregorio-Monsalvo, Ilseung Han, Miyu Kido, Patrick M. Koch, Shih-Ping Lai, Chang Won Lee, Jeong-Eun Lee,
Zhi-Yun Li, Zhe-Yu Daniel Lin, Leslie W. Looney, Suchitra Narayanan, Nguyen Thi Phuong, Jinshi Sai, Kazuya
Saigo, Alejandro Santamaria-Miranda, Rajeeb Sharma, Shigehisa Takakuwa, Travis J. Thieme, Kengo Tomida,
Jonathan P. Williams, Hsi-Wei Yen F Precise estimates of protostellar masses are crucial to characterize the formation ofstars of low masses down to brown-dwarfs (BDs; M* < 0.08 Msun). The most accurate estimation of protostellar mass uses the
Keplerian rotation in the circumstellar disk around the protostar. To apply the Keplerian rotation method to a protostar at
the low-mass end, we have observed the Class 0 protostar IRAS 16253-2429 using the Atacama Large Millimeter/submillimeter
Array (ALMA) in the 1.3 mm continuum at an angular resolution of 0.07" (10 au), and in the 12CO, C18O, 13CO (J=2-1), andSO (JN = 6 5-5 4) molecular lines, as part of the ALMA Large Program Early Planet Formation in Embedded Disks (eDisk).
The continuum emission traces a non-axisymmetric, disk-like structure perpendicular to the associated 12CO outflow. The
position-velocity (PV) diagrams in the C18O and 13CO lines can be interpreted as infalling and rotating motions. In contrast,
the PV diagram along the major axis of the disk-like structure in the 12CO line allows us to identify Keplerian rotation. The
central stellar mass and the disk radius are estimated to be 0.12-0.17 Msun and 13-19 au, respectively. The SO line suggests
the existence of an accretion shock at a ring (r 28 au) surrounding the disk and a streamer from the eastern side of the envelope.
IRAS 16253-2429 is not a proto-BD but has a central stellar mass close to the BD mass regime, and our results provide a typical
picture of such very low-mass protostars.

2

Tracing Evolution in Massive Protostellar Objects (TEMPO) – I: Fragmentation and3. emission properties of massive star-forming clumps in a luminosity limited ALMA sample
A. Avison, G. A. Fuller, N. Asabre Frimpong, S. Etoka, M. Hoare, B. M. Jones, N. Peretto, A. Traficante, F.
van der Tak, J. E. Pineda, M. Beltrán, F. Wyrowski, M. Thompson, S. Lumsden, Z. Nagy, T. Hill, S. Viti,
F. Fontani, P. Schilke F The role of massive (≥ 8M ) stars in defining the energy budget and chemical enrichment of theinterstellar medium in their host galaxy is significant. In this first paper from the Tracing Evolution in Massive Protostellar
Objects (TEMPO) project we introduce a colour-luminosity selected (L∗ ∼ 3×103 to 1×105 L ) sample of 38 massive star
forming regions observed with ALMA at 1.3mm and explore the fragmentation, clustering and flux density properties of thesample. The TEMPO sample fields are each found to contain multiple fragments (between 2-15 per field). The flux density
budget is split evenly (53%-47%) between fields where emission is dominated by a single high flux density fragment and thosein which the combined flux density of fainter objects dominates. The fragmentation scales observed in most fields are not comparable with the thermal Jeans length, λJ , being larger in the majority of cases, suggestive of some non-thermal mechanism.
A tentative evolutionary trend is seen between luminosity of the clump and the ‘spectral line richness’ of the TEMPO fields;with 6.7GHz maser associated fields found to be lower luminosity and more line rich. This work also describes a method ofline-free continuum channel selection within ALMA data and a generalised approach used to distinguishing sources which arepotentially star-forming from those which are not, utilising interferometric visibility properties.

Atmospheric Retrieval of L Dwarfs: Benchmarking Results and Characterizing the
4. Young Planetary Mass Companion HD 106906 b in the Near-Infrared
Arthur D. Adams, Michael R. Meyer, Alex R. Howe, Ben Burningham, Sebastian Daemgen, Jonathan Fortney, Mike Line, Mark Marley, Sascha P. Quanz, Kamen Todorov F We present model constraints on the atmosphericstructure of HD 106906 b, a planetary-mass companion orbiting at a 700 AU projected separation around a 15 Myr-old stellar
binary, using the APOLLO retrieval code on spectral data spanning 1.1-2.5 µm. C/O ratios can provide evidence for companion
formation pathways, as such pathways are ambiguous both at wide separations and at star-to-companion mass ratios in theoverlap between the distributions of planets and brown dwarfs. We benchmark our code against an existing retrieval of the
field L dwarf 2M2224-0158, returning a C/O ratio consistent with previous fits to the same JHKs data, but disagreeing in thethermal structure, cloud properties, and atmospheric scale height. For HD 106906 b, we retrieve C/O = 0.53+0.15−0.25 , consistent
with the C/O ratios expected for HD 106906’s stellar association and therefore consistent with a stellar-like formation for thecompanion. We find abundances of H2 O and CO near chemical equilibrium values for a solar metallicity, but a surface gravity
lower than expected, as well as a thermal profile with sharp transitions in the temperature gradient. Despite high signal-tonoise and spectral resolution, more accurate constraints necessitate data across a broader wavelength range. This work serves
as preparation for subsequent retrievals in the era of JWST, as JWST’s spectral range provides a promising opportunity toresolve difficulties in fitting low-gravity L dwarfs, and also underscores the need for simultaneous comparative retrievals on L
dwarf companions with multiple retrieval codes.

PENELLOPE V. The magnetospheric structure and the accretion variability of the
5. classical T Tauri star HM Lup
A. Armeni, B. Stelzer, R. A. B. Claes, C. F. Manara, A. Frasca, J. M. Alcalá, F. M. Walter, Á. Kóspál, J.
Campbell-White, M. Gangi, K. Mauco, L. Tychoniec F HM Lup is a young M-type star that accretes material from acircumstellar disk through a magnetosphere. Our aim is to study the inner disk structure of HM Lup and to characterize its
variability. We used spectroscopic data from HST/STIS, X-Shooter, and ESPRESSO taken in the framework of the ULLYSES
and PENELLOPE programs, together with photometric data from TESS and AAVSO. The 2021 TESS light curve shows
variability typical for young stellar objects of the "accretion burster" type. The spectra cover the temporal evolution of themain burst in the 2021 TESS light curve. We compared the strength and morphology of emission lines from different species
and ionization stages. We determined the mass accretion rate from selected emission lines and from the UV continuum excess
emission at different epochs, and we examined its relation to the photometric light curves. The emission lines in the optical
spectrum of HM Lup delineate a temperature stratification along the accretion flow. While the wings of the H I and He I
lines originate near the star, the lines of species such as Na I, Mg I, Ca I, Ca II, Fe I, and Fe II are formed in an outer andcolder region. The shape and periodicity of the 2019 and 2021 TESS light curves, when qualitatively compared to predictions
from magnetohydrodynamic models, suggest that HM Lup was in a regime of unstable ordered accretion during the 2021 TESS
observation due to an increase in the accretion rate. Although HM Lup is not an extreme accretor, it shows enhanced emission
in the metallic species during this high accretion state that is produced by a density enhancement in the outer part of theaccretion flow.

36. Enriching inner discs and giant planets with heavy elements

Bertram Bitsch, Jingyi Mah F Giant exoplanets seem to have on average a much larger heavy element content than thesolar system giants. Past attempts to explain these heavy element contents include collisions between planets, accretion ofvolatile rich gas and accretion of gas enriched in micro-metre sized solids. However, these different theories individually could
not explain the heavy element content of giants and the volatile to refractory ratios in atmospheres of giant planets at thesame time. Here we combine the approaches of gas accretion enhanced with vapor and small micro-meter sized dust grains.
As pebbles drift inwards, the volatile component evaporates and enriches the disc, while the smaller silicate core of the pebble
continues to move inwards. The smaller silicate pebbles drift slower, leading to a pile-up of material interior to the water ice
line, increasing the dust-to-gas ratio interior to the ice line. Under the assumption that these small dust grains follow the motionof the gas, gas accreting giants accrete large fractions of small solids in addition to the volatile vapor. The effectiveness of thesolid enrichment requires a large disc radius to maintain the pebble flux for a long time and a large viscosity that reduces thesize and inward drift of the small dust grains. However, this process depends crucially on the debated size difference of thepebbles interior and exterior of the water ice line. On the other hand, the volatile component released by the inward drifting
pebbles can lead to a large enrichment with heavy element vapor, independently of a size difference of pebbles interior andexterior to the water ice line. Our model stresses the importance of the disc’s radius and viscosity on the enrichment of dust
and vapor. Consequently we show how our model could explain the heavy element content of the majority of giant planets byusing combined estimates of dust and vapor enrichment.

7. Astrochemical Modeling of Propargyl Radical Chemistry in TMC-1

Alex N. Byrne, Ci Xue, Ilsa R. Cooke, Michael C. McCarthy, Brett A. McGuire F Recent detections of aromatic
species in dark molecular clouds suggest formation pathways may be efficient at very low temperatures and pressures, yet current
astrochemical models are unable to account for their derived abundances, which can often deviate from model predictions
by several orders of magnitude. The propargyl radical, a highly abundant species in the dark molecular cloud TMC- 1, is
an important aromatic precursor in combustion flames and possibly interstellar environments. We performed astrochemical
modeling of TMC-1 using the three-phase gas-grain code NAUTILUS and an updated chemical network, focused on refining thechemistry of the propargyl radical and related species. The abundance of the propargyl radical has been increased by half anorder of magnitude compared to the previous GOTHAM network. This brings it closer in line with observations, but it remains
underestimated by two orders of magnitude compared to its observed value. Predicted abundances for the chemically related
C4H3N isomers within an order of magnitude of observed values corroborate the high efficiency of CN addition to closed-shellhydrocarbons under dark molecular cloud conditions. The results of our modeling provide insight into the chemical processes ofthe propargyl radical in dark molecular clouds and highlight the importance of resonance-stabilized radicals in PAH formation.

cores in Sagittarius B2 N and M
8. Protostellar
Nazar Budaiev, Adam Ginsburg, Desmond Jeff, Ciriaco Goddi, Fanyi Meng, Álvaro Sánchez-Monge, Peter
Schilke, Anika Schmiedeke, Taehwa Yoo F We present 500 AU and 700 AU resolution 1 mm and 3 mm ALMA observations,
respectively, of protostellar cores in protoclusters Sagittarius B2 (Sgr B2) North (N) and Main (M), parts of the most actively
star-forming cloud in our Galaxy. Previous lower resolution (5000 AU) 3 mm observations of this region detected ∼150 sources
inferred to be young stellar objects (YSOs) with M > 8 M . With a tenfold increase in resolution, we detect 371 sources at
3 mm and 218 sources in the smaller field of view at 1 mm. The sources seen at low resolution are observed to fragment into
an average of two objects. About a third of the observed sources fragment. Most of the sources we report are marginallyresolved and are at least partially optically thick. We determine that the observed sources are most consistent with Stage 0/I
YSOs, i.e., rotationally supported disks with an active protostar and an envelope, that are warmer than those observed in thesolar neighborhood. We report source-counting-based inferred stellar mass and the star formation rate of the cloud: 2800 M ,0.0038 M yr−1 for Sgr B2 N and 6900 M , 0.0093 M yr−1 for Sgr B2 M respectively.

Transient Corotating Clumps Around Adolescent Low-Mass Stars From Four Years of
9. TESS
Luke G. Bouma, Rahul Jayaraman, Saul Rappaport, Luisa M. Rebull, Lynne A. Hillenbrand, Joshua N. Winn,
Alexandre David-Uraz, Gáspár Á. Bakos F Complex periodic variables (CPVs) are stars that exhibit highly structured
and periodic optical light curves. Previous studies have indicated that these stars are typically disk-free pre-main-sequence M
dwarfs with rotation periods ranging from 0.2 to 2 days. To advance our understanding of these enigmatic objects, we conducteda blind search using TESS 2-minute data of 65,760 K and M dwarfs with T <16 and d<150 pc. We found 50 high-quality CPVs,
and subsequently determined that most are members of stellar associations. Among the new discoveries are the brightest(T ≈9.5), closest (d≈20 pc), and oldest (≈200 Myr) CPVs known. One exceptional object, LP 12-502, exhibited up to eight flux
dips per cycle. Some of these dips coexisted with slightly different periods, and the shortest-duration dips precisely matched
the expected timescale for transiting small bodies at the corotation radius. Broadly, our search confirms that CPVs are mostly
young (.150 Myr) and low-mass (.0.4 M ). The flux dips characteristic of the class have lifetimes of ≈100 cycles, although4stellar flares seem to induce sudden dip collapse once every few months. The most plausible explanation for these phenomena
remains corotating concentrations of gas or dust. The gas or dust is probably entrained by the star’s magnetic field, and the
sharp features could result from a multipolar field topology, a hypothesis supported by correspondences between the light curvesof CPVs and of rapidly rotating B stars known to have multipolar magnetic fields.

reveals excess cool water near the snowline in compact disks, consistent with
10. JWST
pebble drift
Andrea Banzatti, Klaus M. Pontoppidan, John Carr, Evan Jellison, Ilaria Pascucci, Joan Najita, Carlos E.
Munoz-Romero, Karin I. Oberg, Anusha Kalyaan, Paola Pinilla, Sebastiaan Krijt, Feng Long, Michiel Lambrechts, Giovanni Rosotti, Gregory J. Herczeg, Colette Salyk, Ke Zhang, Edwin Bergin, Nick Ballering, Michael
R. Meyer, Simon Bruderer, the JDISCS collaboration F Previous analyses of mid-infrared water spectra from young
protoplanetary disks observed with the Spitzer-IRS found an anti-correlation between water luminosity and the millimeter dust
disk radius observed with ALMA. This trend was suggested to be evidence for a fundamental process of inner disk water enrichment, used to explain properties of the Solar System 40 years ago, in which icy pebbles drift inward from the outer disk andsublimate after crossing the snowline. Previous analyses of IRS water spectra, however, were uncertain due to the low spectral
resolution that blended lines together. We present new JWST-MIRI spectra of four disks, two compact and two large withmultiple radial gaps, selected to test the scenario that water vapor inside the snowline is regulated by pebble drift. The higher
spectral resolving power of MIRI-MRS now yields water spectra that separate individual lines, tracing upper level energies from900 K to 10,000 K. These spectra clearly reveal excess emission in the low-energy lines in compact disks, compared to the large
disks, demonstrating an enhanced cool component with T ≈ 170-400 K and equivalent emitting radius Req ≈ 1-10 au. Weinterpret the cool water emission as ice sublimation and vapor diffusion near the snowline, suggesting that there is indeed ahigher inwards mass flux of icy pebbles in compact disks. Observation of this process opens up multiple exciting prospects tostudy planet formation chemistry in inner disks with JWST.

11. Disk Cooling and Wind Lines As Seen In the Spectral Line Evolution of V960 Mon
Adolfo S. Carvalho, Lynne A. Hillenbrand, Jerome Seebeck F We follow up our photometric study of the post-outburst
evolution of the FU Ori object V960 Mon with a complementary spectroscopic study at high dispersion that uses time series
spectra from Keck/HIRES. Consistent with the photometric results reported in Carvalho et al. 2023, we find that the spectral
evolution of V960 Mon corresponds to a decrease in the temperature of the inner disk, driven by a combination of decreasing
accretion rate and increasing inner disk radius. We also find that although the majority of the absorption lines are well-matchedby our accretion disk model spectrum, there are several strong absorption line families and a few emission lines that are notcaptured by the model. By subtracting the accretion disk model from the data at each epoch, we isolate the wind/outflow
components of the system. The residuals show both broad and highly blueshifted profiles, as well as narrow and only slightly
blueshifted profiles, with some lines displaying both types of features.

JWST imaging of edge-on protoplanetary disks. I. Fully vertically mixed 10µm grains
12. in the outer regions of a 1000 au disk
G. Duchene, F. Menard, K. Stapelfeldt, M. Villenave, S. G. Wolff, M. D. Perrin, C. Pinte, R. Tazaki, D. L.
Padgett F Scattered light imaging of protoplanetary disks provides key insights on the geometry and dust properties in the disk
surface. Here we present JWST 2–21 µm images of a 1000 au-radius edge-on protoplanetary disk surrounding an 0.4 M youngstar in Taurus, 2MASS J04202144+2813491. These observations represent the longest wavelengths at which a protoplanetary
disk is spatially resolved in scattered light. We combine these observations with HST optical images and ALMA continuumand CO mapping. We find that the changes in the scattered light disk morphology are remarkably small across a factor of 30
in wavelength, indicating that dust in the disk surface layers is characterized by an almost gray opacity law. Using radiativetransfer models, we conclude that grains up to & 10 µm in size are fully coupled to the gas in this system, whereas grains& 100 µm are strongly settled towards the midplane. Further analyses of these observations, and similar ones of other edge-on
disks, will provide strong empirical constraints on disk dynamics and evolution and grain growth models. In addition, the 7.7
and 12. µm JWST images reveal an X-shaped feature located above the warm molecular layer traced by CO line emission.
The highest elevations at which this feature is detectable roughly match the maximal extent of the disk in visible wavelength
scattered light as well as of an unusual kinematic signature in CO. We propose that these phenomena could be related to a disk
wind entraining small dust grains.

13. Velocity-resolved high-J CO emission from massive star-forming clumps

Hoang Thanh Dat, Agata Karska, Min Young Lee, Friedrich Wyrowski, Le Ngoc Tram, Aiyuan Y. Yang, Karl
M. Menten F (Abridged) Context. Massive star formation is associated with energetic processes, which result in significant
gas cooling via far-infrared (IR) lines. Velocity-resolved observations can constrain the kinematics of the gas, allowing the5identification of the physical mechanisms responsible for gas heating. Aims. Our aim is to quantify far-infrared CO line
emission toward high-mass star-forming regions, identify the high-velocity gas component associated with outflows, and estimate
the physical conditions required for the excitation of the observed lines. Methods. Velocity-resolved SOFIA/GREAT spectra of
13 high-mass star forming clumps of various luminosities and evolutionary stages are studied using CO 11-10 and 16-15 lines.
Results. All targets show strong high-J CO emission in the far-IR, characterized by broad line wings associated with outflows,
thereby significantly increasing the sample of sources with velocity-resolved high-J CO spectra. The contribution of the emission
in the line wings does not correlate with the envelope mass or evolutionary stage. Gas rotational temperatures cover a narrow
range of 120-220 K for the line wings. The non-LTE radiative transfer models indicate gas densities of 1e5-1e7 cm-3 and N(CO)of 1e17- 1e18 cm-2, similar to physical conditions in deeply-embedded low- and high-mass protostars. The velocity-integrated
CO line fluxes correlate with the bolometric luminosity over 7 orders of magnitude including data on the low-mass protostars,
suggesting similar processes are responsible for the high-J CO excitation over a significant range of physical scales. Conclusions.
Velocity-resolved line profiles allow the detection of outflows toward massive star-forming clumps spanning a broad range ofevolutionary stages. The lack of clear evolutionary trends suggest that mass accretion and ejection prevail during the entire
lifetime of star-forming clumps.

Low NH3 /H2 O ratio in comet C/2020 F3 (NEOWISE) at 0.7 au from the Sun
14. Maria N. Drozdovskaya,
Dominique Bockelée-Morvan, Jacques Crovisier, Brett A. McGuire, Nicolas Biver,
Steven B. Charnley, Martin A. Cordiner, Stefanie N. Milam, Cyrielle Opitom, Anthony J. Remijan F A
lower-than-solar elemental nitrogen content has been demonstrated for several comets, including 1P/Halley and 67P/C-G withindependent in situ measurements of volatile and refractory budgets. The recently discovered semi-refractory ammonium salts
in 67P/C-G are thought to be the missing nitrogen reservoir in comets. The thermal desorption of ammonium salts fromcometary dust particles leads to their decomposition into ammonia and a corresponding acid. The NH3 /H2 O ratio is expected
to increase with decreasing heliocentric distance with evidence for this in near-infrared observations. NH3 has been claimed tobe more extended than expected for a nuclear source. Here, the aim is to constrain the NH3 /H2 O ratio in comet C/2020 F3(NEOWISE) during its July 2020 passage. OH emission from comet C/2020 F3 (NEOWISE) was monitored for 2 months with
NRT and observed from GBT on 24 July and 11 August 2020. Contemporaneously with the 24 July 2020 OH observations, theNH3 hyperfine lines were targeted with GBT. The concurrent GBT and NRT observations allowed the OH quenching radius
to be determined at (5.96 ± 0.10) × 104 km on 24 July 2020, which is important for accurately deriving Q(OH). C/2020 F3(NEOWISE) was a highly active comet with Q(H2 O) ≈ 2 × 1030 molec s−1 one day before perihelion. The 3σ upper limit for
QNH3 /QH2 O is < 0.29% at 0.7 au from the Sun. The obtained NH3 /H2 O ratio is a factor of a few lower than measurements forother comets at such heliocentric distances. The abundance of NH3 may vary strongly with time depending on the amount ofwater-poor dust in the coma. Lifted dust can be heated, fragmented, and super-heated; whereby, ammonium salts, if present,
can rapidly thermally disintegrate and modify the NH3 /H2 O ratio.

15. FAUST X: Formaldehyde in the Protobinary System [BHB2007] 11: Small Scale Deuteration
Lucy Evans, Charlotte Vastel, Francisco Fontani, Jaime Pineda, Izaskun Jiménez-Serra, Felipe Alves, Takeshi
Sakai, Mathilde Bouvier, Paola Caselli, Cecilia Ceccarelli, Claire Chandler, Brian Svoboda, Luke Maud, Claudio Codella, Nami Sakai, Romane Le Gal, Ana López-Sepulcre, George Moellenbrock, Satoshi Yamamoto F
Context. Deuterium in H-bearing species is enhanced during the early stages of star formation, however, only a small number ofhigh spatial resolution deuteration studies exist towards protostellar objects, leaving the small-scale structures unrevealed andunderstudied. Aims. We aim to constrain the deuterium fractionation ratios in a Class 0/I protostellar object in formaldehyde(H2CO), which has abundant deuterated isotopologues in this environment. Methods. We observed the Class 0/I protobinary
system [BHB2007] 11, whose emission components are embedded in circumstellar disks that have radii of 2-3 au, using ALMA
within the context of the Large Program FAUST. The system is surrounded by a complex filamentary structure connecting to
the larger circumbinary disk. In this work we present the first study of formaldehyde D-fractionation towards this source with
detections of H2CO 3(0,3)-2(0,2), combined with HDCO 4(2,2)-3(2,1), HDCO 4(1,4)-3(1,3) and D2CO 4(0,4)-3(0,3). Theseobservations enable multiple velocity components associated with the methanol hotspots also uncovered by FAUST data, as
well as the external envelope, to be resolved. In addition, based on the kinematics seen in the observations of the H2CO
emission, we propose the presence of a second large scale outflow. Results. HDCO and D2CO are only found in the central
regions of the core while H2CO is found more ubiquitously. From radiative transfer modelling, the column densities ranges
found for H2CO, HDCO and D2CO are (3-8)x1014 cm−2 , (0.8-2.9)x1013 cm−2 and (2.6-4.3)x1012 cm−2 , respectively, yielding
an average D/H ratio of 0.01-0.04. Following the results of kinematic modelling, the second large scale feature is inconsistent
with a streamer-like nature and we thus tentatively conclude that the feature is an asymmetric molecular outflow launched bya wide-angle disk wind.

6

Evolution of Chemistry in the envelope of Hot Corinos (ECHOS). I. Extremely young
16. sulphur chemistry in the isolated Class 0 object B335
G. Esplugues, M. Rodríguez-Baras, D. San Andrés, D. Navarro-Almaida, A. Fuente, P. Rivière-Marichalar, Á.
Sánchez-Monge, M. N. Drozdovskaya, S. Spezzano, P. Caselli F Within the project Evolution of Chemistry in theenvelope of HOt corinoS (ECHOS), we present a study of sulphur chemistry in the envelope of the Class 0 source B335 throughobservations in the spectral range 7, 3, and 2 mm. We have modelled observations assuming LTE and LVG approximation. We
have also used the code Nautilus to study the time evolution of sulphur species. We have detected 20 sulphur species with a
total gas-phase S abundance similar to that found in the envelopes of other Class 0 objects, but with significant differences in
the abundances between sulphur carbon chains and sulphur molecules containing oxygen and nitrogen. Our results highlightthe nature of B335 as a source especially rich in sulphur carbon chains unlike other Class 0 sources. The low presence or absenceof some molecules, such as SO and SO+, suggests a chemistry not particularly influenced by shocks. We, however, detect alarge presence of HCS+ that, together with the low rotational temperatures obtained for all the S species (<15 K), reveals
the moderate or low density of the envelope of B335. We also find that observations are better reproduced by models with asulphur depletion factor of 10 with respect to the sulphur cosmic elemental abundance. The comparison between our modeland observational results for B335 reveals an age of 104 <t<105 yr, which highlights the particularly early evolutionary stageof this source. B335 presents a different chemistry compared to other young protostars that have formed in dense molecular
clouds, which could be the result of accretion of surrounding material from the diffuse cloud onto the protostellar envelope of
B335. In addition, the analysis of the SO2/C2S, SO/CS, and HCS+/CS ratios within a sample of prestellar cores and Class 0
objects show that they could be used as good chemical evolutionary indicators of the prestellar to protostellar transition.

Millimetre and submillimetre spectroscopy of isobutene and its detection in the molec17. ular cloud G+0.693
Mariyam Fatima, Holger S. P. Müller, Oliver Zingsheim, Frank Lewen, Víctor M. Rivilla, Izaskun JiménezSerra, Jesús Martín-Pintado, Stephan Schlemmer F Isobutene ((CH3 )2 C=CH2 ) is one of the four isomers of butene(C4 H8 ). Given the detection of propene (CH3 CH=CH2 ) toward TMC-1, and also in the warmer environment of the solar-type
protostellar system IRAS 16293−2422, one of the next alkenes, isobutene, is a promising candidate to be searched for in space.
We aim to extend the limited line lists of the main isotopologue of isobutene from the microwave to the millimetre region inorder to obtain a highly precise set of rest frequencies and to facilitate its detection in the interstellar medium. We investigated the rotational spectrum of isobutene in the 35−370 GHz range using absorption spectroscopy at room temperature.
Quantum-chemical calculations were carried out to evaluate vibrational frequencies. We determined new or improved spectroscopic parameters for isobutene up to a sixth-order distortion constant. These new results enabled its detection in the G+0.693
molecular cloud for the first time, where propene was also recently found. The propene to isobutene column density ratio
was determined to be about 3:1. The observed spectroscopic parameters for isobutene are sufficiently accurate that calculatedtransition frequencies should be reliable up to 700 GHz. This will further help in observing this alkene in other, warmer regionsof the ISM.

emission in photoevaporating disks is determined by early substructures
18. Millimeter
Matías Gárate, Til Birnstiel, Paola Pinilla, Sean M. Andrews, Raphael Franz, Sebastian Markus Stammler,
Giovanni Picogna, Barbara Ercolano, Anna Miotello, Nicolás T. Kurtovic F [abridged]Photoevaporation and dusttrapping are individually considered to be important mechanisms in the evolution and morphology of protoplanetary disks.
We studied how the presence of early substructures affects the evolution of the dust distribution and flux in the millimeter
continuum of disks that are undergoing photoevaporative dispersal. We also tested if the predicted properties resemble thoseobserved in the population of transition disks. We used the numerical code Dustpy to simulate disk evolution considering gas
accretion, dust growth, dust-trapping at substructures, and mass loss due to X-ray and EUV (XEUV) photoevaporation and dust
entrainment. Then, we compared how the dust mass and millimeter flux evolve for different disk models. We find that, during
photoevaporative dispersal, disks with primordial substructures retain more dust and are brighter in the millimeter continuum
than disks without early substructures, regardless of the photoevaporative cavity size. Once the photoevaporative cavity opens,
the estimated fluxes for the disk models that are initially structured are comparable to those found in the bright transition
disk population (Fmm > 30 mJy), while the disk models that are initially smooth have fluxes comparable to the transition disks
from the faint population (Fmm < 30 mJy), suggesting a link between each model and population. Our models indicate that theefficiency of the dust trapping determines the millimeter flux of the disk, while the gas loss due to photoevaporation controls
the formation and expansion of a cavity, decoupling the mechanisms responsible for each feature. In consequence, even a planetwith a mass comparable to Saturn could trap enough dust to reproduce the millimeter emission of a bright transition disk, while
its cavity size is independently driven by photoevaporative dispersal.

7

A global view on star formation: The GLOSTAR Galactic plane survey VIII. Formalde19. hyde absorption in Cygnus X
Y. Gong, G. N. Ortiz-León, M. R. Rugel, K. M. Menten, A. Brunthaler, F. Wyrowski, C. Henkel, H. Beuther,S. A. Dzib, J. S. Urquhart, A. Y. Yang, J. D. Pandian, R. Dokara, V. S. Veena, H. Nguyen, S. -N. X. Medina,W. D. Cotton, W. Reich, B. Winkel, P. Müller, I. Skretas, T. Csengeri, S. Khan, A. Cheema F Cygnus X is oneof the closest and most active high-mass star-forming regions in our Galaxy, making it one of the best laboratories for studying
massive star formation. As part of the GLOSTAR Galactic plane survey, we performed large scale simultaneous H2 CO (11,0 11,1 ) spectral line and radio continuum imaging observations toward Cygnus X at λ ∼6 cm with the Karl G. Jansky Very Large
Array and the Effelsberg-100 m radio telescope. Our Effelsberg observations reveal widespread H2 CO (11,0 -11,1 ) absorption
with a spatial extent of &50 pc in Cygnus X for the first time. On large scales of 4.4 pc, the relative orientation between local
velocity gradient and magnetic field tends to be more parallel at H2 column densities of &1.8×1022 cm−2 . On the smaller scaleof 0.17 pc, our VLA+Effelsberg combined data reveal H2 CO absorption only toward three bright HII regions. Our observations
demonstrate that H2 CO (11,0 -11,1 ) is commonly optically thin. Kinematic analysis supports the assertion that molecular clouds
generally exhibit supersonic motions on scales of 0.17-4.4 pc. We show a non-negligible contribution of the cosmic microwave
background radiation in producing extended absorption features in Cygnus X. Our observations suggest that H2 CO (11,0 − 11,1 )can trace molecular gas with H2 column densities of & 5 × 1021 cm−2 . The ortho-H2 CO fractional abundance with respect toH2 has a mean value of 7.0×10−10 . A comparison of velocity dispersions on different linear scales suggests that the dominant−3 km s−1 velocity component in the prominent DR21 region has nearly identical velocity dispersions on scales of 0.17-4.4 pc,
which deviates from the expected behavior of classic turbulence.

Protonated hydrogen cyanide as a tracer of pristine molecular gas
20. Y. Gong, F. J. Du, C. Henkel, A. M. Jacob, A. Belloche, J. Z. Wang, K. M. Menten, W. Yang, D. H. Quan,
C. T. Bop, G. N. Ortiz-León, X. D. Tang, M. R. Rugel, S. Liu F Protonated hydrogen cyanide, HCNH+ , plays afundamental role in astrochemistry because it is an intermediary in gas-phase ion-neutral reactions within cold molecular clouds.
However, the impact of the environment on the chemistry of HCNH+ remains poorly understood. With the IRAM-30 m and
APEX-12 m observations, we report the first robust distribution of HCNH+ in the Serpens filament and in Serpens South. Ourdata suggest that HCNH+ is abundant in cold and quiescent regions, but is deficit in active star-forming regions. The observed
HCNH+ fractional abundances relative to H2 range from 3.1 × 10−11 in protostellar cores to 5.9 × 10−10 in prestellar cores,
and the HCNH+ abundance generally decreases with increasing H2 column density, which suggests that HCNH+ coevolves withcloud cores. Our observations and modeling results suggest that the abundance of HCNH+ in cold molecular clouds is strongly
dependent on the H2 number density. The decrease in the abundance of HCNH+ is caused by the fact that its main precursors(e.g., HCN and HNC) undergo freeze-out as the number density of H2 increases. However, current chemical models cannot
explain other observed trends, such as the fact that the abundance of HCNH+ shows an anti-correlation with that of HCN and
HNC, but a positive correlation with that of N2 H+ in the southern part of the Serpens South northern clump. This indicatesthat additional chemical pathways have to be invoked for the formation of HCNH+ via molecules like N2 in regions in which
HCN and HNC freeze out. Both the fact that HCNH+ is most abundant in molecular cores prior to gravitational collapse andthe fact that low-J HCNH+ transitions have very low H2 critical densities make this molecular ion an excellent probe of pristine
molecular gas.

Disentangling the warm and cold material in the high-mass IRAS 23385+6053
21. JOYS:
cluster
C. Gieser, H. Beuther, E. F. van Dishoeck, L. Francis, M. L. van Gelder, L. Tychoniec, P. J. Kavanagh,
G. Perotti, A. Caratti o Garatti, T. P. Ray, P. Klaassen, K. Justtanont, H. Linnartz, W. R. M. Rocha, K.
Slavicinska, L. Colina, M. Güdel, Th. Henning, P. -O. Lagage, G. Östlin, B. Vandenbussche, C. Waelkens,
G. Wright F (abridged) We study and compare the warm (>100 K) and cold (<100 K) material toward the high-mass starforming region IRAS 23385+6053 (IRAS 23385 hereafter) combining high angular resolution observations in the mid-infrared(MIR) with the JWST Observations of Young protoStars (JOYS) project and with the NOEMA at mm wavelengths at angularresolutions of 0.2"-1". The spatial morphology of atomic and molecular species is investigated by line integrated intensity maps.
The temperature and column density of different gas components is estimated using H2 transitions (warm and hot component)
and a series of CH3CN transitions as well as 3 mm continuum emission (cold component). Toward the central dense core in
IRAS 23385 the material consists of relatively cold gas and dust ( 50 K), while multiple outflows create heated and/or shocked
H2 and show enhanced temperatures ( 400 K) along the outflow structures. An energetic outflow with enhanced emission knotsof [Fe II] and [Ni II] hints at J-type shocks, while two other outflows have enhanced emission of only H2 and [S I] caused by
C-type shocks. The latter two outflows are also more prominent in molecular line emission at mm wavelengths (e.g., SiO, SO,
H2CO, and CH3OH). Even higher angular resolution data are needed to unambiguously identify the outflow driving sources
given the clustered nature of IRAS 23385. While most of the forbidden fine structure transitions are blueshifted, [Ne II] and[Ne III] peak at the source velocity toward the MIR source A/mmA2 suggesting that the emission is originating from closer to8the protostar.

Grain Growth and Dust Segregation Revealed by Multi-wavelength Analysis of the
22. Class I Protostellar Disk WL 17
Ilseung Han, Woojin Kwon, Yusuke Aso, Jaehan Bae, Patrick Sheehan F The first step toward planet formation
is grain growth from (sub-)micrometer to millimeter/centimeter sizes. Grain growth has been reported not only in Class II
protoplanetary disks but also in Class 0/I protostellar envelopes. However, early-stage grain growth occurring in Class 0/I stages
has rarely been observed on the protostellar disk scale. Here we present the results from the ALMA Band 3 (λ = 3.1 mm) and7 (λ = 0.87 mm) archival data of the Class I protostellar disk WL 17 in the ρ Ophiuchus molecular cloud. Disk substructures
are found in both bands, but they are different: while a central hole and a symmetric ring appear in Band 3, an off-center holeand an asymmetric ring are shown in Band 7. Furthermore, we obtain an asymmetric spectral index map with a low meanvalue of α = 2.28 ± 0.02, suggestive of grain growth and dust segregation on the protostellar disk scale. Our radiative transfer
modeling verifies these two features by demonstrating that 10 cm-sized large grains are symmetrically distributed, whereas 10µm-sized small grains are asymmetrically distributed. Also, the analysis shows that the disk is expected to be massive andgravitationally unstable. We thus suggest a single Jupiter-mass protoplanet formed by gravitational instability as the origin of
the ring-like structure, grain growth, and dust segregation identified in WL 17.

of icy planetesimals to inner planets in the Proxima Centauri planetary system
23. Delivery
S. I. Ipatov F The estimates of the delivery of icy planetesimals from the feeding zone of Proxima Centauri c (with massequal to 7mE, mE is the mass of the Earth) to inner planets b and d were made. They included the studies of the total massof planetesimals in the feeding zone of planet c and the probabilities of collisions of such planetesimals with inner planets. This
total mass could be about 10-15mE. It was estimated based on studies of the ratio of the mass of planetesimals ejected into
hyperbolic orbits to the mass of planetesimals collided with forming planet c. At integration of the motion of planetesimals,
the gravitational influence of planets c and b and the star was taken into account. In most series of calculations, planetesimals
collided with planets were excluded from integrations. Based on estimates of the mass of planetesimals ejected into hyperbolic
orbits, it was concluded that during the growth of the mass of planet c the semi-major axis of its orbit could decrease by atleast a factor of 1.5. Depending on possible gravitational scattering due to mutual encounters of planetesimals, the total massof material delivered by planetesimals from the feeding zone of planet c to planet b was estimated to be between 0.002mE and0.015mE. Probably, the amount of water delivered to Proxima Centauri b exceeded the mass of water in Earth’s oceans. The
amount of material delivered to planet d could be a little less than that delivered to planet b.

24. The Global Structure of Molecular Clouds: I. Trends with Mass and Star Formation
Rate
Nia Imara, John C. Forbes F We introduce a model for the large-scale, global 3D structure of molecular clouds. Motivatedby the morphological appearance of clouds in surface density maps, we model clouds as cylinders, with the aim of backing out
information about the volume density distribution of gas and its relationship to star formation. We test our model by applying
it to surface density maps for a sample of nearby clouds and find solutions that fit each of the observed radial surface density
profiles remarkably well. Our most salient findings are that clouds with higher central volume densities are more compact andalso have lower total mass. These same lower-mass clouds tend to have shorter gas depletion times, regardless of whether weconsider their total mass or dense mass. Our analyses lead us to conclude that cylindrical clouds can be characterized by auniversal structure that sets the timescale on which they form stars.

25. The population of young low-mass stars in Trumpler 14

Dominika Itrich, Leonardo Testi, Giacomo Beccari, Carlo F. Manara, Megan Reiter, Thomas Preibisch, Anna
F. McLeod, Giovanni Rosotti, Ralf Klessen, Sergio Molinari, Patrick Hennebelle F Massive star-forming regions
are thought to be the most common birth environments in the Galaxy and the only birth places of very massive stars. Their
presence in the stellar cluster alters the conditions within the cluster impacting at the same time the evolution of other cluster
members. In principle, copious amounts of ultraviolet radiation produced by massive stars can remove material from outer partsof the protoplanetary disks around low- and intermediate-mass stars in the process of external photoevaporation, effectively
reducing the planet-formation capabilities of those disks. Here, we present deep VLT/MUSE observations of low-mass stars in
Trumpler 14, one of the most massive, young, and compact clusters in the Carina Nebula Complex. We provide spectral andstellar properties of 717 sources and based on the distribution of stellar ages derive the cluster age of ∼1 Myr. The majority ofthe stars in our sample have masses 61 M , what makes our spectroscopic catalogue the most deep to date in term of masses,
and proves that detailed investigations of low-mass stars are possible in the massive but distant regions. Spectroscopic studiesof low-mass members of the whole Carina Nebula Complex are missing. Our work provides an important step forward towards
filling this gap and set the stage for follow-up investigation of accretion properties in Trumpler 14.

9Variability and Detection of Superflares in a Young Brown Dwarf by TESS
26. Rotational
Rajib Kumbhakar, Soumen Mondal, Samrat Ghosh, Diya Ram, Sudip Pramanik F We present a comprehensive
analysis of a Transiting Exoplanet Survey Satellite (TESS) high-quality light curve for a young brown dwarf, MHO 4 having
spectral type M7.0, in the Taurus star-forming region. We investigate the rotation periods and characterize the BD’s dynamic
atmosphere and surface features. We present light curve analysis of MHO 4, and estimate the rotation period to be around2.224 d. Remarkably, MHO 4 exhibits two significant flaring events. Furthermore, we also estimated bolometric flare energies
to be within the energy range of 1034 to 1035 erg, which sits in the superflare category.

FEEDBACK Survey: The Pillars of Creation in [C II] and Molecular Lines
27. SOFIA
Ramsey L. Karim, Marc W. Pound, Alexander G. G. M. Tielens, Maitraiyee Tiwari, Lars Bonne, Mark G.
Wolfire, Nicola Schneider, Ümit Kavak, Lee G. Mundy, Robert Simon, Rolf Güsten, Jürgen Stutzki, Friedrich
Wyrowski, Netty Honingh F We investigate the physical structure and conditions of photodissociation regions (PDRs) andmolecular gas within the Pillars of Creation in the Eagle Nebula using SOFIA FEEDBACK observations of the [C II] 158 micronline. These observations are velocity resolved to 0.5 km s−1 and are analyzed alongside a collection of complimentary data withsimilar spatial and spectral resolution: the [O I] 63 micron line, also observed with SOFIA, and rotational lines of CO, HCN,
HCO+ , CS, and N2 H+ . Using the superb spectral resolution of SOFIA, APEX, CARMA, and BIMA, we reveal the relationships
between the warm PDR and cool molecular gas layers in context of the Pillars’ kinematic structure. We assemble a geometricpicture of the Pillars and their surroundings informed by illumination patterns and kinematic relationships and derive physicalconditions in the PDRs associated with the Pillars. We estimate an average molecular gas density nH2 ∼ 1.3 × 105 cm−3 andan average atomic gas density nH ∼ 1.8 × 104 cm−3 and infer that the ionized, atomic, and molecular phases are in pressure
equilibrium if the atomic gas is magnetically supported. We find pillar masses of 103, 78, 103, and 18 solar masses for P1a,
P1b, P2, and P3 respectively, and evaporation times of ∼1-2 Myr. The dense clumps at the tops of the pillars are currently
supported by the magnetic field. Our analysis suggests that ambipolar diffusion is rapid and these clumps are likely to collapse
within their photoevaporation timescales.

28. A resolved rotating disk wind from a young T Tauri star in the Bok globule CB26

R. Launhardt, Ya. N. Pavlyuchenkov, V. V. Akimkin, A. Dutrey, F. Gueth, S. Guilloteau, Th. Henning,
V. Pietu, K. Schreyer, D. Semenov, B. Stecklum, T. L. Bourke F The disk-outflow connection plays a key role inextracting excess angular momentum from a forming protostar. We have previously reported the discovery of a small molecular
outflow from the edge-on T Tauri star in the Bok globule CB26 that shows a peculiar velocity pattern, reminiscent of an outflow
that corotates with the disk. We report new, high-resolution mm-interferometric observations of CB26 with the aim of revealing
the morphology and kinematics of the outflow at the disk-outflow interface. The IRAM PdBI was used to observe CO(2-1) at
1.3mm with a resolution of 0.5". Using a physical model of the disk, which was derived from the dust emission, we employedchemo-dynamical modeling combined with line radiative transfer to constrain kinematic parameters and to construct a modelof the CO emission from the disk that allowed us to separate the emission of the disk from that of the outflow. Our observations
confirm the disk-wind nature of the rotating molecular outflow from CB26. The new high-resolution data reveal an X-shaped
morphology of the CO emission close to the disk, and vertical streaks extending from the disk surface with a small half-opening
angle of 7deg, which can be traced out to vertical heights of 500au. We interpret this emission as the combination of the disk
atmosphere and a well-collimated disk wind, which we trace down to vertical heights of 40au, where it is launched from thesurface of the flared disk at radii of 20-45au. The observed CO outflow has a total momentum flux of 1e-5 Msun km/s/yr, which
is nearly three orders of magnitude larger than the maximum thrust that can be provided by the luminosity of the central star.
We conclude that photoevaporation cannot be the main driving mechanism for this outflow, but it must be predominantly an
MHD disk wind. It is thus far the best-resolved rotating disk wind observed to be launched from a circumstellar disk.

Testing external photoevaporation in the σ-Orionis cluster with spectroscopy and disk
29. mass measurements
K. Maucó, C. F. Manara, M. Ansdell, G. Bettoni, R. Claes, J. Alcala, A. Miotello, S. Facchini, T. J. Haworth, G.
Lodato, J. P. Williams F The evolution of protoplanetary disks is regulated by an interplay of several processes, either internal
to the system or related to the environment. As most of the stars and planets have formed in massive stellar clusters, studying
the effects of UV radiation on disk evolution is of paramount importance. Here we test the impact of external photoevaporationon the evolution of disks in the σ Orionis cluster by conducting the first combined large-scale UV to IR spectroscopic andmm-continuum survey of this region. We study a sample of 50 targets located at increasing distances from the central, OB
system σ Ori. We combine new VLT/X-Shooter spectra with new and previously published ALMA measurements of disk dust
and gas fluxes and masses. We confirm the previously found decrease of Mdust in the inner ∼0.5 pc of the cluster. This isparticularly evident when considering the disks around the more massive stars (≥ 0.4 M ), where those located in the innerpart (< 0.5 pc) have Mdust about an order of magnitude lower than the more distant ones. About half of the sample is locatedin the region of the Ṁacc vs Mdisk expected by models of external photoevaporation, namely showing shorter disk lifetimes.

10

These are observed for all targets with projected separation from σ Ori < 0.5 pc, proving that the presence of a massive stellar
system affects disk evolution. External photoevaporation is a viable mechanism to explain the observed shorter disk lifetimes
and lower Mdust in the inner ∼0.5 pc of the cluster. Follow-up observations of the low stellar mass targets are crucial to confirm
the dependence of the external photoevaporation process with stellar host mass. This work confirms that the effects of external
photoevaporation are significant down to impinging radiation as low as ∼ 104 G0 .

30. Finding substructures in protostellar disks in Ophiuchus

Arnaud Michel, Sarah I. Sadavoy, Patrick D. Sheehan, Leslie W. Looney, Erin G. Cox, John J. Tobin, Nienke
van der Marel, Dominique M. Segura-Cox F High-resolution, millimeter observations of disks at the protoplanetary stage
reveal substructures such as gaps, rings, arcs, spirals, and cavities. While many protoplanetary disks host such substructures,
only a few at the younger protostellar stage have shown similar features. We present a detailed search for early disk substructures
in ALMA 1.3 and 0.87 mm observations of ten protostellar disks in the Ophiuchus star-forming region. Of this sample, fourdisks have identified substructure, two appear to be smooth disks, and four are considered ambiguous. The structured disks
have wide Gaussian-like rings (σR /Rdisk ∼ 0.26) with low contrasts (C < 0.2) above a smooth disk profile, in comparison to
protoplanetary disks where rings tend to be narrow and have a wide variety of contrasts (σR /Rdisk ∼ 0.08 and C ranges from0 − 1). The four protostellar disks with the identified substructures are among the brightest sources in the Ophiuchus sample,
in agreement with trends observed for protoplanetary disks. These observations indicate that substructures in protostellar disks
may be common in brighter disks. The presence of substructures at the earliest stages suggests an early start for dust grain
growth and, subsequently, planet formation. The evolution of these protostellar substructures is hypothesized in two potential
pathways: (1) the rings are the sites of early planet formation, and the later observed protoplanetary disk ring-gap pairs aresecondary features, or (2) the rings evolve over the disk lifetime to become those observed at the protoplanetary disk stage.

31. Global kinematics study of OH masers in W49N
Mendoza-Torres, J. E., Juárez-Gama, M., Rodríguez-Esnard, I. T F Star formation is underway in the W49N
molecular cloud (MC) at a high level of efficiency, with almost twenty ultra-compact (UC) HII regions observed thus far,indicating a recent formation of massive stars. Previous works have suggested that this cloud is undergoing a global contraction.
We analyse the data on OH masers in the molecular cloud W49N, observed with the VLBA at the 1612, 1665, and 1667 MHztransitions in LCP and RCP with an aim to study the global kinematics of the masers. We carried out our study based on
the locations and observed velocities of the maser spots. The velocities were fitted to the straight line of Vobs -Vsys versusd(α,δ)m , resulting in Vf td . The difference between the fitted values and those obtained from observations is ∆V. The Vobs -Vsys
velocity shows a gradient as a function of the distance to (α, δ)m , where the closer spots have the largest velocities. Spots withsimilar velocities are located in different sectors, with respect to (α, δ)m . Then, we assumed that the spots are moving towards
a contraction centre (CCOH ), which is at the apex of a CONUS. We also assumed that the distance of each spot to CCOH isdcc and that they fall with a velocity VCC , with the total velocity being VT ot . Using this velocity, we estimated the free-fallvelocity. The observed dispersion with respect to the global trend against dcc , shows a maximum at 0.12 pc, with a decay from
0.12 to 0.19 pc, which is faster than that taking place between 0.19 and 0.42 pc. Based on Vtot an inner mass of Minn =2500
M was estimated.The velocities of the OH spots at W49N, together with their positions respect (α, δ)m , make it possible totrace a global kinematics, which seems to be due to a subcollapse in the W49N molecular cloud.

32. Constraining the geometry of the reflection nebula NGC 2023 with [O I]: Emission &Absorption
Bhaswati Mookerjea, Goeran Sandell, Rolf Guesten, Helmut Wiesemeyer, Yoko Okada, Karl Jacobs F We havemapped the NGC 2023 reflection nebula in the 63 and 145 micron transitions of [O I] and the 158 micron [C II] spectral lines
using the heterodyne receiver upGREAT on SOFIA. The observations were used to identify the diffuse and dense componentsof the PDR traced by the [C II] and [O I] emission, respectively. The velocity-resolved observations reveal the presence ofa significant column of low-excitation atomic oxygen, seen in absorption in the [O I] 63 micron spectra, amounting to about
20-60% of the oxygen column seen in emission in the [O I] 145 micron spectra. Some self-absorption is also seen in [C II], but
for the most part it is hardly noticeable. The [C II] and [O I] 63 micron spectra show strong red- and blue-shifted wings dueto photo evaporation flows especially in the southeastern and southern part of the reflection nebula, where comparison withthe mid- and high-J CO emission indicates that the C+ region is expanding into a dense molecular cloud. Using a two-slab
toy model the large-scale self-absorption seen in [O I] 63 micron is readily explained as originating in foreground low-excitation
gas associated with the source. Similar columns have also been observed recently in other Galactic photon-dominated-regions(PDRs). These results have two implications: for the velocity-unresolved extra-galactic observations this could impact the useof [O I] 63 micron as a tracer of massive star formation and secondly the widespread self-absorption in [O I] 63 micron leads tounderestimate of the column density of atomic oxygen derived from this tracer and necessitates the use of alternative indirect
methods.

11

Correlation between the optical veiling and accretion properties: A case study of the
33. classical T Tauri star DK Tau
M. Nelissen, A. Natta, P. McGinnis, C. Pittman, C. Delvaux, T. Ray F Classical T Tauri stars (cTTs) accrete
from their circumstellar disk. The material falls onto the stellar surface, producing an accretion shock, which generates veilingin a star’s spectra. In addition, the shock causes a localized accretion spot at the level of the chromosphere. Our goal is toinvestigate the accretion, particularly the mass accretion rates (Macc), for the cTTs DK Tau, over two periods of 17 and 29 days,
using two different procedures for comparison purposes. The first method relies on the derivation of the accretion luminosity
via accretion-powered emission lines. The second compares the variability of the optical veiling with accretion shock models
to determine mass accretion rates. We used observations taken in 2010 and 2012 with the ESPaDOnS spectropolarimeter at
the CFHT. We find peak values of the veiling (at 550 nm) ranging from 0.2 to 1.3, with a steeper trend across the wavelength
range for higher peak values. When using the accretion-powered emission lines, we find mass accretion rate values ranging fromlog(Macc[Msol/yr]) = -8.20 to log(Macc[Msol/yr]) = -7.40. This agrees with the values found in the literature, as well as thevalues calculated using the accretion shock models and the veiling. In addition, we identify a power-law correlation between thevalues of the accretion luminosity and the optical veiling. For the 2010 observations, using the values of the filling factors (which
represent the area of the star covered by an accretion spot) derived from the shock models, we infer that the accretion spot was
located between +45 degrees and +75 degrees in latitude. We show that both methods of determining the mass accretion rateyield similar results. We also present a helpful means of confirming the accretion luminosity values by measuring the veiling ata single wavelength in the optical.

34. Impact of hot exozodiacal dust on the polarimetric analysis of close-in exoplanets

Kevin Ollmann, Sebastian Wolf, Moritz Lietzow, Thomas A. Stuber F Hot exozodiacal dust (HEZD) found aroundmain-sequence stars through interferometric observations in the photometric bands H to L is located close to the dust sublimation
radius, potentially at orbital radii comparable to those of close-in exoplanets. Consequently, HEZD has a potential influenceon the analysis of the scattered-light polarization of close-in exoplanets and vice versa. We analyze the impact of HEZD on thepolarimetric characterization of close-in exoplanets. This study is motivated in particular by the recently proven feasibility of
exoplanet polarimetry. Applying the 3D Monte Carlo radiative transfer code POLARIS in an extended and optimized version
for radiative transfer in exoplanetary atmospheres and an analytical tool for modeling the HEZD, we simulated and compared
the polarization characteristics of the wavelength-dependent scattered-light polarization of HEZD and close-in exoplanets. The
varied parameters are the planetary phase angle (0◦ − 180◦ ), the dust grain radius (0.02 µm − 10 µm), the HEZD mass
(10−10 M⊕ − 10−8 M⊕ ), the orbital inclination (0◦ − 90◦ ), the composition of the planetary atmosphere (Mie and Rayleighscattering atmosphere), the orbital radius of the HEZD (0.02 au − 0.4 au), and the planetary orbital radius (0.01 au − 0.05 au).
The dust grain radius has the strongest influence on the polarimetric analysis due to its significant impact on the wavelengthdependent polarization characteristics and the total order of magnitude of the scattered-light polarization. In certain scenarios,
the scattered-light polarization of the HEZD even exceeds that of the close-in exoplanet.

35. Dissecting the morphology of star forming complex S193

Rakesh Pandey, Saurabh Sharma, Lokesh Dewangan, D. K. Ojha, Neelam Panwar Arpan Ghosh, Tirthendu
Sinha, Aayushi Verma, Harmeen Kaur F We have studied a star-forming complex S193 using near-infrared (NIR)
observations and other archival data covering optical to radio wavelengths. We identified stellar clusters in the complex using
the NIR photometric data and estimated the membership and distance of the clusters. Using the mid-infrared (MIR) and
far-infrared (FIR) images, the distribution of the dust emission around H ii regions is traced in the complex. The Herschelcolumn density and temperature maps analysis reveal 16 cold dust clumps in the complex. The Hα image and 1.4 GHz radio
continuum emission map are employed to study the ionised gas distribution and infer the spectral type and the dynamical
age of each H ii region/ionised clump in the complex. The 12 CO(J =3−2) and 13 CO(J =1−0) molecular line data hint at thepresence of two velocity components around [-43,-46] and [-47,-50] km/s, and their spatial distribution reveals two overlappingzones toward the complex. By investigating the immediate surroundings of the central cluster [BDS2003]57 and the pressure
calculations, we suggest that the feedback from the massive stars seems responsible for the observed velocity gradient and might
have triggered the formation of the central cluster [BDS2003]57.

36. Merging Filaments and Hub Formation in the G083.097+03.270 Molecular Complex
Alik Panja, Lokesh K. Dewangan, Tapas Baug, Wen Ping Chen, Yan Sun, Tirthendu Sinha, Soumen Mondal

F We uncover a hub-filament system associated with massive star formation in the G083.097+03.270. Diagnosed
with simultaneous 12 CO, 13 CO, and C18 O line observations, the region is found to host two distinct and elongatedfilaments having separate velocity components, interacting spatially and kinematically, that appear to have seeded
the formation of a dense hub at the intersection. A large velocity spread at the hub in addition to clear bridging

12

feature connecting the filaments in velocity are indicating merging of filaments. Along the filaments axis, the velocity
gradient reveals a global gas motion with an increasing velocity dispersion inward to the hub signifying turbulence.
Altogether, the clustering of Class I sources, a high excitation temperature, a high column density, and presence of a
massive outflow at the central hub suggest enhanced star formation. We propose that merging of large-scale filaments
and velocity gradients along filaments are the driving factors in the mass accumulation process at the hub that havesequentially led to the massive star formation. With two giant filaments merging to coincide with a hub therein withongoing star formation, this site serves as a benchmark for the ‘filaments to clusters’ star-forming paradigm.

High-resolution [OI] line spectral mapping of TW Hya consistent with X-ray driven
37. photoevaporation
Ch. Rab, M. Weber, G. Picogna, B. Ercolano, J. Owen F Theoretical models indicate that photoevaporativeand magnetothermal winds play a crucial role in the evolution and dispersal of protoplanetary disks and affect theformation of planetary systems. However, it is still unclear what wind-driving mechanism is dominant or if both are
at work, perhaps at different stages of disk evolution. Recent spatially resolved observations by Fang et al. (2023) ofthe [OI] 6300 Angstrom spectral line, a common disk wind tracer, in TW Hya revealed that about 80% of the emission
is confined to the inner few au of the disk. In this work, we show that state-of-the-art X-ray driven photoevaporation
models can reproduce the compact emission and the line profile of the [OI] 6300 Angstrom line. Furthermore, we showthat the models also simultaneously reproduce the observed line luminosities and detailed spectral profiles of both the[OI] 6300 Angstrom and the [NeII] 12.8 micron lines. While MHD wind models can also reproduce the compact radial
emission of the [OI] 6300 Angstrom line, they fail to match the observed spectral profile of the [OI] 6300 Angstromline and underestimate the luminosity of the [NeII] 12.8 micron line by a factor of three. We conclude that, while wecannot exclude the presence of an MHD wind component, the bulk of the wind structure of TW Hya is predominantly
shaped by a photoevaporative flow.

38. Into the Mystic: ALMA ACA observations of the Mystic Mountains in Carina

Megan Reiter, P. D. Klaassen, L. Moser-Fischer, A. F. McLeod, D. Itrich F We present new observations of

the Mystic Mountains cloud complex in the Carina Nebula using the ALMA Atacama Compact Array (ACA) to
quantify the impact of strong UV radiation on the structure and kinematics of the gas. Our Band 6 observations
target CO, 13 CO, and C18 O; we also detect DCN J=3-2 and 13 CS J=5-4. A dendrogram analysis reveals that the
Mystic Mountains are a coherent structure, with continuous emission over −10.5 km s−1 < v < −2 km s−1 . We
perform multiple analyses to isolate non-thermal motions in the Mystic Mountains including computing the turbulent
driving parameter, b, which indicates whether compressive or solenoidal modes dominate. Each analysis yields values
similar to other pillars in Carina that have been observed in a similar way but are subject to an order of magnitudeless intense ionizing radiation. We find no clear correlation between the velocity or turbulent structure of the gas andthe incident radiation, in contrast to other studies targeting different regions of Carina. This may reflect differencesin the initial densities of regions that go on to collapse into pillars and those that still look like clouds or walls in
the present day. Pre-existing over-densities that enable pillar formation may also explain why star formation in thepillars appears more evolved (from the presence of jets) than in other heavily-irradiated but non-pillar-like regions.
High resolution observations of regions subject to an array of incident radiation are required to test this hypothesis.

Protoplanetary and debris disks in the η Chamaeleontis Association: A sub-millimeter
39. survey obtained with APEX/LABOCA
V. Roccatagliata, A. Sicilia-Aguilar, M. Kim, J. Campbell-White, M. Fang, S. J. Murphy, S. Wolf, W. A.
Lawson, Th. Henning, J. Bouwman F Nearby associations are ideal regions to study coeval samples of protoplane-tary and debris disks down to late M-type stars. Those aged 5-10,Myrs, where most of the disk should have alreadydissipated forming planets, are of particular interest. We present the first complete study of both protoplanetaryand debris disks in a young region, using the η Chamaeleontis association as a test bench to study the cold disk
content. We obtained sub-millimeter data for the entire core population down to late M-type stars, plus a few halo
members. We performed a continuum sub-millimeter survey with APEX/LABOCA of all the core populations of η
Cha association. Disk properties have been derived by modeling protoplanetary and debris disks using RADMC 2D
and DMS, respectively. We find that protoplanetary disks in η Cha typically have holes with radii of the order of 0.01
to 0.03 AU, while ring-like emission from the debris disks is located between 20 au and 650 au from the central star.

13

The parallaxes and Gaia eDR3 photometry, in combination with the PARSEC and COLIBRI isochrones, enable us
to confirm an age of η Cha between 7 and 9 Myrs. In general, the disk mass seems insufficient to support accretionover a long time, even for the lowest mass accretors, a clear difference compared with other regions and also a signthat the mass budget is further underestimated. We do not find a correlation between the stellar masses, accretion
rates, and disk masses, although this could be due to sample issues. We confirm that the presence of inner holes is notenough to stop accretion unless accompanied by dramatic changes to the total disk mass content. Comparing η Cha
with other regions at different ages, we find that the physical processes responsible for debris disks (e.g., dust growth,
dust trapping) efficiently act in less than 5 Myrs.

Early Planet Formation in Embedded Disks (eDisk) IX: High-resolution ALMA Obser40. vations of the Class 0 Protostar R CrA IRS5N and its surrounding
Rajeeb Sharma, Jes K. Jørgensen, Sacha Gavino, Nagayoshi Ohashi, John J. Tobin, Zhe-Yu Daniel Lin, Zhi-Yun
Li, Shigehisa Takakuwa, Chang Won Lee, Jinshi Sai, Woojin Kwon, Itziar de Gregorio-Monsalvo, Alejandro
Santamaría-Miranda, Hsi-Wei Yen, Yuri Aikawa, Yusuke Aso, Shih-Ping Lai, Jeong-Eun Lee, Leslie W. Looney,
Nguyen Thi Phuong, Travis J. Thieme, Jonathan P. Williams F We present high-resolution, high-sensitivity ob-

servations of the Class 0 protostar RCrA IRS5N as part of the Atacama Large Milimeter/submilimeter Array (ALMA)
large program Early Planet Formation in Embedded Disks (eDisk). The 1.3 mm continuum emission reveals a flattened continuum structure around IRS5N, consistent with a protostellar disk in the early phases of evolution. The
continuum emission appears smooth and shows no substructures. However, a brightness asymmetry is observed along
the minor axis of the disk, suggesting the disk is optically and geometrically thick. We estimate the disk mass to be
between 0.007 and 0.02 M . Furthermore, molecular emission has been detected from various species, including C18 O(2−1), 12 CO (2−1), 13 CO (2−1), and H2 CO (30,3 − 20,2 , 32,1 − 22,0 , and 32,2 − 22,1 ). By conducting a position-velocity
analysis of the C18 O (2−1) emission, we find that the disk of IRS5N exhibits characteristics consistent with Keplerianrotation around a central protostar with a mass of approximately 0.3 M . Additionally, we observe dust continuum
emission from the nearby binary source, IRS5a/b. The emission in 12 CO toward IRS5a/b seems to emanate from
IRS5b and flow into IRS5a, suggesting material transport between their mutual orbits. The lack of a detected outflow
and large-scale negatives in observed toward IRS5N suggests that much of the flux from IRS5N is being resolved out.
Due to this substantial surrounding envelope, the central IRS5N protostar is expected to be significantly more massivein the future.

41. How to make giant planets via pebble accretion

Sofia Savvidou, Bertram Bitsch F Planet formation is directly linked to the birthing environment that protoplanetarydisks provide. The disk properties determine whether a giant planet will form and how it evolves. The numberof exoplanet and disk observations is consistently rising, however, it is not yet possible to directly link these two
populations. Therefore, a deep theoretical understanding of how planets form is crucial. We performed numericalsimulations of planet formation via pebble and gas accretion, while including migration, in a viscously evolving
protoplanetary disk, with dust growing, drifting, and evaporating at the ice lines. In our investigation of the mostfavorable conditions for giant planet formation, we find that these are high disk masses, early formation, and a large
enough disk to host a long-lasting pebble flux. However, small disks with the same mass allow more efficient gas
accretion onto planetary cores, leading to more massive gas giants. Given the right conditions, high viscosity leads
to more massive cores and it enhances gas accretion. It also causes faster type II migration rates, so the giants havea decreasing final position for increasing viscosity. Intermediate dust fragmentation velocities provide the necessary
pebble sizes and radial drift velocities for maximized pebble accretion and pebble flux. An enhanced dust-to-gas
ratio can compensate for lower disk masses, but early formation is still crucial. We conclude that there is no specificinitial parameter that leads to giant planet formation; rather, it is the outcome of a combination of complementaryfactors. This also implies that the diversity of the exoplanet systems is the product of the intrinsic diversity ofthe protoplanetary disks and it is crucial to take advantage of the increasing number and quality of observations toconstrain the disk population properties and ultimately devise planet formation theories.

14

The time evolution of Md /Ṁ in protoplanetary discs as a way to disentangle between
42. viscosity and MHD winds
Alice Somigliana, Leonardo Testi, Giovanni Rosotti, Claudia Toci, Giuseppe Lodato, Benoît Tabone, Carlo
Manara, Marco Tazzari F As the classic viscous paradigm for protoplanetary disk accretion is challenged by theobservational evidence of low turbulence, the alternative scenario of MHD disk winds is being explored as potentiallyable to reproduce the same observed features traditionally explained with viscosity. Although the two models lead todifferent disk properties, none of them has been ruled out by observations - mainly due to instrumental limitations. In
this work, we present a viable method to distinguish between the viscous and MHD framework based on the different
evolution of the distribution in the disk mass (Md ) - accretion rate (Ṁ ) plane of a disk population. With a synergyof analytical calculations and 1D numerical simulations, performed with the population synthesis code Diskpop, wefind that both mechanisms predict the spread of the observed ratio Md /Ṁ in a disk population to decrease overtime; however, this effect is much less pronounced in MHD-dominated populations as compared to purely viscous
populations. Furthermore, we demonstrate that this difference is detectable with the current observational facilities:
we show that convolving the intrinsic spread with the observational uncertainties does not affect our result, as theobserved spread in the MHD case remains significantly larger than in the viscous scenario. While the most recent
data available show a better agreement with the wind model, ongoing and future efforts to obtain direct gas massmeasurements with ALMA and ngVLA will cause a reassessment of this comparison in the near future.

A JWST inventory of protoplanetary disk ices: The edge-on protoplanetary disk HH
43. 48 NE, seen with the Ice Age ERS programJ. A. Sturm, M. K. McClure, T. L. Beck, D. Harsono, J. B. Bergner, E. Dartois, A. C. A. Boogert, J. E.
Chiar, M. A. Cordiner, M. N. Drozdovskaya, S. Ioppolo, C. J. Law, H. Linnartz, D. C. Lis, G. J. Melnick, B.
A. McGuire, J. A. Noble, K. I. Öberg, M. E. Palumbo, Y. J. Pendleton, G. Perotti, K. M. Pontoppidan, D.
Qasim, W. R. M. Rocha, H. Terada, R. G. Urso, E. F. van Dishoeck F Ices are the main carriers of volatiles inprotoplanetary disks and are crucial to our understanding of the chemistry that ultimately sets the organic compositionof planets. The ERS program Ice Age on the JWST follows the ice evolution through all stages of star and planet
formation. JWST/NIRSpec observations of the edge-on Class II protoplanetary disk HH 48 NE reveal spatiallyresolved absorption features of the major ice components H2 O, CO2 , CO, and multiple weaker signatures from lessabundant ices NH3 , OCN− , and OCS. Isotopologue 13 CO2 ice has been detected for the first time in a protoplanetary
disk. Since multiple complex light paths contribute to the observed flux, the ice absorption features are filled in by
ice-free scattered light. The 12 CO2 /13 CO2 ratio of 14 implies that the 12 CO2 feature is saturated, without the flux
approaching 0, indicative of a very high CO2 column density on the line of sight, and a corresponding abundance withrespect to hydrogen that is higher than ISM values by a factor of at least a few. Observations of rare isotopologues are
crucial, as we show that the 13 CO2 observation allows us to determine the column density of CO2 to be at an orderof magnitude higher than the lower limit directly inferred from the observed optical depth. Radial variations in ice
abundance, e.g., snowlines, are significantly modified since all observed photons have passed through the full radialextent of the disk. CO ice is observed at perplexing heights in the disk, extending to the top of the CO-emitting gas
layer. We argue that the most likely interpretation is that we observe some CO ice at high temperatures, trapped inless volatile ices like H2 O and CO2 . Future radiative transfer models will be required to constrain the implications on
our current understanding of disk physics and chemistry.

The Cygnus Allscale Survey of Chemistry and Dynamical Environments: CASCADE.
44. II. A detailed kinematic analysis of the DR21 Main outflow
I. M. Skretas, A. Karska, F. Wyrowski, K. M. Menten, H. Beuther, A. Ginsburg, A. Hernández-Gómez,C. Gieser, S. Li, W. -J. Kim, D. A. Semenov, L. Bouscasse, I. B. Christensen, J. M. Winters, A. Hacar

F Molecular outflows are believed to be a key ingredient in the process of star formation. The molecular outflow
associated with DR21 Main in Cygnus-X is one of the most extreme, in mass and size, molecular outflows in the MilkyWay. The outflow is suggested to belong to a rare class of explosive outflows which are formed by the disintegrationof protostellar systems.We aim to explore the morphology, kinematics,and energetics of the DR21 Main outflow, andcompare those properties to confirmed explosive outflows to unravel the underlying driving mechanism behind DR21.
Line and continuum emission are studied at a wavelength of 3.6 mm with IRAM 30 m and NOEMA telescopes aspart of the Cygnus Allscale Survey of Chemistry and Dynamical Environments (CASCADE) program. The spectra
include (J = 1 − 0) transitions of HCO+ , HCN, HNC, N2 H+ , H2 CO, CCH tracing different temperature and density
15

regimes of the outflowing gas at high-velocity resolution (∼ 0.8 km s−1 ). The map encompasses the entire DR21 Main
outflow and covers all spatial scales down to a resolution of 3" (∼ 0.02 pc). Integrated intensity maps of the HCO+
emission reveal a strongly collimated bipolar outflow with significant overlap of the blue- and red-shifted emission.
The opening angles of both outflow lobes decrease with velocity, from ∼ 80 to 20◦ for the velocity range from 5 to 45
km s−1 relative to the source velocity. No evidence is found for the presence of elongated, "filament-like" structures
expected in explosive outflows. N2 H+ emission near the western outflow lobe reveals the presence of a dense molecular
structure which appears to be interacting with the DR21 Main outflow. The overall morphology as well as the detailed
kinematics of the DR21 Main outflow is more consistent with that of a typical bipolar outflow instead of an explosive
counterpart.

45. Explaining the Chemical Inventory of Orion KL through Machine Learning

Haley N. Scolati, Anthony J. Remijan, Eric Herbst, Brett A. McGuire, Kin Long Kelvin Lee F The interplayof the chemistry and physics that exists within astrochemically relevant sources can only be fully appreciated if we
can gain a holistic understanding of their chemical inventories. Previous work by Lee et al. (2021) demonstrated
the capabilities of simple regression models to reproduce the abundances of the chemical inventory of the Taurus
Molecular Cloud 1 (TMC-1), as well as provide abundance predictions for new candidate molecules. It remains to beseen, however, to what degree TMC-1 is a “unicorn” in astrochemistry, where the simplicity of its chemistry and physics
readily facilitates characterization with simple machine learning models. Here we present an extension in chemicalcomplexity to a heavily studied high-mass star forming region: the Orion Kleinmann-Low (Orion KL) nebula. Unlike
TMC-1, Orion KL is composed of several structurally distinct environments that differ chemically and kinematically,
wherein the column densities of molecules between these components can have non-linear correlations that cause theunexpected appearance or even lack of likely species in various environments. This proof-of-concept study used similar
regression models sampled by Lee et al. (2021) to accurately reproduce the column densities from the XCLASS fitting
program presented in Crockett et al. (2014).

The Detection of Higher-Order Millimeter Hydrogen Recombination Lines in the Large
46. Magellanic Cloud
Marta Sewiło, Kazuki Tokuda, Stan E. Kurtz, Steven B. Charnley, Thomas Möller, Jennifer Wiseman, C. -H.
Rosie Chen, Remy Indebetouw, Álvaro Sánchez-Monge, Kei E. I. Tanaka, Peter Schilke, Toshikazu Onishi,
Naoto Harada F We report the first extragalactic detection of the higher-order millimeter hydrogen recombinationlines (∆n > 2). The γ-, -, and η-transitions have been detected toward the millimeter continuum source N105-1A inthe star-forming region N105 in the Large Magellanic Cloud (LMC) with the Atacama Large Millimeter/submillimeter
Array (ALMA). We use the H40α line, the brightest of the detected recombination lines (H40α, H36β, H50β, H41γ,
H57γ, H49, H53η, and H54η), and/or the 3 mm free-free continuum emission to determine the physical parametersof N105-1A (the electron temperature, emission measure, electron density, and size) and study ionized gas kinematics.
We compare the physical properties of N105-1A to a large sample of Galactic compact and ultracompact (UC) H II
regions and conclude that N105-1A is similar to the most luminous (L > 105 L ) UC H II regions in the Galaxy.
N105-1A is ionized by an O5.5 V star, it is deeply embedded in its natal molecular clump, and likely associated witha (proto)cluster. We incorporate high-resolution molecular line data including CS, SO, SO2 , and CH3 OH (∼0.12pc), and HCO+ and CO (∼0.087 pc) to explore the molecular environment of N105-1A. Based on the CO data, wefind evidence for a cloud-cloud collision that likely triggered star formation in the region. We find no clear outflow
signatures, but the presence of filaments and streamers indicates on-going accretion onto the clump hosting the UC
H II region. Sulfur chemistry in N105-1A is consistent with the accretion shock model predictions.

47. On the distribution of the Cold Neutral Medium in galaxy discs
Rowan J. Smith, Robin Tress, Juan D. Soler, Ralf S. Klessen, Simon C. O. Glover, Patrick Hennebelle, Sergio
Molinari, Mordecai-Mark Mac Low, David Whitworth F The Cold Neutral Medium (CNM) is an important partof the galactic gas cycle and a precondition for the formation of molecular and star forming gas, yet its distribution
is still not fully understood. In this work we present extremely high resolution simulations of spiral galaxies with
time-dependent chemistry such that we can track the formation of the CNM, its distribution within the galaxy, andits correlation with star formation. We find no strong radial dependence between the CNM fraction and total HI
due to the decreasing interstellar radiation field counterbalancing the decreasing gas column density at larger galactic

16

radii.However, the CNM fraction does increase in spiral arms where the CNM distribution is clumpy, rather thancontinuous, overlapping more closely with H2. The CNM doesn’t extend out radially as far as HI, and the verticalscale height is smaller in the outer galaxy compared to HI with no flaring. The CNM column density scales with total
midplane pressure and disappears from the gas phase below values of PT/kB =1000 K/cm3. We find that the starformation rate density follows a similar scaling law with CNM column density to the total gas Kennicutt-Schmidt law.
In the outer galaxy we produce realistic vertical velocity dispersions in the HI purely from galactic dynamics but ourmodels do not predict CNM at the extremely large radii observed in HI absorption studies of the Milky Way. We
suggest that extended spiral arms might produce isolated clumps of CNM at these radii.

48. Combined model for

15

N, 13 C, and spin-state chemistry in molecular clouds

O. Sipilä, L. Colzi, E. Roueff, P. Caselli, F. Fontani, E. Wirström F We present a new gas-grain chemical modelfor the combined isotopic fractionation of carbon and nitrogen in molecular clouds, in which the isotope chemistryof carbon and nitrogen is coupled with a time-dependent description of spin-state chemistry. We updated the rate
coefficients of some isotopic exchange reactions considered in the literature, and present here a set of new exchange
reactions involving molecules substituted in 13 C and 15 N simultaneously. We apply the model to a series of zerodimensional simulations representing a set of physical conditions across a prototypical prestellar core, exploring thedeviations of the isotopic abundance ratios in the various molecules from the elemental isotopic ratios as a functionof physical conditions and time. We find that the 12 C/13 C ratio can deviate from the elemental ratio by up to afactor of several depending on the molecule, and that there are highly time-dependent variations in the ratios. The
HCN/H13 CN ratio, for example, can obtain values of less than 10 depending on the simulation time. The 14 N/15 N
ratios tend to remain close to the assumed elemental ratio within ∼ ten per cent, with no clear trends as a functionof the physical conditions. Abundance ratios between 13 C-containing molecules and 13 C+15 N-containing molecules
show somewhat increased levels of fractionation due to the newly included exchange reactions, though still remaining
within a few tens of per cent of the elemental 14 N/15 N ratio. Our results imply the existence of gradients in isotopic
abundance ratios across prestellar cores, suggesting that detailed simulations are required to interpret observations ofisotopically substituted molecules correctly, especially given that the various isotopic forms of a given molecule do notnecessarily trace the same gas layers.

A comparison of the Milky Way’s recent star formation revealed by dust thermal emis49. sion and high-mass stars
J. D. Soler, E. Zari, D. Elia, S. Molinari, C. Mininni, E. Schisano, A. Traficante, R. S. Klessen, S. C. O. Glover,
P. Hennebelle, T. Colman, N. Frankel, T. Wenger F We present a comparison of the Milky Way’s star formation

rate (SFR) surface density (ΣSFR ) obtained with two independent state-of-the-art observational methods. The first
method infers ΣSFR from observations of the dust thermal emission from interstellar dust grains in far-infrared wavelengths registered in the Herschel infrared Galactic Plane Survey (Hi-GAL). The second method determines ΣSFR bymodeling the current population of O-, B-, and A-type stars in a 6 kpc × 6 kpc area around the Sun. We find an
agreement between the two methods within a factor of two for the mean SFRs and the SFR surface density profiles.
Given the broad differences between the observational techniques and the independent assumptions in the methods
for computing the SFRs, this agreement constitutes a significant advance in our understanding of the star formationof our Galaxy and implies that the local SFR has been roughly constant over the past 10 Myr.

Predicting reliable H2 column density maps from molecular line data using machine
50. learning
Yoshito Shimajiri, Yasutomo Kawanishi, Shinji Fujita, Yusuke Miyamoto, Atsushi M. Ito, Doris Arzoumanian, Philippe André, Atsushi Nishimura, Kazuki Tokuda, Hiroyuki Kaneko, Shunya Takekawa, Shota Ueda,
Toshikazu Onishi, Tsuyoshi Inoue, Shimpei Nishimoto, Ryuki Yoneda F The total mass estimate of molecular

clouds suffers from the uncertainty in the H2 -CO conversion factor, the so-called XCO factor, which is used to convert
the 12 CO (1–0) integrated intensity to the H2 column density. We demonstrate the machine learning’s ability to predict
the H2 column density from the 12 CO, 13 CO, and C18 O (1–0) data set of four star-forming molecular clouds; Orion A,
Orion B, Aquila, and M17. When the training is performed on a subset of each cloud, the overall distribution of thepredicted column density is consistent with that of the Herschel column density. The total column density predicted
and observed is consistent within 10%, suggesting that the machine learning prediction provides a reasonable total

17

mass estimate of each cloud. However, the distribution of the column density for values >∼ 2 × 1022 cm−2 , whichcorresponds to the dense gas, could not be predicted well. This indicates that molecular line observations tracing thedense gas are required for the training. We also found a significant difference between the predicted and observed
column density when we created the model after training the data on different clouds. This highlights the presenceof different XCO factors between the clouds, and further training in various clouds is required to correct for thesevariations. We also demonstrated that this method could predict the column density toward the area not observed
by Herschel if the molecular line and column density maps are available for the small portion, and the molecular line
data are available for the larger areas.

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

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

Cold atomic gas identified by HI self-absorption. Cold atomic clouds toward giant
52. molecular filaments
J. Syed, H. Beuther, P. F. Goldsmith, Th. Henning, M. Heyer, R. S. Klessen, J. M. Stil, J. D. Soler, L. D.
Anderson, J. S. Urquhart, M. R. Rugel, K. G. Johnston, A. Brunthaler F Stars form in the dense interiors ofmolecular clouds. The dynamics and physical properties of the atomic interstellar medium (ISM) set the conditions
under which molecular clouds and eventually stars will form. It is, therefore, critical to investigate the relationshipbetween the atomic and molecular gas phase to understand the global star formation process. Using the high angularresolution data from The HI/OH/Recombination line survey of the Milky Way (THOR), we aim to constrain the
kinematic and physical properties of the cold atomic hydrogen gas phase toward the inner Galactic plane. HI selfabsorption (HISA) has proven to be a viable method to detect cold atomic hydrogen clouds in the Galactic plane.
With the help of a newly developed self-absorption extraction routine (astroSABER), we build upon previous casestudies to identify HI self-absorption toward a sample of Giant Molecular Filaments (GMFs). We find the cold atomic
gas to be spatially correlated with the molecular gas on a global scale. The column densities of the cold atomic gas
traced by HISA are usually of the order of 1020 cm−2 whereas those of molecular hydrogen traced by 13 CO are atleast an order of magnitude higher. The HISA column densities are attributed to a cold gas component that accounts
for a fraction of ∼5% of the total atomic gas budget within the clouds. The HISA column density distributions showpronounced log-normal shapes that are broader than those traced by HI emission. The cold atomic gas is found to
be moderately supersonic with Mach numbers of a ∼few. In contrast, highly supersonic dynamics drive the moleculargas within most filaments.

1853. Protoplanetary Disk Chemistry
Karin I. Öberg, Stefano Facchini, Dana E. Anderson F Planets form in disks of gas and dust around young stars.

The disk molecular reservoirs and their chemical evolution affect all aspects of planet formation, from the coagulationof dust grains into pebbles, to the elemental and molecular compositions of the mature planet. Disk chemistry alsoenables unique probes of disk structures and dynamics, including those directly linked to ongoing planet formation.
Here we review the protoplanetary disk chemistry of the volatile elements HOCNSP, the associated observational
and theoretical methods, and the links between disk and planet chemical compositions. Three takeaways from thisreview are: (1) The disk chemical composition, including the organic reservoirs, is set by both inheritance and in situ
chemistry. (2) Disk gas and solid O/C/N/H elemental ratios often deviate from stellar values due to a combinationof condensation of molecular carriers, chemistry, and dynamics. (3) Chemical, physical, and dynamical processes indisks are closely linked, which complicates disk chemistry modeling, but these links also present an opportunity todevelop chemical probes of different aspects of disk evolution and planet formation.

An ALMA resoved view of 7,000 au Protostellar Gas Ring around the Class I source
54. CrA-IRS 2 as a possible sign of magnetic flux advection
Kazuki Tokuda, Naofumi Fukaya, Kengo Tachihara, Mitsuki Omura, Naoto Harada, Shingo Nozaki, Ayumu
Shoshi, Masahiro N. Machida F Transferring a significant fraction of the magnetic flux from a dense cloud coreis essential in the star formation process. A ring-like structure produced by magnetic flux loss has been predicted
theoretically, but no observational identification has been presented. We have performed ALMA observations of theClass I protostar IRS 2 in the Corona Australis star-forming region and resolved a distinctive gas ring in the C18 O (J =2-1) line emission. The center of this gas ring is ∼5,000 au away from the protostar, with a diameter of ∼7,000 au. The
radial velocity of the gas is . 1 km s−1 blueshifted from that of the protostar, with a possible expanding feature judged
from the velocity-field (moment 1) map and position-velocity diagram. These features are either observationally newor have been discovered but not discussed in depth because they are difficult to explain by well-studied protostellar
phenomena such as molecular outflows and accretion streamers. A plausible interpretation is a magnetic wall createdby the advection of magnetic flux which is theoretically expected in the Class 0/I phase during star formation as aremoval mechanism of magnetic flux. Similar structures reported in the other young stellar sources could likely becandidates formed by the same mechanism, encouraging us to revisit the issue of magnetic flux transport in the earlystages of star formation from an observational perspective.

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

19

56. Clustering properties of intermediate and high-mass Young Stellar Objects

Miguel Vioque, Manuel Cavieres, Michelangelo Pantaleoni González, Álvaro Ribas, René D. Oudmaijer, Ignacio
Mendigutía, Lena Kilian, Héctor Cánovas, Michael A. Kuhn F We have selected 337 intermediate and high-mass

YSOs (1.5 to 20 M ) well-characterised with spectroscopy. By means of the clustering algorithm HDBSCAN, westudy their clustering and association properties in the Gaia DR3 catalogue as a function of stellar mass. We findthat the lower mass YSOs (1.5 − 4 M ) have clustering rates of 55 − 60% in Gaia astrometric space, a percentage
similar to the one found in the T Tauri regime. However, intermediate-mass YSOs in the range 4 − 10 M show adecreasing clustering rate with stellar mass, down to 27%. We find tentative evidence suggesting that massive YSOs(> 10 M ) often appear −yet not always− clustered. We put forward the idea that most massive YSOs form via amechanism that demands many low-mass stars around them. However, intermediate-mass YSOs form in a classicalcore-collapse T Tauri way, yet they do not appear often in the clusters around massive YSOs. We also find thatintermediate and high-mass YSOs become less clustered with decreasing disk emission and accretion rate. This points
towards an evolution with time. For those sources that appear clustered, no major correlation is found between theirstellar properties and the cluster sizes, number of cluster members, cluster densities, or distance to cluster centres.
In doing this analysis, we report the identification of 55 new clusters. We present tabulated all the derived cluster
parameters for the considered intermediate and high-mass YSOs.

The Perseus ALMA Chemical Survey (PEACHES). III. Sulfur-bearing species tracing
57. accretion and ejection processes in young protostars
E. Artur de la Villarmois, V. V. Guzman, Y. -L. Yang, Y. Zhang, N. Sakai F (Abridged) Sulfur chemistry is poorly

understood in the process of low-mass star and planet formation, where the main carriers of sulfur are still unknown.
Despite the fact that simple S-bearing molecules are usually detected toward embedded sources, large surveys of Sbearing molecules with high angular resolution and sensitive observations are currently lacking. The goal of this work
is to present an unbiased survey of simple sulfur-bearing species in protostars and provide new statistics. In addition,
we investigate the role of S-bearing molecules in accretion processes and the connection between (non-)detection ofcomplex organic molecules (COMs) and S-related species. We present the observations of sulfur-bearing species thatare part of the Perseus ALMA Chemical Survey (PEACHES). We analyzed a total of 50 Class 0/I sources with anaverage angular resolution of about 0.6" ( 180 au) in ALMA band 6. We present detection rates for CS, SO, 34SO,
and SO2. The SO/34SO ratio is lower than the canonical value of 22 and the lowest values are found for those sourcesrich in COMs. This ratio, therefore, seems to be a good tracer of the inner high-density envelope. The detectionof multiple COMs seems to be related to the presence of collimated outflows and SO2 emission seems to trace thewarm gas in those sources where CH3OH is also detected. The SO2 abundances toward the PEACHES sample are,on average, two orders of magnitude lower than values from the Ophiuchus star-forming region and comparable withsources in Taurus, suggesting that the sulfur depletion in the gas-phase could depend on the external UV radiation.
Finally, the SO2 emission detected in different evolutionary stages seems to arise from different physical mechanisms:
high column density of warm material in Class 0 sources, shocks in Class I/II, and exposure to UV radiation from theprotostar in more evolved Class II disks.

ALMA observations of the Extended Green Object G19.01−0.03: II. A massive pro58. tostar with typical chemical abundances surrounded by four low-mass prestellar core
candidates
Gwenllian M. Williams, Claudia J. Cyganowski, Crystal L. Brogan, Todd R. Hunter, Pooneh Nazari, Rowan J.
Smith F We present a study of the physical and chemical properties of the Extended Green Object (EGO) G19.01−0.03

using sub-arcsecond angular resolution Atacama Large Millimeter/submillimeter Array (ALMA) 1.05mm and Karl G.
Jansky Very Large Array (VLA) 1.21cm data. G19.01−0.03 MM1, the millimetre source associated with the central
massive young stellar object (MYSO), appeared isolated and potentially chemically young in previous Submillimeter
Array observations. In our ∼ 0.400 -resolution ALMA data, MM1 has four low-mass millimetre companions within
0.12pc, all lacking maser or outflow emission, indicating they may be prestellar cores. With a rich ALMA spectrum
full of complex organic molecules, MM1 does not appear chemically young, but has molecular abundances typical ofhigh-mass hot cores in the literature. At the 1.05mm continuum peak of MM1, N(CH3 OH) = (2.22 ± 0.01) × 1018 cm−2
+0.3
and Tex = 162.7−0.5
K based on pixel-by-pixel Bayesian analysis of LTE synthetic methanol spectra across MM1.
Intriguingly, the peak CH3 OH Tex = 165.5 ± 0.6 K is offset from MM1’s millimetre continuum peak by 0.2200 ∼ 880au,
and a region of elevated CH3 OH Tex coincides with free-free VLA 5.01cm continuum, adding to the tentative evidence
20

for a possible unresolved high-mass binary in MM1. In our VLA 1.21cm data, we report the first NH3 (3,3) maser detections towards G19.01−0.03, along with candidate 25GHz CH3 OH 5(2, 3) − 5(1, 4) maser emission; both are spatiallyand kinematically coincident with 44GHz Class I CH3 OH masers in the MM1 outflow. We also report the ALMA
detection of candidate 278.3GHz Class I CH3 OH maser emission towards this outflow, strengthening the connectionof these three maser types to MYSO outflows.

59. Monitoring Hα Emission from the Wide-orbit Brown-dwarf Companion FU Tau B

Ya-Lin Wu, Yu-Chi Cheng, Li-Ching Huang, Brendan Bowler, Laird Close, Wei-Ling Tseng, Ning Chen, Da-Wei
Chen F Monitoring mass accretion onto substellar objects provides insights into the geometry of the accretion flows.

We use the Lulin One-meter Telescope to monitor Hα emission from FU Tau B, a ∼19 MJup brown-dwarf companion
at 5.7" (719 au) from the host star, for six consecutive nights. This is the longest continuous Hα monitoring for a
substellar companion near the deuterium-burning limit. We aim to investigate if accretion near the planetary regime
could be rotationally modulated as suggested by magnetospheric accretion models. We find tentative evidence thatHα mildly varies on hourly and daily timescales, though our sensitivity is not sufficient to definitively establish any
rotational modulation. No burst-like events are detected, implying that accretion onto FU Tau B is overall stable
during the time baseline and sampling windows over which it was observed. The primary star FU Tau A also exhibits
Hα variations over timescales from minutes to days. This program highlights the potential of monitoring accretion
onto substellar objects with small telescopes.

60. A Gigantic Outburst in an Embedded Class-I Young Stellar Object J064722.95+031644.6
Tinggui Wang, Jiaxun Li, Gregory M. Mace, Tuo Ji, Ning Jiang, Qingfeng Zhu, Min Fang F We report the
serendipitous discovery of a giant mid-infrared (MIR) outburst from a previously unknown source near a star-forming
region in the constellation Monoceros. The source gradually brightened by a factor of 5 from 2014 to 2016 before
an abrupt rise by a factor of more than 100 in 2017. A total amplitude increase of >500 at 4.5 microns has since
faded by a factor of about 10. Prior to the outburst, it was only detected at wavelengths longer than 1.8 microns in
UKIDSS, Spitzer, and Herschel with a spectral energy distribution of a Class I Young Stellar Object (YSO). It has
not been detected in recent optical surveys, suggesting that it is deeply embedded. With a minimum distance of 3.5
kpc, the source has a bolometric luminosity of at least 9 L in the quiescent state and 400 L at the peak of theeruption. The maximum accretion rate is estimated to be at least a few 10−5 M year−1 . It shares several common
properties with another eruptive event, WISE J142238.82-611553.7: exceptionally large amplitude, featureless nearinfrared spectrum with the exception of H2 lines, intermediate eruption duration, an embedded Class I YSO, and a
low radiative temperature (<600-700 K) in outburst. We interpret that the radiation from the inner accretion disk
and young star is obscured and reprocessed by either an inflated outer disk or thick dusty outflow on scales > 6.5 AU
during the outburst.

and clumps in V960 Mon: signs of planet formation via gravitational instability
61. Spirals
around an FU Ori star?
P. Weber, S. Pérez, A. Zurlo, J. Miley, A. Hales, L. Cieza, D. Principe, M. Cárcamo, A. Garufi, Á. Kóspál,
M. Takami, J. Kastner, Z. Zhu, J. Williams F The formation of giant planets has traditionally been divided into

two pathways: core accretion and gravitational instability. However, in recent years, gravitational instability has
become less favored, primarily due to the scarcity of observations of fragmented protoplanetary disks around youngstars and low occurrence rate of massive planets on very wide orbits. In this study, we present a SPHERE/IRDIS
polarized light observation of the young outbursting object V960 Mon. The image reveals a vast structure of intricately
shaped scattered light with several spiral arms. This finding motivated a re-analysis of archival ALMA 1.3 mm dataacquired just two years after the onset of the outburst of V960 Mon. In these data, we discover several clumps ofcontinuum emission aligned along a spiral arm that coincides with the scattered light structure. We interpret the
localized emission as fragments formed from a spiral arm under gravitational collapse. Estimating the mass of solids
within these clumps to be of several Earth masses, we suggest this observation to be the first evidence of gravitational
instability occurring on planetary scales. This study discusses the significance of this finding for planet formation andits potential connection with the outbursting state of V960 Mon.

21

Predicting the Radiation Field of Molecular Clouds using Denoising Diffusion Proba62. bilistic Models
Duo Xu, Stella Offner, Robert Gutermuth, Michael Grudic, David Guszejnov, Philip Hopkins F Accurately
quantifying the impact of radiation feedback in star formation is challenging. To address this complex problem, we employ deep learning techniques, denoising diffusion probabilistic models (DDPMs), to predict the interstellar radiation
field (ISRF) strength based on three-band dust emission at 4.5 µm, 24 µm, and 250 µm. We adopt magnetohydrodynamic simulations from the STARFORGE (STAR FORmation in Gaseous Environments) project that model starformation and giant molecular cloud (GMC) evolution. We generate synthetic dust emission maps matching observed
spectral energy distributions in the Monoceros R2 (MonR2) GMC. We train DDPMs to estimate the ISRF usingsynthetic three-band dust emission. The dispersion between the predictions and true values is within a factor of 0.1
for the test set. We extended our assessment of the diffusion model to include new simulations with varying physicalparameters. While there is a consistent offset observed in these out-of-distribution simulations, the model effectively
constrains the relative intensity to within a factor of 2. Meanwhile, our analysis reveals weak correlation between
the ISRF solely derived from dust temperature and the actual ISRF. We apply our trained model to predict the
ISRF in MonR2, revealing a correspondence between intense ISRF, bright sources, and high dust emission, confirming
the model’s ability to capture ISRF variations. Our model robustly predicts radiation feedback distribution, even incomplex, poorly constrained ISRF environments like those influenced by nearby star clusters. However, precise ISRF
predictions require an accurate training dataset mirroring the target molecular cloud’s unique physical conditions.

63. Understanding the Kinetic Energy deposition within Molecular Clouds

Lixia Yuan, Ji Yang, Fujun Du, Yang Su, Shaobo Zhang, Qing-Zeng Yan, Yan Sun, Xin Zhou, Xuepeng Chen,
Hongchi Wang, Zhiwei Chen F According to the structures traced by 13 CO spectral lines within the 12 CO molecular

clouds (MCs), we investigate the contributions of their internal gas motions and relative motions to the total velocity
dispersions of 12 CO MCs. Our samples of 2851 12 CO MCs harbor a total of 9556 individual 13 CO structures, among
which 1848 MCs (∼ 65%) have one individual 13 CO structure and the other 1003 MCs (∼ 35%) have multiple 13 CO
structures. We find that the contribution of the relative motion between 13 CO structures (σ13 CO,re ) is larger thanthat from their internal gas motion (σ13 CO,in ) in ∼ 62% of 1003 MCs in the ‘multiple’ regime. In addition, we find theσ13 CO,re tends to increase with the total velocity dispersion(σ12 CO,tot ) in our samples, especially for the MCs having
multiple 13 CO structures. This result provides a manifestation of the macro-turbulent within MCs, which gradually
becomes the dominant way to store the kinetic energy along with the development of MC scales.

TRAO Survey of Nearby Filamentary Molecular clouds, the Universal Nursery of Stars
64. (TRAO-FUNS). III. Filaments and dense cores in the NGC 2068 and NGC 2071 regionsof Orion B
Hyunju Yoo, Chang Won Lee, Eun Jung Chung, Shinyoung Kim, Mario Tafalla, Paola Caselli, Philip C.
Myers, Kyoung Hee Kim, Tie Liu, Woojin Kwon, Archana Soam, Jongsoo Kim F We present the results ofmolecular line observations performed toward the NGC 2068 and NGC 2071 regions of the Orion B cloud as the
TRAO-FUNS project to study the roles of the filamentary structure in the formation of dense cores and stars in theclouds. Gaussian decomposition for the C18 O spectra with multiple velocity components and application of a Friendsof-Friends algorithm for the decomposed components allowed us to identify a few tens of velocity coherent filaments.
We also identified 48 dense cores from the observations of N2 H+ using a core finding tool, FellWalker. We made thevirial analysis for these filaments and dense cores, finding that the filaments with N2 H+ dense core are thermallysupercritical, and the filaments with larger ratio between the line mass and the thermal critical line mass tend to havemore dense cores. We investigated the contribution of the nonthermal motions in dense cores and filaments, showing
the dense cores are mostly in transonic/subsonic motions while their natal filaments are mostly in supersonic motions.
This may indicates that gas turbulent motions in the filaments have been dissipated at the core scale to form thedense cores there. The filaments with (dynamically evolved) dense cores in infalling motions or with NH2 D bright (orchemically evolved) dense cores are all found to be gravitationally critical. Therefore, the criticality of the filamentis thought to provide a key condition for its fragmentation, the formation of dense cores, and their kinematical andchemical evolution.

22

In Search of Infall Motion in Molecular Clumps. IV. Mapping of the Global Infall
65. Sources
Yang Yang, Xi Chen, Zhibo Jiang, Zhiwei Chen, Shuling Yu, Jun Li F We have used the IRAM 30-m telescope

to map some targets with HCO+ (1-0) and H13 CO+ (1-0) lines in order to search for gas infall evidence in theclumps. In this paper, we report the mapping results for 13 targets. All of these targets show HCO+ emissions, while
H13 CO+ emissions are observed in ten of them. The HCO+ integrated intensity maps of ten targets show clear clumpy
structures, and nine targets show clumpy structures in the H13 CO+ maps. Using the RADEX radiative transfer code,
we estimate the column density of H13 CO+ , and determine the abundance ratio [H13 CO+ ]/[H2 ] to be approximately
10−12 to 10−10 . Based on the asymmetry of the HCO+ line profiles, we identify 11 targets show blue profiles, while
six clumps have global infall evidence. We use the RATRAN and two-layer models to fit the HCO+ line profiles ofthese infall sources, and analyze their spatial distribution of the infall velocity. The average infall velocities estimatedby these two models are 0.24 – 1.85 km s−1 and 0.28 – 1.45 km s−1 , respectively. The mass infall rate ranges fromapproximately 10−5 to 10−2 M yr−1 , which suggests that intermediate- or high-mass stars may be forming in thetarget regions.

The PCA Filtering method for an unbiased spectral survey of Complex Organic Molecules
66. (COMs)
Hyeong-Sik Yun, Jeong-Eun Lee F A variety of interstellar complex organic molecules (COMs) have been detectedin various physical conditions. However, in the protostellar and protoplanetary environments, their complex kinematics make line profiles blend each other and the line strength of weak lines weaker. In this paper, we utilize theprincipal component analysis (PCA) technique to develop a filtering method which can extract COM spectra fromthe main kinematic component associated with COM emission and increase the signal-to-noise ratio (SNR) of spectra.
This filtering method corrects non-Gaussian line profiles caused by the kinematics. For this development, we adopt
the ALMA BAND 6 spectral survey data of V883 Ori, an eruptive young star with a Keplerian disk. A filter was,first, created using 34 strong and well-isolated COM lines and then applied to the entire spectral range of the dataset.
The first principal component (PC1) describes the most common emission structure of the selected lines, which is
confined within the water sublimation radius (∼ 0.3 arcsec) in the Keplerian disk of V883 Ori. Using this PC1 filter,
we extracted high-SNR kinematics-corrected spectra of V883 Ori over the entire spectral coverage of ∼50 GHz. The
PC1-filtering method reduces the noise by a factor of ∼ 2 compared to the average spectra over the COM emission
region. One important advantage of this PC1-filtering method over the previously developed matched filtering method
is to preserve the original integrated intensities of COM lines.

High-resolution APEX/LAsMA 12 CO and 13 CO (3-2) observation of the G333 giant
67. molecular cloud complex : II. Survival and gravitational collapse of dense gas structures
under feedback
J. W. Zhou, F. Wyrowski, S. Neupane, I. Barlach Christensen, K. M. Menten, S. H. Li, T. Liu F We investigate

the physical properties of gas structures under feedback in the G333 complex using data of the 13CO (3-2) line in the
LAsMA observation. We used the Dendrogram algorithm to identify molecular gas structures based on the integrated
intensity map of the 13CO (3-2) emission, and extracted the average spectra of all structures to investigate theirvelocity components and gas kinematics. We derive the column density ratios between different transitions of the
13CO emission pixel-by-pixel, and find the peak values N(2-1)/N(1-0) 0.5, N(3-2)/N(1-0) 0.3, N(3-2)/N(2-1) 0.5.
These ratios can also be roughly predicted by RADEX for an average H2 volume density of 4.2 * 103 cm−3 . A
classical virial analysis does not reflect the true physical state of the identified structures, and we find that externalpressure from the ambient cloud plays an important role in confining the observed gas structures. For high column
density structures, velocity dispersion and density show a clear correlation, while for low column density structures
they do not, indicating the contribution of gravitational collapse to the velocity dispersion. For both leaf and branch
structures, σ − N ∗ R always has a stronger correlation compared to σ − N and σ − R. The scaling relations arestronger, and have steeper slopes when considering only self-gravitating structures, which are the structures mostclosely associated with the Heyer-relation. Although the feedback disrupting the molecular clouds will break up theoriginal cloud complex, the substructures of the original complex can be reorganized into new gravitationally governed
configurations around new gravitational centers. This process is accompanied by structural destruction and generation,and changes in gravitational centers, but gravitational collapse is always ongoing.

2368. One, Two, Three ... An Explosive Outflow in IRAS 12326−6245 revealed by ALMA
Luis A. Zapata, Manuel Fernández-López, Silvia Leurini, Estrella Guzmán Ccolque, Luis F. Rodriguez, Aina
Palau, Karl M. Menten, Friedrich Wyrowski F In the last years there has been a substantial increase in thenumber of the reported massive and luminous star-forming regions with related explosive outflows thanks to thesuperb sensitivity and angular resolution provided by the new radio, infrared, and optical facilities. Here, we report
one more explosive outflow related with the massive and bright star-forming region IRAS 12326−6245 using Band 6
sensitive and high angular resolution (∼0.2”) Atacama Large Millimeter/Submillimeter Array (ALMA) observations.
We find over 10 molecular and collimated well-defined streamers, with Hubble-Lemaitre like expansion motions, andpointing right to the center of a dusty and molecular shell (reported for the first time here) localized in the northernpart of the UCHII region known as G301.1A. The estimated kinematic age, and energy for the explosion are ∼700
yrs, and 1048 erg, respectively. Taking into account the recently reported explosive outflows together with IRAS
12326−6245, we estimate an event rate of once every 90 yr in our Galaxy, similar to the formation rate of massive
stars.

24