The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 375 — 31 Mar 2024
Editor: João Alveswww.starformation.news

Cover image caption
RGB broad band and Hα color composite of NGC 6914 in the Cygnus massive star formation region.
Credits: Photo Gallery of Calar Alto Observatory (RECTA/CAHA/DSA). Vicent Peris (DSA/OAUV/PTeam), Jack Harvey(DSA/SSRO/PTeam), Juan Conejero (DSA/PTeam)

Note from the Editor

The Star Formation Newsletter is now on the web at www.starformation.news. This PDF file contains the monthly
Abstracts and links. Red text in this PDF is a url link. Submitting an abstract to the SFN is as simple as entering
the arXiv ID (e.g., 2006.10139) in a web form on the SFN web site. Do not remove the LATEX formatting whensubmitting to the arXiv. If you do, your abstract will not look great either at the arXiv or the SFN.

Abstracts
1.

Molecular Gas Tracers in Young and Old Protoplanetary Disks
Dana E. Anderson, L. Ilsedore Cleeves, Geoffrey A. Blake, Chunhua Qi, Edwin A. Bergin, John M. Carpenter,
Kamber R. Schwarz, Claire Thilenius, Ke Zhang F Molecular emission is used to investigate both the physicaland chemical properties of protoplanetary disks. Therefore, to accurately derive disk properties, we need a thoroughunderstanding of the behavior of the molecular probes we rely on. Here we investigate how the molecular line emissionof N2 H+ , HCO+ , HCN, and C18 O compare to other measured quantities in a set of 20 protoplanetary disks. Overall,
we find positive correlations between multiple line fluxes and the disk dust mass and radius. We also generallyfind strong positive correlations between the line fluxes of different molecular species. However, some disks do show
noticeable differences in the relative fluxes of N2 H+ , HCO+ , HCN, and C18 O. These differences occur even within asingle star-forming region. This results in a potentially large range of different disk masses and chemical compositions
for systems of similar age and birth environment. While we make preliminary comparisons of molecular fluxes acrossdifferent star-forming regions, more complete and uniform samples are needed in the future to search for trends withbirth environment or age.

2. Unveiling two expanding stellar groups formed through violent relaxation in The Lagoon
Nebula Cluster
A. Bonilla-Barroso, J. Ballesteros-Paredes, J. Hernández, L. Aguilar, M. Zamora-Avilés F The current kinematicstate of young stellar clusters can give clues on their actual dynamical state and origin. In this contribution, we use
Gaia DR3 data of the Lagoon Nebula Cluster (LNC) to show that the cluster is composed of two expanding groups,
likely formed from different molecular cloud clumps. We find no evidence of massive stars having larger velocity
dispersion than low-mass stars or being spatially segregated across the LNC, as a whole, or within the Primary group.
However, the Secondary group, with 1/5th of the stars, exhibits intriguing features. On the one hand, it shows a bipolar
nature, with an aspect ratio of ∼3:1. In addition, the massive stars in this group exhibit larger velocity dispersion thanthe low-mass stars, although they are not concentrated towards the center of the group. This suggests that this group
may have undergone dynamical relaxation, first, and some explosive event afterward. However, further observations
and numerical work have to be performed to confirm this hypothesis. The results of this work suggest that, althoughstellar clusters may form by the global and hierarchical collapse of their parent clump, still some dynamical relaxation
may take place.

3. JWST MIRI/MRS Observations of T Cha: Discovery of a Spatially Resolved Disk Wind
Naman S. Bajaj, Ilaria Pascucci, Uma Gorti, Richard Alexander, Andrew Sellek, Jane Morrison, Andras Gaspar, Cathie Clarke, Chengyan Xie, Giulia Ballabio, Dingshan Deng F Understanding when and how circumstellar

disks disperse is crucial to constrain planet formation and migration. Thermal winds powered by high-energy stellar
photons have long been theorized to drive disk dispersal. However, evidence for these winds is currently based only onsmall ( 3-6 km/s) blue-shifts in [Ne II] 12.81 um lines, which does not exclude MHD winds. We report JWST MIRI

2MRS spectro-imaging of T Cha, a disk with a large dust gap ( 30 au in radius) and blue-shifted [Ne II] emission. We
detect four forbidden noble gas lines, [Ar II], [Ar III], [Ne II], and [Ne III], of which [Ar III] is the first detection inany protoplanetary disk. We use line flux ratios to constrain the energy of the ionizing photons and find that Argon
is ionized by EUV whereas Neon is most likely ionized by X-rays. After performing continuum and Point Spread
Function (PSF) subtraction on the IFU cube, we discover a spatial extension in the [Ne II] emission off the disk
continuum emission. This is the first spatially resolved [Ne II] disk wind emission. The mostly ionic spectrum of T
Cha, in combination with the extended [Ne II] emission, points to an evolved stage for any inner MHD wind and isconsistent with the existence of an outer thermal wind ionized and driven by high-energy stellar photons. This work
acts as a pathfinder for future observations aiming at investigating disk dispersal using JWST.

4. A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk
Olivier Berné et al. F Most low-mass stars form in stellar clusters that also contain massive stars, which are sourcesof far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photo-dissociation
regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, impacting planet formation within thedisks. We report JWST and Atacama Large Millimetere Array observations of a FUV-irradiated protoplanetary disk
in the Orion Nebula. Emission lines are detected from the PDR; modelling their kinematics and excitation allows us
to constrain the physical conditions within the gas. We quantify the mass-loss rate induced by the FUV irradiation,
finding it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant
planet formation in the disk.

5. Complex organic molecules uncover deeply embedded precursors of hot cores

Laure Bouscasse, Timea Csengeri, Friedrich Wyrowski, K. M. Menten, S. Bontemps F During the process ofstar formation, the dense gas undergoes significant chemical evolution leading to the emergence of a rich variety ofmolecules associated with hot cores and hot corinos. However, the physical and chemical conditions involved in thisevolution are poorly constrained. We provide here a full inventory of the emission from complex organic molecules(COMs) to investigate the physical structure and chemical composition of six high-mass protostellar envelopes. We
aim to investigate the conditions for the emergence of COMs in hot cores. We performed an unbiased spectral survey
towards six infrared-quiet massive clumps between 159 GHz and 374 GHz with the APEX 12 m telescope. We detect
up to 11 COMs, of which at least five COMs are detected towards all sources. Towards all the objects, most of
the COM emission is found to be cold, with respect to the typical temperatures at which COMs are found, with atemperature of 30 K and extended with a size of 0.3 pc. Although for our sample of young massive clumps the bulkof the gas has a cold temperature, we also detect emission from COMs originating from the immediate vicinity of the
protostar revealing a compact and hot component of the envelope. Only three out of the six sources exhibit a hot gas
component. We find a gradual emergence of the warm component in terms of size and temperature, together withan increasing molecular complexity, allowing us to establish an evolutionary sequence for our sample based on COMs.
Our findings confirm that our sample of infrared-quiet massive clumps are in an early evolutionary stage during which
the bulk of the gas is cold. The presence of COMs is found to be characteristic of these early evolutionary stages. We
suggest that the emergence of hot cores is preceded by a phase in which mostly O-bearing COMs appear first withsimilar abundances to hot corinos albeit with larger source sizes.

6.

The Carbon Isotopic Ratio and Planet Formation
Edwin A. Bergin, Arthur Bosman, Richard Teague, Jenny Calahan, Karen Willacy, L. Ilsedore Cleeves, Kamber
Schwarz, Ke Zhang, Simon Bruderer F We present the first detection of 13CCH in a protoplanetary disk (TW Hya).

Using observations of C2H we measure CCH/13CCH = 65 +/- 20 in gas with a CO isotopic ratio of 12CO/13CO =21 +/- 5 (Yoshida et al. 2022a). The TW Hya disk exhibits a gas phase C/O that exceeds unity and C2H is the tracerof this excess carbon. We confirm that the TW Hya gaseous disk exhibits two separate carbon isotopic reservoirs as
noted previously (Yoshida et al. 2022a). We explore two theoretical solutions for the development of this dichotomy.
One model represents TW Hya today with a protoplanetary disk exposed to a cosmic ray ionization rate that is below
interstellar as consistent with current estimates. We find that this model does not have sufficient ionization in cold (T< 40 K) layers to activate carbon isotopic fractionation. The second model investigates a younger TW Hya protostellar
disk exposed to an interstellar cosmic ray ionization rate. We find that the younger model has sources of ionization
deeper in a colder disk that generates two independent isotopic reservoirs. One reservoir is 12C-enriched carried by3

methane/hydrocarbon ices and the other is 13C-enriched carried by gaseous CO. The former potentially provides asource of methane/hydrocarbon ices to power the chemistry that generates the anomalously strong C2 H emission inthis (and other) disk systems in later stages. The latter provides a source of gaseous 13C-rich material to generate
isotopic enrichments in forming giant planets as recently detected in the super-Jupiter TYC 8998-760-1 b by Zhang
et al. (2021).

7. Large Fluctuations within 1 AU in Protoplanetary DisksJohn Chambers F Protoplanetary disks are often assumed to change slowly and smoothly during planet formation.

Here, we investigate the time evolution of isolated disks subject to viscosity and a disk wind. The viscosity is assumed
to increase rapidly at around 900 K due to thermal ionization of alkali metals, or thermionic and ion emission fromdust, and the onset of magneto-rotational instability (MRI). The disks generally undergo large, rapid fluctuations fora wide range of time-averaged mass accretion rates. Fluctuations involve coupled waves in temperature and surface
density that move radially in either direction through the inner 1.5 AU of the disk. Two types of wave are seen withradial speeds of roughly 50 and 1000 cm/s respectively. The pattern of waves repeats with a period of roughly 10,000
years that depends weakly on the average mass accretion rate. Viscous transport due to MRI is confined to the innerdisk. This region is resupplied by mass flux from the outer disk driven by the disk wind. Interior to 1 AU, thetemperature and surface density can vary by a factor of 2–10 on timescales of years to ky. The stellar mass accretion
rate varies by 3 orders of magnitude on a similar timescale. This behavior lasts for at least 1 My for initial disks
comparable to the minimum-mass solar nebula.

Radio outburst from a massive (proto)star. III. Unveiling the bipolarity of the radio
8. jet from S255IR NIRS3
R. Cesaroni, L. Moscadelli, A. Caratti o Garatti, J. Eisloeffel, R. Fedriani, R. Neri, T. Ray, A. Sanna, B.
Stecklum F We report new Very Large Array high-resolution observations of the radio jet from the outburstinghigh-mass star S255IR NIRS3. The images at 6, 10, and 22.2 GHz confirm the existence of a new lobe emerging to
the SW and expanding at a mean speed of 285 km/s, about half as fast as the NE lobe. The new data allow us toreproduce both the morphology and the continuum spectrum of the two lobes with the model already adopted in ourprevious studies. We conclude that in all likelihood both lobes are powered by the same accretion outburst. We alsofind that the jet is currently fading down, recollimating, and recombining.

9.

A consistent explanation for the unusual initial mass function and star formation ratein the Central Molecular Zone (CMZ)
Gilles Chabrier, Pierre Dumond F We examine various physical processes that may explain the shallow high-massslope of the IMF as well as the low SFR in star-forming molecular clouds (MCs) in the Central Molecular Zone (CMZ).
We show that the strong tidal field and the tidal shear experienced by the CMZ have opposite effects on the collapseof density fluctuations and nearly compensate, but in any case have a negligible impact and can not explain theseunusual properties. Similarly, we show that the intense magnetic field in the CMZ provides a negligible pressure
support and, for the high densities at play should not modify the probability density function (PDF) of the turbulent
gas flow in the clouds, thus affecting negligibly the slope of the IMF. However, we show that, in contrast to MCs in
the Galactic disk, the ones in the CMZ experience only one single episode of turbulence injection at large scale, most
likely due dominantly to bar gas inflow. Indeed, their rather short lifetime, due to their high mean densities, is similar
to one typical turbulence crossing time. Consequently, according to the Hennebelle-Chabrier theory of star formation,
within this ’single turbulence episode’ scenario, the cloud experiences one single field of turbulence induced density
fluctuations, leading eventually to gravitationally unstable prestellar cores. As shown in Hennebelle & Chabrier 2013,
this yields a flatter IMF than usual and leads to the correct observed slope for the CMZ star-forming clouds. Similarly,
this single large scale turbulence event within the cloud lifetime yields a 5 to 6 lower SFR than under usual MW cloud
conditions, again in agreement with the observed values. Therefore, we suggest that this ’single large scale turbulence
injection’ episode can explain both the shallow IMF high-mass slope and low SFR of clouds in the CMZ.

4

10. Episodicity in accretion-ejection processes associated with IRAS 15398-3359
E. Guzmán Ccolque, M. Fernández López, M. M. Vazzano, I. de Gregorio, A. Plunkett, A. Santamaría-Miranda

F The protostar IRAS 15398-3359 is associated with a bipolar molecular outflow ejected in an nearly northeastsouthwest (NE-SW) direction which has been extensively studied. It has been suggested previous episodic accretion
events by this source. Furthermore, the analysis of the morphology and kinematics of the molecular outflow revealed
the presence of four 12 CO(2-1) bipolar elliptical shock-like structures identified in both lobes. These structures seemto trace different ejections inclined ∼10 deg on the plane of the sky from each other. This led to the hypothesisthat the outflow axis likely precesses and launches material episodically. We analyze ALMA archive observations inBand 6, revealing the presence of low-velocity (< 3.5km s−1 ) emission from the line 12 CO(2-1) to the south and northof the protostar. We study the morphology and kinematics of the gas, which seems to support the hypothesis of aprecessing episodic outflow. The ALMA observations reveal a north-south (N-S) outflow most likely associated with
the IRAS 15398-3359 protostellar system. This outflow could be older than the well-studied NE-SW outflow. The
orientation of the N-S outflow is 50 deg - 60 deg on the plane of the sky away from that of the NE-SW outflow. We
also analyze the Spectral Energy Distribution of a far away young star and preliminary discard it as the driver of
the SE outflow remnants. The new observations support the hypothesis of strong episodic accretion-ejection eventsin IRAS 15398-3359, accompanied by dramatic changes in the orientation of its ejection axis, implying that all theoutflows in the region may have been driven by the same protostar.

11. MINDS: JWST/NIRCam imaging of the protoplanetary disk PDS 70
V. Christiaens, M. Samland, Th. Henning, B. Portilla-Revelo, G. Perotti, E. Matthews, O. Absil, L. Decin, I.
Kamp, A. Boccaletti, B. Tabone, G. -D. Marleau, E. F. van Dishoeck, M. Güdel, P. -O. Lagage, D. Barrado,
A. Caratti o Garatti, A. M. Glauser, G. Olofsson, T. P. Ray, S. Scheithauer, B. Vandenbussche, L. B. F. M.
Waters, A. M. Arabhavi, S. L. Grant, H. Jang, J. Kanwar, J. Schreiber, K. Schwarz, M. Temmink, G. Östlin

F Context. Two protoplanets have recently been discovered within the PDS 70 protoplanetary disk. JWST/NIRCam
offers a unique opportunity to characterize them and their birth environment at wavelengths difficult to access from theground. Aims. We aim to image the circumstellar environment of PDS 70 at 1.87 µm and 4.83 µm, assess the presenceof Pa-α emission due to accretion onto the protoplanets, and probe any IR excess indicative of heated circumplanetary
material. Methods. We obtain non-coronagraphic JWST/NIRCam images of PDS 70 within the MINDS (MIRI midINfrared Disk Survey) program. We leverage the Vortex Image Processing (VIP) package for data reduction, anddevelop dedicated routines for optimal stellar PSF subtraction, unbiased imaging of the disk, and protoplanet flux
measurement in this type of dataset. A radiative transfer model of the disk is used to disentangle the contributions
from the disk and the protoplanets. Results. We re-detect both protoplanets and identify extended emission after
subtracting a disk model, including a large-scale spiral-like feature. We interpret its signal in the direct vicinity ofplanet c as tracing the accretion stream feeding its circumplanetary disk, while the outer part of the feature may rather
reflect asymmetric illumination of the outer disk. We also report a bright signal consistent with a previously proposed
protoplanet candidate enshrouded in dust, near the 1:2:4 mean-motion resonance with planets b and c. The 1.87
µm flux of planet b is consistent with atmospheric model predictions, but not that of planet c. We discuss potential
origins for this discrepancy, including significant Pa-α line emission. The 4.83 µm fluxes of planets b and c suggest
enshrouding dust or heated CO emission from their circumplanetary environment.

Herschel investigation of cores and filamentary structures in L1251 located in the Cepheus
12. flare
Divyansh Dewan, Archana Soam, Guo-Yin Zhang, Akhil Lasrado, Saikhom Pravash Singh, Chang Won Lee

F Context: Molecular clouds are the prime locations of star formation. These clouds contain filamentary structuresand cores which are crucial in the formation of young stars. Aims: In this work, we aim to quantify the physicalproperties of structural characteristics within the molecular cloud L1251 to better understand the initial conditions
for star formation. Methods: We applied the getsf algorithm to identify cores and filaments within the molecular
cloud L1251 using the Herschel multiband dust continuum image, enabling us to measure their respective physicalproperties. Additionally, we utilized an enhanced differential term algorithm to produce high-resolution temperaturemaps and column density maps with a resolution of 13.500 . Results: We identified 122 cores in the region. Out of them,
23 are protostellar cores, 13 are robust prestellar cores, 32 are candidate prestellar cores (including 13 robust prestellar
cores and 19 strictly candidate prestellar cores), and 67 are unbound starless cores. getsf also found 147 filament
structures in the region. Statistical analysis of the physical properties (mass (M), temperature (T), size, and core5

brightness (hereafter, we are using the word luminosity (L)) for the core brightness) of obtained cores shows a negative
correlation between core mass and temperature and a positive correlation between (M/L) and (M/T). Analysis of thefilaments gives a median width of 0.14 pc and no correlation between width and length. Out of those 122 cores, 92
are present in filaments (75.4%) and the remaining were outside them. Out of the cores present in filaments, 57 (62%)
cores are present in supercritical filaments (Mline > 16M /pc).

The classical T Tauri star CI Tau observed with SPIRou: magnetospheric accretion and13. planetary formation
J. -F. Donati, B. Finociety, P. I. Cristofari, S. H. P. Alencar, C. Moutou, X. Delfosse, P Fouqué, L. Arnold,
C. Baruteau, Á. Kóspál, F. Ménard, A. Carmona, K. Grankin, M. Takami, E. Artigau, R. Doyon, G. Hébrard,
the SLS collaboration F We report new observations of the classical T Tauri star CI Tau with the SPIRou near-infrared spectropolarimeter and velocimeter at the Canada-France-Hawaii Telescope (CFHT) in late 2019, 2020 and
2022, complemented with observations obtained with the ESPaDOnS optical spectropolarimeter at CFHT in late 2020.
From our SPIRou and ESPaDOnS spectra, to which we applied Least-Squares Deconvolution, we infer longitudinal
fields clearly modulated with the 9-d rotation period of CI Tau. Using Zeeman-Doppler imaging, we reconstruct
the large-scale magnetic topology, first from SPIRou data only in all three seasons, then from our 2020 SPIRou and
ESPaDOnS data simultaneously. We find that CI Tau hosts a mainly axisymmetric poloidal field, with a 1 kG dipole
slightly tilted to the rotation axis and dark spots close to the pole that coincide with the footpoints of accretion funnels
linking the star to the inner disc. Our results also suggest that CI Tau accretes mass from the disc in a stable fashion.
We further find that radial velocities (RV) derived from atomic and CO lines in SPIRou spectra are both rotationally
modulated, but with a much lower amplitude than that expected from the putative candidate planet CI Tau b. We
confirm the presence of a RV signal at a period of 23.86 d reported in a separate analysis, but detect it clearly in CO
lines only and not in atomic lines, suggesting that it likely traces a non-axisymmetric structure in the inner disc of
CI Tau rather than a massive close-in planet.

Early Planet Formation in Embedded Disks (eDisk) XIII: Aligned Disks with Non14. Settled Dust Around the Newly Resolved Class 0 Protobinary R CrA IRAS 32
Frankie J. Encalada, Leslie W. Looney, Shigehisa Takakuwa, John J. Tobin, Nagayoshi Ohashi, Jes K. Jørgensen,
Zhi-Yun Li, Yuri Aikawa, Yusuke Aso, Patrick M. Koch, Woojin Kwon, Shih-Ping Lai, Chang Won Lee, Zhe-Yu
Daniel Lin, Alejandro Santamarıa-Miranda, Itziar de Gregorio-Monsalvo, Nguyen Thi Phuong, Adele Plunkett,
Jinshi Sai, Rajeeb Sharma, Hsi-Wei Yen, Ilseung Han F Young protostellar binary systems, with expected ages

less than ∼105 years, are little modified since birth, providing key clues to binary formation and evolution. We present
a first look at the young, Class 0 binary protostellar system R CrA IRAS 32 from the Early Planet Formation in
Embedded Disks (eDisk) ALMA large program, which observed the system in the 1.3 mm continuum emission, 12 CO(2-1), 13 CO (2-1), C18 O (2-1), SO (65 -54 ), and nine other molecular lines that trace disk, envelope, shocks, and outflows.
With a continuum resolution of ∼0.0300 (∼5 au, at a distance of 150 pc), we characterize the newly discovered binary
system with a separation of 207 au, their circumstellar disks, and a circumbinary disk-like structure. The circumstellar
disk radii are 26.9±0.3 and 22.8±0.3 au for sources A and B, respectively, and their circumstellar disk dust masses
are estimated as 22.5±1.1 and 12.4±0.6 MEarth . The circumstellar disks and the circumbinary structure have wellaligned position angles and inclinations, indicating formation in a smooth, ordered process such as disk fragmentation.
In addition, the circumstellar disks have a near/far-side asymmetry in the continuum emission suggesting that the
dust has yet to settle into a thin layer near the midplane. Spectral analysis of CO isotopologues reveals outflows thatoriginate from both of the sources and possibly from the circumbinary disk-like structure. Furthermore, we detect
Keplerian rotation in the 13 CO isotopologues toward both circumstellar disks and likely Keplerian rotation in thecircumbinary structure; the latter suggests that it is probably a circumbinary disk.

15. Spectroscopic and Photometric Behaviour of LP Ori
Asli Elmasli, K. Ozge Unal, Dogus Ozuyar F We performed spectroscopic and photometric analyses on the earlyB-type LP Ori young stellar object located in the Orion Nebula. The high-resolution spectra of LP Ori was obtainedat the Ankara University Kreiken Observatory in 2023, while all spectra recorded over the past 19 years were extracted
from the ESO and ESPaDOnS archives. In these spectra of LP Ori, there is typically an emission observed in the coreof the Balmer profile. This structure is accompanied by a ∼14-year interval inverse P-Cygni repetition superimposed6

on the Balmer profile. Additionally, an emission in the λ5875 He I line is visible in the spectra in the year 2023. When
this emission is considered together with the inverse P-Cygni structures, these observations suggest that LP Ori is a
Herbig Ae/Be star. The abundance pattern of LP Ori is close to solar with the exception of a slightly rich heliumand slightly poor Al abundance. Additionally, the spectral energy distribution of LP Ori was constructed to confirm
the infrared excess caused by its circumstellar disk. Furthermore, the photometric analysis performed on the TESS
observations of LP Ori shows significant photometric variability and the frequency analysis reveals a β Cephei star in
its forthcoming evolution.

Resolved ALMA observations of water in the inner astronomical units of the HL Tau
16. disk
Stefano Facchini, Leonardo Testi, Elizabeth Humphreys, Mathieu Vander Donckt, Andrea Isella, Ramon Wrzosek, Alain Baudry, Malcom D. Gray, Anita M. S. Richards, Wouter Vlemmmings F The water molecule isa key ingredient in the formation of planetary systems, with the water snowline being a favourable location for thegrowth of massive planetary cores. Here we present Atacama Large Millimeter/ submillimeter Array data of theringed protoplanetary disk orbiting the young star HL Tauri that show centrally peaked, bright emission arising fromthree distinct transitions of the main water isotopologue. The spatially and spectrally resolved water content probes
gas in a thermal range down to the water sublimation temperature. Our analysis implies a stringent lower limit of
3.7 Earth oceans of water vapour available within the inner 17 astronomical units of the system. We show that ourobservations are limited to probing the water content in the atmosphere of the disk, due to the high dust column
density and absorption, and indicate that the main water isotopologue is the best tracer to spatially resolve water
vapour in protoplanetary disks.

17. The Enigma of Gaia18cjb: a Rare Hybrid of FUor and EXor?

Eleonora Fiorellino, Peter Abraham, Agnes Kospal, Maria Kun, Juan M. Alcala, Alessio Caratti o Garatti,
Fernando Cruz-Saenz de Miera, David Garcia-Alvarez, Teresa Giannini, Sunkyung Park, Michal Siwak, Mate
Szilagyi, Elvira Covino, Gabor Marton, Zsofia Nagy, Brunella Nisini, Zsofia Marianna Szabo, Zsofia Bora,
Borbala Cseh, Csilla Kalup, Mate Krezinger, Levente Kriskovics, Waldemar Ogloza, Andras Pal, Adam Sodor,
Eda Sonbas, Robert Szakats, Krisztian Vida, Jozsef Vinko, Lukasz Wyrzykowski, Pawel Zielinski F Context.

Gaia18cjb is one of the Gaia-alerted eruptive young star candidates which has been experiencing a slow and strong
brightening during the last 13 years, similar to some FU Orionis-type objects. Aims. The aim of this work is toderive the young stellar nature of Gaia18cjb, determine its physical and accretion properties to classify its variability.
Methods. We conducted monitoring observations using multi-filter optical and near-infrared photometry, as well as
near-infrared spectroscopy. We present the analysis of pre-outburst and outburst optical and infrared light curves,
color-magnitude diagrams in different bands, the detection of near-IR spectral lines, and estimates of both stellar
and accretion parameters during the burst. Results. The optical light curve shows an unusually long (8 years)
brightening event of 5 mag in the last 13 years, before reaching a plateau indicating that the burst is still on-going,suggesting a FUor-like nature. The same outburst is less strong in the infrared light curves. The near-infrared spectra,
obtained during the outburst, exhibit emission lines typical of highly accreting low-intermediate mass young stars withtypical EXor features. The spectral index of Gaia18cjb SED classifies it as a Class I in the pre-burst stage and a
Flat Spectrum young stellar object (YSO) during the burst. Conclusions. Gaia18cjb is an eruptive YSO which shows
FUor-like photometric features (in terms of brightening amplitude and length of the burst) and EXor-like spectroscopic
features and accretion rate, as V350 Cep and V1647 Ori, classified as objects in between FUors and EXors

18. Clumpy accretion as a possible reason of prolonged eclipses of UX Ori type stars
Vladimir Grinin, Tatiana Demidova F The paper proposes a model of deep and prolonged eclipses of young starsof the UX Ori type. Some of these events continue for decades and existing models cannot explain them. Our paper
shows that such eclipses can be caused by the falling of gas and dust clump from the remnants of the protostellar
cloud onto the protoplanetary disk. The disturbance in the disk caused by the fall of the clump leads to a surge in
the accretion activity of the star and, as a consequence, to an increase in the disk wind. If the circumstellar disk istilted at a slight angle to the line of sight, then dust raised by the wind from the surface of the disk can cause a strong
decrease in the star’s brightness, which can last for decades.

719. The SPHERE view of the Taurus star-forming region
A. Garufi, C. Ginski, R. G. van Holstein, M. Benisty, C. F. Manara, S. Pérez, P. Pinilla, Á. Ribas, P. Weber,
J. Williams, L. Cieza, C. Dominik, S. Facchini, J. Huang, A. Zurlo, J. Bae, J. Hagelberg, Th. Henning, M.
R. Hogerheijde, M. Janson, F. Ménard, S. Messina, M. R. Meyer, C. Pinte, S. P. Quanz, E. Rigliaco, V.
Roccatagliata, H. M. Schmid, J. Szulágyi, R. van Boekel, Z. Wahhaj, J. Antichi, A. Baruffolo, T. Moulin

F The sample of planet-forming disks observed by high-contrast imaging campaigns over the last decade is mature
enough to enable the demographical analysis of individual star-forming regions. We present the full census of Taurus
sources with VLT/SPHERE polarimetric images available. The whole sample sums up to 43 targets (of which 31
have not been previously published) corresponding to one-fifth of the Class II population in Taurus and about half ofsuch objects that are observable. A large fraction of the sample is apparently made up of isolated faint disks (equallydivided between small and large self-shadowed disks). Ambient signal is visible in about one-third of the sample. Thisprobes the interaction with the environment and with companions or the outflow activity of the system. The central
portion of the Taurus region almost exclusively hosts faint disks, while the periphery also hosts bright disks interactingwith their surroundings. The few bright disks are found around apparently older stars. The overall picture is that the
Taurus region is in an early evolutionary stage of planet formation. Yet, some objects are discussed individually, as in
an intermediate or exceptional stage of the disk evolution. This census provides a first benchmark for the comparisonof the disk populations in different star forming regions.

20. H2CO and CS in diffuse clouds: Excitation and abundance
Maryvonne Gerin, Harvey Liszt, Jerome Pety, Alexandre Faure F To provide constraints on the chemical processes

responsible for the observed columns of organic species, we used NOEMA to observe the sight line toward NRAO150 in
the 2mm spectral window. We targeted the low excitation lines of o-H2CO 2(1,1)-1(1,0) and p-H2CO 2(0,2)-1(0,1) as
well as the nearby transitions of CS(3-2) and c-C3H2. We combined these data with previous observations to determine
the excitation conditions, column densities, and abundances relative to H2 in the different velocity components. We
performed non-LTE radiative transfer calculations including collision cross sections with ortho and para H2 andwith electrons. New collision cross sections with electrons were computed for ortho and para formaldehyde. The
c-C3H2 line profiles are very similar to those of HCO+ and CCH, while the CS absorption features are narrower
and mostly concentrated in two main velocity components at V = -17 and -10 km/s. H2CO absorption lines present
an intermediate pattern with absorption in all velocity components but larger opacities in the two main velocity
components. The ortho-to-para ratios of H2CO and c-C3H2 are consistent with the statistical value of 3. While theexcitation temperature of all c-C3H2 velocity components is consistent with the CMB, the two strong components
detected in CS show a clear excess over the CMB indicating that CS resides at higher densities than other species
along this particular sightline, n(H2) 2500 cm-3 while n(H2) < 500 cm-3 for the other velocity components. We
detected faint absorption from o-H213CO and C34S allowing us to derive isotopic ratios: o-H2CO/o-H213CO = 61
and C32S/C34S = 24. The excitation of the 4.8GHz line of formaldehyde is sensitive to the electron fraction and its
excitation temperature is predicted to be lower than the CMB at low and moderate electron fractions, x(e)< 6E-5,
and to rise above the CMB at high electron fractions, > 1e-4.

21. The SPHERE view of the Chamaeleon I star-forming region
C. Ginski, A. Garufi, M. Benisty, R. Tazaki, C. Dominik, A. Ribas, N. Engler, T. Birnstiel, G. Chauvin, G.
Columba, S. Facchini, A. Goncharov, J. Hagelberg, T. Henning, M. Hogerheijde, R. G. van Holstein, J. Huang,
T. Muto, P. Pinilla, K. Kanagawa, S. Kim, N. Kurtovic, M. Langlois, C. Manara, J. Milli, M. Momose, R.
Orihara, N. Pawellek, C. Pinte, C. Rab, T. O. B. Schmidt, F. Snik, Z. Wahhaj, J. Williams, A. Zurlo F We used

VLT/SPHERE to observe 20 systems in the Cha I cloud in polarized scattered light in the near-infrared. We combined
the scattered light observations with existing literature data on stellar properties and with archival ALMA continuum
data to study trends with system age and dust mass. We also connected resolved near-infrared observations withthe spectral energy distributions of the systems. In 13 of the 20 systems included in this study we detected resolved
scattered light signals from circumstellar dust. For the CR Cha, CT Cha, CV Cha, SY Cha, SZ Cha, and VZ Cha
systems we present the first detailed descriptions of the disks in scattered light. The observations found typicallysmooth or faint disks, often with little substructure, with the notable exceptions of SZ Cha, which shows an extended
multiple-ringed disk, and WW Cha, which shows interaction with the cloud environment. New high S/N K- band
observations of the HD 97048 system in our survey reveal a significant brightness asymmetry that may point to disk
misalignment and subsequent shadowing of outer disk regions, possibly related to the suggested planet candidate in8the disk. We resolve for the first time the stellar binary in the CS Cha system. Multiple wavelength observations of thedisk around CS Cha have revealed that the system contains small, compact dust grains that may be strongly settled,
consistent with numerical studies of circumbinary disks. We find in our sample that there is a strong anti-correlation
between the presence of a (close) stellar companion and the detection of circumstellar material with five of our sevennondetections located in binary systems.

22. The Dynamic, Chimeric Inner Disk of PDS 70
Eric Gaidos, Thanawuth Thanathibodee, Andrew Hoffman, Joel Ong, Jason Hinkle, Benjamin J. Shappee,
Andrea Banzatti F Transition disks, with inner regions depleted in dust and gas, could represent later stages ofprotoplanetary disk evolution when newly-formed planets are emerging. The PDS 70 system has attracted particularinterest because of the presence of two giant planets at tens of au orbits within the inner disk cavity, at least one ofwhich is itself accreting. However, the region around PDS 70 most relevant to understanding the planet populations
revealed by exoplanet surveys of middle-aged stars is the inner disk, which is the dominant source of the system’s
excess infrared emission but only marginally resolved by ALMA. Here we present and analyze time-series optical andinfrared photometry and spectroscopy that reveal the inner disk to be dynamic on timescales of days to years, withoccultation of sub-micron dust dimming the star at optical wavelengths and 3-5 µm emission varying due to changes
in disk structure. Remarkably, the infrared emission from the innermost region (nearly) disappears for 1 year. We
model the spectral energy distribution of the system and its time variation with a flattened warm (T < 600K) disk
and a hotter (1200K) dust that could represent an inner rim or wall. The high dust-to-gas ratio of the inner disk
relative to material accreting from the outer disk, means that the former could be a chimera consisting of depleted
disk gas that is subsequently enriched with dust and volatiles produced by collisions and evaporation of planetesimals
in the inner zone.

A survey for variable stars with small telescopes: IX – Evolution of Spot Properties on
23. YSOs in IC5070
Carys Herbert et al. F We present spot properties on 32 periodic young stellar objects in IC 5070. Long term, ∼5
yr, light curves in the V , R, and I-bands are obtained through the HOYS (Hunting Outbursting Young Stars) citizen
science project. These are dissected into six months long slices, with 3 months oversampling, to measure 234 sets ofamplitudes in all filters. We fit 180 of these with reliable spot solutions. Two thirds of spot solutions are cold spots,
the lowest is 2150 K below the stellar temperature. One third are warm spots that are above the stellar temperatureby less than ∼2000 K. Cold and warm spots have maximum surface coverage values of 40 percent, although only
16 percent of warm spots are above 20 percent surface coverage as opposed to 60 percent of the cold spots. Warmspots are most likely caused by a combination of plages and low density accretion columns, most common on objects
without inner disc excess emission in K − W 2. Five small hot spot solutions have < 3 percent coverage and are 3000 5000 K above the stellar temperature. These are attributed to accretion, and four of them occur on the same object.
The majority of our objects are likely to be accreting. However, we observe very few accretion hot spots as either
the accretion is not stable on our timescale or the photometry is dominated by other features. We do not identify
cyclical spot behaviour on the targets. We additionally identify and discuss a number of objects that have interesting
amplitudes, phase changes, or spot properties.

Fractionation in young cores: Direct determinations of nitrogen and carbon fractiona24. tion in HCN
S. S. Jensen, S. Spezzano, P. Caselli, O. Sipilä, E. Redaelli, K. Giers, J. Ferrer Asensio F We aim to determine
the 14 N/15 N and 12 C/13 C ratios for HCN in six starless and prestellar cores and compare the results between the direct method using radiative transfer modeling and the indirect double isotope method assuming a fixed 12 C/13 C ratio.
We present IRAM 30m observations of the HCN 1-0, HCN 3-2, HC15N 1-0 and H13CN 1-0 transitions toward six
embedded cores. The 14 N/15 N ratio was derived using both the indirect double isotope method and directly throughnon-local thermodynamic equilibrium (NLTE) 1D radiative transfer modeling of the HCN emission. The latter also
provides the 12 C/13 C ratio, which we compared to the local interstellar value. The derived 14 N/15 N ratios using theindirect method are generally in the range of 300-550. This result could suggest an evolutionary trend in the nitrogen
fractionation of HCN between starless cores and later stages of the star formation process. However, the direct method
reveals lower fractionation ratios of around ∼250, mainly resulting from a lower 12 C/13 C ratio in the range ∼20-40, as

9compared to the local interstellar medium value of 68. This study reveals a significant difference between the nitrogen
fractionation ratio in HCN derived using direct and indirect methods. This can influence the interpretation of thechemical evolution and reveal the pitfalls of the indirect double isotope method for fractionation studies. However,the direct method is challenging, as it requires well-constrained source models to produce accurate results. No trend
in the nitrogen fractionation of HCN between earlier and later stages of the star formation process is evident when
the results of the direct method are considered.

The Emerging Stellar Complex in Mon R2: Membership and Optical Variability Clas25. sification
Sally D. Jiang, Lynne A. Hillenbrand F Monoceros R2 (Mon R2) is one of the closest large active star-forming

regions. This extremely young and partially embedded region provides an excellent laboratory for studying star formation and the early evolution of young stellar objects (YSOs). In this paper, we conduct an optical study of thegreater Mon R2 region. Beginning with 1690 previously identified candidate YSOs, we used 496 sources with good
proper motions and parallaxes from Gaia DR3 to determine the astrometric properties for likely members of Mon R2.
We then used both astrometric and photometric (isochronal and variability) criteria to determine that 308 of thesestars are highly probable members. Using the same criteria, we considered a broad area search around Mon R2 in
Gaia DR3, and separated candidate members from field stars. In total, we selected 651 likely new cluster membersthat had been missed in the previous x-ray and infrared excess selection techniques used in the past to establish
cluster membership. Revised astrometric properties of the cluster were found using the combined sample of 959
highly probable member stars. For the literature plus new candidate member list, optical light curves were compiled
from the Zwicky Transient Facility. For 470 identified variable sources, we attempted classification based on the Flux
Asymmetry (M) and Quasi-Periodicity (Q) metrics. We find that Mon R2 is dominated by quasi-periodic symmetricvariables, with aperiodic sources also a significant population. A few tens of large-amplitude variables are identified
that may be of interest for further study.

The Emerging Stellar Complex in Mon R2: Membership and Optical Variability Clas26. sification
Sally D. Jiang, Lynne A. Hillenbrand F Monoceros R2 (Mon R2) is one of the closest large active star-forming

regions. This extremely young and partially embedded region provides an excellent laboratory for studying star formation and the early evolution of young stellar objects (YSOs). In this paper, we conduct an optical study of thegreater Mon R2 region. Beginning with 1690 previously identified candidate YSOs, we used 496 sources with good
proper motions and parallaxes from Gaia DR3 to determine the astrometric properties for likely members of Mon R2.
We then used both astrometric and photometric (isochronal and variability) criteria to determine that 308 of thesestars are highly probable members. Using the same criteria, we considered a broad area search around Mon R2 in
Gaia DR3, and separated candidate members from field stars. In total, we selected 651 likely new cluster membersthat had been missed in the previous x-ray and infrared excess selection techniques used in the past to establish
cluster membership. Revised astrometric properties of the cluster were found using the combined sample of 959
highly probable member stars. For the literature plus new candidate member list, optical light curves were compiled
from the Zwicky Transient Facility. For 470 identified variable sources, we attempted classification based on the Flux
Asymmetry (M) and Quasi-Periodicity (Q) metrics. We find that Mon R2 is dominated by quasi-periodic symmetricvariables, with aperiodic sources also a significant population. A few tens of large-amplitude variables are identified
that may be of interest for further study.

27. [N I] 10400/10410 Å Lines as Possible Disk Wind Tracers in a Young Intermediate-MassStar
Haruki Katoh, Chikako Yasui, Yuji Ikeda, Naoto Kobayashi, Noriyuki Matsunaga, Sohei Kondo, Hiroaki
Sameshima, Satoshi Hamano, Misaki Mizumoto, Hideyo Kawakita, Kei Fukue, Shogo Otsubo, Keiichi Takenaka F In this study, we performed high-resolution near-infrared (NIR) spectroscopy (R = 28,000; λ = 0.90-1.35µm) with a high signal-to-noise ratio on HD 200775, a very young (∼0.1 Myr old) and massive intermediate-massstar (a binary star with a mass of about 10 M each) with a protoplanetary disk. The obtained spectra show eight
forbidden lines of three elements: two of [S II] (10289 and 10323 Å), two of [N I] (10400 and 10410 Å), and four of [Fe II](12570, 12946, 12981, and 13209 Å). This is the first time that the [N I] lines are detected in a young stellar object with10

a doublet deblended. Gaussian fitting of the spectra indicates that all line profiles have low-velocity components andexhibit blueshifted features, suggesting that all lines originate from the disk winds (magnetohydrodynamic disk wind
and/or photoevaporative wind). Based on the fit, the [N I] and [Fe II] lines are categorized into narrow components,
while the [S II] lines are at the boundary between broad and narrow components. These forbidden lines are suggested
to be very promising disk wind tracers among the existing ones because they are in the NIR-wavelength range, which
can be observed from early stages with high sensitivities. Among these lines, [N I] lines would be a rather powerfulprobe for deriving the basic physical parameters of disk wind gases. However, the study of these lines herein is limited
to one object; thus, further studies are needed to examine their properties.

28. Feasibility of detecting shadows in disks induced by infall
A. Krieger, M. Kuffmeier, S. Reissl, C. P. Dullemond, C. Ginski, S. Wolf F Observations performed with high-resolution imaging techniques revealed the existence of shadows in circumstellar disks that can be explained by themisalignment of an inner with respect to an outer disk. The cause of misalignment, however, is still debated. In thisstudy, we investigate the feasibility of observing shadows induced by one prominent scenario that may lead to misalignment, which involves the late infall of material onto a protostellar system. In particular, we use previously performedhydrodynamical simulations of such events, and generate flux maps in the visible, near-infrared, submillimeter, andmillimeter wavelength range using Monte Carlo radiative transfer. Based on that, we derive synthetic observations ofthese systems performed with the instruments SPHERE/VLT and ALMA, which we use as a basis for our subsequent
analysis. We find that near-infrared observations with SPHERE are particularly well suited for detecting shadows
via direct imaging alongside other features such as gaps, arcs, and streamers. On the contrary, performing a shadow
detection based on reconstructed ALMA observations is very challenging due to the high sensitivity that is required
for this task. Thus, in cases that allow for a detection, sophisticated analyses may be needed, for instance by theutilization of carefully constructed azimuthal profiles, aiding the search for potentially shallow shadows. Lastly, we
conclude that late infall-induced disk misalignment offers a plausible explanation for the emergence of shadows thatare observed in various systems.

29. The GUAPOS project. V: The chemical ingredients of a massive stellar protocluster inthe making
Á. López-Gallifa, V. M. Rivilla, M. T. Beltrán, L. Colzi, C. Mininni, Á. Sánchez-Monge, F. Fontani, S. Viti, I.
Jiménez-Serra, L. Testi, R. Cesaroni, A. Lorenzani F Most stars, including the Sun, are born in rich stellar clusters

containing massive stars. Therefore, the study of the chemical reservoir of massive star-forming regions is crucial tounderstand the basic chemical ingredients available at the dawn of planetary systems. We present a detailed studyof the molecular inventory of the hot molecular core G31.41+0.31 from the project GUAPOS (G31.41+0.31 Unbiased
ALMA sPectral Observational Survey). We analyze 34 species for the first time plus 20 species analyzed in previous
GUAPOS works, including oxygen, nitrogen, sulfur, phosphorus, and chlorine species. We compare the abundances
derived in G31.41+0.31 with those observed in other chemically-rich sources that represent the initial and last stagesof the formation of stars and planets: the hot corino in the Solar-like protostar IRAS 16293-2422 B, and the comets
67P/Churyumov-Gerasimenko and 46P/Wirtanen. The comparative analysis reveals that the chemical feedstock of
the two star-forming regions are similar. The abundances of oxygen- and nitrogen-bearing molecules exhibit a goodcorrelation for all pair of sources, including the two comets, suggesting a chemical heritage of these species during theprocess of star formation, and hence an early phase formation of the molecules. However, sulfur- and phosphorusbearing species present worse correlations, being more abundant in comets. This suggests that while sulfur- andphosphorus-bearing species are predominantly trapped on the surface of icy grains in the hot close surroundings ofprotostars, they could be more easily released into gas phase in comets, allowing their cosmic abundances to be almost
recovered.

ALMA Spectral Survey of An eruptive Young star, V883 Ori (ASSAY): I. What trig30. gered the current episode of eruption?
Jeong-Eun Lee, Chul-Hwan Kim, Seokho Lee, Seonjae Lee, Giseon Baek, Hyeong-Sik Yun, Yuri Aikawa, Doug
Johnstone, Gregory J. Herczeg, Lucas Cieza F An unbiased spectral survey of V883 Ori, an eruptive young star,was carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 6. The detected line emission from various molecules reveals morphological/kinematical features in both the Keplerian disk and the infalling11

envelope. A direct infall signature, red-shifted absorption against continuum, has been detected in CO, HCO+ , HCN,
HNC, and H2 CO. HCO+ and SO show large arm-like structures that probably connect from an infalling envelope tothe disk. HCN and H2 CO reveal a distinct boundary between the inner and outer disk and reveal tentative spiralstructures connecting the outer disk to the inner disk. HNC shows a large central emission hole (r ∼0.3 arcsec) due
to its chemical conversion to HCN at high temperatures. The HDO emission, a direct tracer of the water sublimation
region, has been detected in the disk. Molecular emission from complex organic molecules (COMs) is confined within
the HDO emission boundary, and HCO+ has an emission hole in its distribution due to its destruction by water.
Together, these features suggest that the current episode of eruption in V883 Ori may be triggered by the infall fromthe envelope to the outer disk, generating a spiral wave, which propagates inward and greatly enhances the accretion
onto the central star.

Dark Dragon Breaks Magnetic Chain: Dynamical Substructures of IRDC G28.34 Form
31. in Supported Environments
Junhao Liu, Qizhou Zhang, Yuxin Lin, Keping Qiu, Patrick M. Koch, Hauyu Baobab Liu, Zhi-Yun Li, Josep
Miquel Girart, Thushara G. S. Pillai, Shanghuo Li, Huei-Ru Vivien Chen, Tao-Chung Ching, Paul T. P.
Ho, Shih-Ping Lai, Ramprasad Rao, Ya-Wen Tang, Ke Wang F We have comprehensively studied the multi-scale

physical properties of the infrared dark cloud (IRDC) G28.34 (the Dragon cloud) with dust polarization and molecularline data from Planck, FCRAO-14m, JCMT, and ALMA. We find that the averaged magnetic fields of clumps tend
to be either parallel with or perpendicular to the cloud-scale magnetic fields, while the cores in clump MM4 tend tohave magnetic fields aligned with the clump fields. Implementing the relative orientation analysis (for magnetic fields,
column density gradients, and local gravity), Velocity Gradient Technique (VGT), and modified Davis-ChandrasekharFermi (DCF) analysis, we find that: G28.34 is located in a trans-to-sub-Alfvénic environment (MA = 0.74 withinr = 15 pc); the magnetic field is effectively resisting gravitational collapse in large-scale diffuse gas, but is distorted bygravity within the cloud and affected by star formation activities in high-density regions; and the normalized massto-flux ratio tends to increase with increasing density and decreasing radius. Considering the thermal, turbulent, andmagnetic supports, we find that the environmental gas of G28.34 is in a super-virial (supported) state, the infrareddark clumps may be in a near-equilibrium state, and core MM4-core4 is in a sub-virial (gravity-dominant) state.
In summary, we suggest that magnetic fields dominate gravity and turbulence in the cloud environment at large
scales, resulting in relatively slow cloud formation and evolution processes. Within the cloud, gravity could overwhelm
magnetic fields and turbulence, allowing local dynamical star formation to happen.

32. Modeling the secular evolution of embedded protoplanetary discs
J. Mauxion, G. Lesur, S. Maret F Context: Protoplanetary discs are known to form around nascent stars from theirparent molecular cloud as a result of angular momentum conservation. As they progressively evolve and dissipate, theyalso form planets. While a lot of modeling efforts have been dedicated to their formation, the question of their secular
evolution, from the so-called class 0 embedded phase to the class II phase where discs are believed to be isolated,remains poorly understood. Aims: We aim to explore the evolution between the embedded stages and the class IIstage. We focus on the magnetic field evolution and the long-term interaction between the disc and the envelope.
Methods: We use the GPU-accelerated code Idefix to perform a 3D, barotropic, non-ideal magnetohydrodynamic(MHD) secular core collapse simulation that covers the system evolution from the collapse of the pre-stellar core until
100 kyr after the first hydrostatic core formation and the disc settling while ensuring sufficient vertical and azimuthal
resolutions (down to 10−2 au) to properly resolve the disc internal dynamics and non-axisymmetric perturbations.
Results: The disc evolution leads to a power-law gas surface density in Keplerian rotation that extends up to a few 10
au. The magnetic flux trapped in the disc during the initial collapse decreases from 100 mG at disc formation down
to 1 mG by the end of the simulation. After the formation of the first hydrostatic core, the system evolves in threephases. A first phase with a small (∼ 10 au), unstable, strongly accreting (∼ 10−5 M yr−1 ) disc that loses magnetic
flux over the first 15 kyr, a second phase where the magnetic flux is advected with a smooth, expanding disc fed by
the angular momentum of the infalling material...

12Angular Momentum Transport in Binary Star Formation: The Enhancement of Magneto33. Rotational Instability and Role of Outflows
Tomoaki Matsumoto F The formation of binary stars is highly influenced by magnetic fields, which play a crucial rolein transporting angular momentum. We conducted three-dimensional numerical simulations of binary star accretion
via a circumbinary disk, taking into account a magnetic field perpendicular to the disk and an infalling envelope. Our
simulations reproduce the following phenomena: (1) spiral arms associated with circumstellar disks, (2) turbulence inthe circumbinary disk, induced by magneto-rotational instability (MRI), (3) a fast outflow launched from each circumstellar disk, and (4) a slow outflow from the circumbinary disk. The binary models exhibit a higher α-parameter
than the corresponding single star models, indicating that the binary stars enhance MRI turbulence. Moreover, an
infalling envelope also enhance the turbulence, leading to a high α-parameter. While the spiral arms promotes radialflow, causing transfer of mass and angular momentum within the circumbinary disk, the MRI turbulence and outflows
are main drivers of angular momentum transfer to reduce the specific angular momentum of the system.

Long period modulation of the classical T Tauri star CI Tau: evidence for an eccentric
34. close-in massive planet at 0.17 au
R. Manick, A. P. Sousa, J. Bouvier, J. M. Almenara, L. Rebull, A. Bayo, A. Carmona, E. Martioli, L. Venuti,
G. Pantolmos, Á. Kóspál, C. Zanni, X. Bonfils, C. Moutou, X. Delfosse, the SLS consortium F Detecting

planets within protoplanetary disks around young stars is essential for understanding planet formation and evolution.
However, planet detection using the radial velocity method faces challenges due to strong stellar activity in these earlystages. We aim to detect long-term periodicities in photometric and spectroscopic time series of the classical T Tauri
star (CTTS) CI Tau, and retrieve evidence for inner embedded planets in its disk. The study conducted photometricand spectroscopic analyses using K2 and Las Cumbres Observatory Global Network light curves, and high-resolution
spectra from ESPaDOnS and SPIRou. We focus our radial velocity analysis on a wavelength domain less affectedby spot activity. To account for spot effects, a quasi-periodic Gaussian process model was applied to K2 light curve,
ESPaDOnS, and SPIRou radial velocity data. Additionally, a detailed bisector analysis on cross-correlation functions
was carried out to understand the cause of long-term periodicity. We detect coherent periods at ∼ 6.6 d, 9 d, ∼ 11.5d, ∼ 14.2 d and ∼ 25.2 d, the latter is seen consistently across all datasets. Bisector analysis of the cross-correlation
functions provides strong hints for combined activity-induced and Doppler reflex signal in the radial velocities at aperiod of 25.2 d. Our analysis suggests that this periodicity is best explained by the presence of a 3.6±0.3 MJup ,eccentric (e∼0.58) planet at a semi-major axis of 0.17 au. Our study outlines the difficulty of searching for diskembedded planets in the inner 0.1 au’s of young and active systems. We demonstrate that, when searching for planetsin actively accreting stars such as CI Tau, the primary limitation is stellar activity rather than the precision of RV
measurements provided by the instrument.

35. JWST/NIRCam Imaging of Young Stellar Objects III: Detailed Imaging of the Nebular
Environment Around the HL Tau Disk
Camryn Mullin, Ruobing Dong, Jarron Leisenring, Gabriele Cugno, Thomas Greene, Doug Johnstone, Michael
R. Meyer, Kevin R. Wagner, Schuyler G. Wolff, Martha Boyer, Scott Horner, Klaus Hodapp, Don McCarthy,
George Rieke, Marcia Rieke, Erick Young F As part of the James Webb Space Telescope (JWST) Guaranteed Time

Observation (GTO) program "Direct Imaging of YSOs" (program ID 1179), we use JWST NIRCam’s direct imaging
mode in F187N, F200W, F405N, and F410M to perform high contrast observations of the circumstellar structures
surrounding the protostar HL Tau. The data reveal the known stellar envelope, outflow cavity, and streamers, but
do not detect any companion candidates. We detect scattered light from an in-flowing spiral streamer previously
detected in HCO+ by ALMA, and part of the structure connected to the c-shaped outflow cavity. For detection limits
in planet mass we use BEX evolutionary tracks when Mp < 2MJ and AMES-COND evolutionary tracks otherwise,
assuming a planet age of 1 Myr (youngest available age). Inside the disk region, due to extended envelope emission,
our point-source sensitivities are ∼ 5 mJy (37 MJ ) at 40 AU in F187N, and ∼ 0.37 mJy (5.2 MJ ) at 140 AU in F405N.
Outside the disk region, the deepest limits we can reach are ∼ 0.01 mJy (0.75 MJ ) at a projected separation of ∼ 525
AU.

13

36. The role of heating on the formation and the dynamics of YSO jets : I. A parametric
study
C. Meskini, C. Sauty, A. Marcowith, N. Vlahakis, V. Brunn F Theoretical arguments as well as observations ofyoung stellar objects (YSO) support the presence of a diversified circumstellar environment. A stellar jet is thoughtto account for most of the stellar spin down and disk wind outflow for the observed high mass loss rate, thus playing
a major role in the launching of powerful jets. RY Tau, for instance, is an extensively studied intermediate mass
pre-main sequence star. Observational data reveal a small scale jet called microjet. Nevertheless, it is not clear how
the microjet shapes the jet observed at a large scale. The goal is to investigate the spatial stability and structure of
the central jet at a large scale by mixing the stellar and disk components. We mix two existing analytical self-similar
models for the disk and the stellar winds to build the initial set-ups. Instead of using a polytropic equation of state,
we map from the analytical solutions, the heating and cooling sources. The heating exchange rate is controlled by
two parameters, its spatial extent and its intensity. The central jet and the surrounding disk are strongly affected bythese two parameters. We separate the results in three categories, which show different emissivity, temperature, andvelocity maps. We reached this categorization by looking at the opening angle of the stellar solution. For cylindrically,
well collimated jets, we have opening angles as low as 10 degrees between 8 and 10 au, and for the wider jets, we canreach 30 degrees with a morphology closer to radial solar winds. Our parametric study shows that the less heatedthe outflow is, the more collimated it appears. We also show that recollimation shocks appear consistently with UV
observations in terms of temperature but not density.

37. Characterizing the 3D Structure of Molecular Cloud Envelopes in the "Cloud Factory"
Simulations
Elijah Mullens, Catherine Zucker, Claire E. Murray, Rowan Smith F We leverage recent numerical simulations ofhighly resolved star-forming regions in a Milky Way-like Galaxy to explore the nature of extended gaseous envelopesaround molecular clouds. We extract a sample of two dozen star-forming clouds from the feedback-dominated suiteof the "Cloud Factory” simulations. With the goal of exploring the 3D thermal and chemical structure of the gas, wemeasure and fit the clouds’ radial profiles in multiple tracers, including nHI , nH2 , nHtot , nCO , and gas temperature. We
find that while solar neighborhood clouds recently detected via 3D dust mapping have radially symmetric, low-density
envelopes that extend ∼ 10-15 pc, the simulated cloud envelopes are primarily radially asymmetric with low-density
envelopes that extend only ∼ 2-3 pc. One potential explanation for the absence of extended envelopes in the simulated
clouds may be the lack of magnetic fields, while a stronger local feedback prescription compared to solar neighborhood
conditions may drive the radially asymmetric cloud morphologies. We make the pipeline to extract and characterize
the radial profile of clouds publicly available, which can be used in complementary and future simulations to shedadditional light on the key physics shaping the formation and evolution of star-forming structures in the Milky Way.

38. UVIT/AstroSat observation of TW Hya
Prasanta K. Nayak, Mayank Narang, P. Manoj, D. K. Ojha, Blesson Mathew, T. Baug, S. Chandra, S. Vig, G.
Maheswar, U. S. Kamath F The paper demonstrates the spectroscopic and photometric capabilities of the Ultra-

Violet Imaging Telescope (UVIT) to study T-Tauri stars (TTSs). We present the first UVIT/Far-UV spectrum of
a TTS, TW Hya. Based on C IV line luminosity, we estimated accretion luminosity (0.1 L ) and mass accretion
rate (2.2 × 10−8 M /yr) of TW Hya, and compared these values with the accretion luminosity (0.03 L ) and massaccretion rate (0.6 × 10−8 M /yr) derived from spectral energy distribution (SED). From the SED, we derive bestfitted parameters for TW Hya: Tef f = 3900±50 K, radius = 1.2±0.03 R , log g = 4.0 and equivalent black-bodytemperatures corresponding to accretion luminosity as 14100±25 K. The parameters of TW Hya derived from UVIT
observations were found to be matched well with the literature. Comparison with IUE spectra also suggests that UVIT
can be used to study the spectroscopic variability of young stars. This study proposes leveraging the FUV spectroscopic
capabilities of UVIT to contribute to the advancement of upcoming UV spectroscopic missions, including the IndianSpectroscopic Imaging Space Telescope (INSIST).

14

39. Grain growth and its chemical impact in the first hydrostatic core phase
D. Navarro-Almaida, U. Lebreuilly, P. Hennebelle, A. Fuente, B. Commerçon, R. Le Gal, V. Wakelam, M.
Gerin, P. Riviére-Marichalar, L. Beitia-Antero, Y. Ascasibar F The first hydrostatic core (FHSC) phase is a brief

stage in the protostellar evolution that is difficult to detect. Our goal is to characterize the chemical evolution ofgas and dust during the formation of the FHSC. Moreover, we are interested in analyzing, for the first time with 3D
magnetohydrodynamic (MHD) simulations, the role of grain growth in its chemistry. We postprocessed 2 × 105 tracer
particles from a RAMSES non-ideal MHD simulation using the codes NAUTILUS and SHARK to follow the chemistry andgrain growth throughout the simulation. A great chemical inheritance is seen, as gas-phase abundances of most of
the C, O, N, and S reservoirs in the hot corino at the end of the simulation match the ice-phase abundances from theprestellar phase. Additionally, interstellar complex organic molecules (iCOMs) such as methyl formate, acetaldehyde,
and formamide are formed during the warm-up process. The typical grain size in the hot corino (nH > 1011 cm−3 )increases forty-fold during the last 30 kyr, with negligible effects on its chemical composition. At moderate densities(1010 < nH < 1011 cm−3 ) and cool temperatures 15 < T < 50 K, increasing grain sizes delay molecular depletion.
Finally, at low densities (nH ∼ 107 cm−3 ), grains do not grow significantly. We also compared our results with a twostep model that reproduces well the abundances of C and O reservoirs, but not the N and S reservoirs. We conclude
that the chemical composition of the FHSC is heavily determined by that of the parent prestellar core, chemo-MHD
computations are needed for an accurate prediction of the abundances of the main N and S elemental reservoirs, andthat the impact of grain growth in moderately dense areas delaying depletion permits the use of abundance ratios as
grain growth proxies.

Simultaneous FUV and NUV observations of T Tauri stars with UVIT/AstroSat: prob40. ing accretion process in young stars
Prasanta K. Nayak, Mayank Narang, P. Manoj, Uma Gorti, Annapurni Subramaniam, Nayana George, Chayan
Mondal F We present results from simultaneous FUV and NUV observations of T-Tauri stars (TTSs) in the Taurus

molecular cloud with UVIT/AstroSat. This is the very first UVIT study of TTSs. From the spectral energy distribution of TTSs from FUV to IR, we show that classical TTSs (CTTSs) emit significantly higher UV excess compared to
weak-line TTSs (WTTSs). The equivalent black-body temperatures corresponding to the UV excess in CTTSs (> 104K) are also found to be relatively higher than that in WTTSs (< 8500 K). From the UV excess, we have re-classified
two WTTSs (BS Tau, V836 Tau) as CTTSs, which has been supported by the follow-up optical spectroscopic study
using the Himalayan Chandra Telescope (HCT), showing strong Hα line emission. We find that CTTS show strong
excess emission in both FUV (>107 ) and NUV (>103 ) bands, while WTTS show strong excess only in the FUV(.105 ), suggesting that excess emission in NUV can be used as a tool to classify the TTSs. We also find a linear
correlation between UV luminosity (a primary indicator of mass accretion) and Hα luminosity (a secondary indicatorof mass accretion) with a slope of 1.21±0.17 and intercept of 2.18±0.56.

Episodic eruptions of young accreting stars: the key role of disc thermal instability due
41. to Hydrogen ionisation
Sergei Nayakshin, Fernando Cruz Saenz de Miera, Agnes Kospal, Aleksandra Calovic, Jochen Eisloffel, Douglas
N. C. Lin F In the classical grouping of large magnitude episodic variability of young accreting stars, FUORs outshine

their stars by a factor of ∼ 100, and can last for up to centuries; EXORs are dimmer, and last months to a year. A disc
Hydrogen ionisation Thermal Instability (TI) scenario was previously proposed for FUORs but required unrealistically
low disc viscosity. In the last decade, many intermediate type objects, e.g., FUOR-like in luminosity and spectra but
EXOR-like in duration were found. Here we show that the intermediate type bursters Gaia20eae, PTF14jg, Gaia19bey
and Gaia21bty may be naturally explained by the TI scenario with realistic viscosity values. We argue that TI predicts
a dearth (desert) of bursts with peak accretion rates between Ṁ ∼ 10−6 M /yr and Ṁ ∼ 10−5 M /yr, and that thisdesert is seen in the sample of all the bursters with previously determined Ṁ burst. Most classic EXORs (FUORs)
appear to be on the cold (hot) branch of the S-curve during the peak light of their eruptions; thus TI may play a rolein this class differentiation. At the same time, TI is unable to explain how classic FUORs can last for up to centuries,
and over-predicts the occurrence rate of short FUORs by at least an order of magnitude. We conclude that TI is arequired ingredient of episodic accretion operating at R < 0.1 au, but additional physics must play a role at larger
scales. Knowledge of TI inner workings from related disciplines may enable its use as a tool to constrain the natureof this additional physics.

15

42. The Effect of Starspots on Spectroscopic Age and Mass Estimates of Non-Accreting
T Tauri Stars in the Taurus-Auriga Star Forming Region
Facundo Pérez Paolino, Jeffrey S. Bary, Lynne A. Hillenbrand, Madison Markham F Accurate age and mass

determinations for young pre-main sequence stars are made challenging by the presence of large-scale starspots. We
present results from a near-infrared spectroscopic survey of ten T-Tauri Stars in Taurus-Auriga that characterize
spot filling factors and temperatures, the resulting effects on temperature and luminosity determinations, and theconsequences for inferred stellar masses and ages. We constructed composite models of spotted stars by combining
BTSettl-CIFIST synthetic spectra of atmospheres to represent the spots and the photosphere along with continuum
emission from a warm inner disk. Using a Markov-Chain Monte-Carlo algorithm, we find the best-fit spot andphotospheric temperatures, spot filling factors, as well as disk filling factors. This methodology allowed us to reproduce
the 0.75-2.40 micron stellar spectra and molecular feature strengths for all of our targets, disentangling the complicatedmulti-component emission. For a subset of stars with multi-epoch observations spanning an entire stellar rotation, we
correlate the spectral variability and changes in the filling factors with rotational periods observed in K2 and AAVSO
photometry. Combining spot-corrected effective temperatures and Gaia distances, we calculate luminosities and use
the Stellar Parameters of Tracks with Starspots (SPOTS) models to infer spot-corrected masses and ages for oursample of stars. Our method of accounting for spots results in an average increase of 60% in mass and a doubling inage with respect to traditional methods using optical spectra that do not account for the effect of spots.

Chemical differentiation and gas kinematics around massive young stellar objects in
43. RCW 120
K. V. Plakitina, M. S. Kirsanova, S. V. Kalenskii, S. V. Salii, D. S. Wiebe F We present results of a spectral

survey towards a dense molecular condensation and young stellar objects (YSOs) projected on the border of the HII
region RCW 120 and discuss emission of 20 molecules which produce the brightest lines. The survey was performed
with the APEX telescope in the frequency range 200 – 260 GHz. We provide evidences for two outflows in the dense
gas. The first one is powered by the RCW 120 S2 YSO and oriented along the line of sight. The second outflow
around RCW 120 S1 is aligned almost perpendicular to the line of sight. We show that area with bright emission of
CH3 OH, CH3 CCH and CH3 CN are organised into an onion-like structure where CH3 CN traces warmer regions aroundthe YSOs than the other molecules. Methanol seems to be released to the gas phase by shock waves in the vicinityof the outflows while thermal evaporation still does not work towards the YSOs. We find only a single manifestationof the UV radiation to the molecules, namely, enhanced abundances of small hydrocarbons CCH and c-C3 H2 in thephoto-dissociation region.

44. Bayesian characterization of the young open cluster NGC 6383 using HDBSCAN and
Gaia DR3
L. M. Pulgar-Escobar, N. A. Henríquez-Salgado F This study focuses on determining the characteristics of theyoung open cluster NGC 6383. To achieve this, the HDBSCAN clustering algorithm is utilized to identify potential
cluster members based on proper motions and parallaxes from Gaia Data Release 3. Various parameters of NGC 6383,
such as tidal radius, core radius, distance through parallax and isochrone-fitting, proper motion, age, metallicity,and relevant others, are assessed. To perform this analysis, we utilize an extension of Hamiltonian Monte Carlo, theNo-U-Turn Sampler. The results of this analysis point out that NGC 6383 is a very young open cluster (∼ 1 − 4 Myr),with a distance of ∼ 1.1 kpc.

45. Mass assembly in massive star formation: a fragmentation study of ATLASGAL clumps
Jagadheep D. Pandian, Rwitika Chatterjee, Timea Csengeri, Jonathan P. Williams, Friedrich Wyrowski, Karl
M. Menten F The mass assembly in star forming regions arises from the hierarchical structure in molecular clouds

in tandem with fragmentation at different scales. In this paper, we present a study of the fragmentation of massive
clumps covering a range of evolutionary states, selected from the ATLASGAL survey, using the compact configurationof the Submillimeter Array. The observations reveal a wide diversity in the fragmentation properties with about
60% of the sources showing limited to no fragmentation at the 2" scale, or a physical scale of 0.015 - 0.09 pc. We
also find several examples where the cores detected with the Submillimeter array are significantly offset from theclump potential suggesting that initial fragmentation does not result in the formation of a large number of Jeans massfragments. The fraction of the clump mass that is in compact structures is seen to increase with source evolution.

16

We also see a significant correlation between the maximum mass of a fragment and the bolometric luminosity of theparent clump. These suggest that massive star formation proceeds through clump fed core accretion with the initial
fragmentation being dependent on the density structure of the clumps and/or magnetic fields.

46. Physical Properties and Kinematics of Dense Cores Associated with Regions of Massive
Star Formation from the Southern Sky
L. E. Pirogov, P. M. Zemlyanukha, E. M. Dombek, M. A. Voronkov F The results of spectral observations in the∼ 84 − 92 GHz frequency range of six objects in the southern sky containing dense cores and associated with regionsof massive stars and star clusters formation are presented. The observations were carried out with the MOPRA-22m
radio telescope. Within the framework of the local thermodynamic equilibrium (LTE) approximation, the column
densities and abundances of the H13 CN, H13 CO+ , HN13 C, HC3 N, c-C3 H2 , SiO, CH3 C2 H and CH3 CN molecules arecalculated. Estimates of kinetic temperatures (∼ 30−50 K), sizes of emission regions (∼ 0.2−3.1 pc) and virial masses(∼ 70 − 4600 M ) are obtained. The line widths in the three cores decrease with increasing distance from the center.
In four cores, asymmetry in the profiles of the optically thick lines HCO+ (1-0) and HCN(1-0) is observed, indicating
the presence of systematic motions along the line of sight. In two cases, the asymmetry can be caused by contractionof gas. The model spectral maps of HCO+ (1-0) and H13 CO+ (1-0), obtained within the framework of the non-LTE
spherically symmetric model, are fitted into the observed ones. The radial profiles of density (∝ r−1.6 ), turbulent
velocity (∝ r−0.2 ), and contraction velocity (∝ r0.5 ) in the G268.42–0.85 core have been calculated. The contraction
velocity profile differs from that expected both in the case of free fall of gas onto a protostar (∝ r−0.5 ), and in thecase of global core collapse (contraction velocity does not depend on distance). A discussion of the obtained results isprovided.

47. Survival of the long-lived inner disk of PDS 70

Paola Pinilla, Myriam Benisty, Rens Waters, Jaehan Bae, Stefano Facchini F The K7 T Tauri star PDS 70

remains the best laboratory for investigating the influence of giant planet formation on the structure of the parental
disk. One of the most intriguing discoveries is the detection of a resolved inner disk from ALMA observations that
extends up to the orbit of PDS 70b. It is challenging to explain this inner disk because most of the dust particles
are expected to be trapped at the outer edge of the gap opened by PDS 70b and PDS 70c. By performing dust
evolution models in combination with radiative transfer simulations that match the gas disk masses obtained fromrecent thermo-chemical models of PDS 70, we find that when the minimum grain size in the models is larger than
0.1µm, there is an efficient filtration of dust particles, and the inner disk is depleted during the first million year of
dust evolution. To maintain an inner disk, the minimum grain size in the models therefore needs to be smaller than
0.1µm. Only when grains are that small are they diffused and dragged along with the gas throughout the gap openedby the planets. The small grains transported in the inner disk grow and drift into it, but the constant reservoir of dust
particles that are trapped at the outer edge of the gap and that continuously fragment allows the inner disk to refill on
million-year timescales. Our flux predictions at millimeter wavelength of these models agree with ALMA observations.
These models predict a spectral index of 3.2 in the outer and 3.6 in the inner disk. Our simple analytical calculations
show that the water emission in the inner disk that was recently observed with the James Webb Space Telescope may
originate from these ice-coated small grains that flow through the gap, grow, and drift toward the innermost disk
regions to reach the water snowline.

48. Benchmarking the IRDC G351.77-0.53: Gaia DR3 distance, mass distribution, and starformation content
S. D. Reyes-Reyes, A. M. Stutz, S. T. Megeath, Fengwei Xu, R. H. Álvarez-Gutiérrez, N. Sandoval-Garrido, H.
-L. Liu F While intensively studied, it remains unclear how the star formation (SF) in Infrared Dark Clouds (IRDCs)

compares to that of nearby clouds. We study G351.77-0.53 (henceforth G351), a cluster-forming filamentary IRDC.
We begin by characterizing its young stellar object (YSO) content. Based on the average parallax of likely members,
we obtain a Gaia distance of ∼ 2.0 ± 0.14 kpc, resolving the literature distance ambiguity. Using our Herschel-derived
N(H2 ) map, we measure a total gas mass of 10200 M (within 11 pc2 ) and the average line-mass profile of the entire
filament, which we model as λ = 1660(w/pc)0.62 M pc−1 . At w < 0.63 pc, our λ profile is higher and has a steeper
power-law index than λ profiles extracted in Orion A and most of its substructures. Based on the YSOs inside thefilament area, we estimate the SF efficiency (SFE) and SF rate (SFR). We calculate a factor of 5 incompleteness17

correction for our YSO catalog relative to Spitzer surveys of Orion A. The G351 SFE is ∼ 1.8 times lower than that ofOrion A and lower than the median value for local clouds. We measure SFR and gas masses to estimate the efficiency
per free-fall time, ff . We find that ff is ∼ 1.1 dex below the previously proposed mean local relation, and ∼ 4.7×
below Orion A. These observations indicate that local SF-relations do not capture variations present in the Galaxy.
We speculate that cloud youth and/or magnetic fields might account for the G351 inefficiency.

49. Observations of spiral and streamer on a candidate proto-brown dwarf
B. Riaz, D. Stamatellos, M. Machida F Spirals and streamers are the hallmarks of mass accretion during the earlystages of star formation. We present the first observations of a large-scale spiral and a streamer towards a very young
brown dwarf candidate in its early formation stages. These observations show, for the first time, the influence of
external environment that results in asymmetric mass accretion via feeding filaments onto a candidate proto-browndwarf in the making. The impact of the streamer has produced emission in warm carbon-chain species close to thecandidate proto-brown dwarf. Two contrasting scenarios, a pseudo-disk twisted by core rotation and the collision ofdense cores, can both explain these structures. The former argues for the presence of a strong magnetic field in browndwarf formation while the latter suggests that a minimal magnetic field allows large-scale spirals and clumps to form
far from the candidate proto-brown dwarf.

50. FAUST XIII. Dusty cavity and molecular shock driven by IRS7B in the Corona Australis
cluster
FAUST collaboration - G. Sabatini et al. F The origin of the chemical diversity observed around low-mass protostars
probably resides in the earliest history of these systems. We aim to investigate the impact of protostellar feedback on
the chemistry and grain growth in the circumstellar medium of multiple stellar systems. In the context of the ALMA
Large Program FAUST, we present high-resolution (50 au) observations of CH3 OH, H2 CO, and SiO and continuum
emission at 1.3 mm and 3 mm towards the Corona Australis star cluster. Methanol emission reveals an arc-likestructure at ∼1800 au from the protostellar system IRS7B along the direction perpendicular to the major axis of thedisc. The arc is located at the edge of two elongated continuum structures that define a cone emerging from IRS7B.
The region inside the cone is probed by H2 CO, while the eastern wall of the arc shows bright emission in SiO, atypical shock tracer. Taking into account the association with a previously detected radio jet imaged with JVLA at
6 cm, the molecular arc reveals for the first time a bow shock driven by IRS7B and a two-sided dust cavity openedby the mass-loss process. For each cavity wall, we derive an average H2 column density of ∼7×1021 cm−2 , a mass of∼9×10−3 M , and a lower limit on the dust spectral index of 1.4. These observations provide the first evidence ofa shock and a conical dust cavity opened by the jet driven by IRS7B, with important implications for the chemicalenrichment and grain growth in the envelope of Solar System analogues.

51. Foreground Dust Properties towards the Cluster NGC 7380
Sadhana Singh, Jeewan C. Pandey, Thiem Hoang, Neelam Panwar, Biman J. Medhi, Vishal Joshi, Shashikiran
Ganesh F Using starlight polarization, we present the properties of foreground dust towards cluster NGC 7380

embedded in Hii region Sh 2-142. Observations of starlight polarization are carried out in four filters using an imaging
polarimeter equipped with a 104-cm ARIES telescope. Polarization vectors of stars are aligned along the Galacticmagnetic field. Towards the east and southeast regions, the dust structure appears much denser than in other regions(inferred from extinction contours and colour composite image) and is also reflected in polarization distribution. We
find that the polarization degree and extinction tend to increase with distance and indication for the presence of a dust
layer at a distance of around 1.2 kpc. We have identified eight potential candidates exhibiting intrinsic polarization by
employing three distinct criteria to distinguish between stars of intrinsic polarization and interstellar polarized stars.
For interstellar polarized stars, we find that the maximum polarization degree increases with the color excess and has astrong scatter, with the mean value of 1.71±0.57%. The peak wavelength spans 0.40 − 0.88µm with the mean value of
0.56±0.07 µm, suggesting similar grain sizes in the region as the average diffuse interstellar medium. The polarization
efficiency is also found to decrease with visual extinction as Pmax /AV ∝ A−0.61. Our observational results are foundV
to be consistent with the predictions by the radiative torque alignment theory.

18

52. Rotational Evolution of Classical T Tauri Stars: Models and Observations

Javier Serna, Giovanni Pinzón, Jesús Hernández, Ezequiel Manzo-Martínez, Karina Mauco, Carlos G. RománZúñiga, Nuria Calvet, Cesar Briceño, Ricardo López-Valdivia, Marina Kounkel, Guy S. Stringfellow, Keivan
G. Stassun, Marc Pinsonneault, Lucia Adame, Lyra Cao, Kevin Covey, Amelia Bayo, Alexandre Roman-Lopes,
Christian Nitschelm, Richard R. Lane F We developed a grid of stellar rotation models for low-mass and solar-

type Classical T Tauri stars (CTTS) (0.3M < M∗ < 1.2M ). These models incorporate the star-disk interaction
and magnetospheric ejections to investigate the evolution of the stellar rotation rate as a function of the mass ofthe star M∗ , the magnetic field (B∗ ), and stellar wind (Ṁwind ). We compiled and determined stellar parametersfor 208 CTTS, such as projected rotational velocity v sin(i), mass accretion rate Ṁacc , stellar mass M∗ , ages, andestimated rotational periods using TESS data. We also estimated a representative value of the mass-loss rate for oursample using the [O I] spectral line. Our results confirm that v sin(i) measurements in CTTS agree with the rotation
rates provided by our spin models in the accretion-powered stellar winds (APSW) picture. In addition, we used
the Approximate Bayesian Computation (ABC) technique to explore the connection between the model parameters
and the observational properties of CTTS. We find that the evolution of v sin(i) with age might be regulated byvariations in (1) the intensity of B∗ and (2) the fraction of the accretion flow ejected in magnetic winds, removing
angular momentum from these systems. The youngest stars in our sample (∼1 Myr) show a median branching ratioṀwind /Ṁacc ∼ 0.16 and median B∗ ∼ 2000 G, in contrast to ∼ 0.01 and 1000 G, respectively, for stars with ages & 3
Myr.

53. Multiple Outflows around a Single Protostar IRAS 15398−3359
Jinshi Sai, Hsi-Wei Yen, Masahiro N. Machida, Nagayoshi Ohashi, Yusuke Aso, Anaëlle J. Maury, Sébastien
Maret F We present the results of our mosaic observations of a single Class 0 protostar IRAS 15398−3359 with

Atacama Compact Array (ACA) in the CO J = 2-1 line. The new observations covering a ∼ 20 square region revealed
elongated redshifted and blueshifted components, which are located at distances of ∼ 3000 -7500 on the northern andsouthern sides of the protostar, respectively, in addition to the previously observed primary and secondary outflows.
These elongated components exhibit Hubble-law like velocity structures, i.e., an increase of velocity with increasing
distance from the protostar, suggesting that it is the third outflow associated with the protostar. Besides, a newredshifted component is detected at radii of ∼ 4000 -7500 on the northwestern side of the protostar. This redshiftedcomponent also exhibits a Hubble-law like velocity profile, which could be the counterpart of the secondary outflow
mostly detected at blueshifted velocities in a previous study. The three outflows are all misaligned by ∼ 20-90◦ , andthe dynamical timescale of the primary outflow is shorter than those of the other outflows approximately by an orderof magnitude. These facts hint that the outflow launch direction has significantly changed with time. The outflow
direction may change if the rotational axis and the magnetic field are misaligned, or if the dense core is turbulent. We
favor the second scenario as the origin of the multiple outflows in IRAS 15398−3359 based on a comparison between
the observational results and numerical simulations.

54. Modeling JWST MIRI-MRS Observations of T Cha: Mid-IR Noble Gas Emission Tracing a Dense Disk Wind
Andrew D. Sellek, Naman S. Bajaj, Ilaria Pascucci, Cathie J. Clarke, Richard Alexander, Chengyan Xie, Giulia
Ballabio, Dingshan Deng, Uma Gorti, Andras Gaspar, Jane Morrison F [Ne II] 12.81 µm emission is a well-used

tracer of protoplanetary disk winds due to its blueshifted line profile. MIRI-MRS recently observed T Cha, detecting
this line along with lines of [Ne III], [Ar II] and [Ar III], with the [Ne II] and [Ne III] lines found to be extended
while the [Ar II] was not. In this complementary work, we use these lines to address long-debated questions about
protoplanetary disk winds regarding their mass-loss rate, the origin of their ionization, and the role of magneticallydriven winds as opposed to photoevaporation. To this end, we perform photoionization radiative transfer on simple
hydrodynamic wind models to map the line emission. We compare the integrated model luminosities to those observedwith MIRI-MRS to identify which models most closely reproduce the data and produce synthetic images from these tounderstand what information is captured by measurements of the line extents. Along with the low degree of ionization
implied by the line ratios, the relative compactness of [Ar II] compared to [Ne II] is particularly constraining. Thisrequires Ne II production by hard X-rays and Ar II production by soft X-rays (and/or EUV) in an extended (& 10 au)
wind that is shielded from soft X-rays - necessitating a dense wind with material launched on scales down to 1 au.
Such conditions could be produced by photoevaporation, whereas an extended MHD wind producing equal shielding
would likely underpredict the line fluxes. However, a tenuous inner MHD wind may still contribute to shielding the19extended wind. This picture is consistent with constraints from spectrally-resolved line profiles.

55. Discovery of thionylimide, HNSO, in space: the first N-, S- and O-bearing interstellar
molecule
Miguel Sanz-Novo, Víctor M. Rivilla, Holger S. P. Müller, Izaskun Jiménez-Serra, Jesús Martín-Pintado,
Laura Colzi, Shaoshan Zeng, Andrés Megías, Álvaro López-Gallifa, Antonio Martínez-Henares, Belén Tercero,
Pablo de Vicente, David San Andrés, Sergio Martín, Miguel A. Requena-Torres F We present the first detectionin space of thionylimide (HNSO) toward the Galactic Center molecular cloud G+0.693-0.027, thanks to the superb
sensitivity of an ultradeep molecular line survey carried out with the Yebes 40 m and IRAM 30 m telescopes. This
molecule is the first species detected in the interstellar medium containing, simultaneously, N, S and O. We haveidentified numerous K a = 0, 1 and 2 transitions belonging to HNSO covering from J up = 2 to J up = 10, including
several completely unblended features. We derive a molecular column density of N = (8 ± 1)×1013 cm−2 , yielding
a fractional abundance relative to H2 of ∼6×10−10 , which is about ∼37 and ∼4.8 times less abundant than SO andSO2, respectively. Although there are still many unknowns in the interstellar chemistry of NSO-bearing molecules,
we propose that HNSO is likely formed through the reaction of the NSO radical and atomic H on the surface of icy
grains, with alternative routes also deserving exploration. Finally, HNSO appears as a promising link between N- , Sand O- interstellar chemistry and its discovery paves the route to the detection of a new family of molecules in space.

56. Outward Migration in Nascent Stellar Groups

Steven W. Stahler F As a stellar group forms within its parent molecular cloud, new members first appear in the deep
interior. These overcrowded stars continually diffuse outward to the cloud boundary, and even beyond. Observations
have so far documented only the interior drift. Those stars that actually leave the cloud form an expanding envelopethat I call the "stellar mantle." Simple fluid models for the cloud and mantle illustrate their basic structure. The
mantle’s expansion speed is subsonic with respect to the cloud’s dynamical temperature. I describe, in qualitative
terms, how the expanding mantle and Galactic tidal radius might together shape the evolution of specific types ofstellar groups. The massive stars in OB associations form in clouds that contract before extruding a substantial
mantle. In contrast, the more slowly evolving clouds forming open clusters and T associations have extended mantles
that encounter a shrinking tidal radius. These clouds are dispersed by internal stellar outflows. If the remaining
group of stars is gravitationally bound, it appears as a long-lived open cluster, truncated by the tidal radius. If thegroup is unbound, it is a late-stage T association that will soon be torn apart by the tidal force. The "distributed"
populations of pre-main sequence stars observed in the outskirts of several star-forming regions are too distant to bestellar mantles. Rather, they could be the remnants of especially low-mass T associations.

57. CO outflows from young stars in the NGC2023 cluster
G. Sandell, B. Mookerjea, R. Güsten F Young early-type HAeBe stars are still embedded in the molecular clouds
in which they formed. They illuminate reflection nebulae, which shape the surrounding molecular cloud and maytrigger star formation. They are therefore ideal places to search for ongoing star formation activity. NGC2023 isilluminated by the Herbig Be star HD37903. It is the most massive member of a small young cluster with about
30 PMS stars, several of which are Class I objects that still heavily accrete. It might therefore be expected thatthey might drive molecular outflows. We examined the whole region for outflows. We analyzed previously published
APEX data to search for and characterize the outflows in the NGC2023 region. This is the first systematic search
for molecular outflows in this region. Since the outflows were mapped in several CO transitions, we can determine
their properties quite well. We have discovered four molecular outflows in the vicinity of NGC2023, three of which
are associated with Class I objects. MIR-63, a bright mid-infrared and submillimeter Class I source, is a binary witha separation of 2.4" and drives two bipolar outflows orthogonal to each other. The large southeast-northwest outflow
excites the Herbig-Haro flow HH247. MIR-73, a Class I object, which is also a far-infrared source, drives a pole-on
outflow. MIR-62 is a Class II object with strong infrared excess and a luminosity of 7 Lsun. It is not detected in the
far-infrared. The Class I sources have bolometric luminosities of about 20 Lsun or lower, that is, they are all low-massstars. One other far-infrared source, MIR-75, may have powered an outflow in the past because it now illuminates an
egg-shaped cavity. The four outflow sources are at a similar evolutionary stage, which suggests that their formation
may have been triggered by the expanding C II region.

2058. Magnetically Aligned Striations in the L914 Filamentary Cloud
Li Sun, Xuepeng Chen, Min Fang, Shaobo Zhang, Yan Gong, Jiancheng Feng, Xuefu Li, Qing-Zeng Yan, Ji
Yang F We present CO (J = 1 − 0) multi-line observations toward the L914 dark cloud in the vicinity of the Cygnus

X region, using the 13.7 m millimeter telescope of the Purple Mountain Observatory (PMO). The CO observations
reveal in the L914 cloud a long filament with an angular length of ∼ 3.◦ 6, corresponding to approximately 50 pc at
the measured distance of ∼ 760 pc. Furthermore, a group of hair-like striations are discovered in the two subregionsof the L914 cloud, which are connected with the dense ridge of the filament. These striations display quasi-periodic
characteristics in both the CO intensity images and position-velocity diagrams. Two of the striations also show
increasing velocity gradients and dispersions toward the dense ridge, which could be fitted by accretion flows undergravity. Based on the P lanck 353 GHz dust polarization data, we find that the striations are well aligned withthe magnetic fields. Moreover, both the striations and magnetic fields are perpendicular to the dense ridge, whichconstructs a bimodal configuration. Using the classic method, we estimate the strength of magnetic field, and further
evaluate the relative importance of gravity, turbulence and magnetic field, and find that the L914 cloud is strongly
magnetized. Our results suggest that magnetic fields play an important role in the formation of filamentary structuresby channelling the material along the striations toward the dense ridge. The comparison between the observations
and simulations suggests that striations could be a product of the magnetohydrodynamic (MHD) process.

HST Survey of the Orion Nebula Cluster in ACS/Visible and WFC3/IR Bands. IV. A
59. Bayesian multi-wavelength study of stellar parameters in the ONC
Giovanni M. Strampelli, Massimo Robberto, Laurent Pueyo, Mario Gennaro, Carlo F. Manara, Elena Sabbi,
Antonio Aparicio F We have performed a comprehensive study of the Orion Nebula Cluster (ONC) combining thephotometric data obtained by the two HST Treasury programs that targeted this region. To consistently analyze
the rich dataset obtained in a wide variety of filters, we adopted a Bayesian approach to fit the Spectral Energy
Distribution of the sources, deriving mass, age, extinction, distance, and accretion for each source in the region. The
three dimensional study of mass distribution for bona-fide cluster members shows that mass segregation in the ONC
extends to sub-solar masses, while the age distribution strongly supports the idea that star formation in the ONC
is best described by a major episode of star formation that happened ∼ 1 Myr ago. For masses & 0.1 Msun, ourderived empirical initial mass function (IMF) is in good agreement with a Chabrier system IMF. Both the accretion
luminosity (Lacc) and mass accretion rates (dMacc) are best described by broken power-law relations. This suggeststhat for the majority of young circumstellar disks in this cluster the excess emission may be dominated by X-raydriven photoevaporation by the central star rather than external photoevaporation. If this is the case, the slopes of thepower-law relations may be largely determined by the initial conditions set at the onset of the star formation process,which may be quite similar between regions that eventually form clusters of different sizes.

60. An Observational View of Structure in Protostellar Systems
John J. Tobin, Patrick D. Sheehan F The envelopes and disks that surround protostars reflect the initial conditionsof star and planet formation and govern the assembly of stellar masses. Characterizing these structures requires
observations that span the near-infrared to centimeter wavelengths. Consequently, the past two decades have seen
progress driven by numerous advances in observational facilities across this spectrum, including the Spitzer Space
Telescope, Herschel Space Observatory, the Atacama Large Millimeter/submillimeter Array, and a host of other groundbased interferometers and single-dish radio telescopes. Nearly all protostars appear to have well-formed circumstellar
disks that are likely to be rotationally-supported; the ability to detect a disk around a protostar is more a questionof spatial resolution than whether or not a disk is present. The disks around protostars have inherently higher
millimeter/submillimeter luminosities as compared to disks around more-evolved pre-main sequence stars, though
there may be systematic variations between star forming regions. The envelopes around protostars are inherently
asymmetric and streamers emphasize that mass flow through the envelopes to the disks may not be homogeneous.
The current mass distribution of protostars may be impacted by selection bias given that it is skewed toward solar-mass
protostars, inconsistent with the stellar initial mass function.

21

Anatomy of the Class I protostar L1489 IRS with NOEMA – I. Disk, streamers, out61. flow(s) and bubbles at 3mm
M. Tanious, R. Le Gal, R. Neri, A. Faure, A. Gupta, C. J. Law, J. Huang, N. Cuello, J. P. Williams, F.
Ménard F Over the past few years, chemical studies have revealed multiple structures in the vicinity of young stellar

objects (YSOs). It has become evident that specific physical conditions are associated with the emission of particularmolecular lines, allowing us to use molecular probes of the YSO physics. Consequently, chemical surveys are now
necessary to fully constrain the origin of the observed structures. Several surveys have been conducted to explore thechemistry of YSOs, focusing on Class 0 and Class II objects. However, our knowledge of intermediate objects, thatare Class I objects, remains limited. To bridge the gap and establish the relationship between observed structures andmolecular line emission at the Class I evolutionary stage, we investigate the spatial distribution of key molecular gas
species in the low-mass Class I protostar L1489 IRS (IRAS 04016+2610), a source part of the ChemYSO survey. We
performed a 3mm line survey at high spatial and high spectral resolution using the NOEMA interferometer and the
IRAM-30m telescope. We present here the ten brightest lines of our survey, in which we identified a new 3 000 au
long streamer in HC3N, C2H, and c-C3H2 emission, likely associated with more localized accretion shocks probed in
SO. In addition, two 10 000 au bubbles are seen with the dense molecular tracers HCO+, CS, and HCN around the
YSO. Additionally, potential indicators of a second outflow appear in CS and HCN emission, but its nature remains
to be confirmed. The late infall identified at large scales may originate from the nearby prestellar core L1489 and islikely responsible for the formation of an external warped disk in this system. The detection of a potential second
outflow could be the direct evidence of a binary system. Finally, we hypothesize that the bubbles may result from themagnetic pressure as observed in numerical simulations.

Discovery of Asymmetric Spike-like Structures of the 10 au Disk around the Very Low62. luminosity Protostar Embedded in the Taurus Dense Core MC 27/L1521F with ALMA
Kazuki Tokuda, Naoto Harada, Mitsuki Omura, Tomoaki Matsumoto, Toshikazu Onishi, Kazuya Saigo, Ayumu
Shoshi, Shingo Nozaki, Kengo Tachihara, Naofumi Fukaya, Yasuo Fukui, Shu-ichiro Inutsuka, Masahiro N.
Machida F Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations have revealed an increasing

number of compact protostellar disks with radii of less than a few tens of astronomical units and that young Class 0/I
objects have an intrinsic size diversity. To deepen our understanding of the origin of such tiny disks, we performed thehighest-resolution configuration observations with ALMA at a beam size of ∼000 03 (4 au) on the very low-luminosity
Class 0 protostar embedded in the Taurus dense core MC 27/L1521F. The 1.3 mm continuum measurement successfully
resolved a tiny, faint (∼1 mJy) disk with a major axis length of ∼10 au, one of the smallest examples in the ALMA
protostellar studies. In addition, we detected spike-like components in the northeastern direction at the disk edge.
Gravitational instability or other fragmentation mechanisms cannot explain the structures, given the central stellar
mass of ∼0.2 M and the disk mass of &10−4 M . Instead, we propose that these small spike structures were formed
by a recent dynamic magnetic flux transport event due to interchange instability that would be favorable to occur if
the parental core has a strong magnetic field. The presence of complex arc-like structures on a larger (∼2000 au) scalein the same direction as the spike structures suggests that the event was not single. Such episodic, dynamical events
may play an important role in maintaining the compact nature of the protostellar disk in the complex gas envelope
during the main accretion phase.

63. The Reservoir of the Per-emb-2 Streamer
Kotomi Taniguchi, Jaime E Pineda, Paola Caselli, Tomomi Shimoikura, Rachel K. Friesen, Dominique M.
Segura-Cox, Anika Schmiedeke F Streamers bring gas from outer regions to protostellar systems and could change

the chemical composition around protostars and protoplanetary disks. We have carried out mapping observations ofcarbon-chain species (HC3 N, HC5 N, CCH, and CCS) in the 3mm and 7mm bands toward the streamer flowing to theClass 0 young stellar object (YSO) Per-emb-2 with the Nobeyama 45m radio telescope. A region with a diameter of∼ 0.04 pc is located north with a distance of ∼ 20, 500 au from the YSO. The streamer connects to this north region
which is the origin of the streamer. The reservoir has high density and low temperature (nH2 ≈ 1.9 × 104 cm−3 ,Tkin = 10 K), which are similar to those of early stage starless cores. By comparisons with the observed abundance
ratios of CCS/HC3 N to the chemical simulations, the reservoir and streamer are found to be chemically young. The
total mass available for the streamer is derived to be 24 − 34 M . If all of the gas in the reservoir will accrete onto
the Per-emb-2 protostellar system, the lifetime of the streamer has been estimated at (1.1 − 3.2)×105 yr, suggestingthat the mass accretion via the streamer would continue until the end of the Class I stage.
22

64. Carbon-Chain Chemistry in the Interstellar Medium

Kotomi Taniguchi, Prasanta Gorai, Jonathan C. Tan F The presence of carbon-chain molecules in the interstellar

medium (ISM) has been known since the early 1970s and > 130 such species have been identified to date, making
up ∼ 43prevalent not only in star-forming regions in our Galaxy but also in other galaxies. These molecules provide
important information on physical conditions, gas dynamics, and evolutionary stages of star-forming regions. Larger
species of polycyclic aromatic hydrocarbons (PAHs) and fullerenes (C60 and C70 ), which may be related to theformation of the carbon-chain molecules, have been detected in circumstellar envelopes around carbon-rich Asymptotic
Giant Branch (AGB) stars and planetary nebulae, while PAHs are also known to be a widespread component of the
ISM in most galaxies. Recently, two line survey projects toward Taurus Molecular Cloud-1 with large single-dishtelescopes have detected many new carbon-chain species, including molecules containing benzene rings. These new
findings raise fresh questions about carbon-bearing species in the Universe. This article reviews various aspects ofcarbon-chain molecules, including observational studies, chemical simulations, quantum calculations, and laboratory
experiments, and discusses open questions and how future facilities may answer them.

65. Ices on pebbles in protoplanetary discs

A. Topchieva, T. Molyarova, V. Akimkin, L. Maksimova, E. Vorobyov F The formation of solid macroscopic

grains (pebbles) in protoplanetary discs is the first step toward planet formation. We aim to study the distribution of
pebbles and the chemical composition of their ice mantles in a young protoplanetary disc. We use the two-dimensionalhydrodynamical code FEOSAD in the thin-disc approximation, which is designed to model the global evolution of aself-gravitating viscous protoplanetary disc taking into account dust coagulation and fragmentation, thermal balance,and phase transitions and transport of the main volatiles (H2 O, CO2 , CH4 and CO), which can reside in the gas, on
small dust (< 1 µm), on grown dust (> 1 µm) and on pebbles. We model the dynamics of the protoplanetary discfrom the cloud collapse to the 500 kyr moment. We determine the spatial distribution of pebbles and composition of
their ice mantles and estimate the mass of volatiles on pebbles, grown dust and small dust. We show that pebbles
form as early as 50 kyr after the disc formation and exist until the end of simulation (500 kyr), providing prerequisites
for planet formation. All pebbles formed in the model are covered by icy mantles. Using a model considering accretionand desorption of volatiles onto dust/pebbles, we find that the ice mantles on pebbles consist mainly of H2 O and CO2 ,and are carbon-depleted compared to gas and ices on small and grown dust, which contain more CO and CH4 . Thissuggests a possible dominance of oxygen in the composition of planets formed from pebbles under these conditions.

Sites of Planet Formation in Binary Systems. I. Evidence for Disk-Orbit Alignment in
66. the Close Binary FO Tau
Benjamin M. Tofflemire, Lisa Prato, Adam L. Kraus, Dominique Segura-Cox, G. H. Schaefer, Rachel Akeson,
Sean Andrews, Eric L. N. Jensen, Christopher M. Johns-Krull, J. J. Zanazzi, M. Simon F Close binary systems

present challenges to planet formation. As binary separations decrease, so too do the occurrence rates of protoplanetarydisks in young systems and planets in mature systems. For systems that do retain disks, their disk masses and sizes
are altered by the presence of the binary companion. Through the study of protoplanetary disks in binary systems
with known orbital parameters, we seek to determine the properties that promote disk retention and, therefore, planet
formation. In this work, we characterize the young binary-disk system, FO Tau. We determine the first full orbital
solution for the system, finding masses of 0.35+0.06−0.05 M and 0.34 ± 0.05 M for the stellar components, a semi-major+0.04
axis of 22(+2
)
AU,
and
an
eccentricity
of
0.21(
−1
−0.03 ). With long-baseline ALMA interferometry, we detect 1.3mm
12continuum and CO (J = 2 − 1) line emission toward each of the binary components; no circumbinary emission
is detected. The protoplanetary disks are compact, consistent with being truncated by the binary orbit. The dust
disks are unresolved in the image plane and the more extended gas disks are only marginally resolved. Fitting thecontinuum and CO visibilities, we determine the inclination of each disk, finding evidence for alignment of the disk
and binary orbital planes. This study is the first of its kind linking the properties of circumstellar protoplanetary disks
to a precisely known binary orbit. In the case of FO Tau, we find a dynamically placid environment (coplanar, loweccentricity), which may foster its potential for planet formation.

23

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

MINDS. The DR Tau disk I: combining JWST-MIRI data with high-resolution CO
68. spectra to characterise the hot gas
MINDS collaboration - Milou Temmink et al. F The MRS mode of the JWST-MIRI instrument has been shown

to be a powerful tool to characterise the molecular gas emission of the inner region of planet-forming disks. Here,
we analyse the spectrum of the compact T-Tauri disk DR Tau, which is complemented by high spectral resolution(R 60000-90000) CO ro-vibrational observations. Various molecular species, including CO, CO2 , HCN, and C2 H2 aredetected in the JWST-MIRI spectrum, for which excitation temperatures of T 325-900 K are retrieved using LTE
slab models. The high-resolution CO observations allow for a full treatment of the line profiles, which show evidence
for two components of the main isotopologue, 12 CO: a broad component tracing the Keplerian disk and a narrowcomponent tracing a slow disk wind. Rotational diagrams yield excitation temperatures of T>725 K for CO, withconsistently lower temperatures found for the narrow components, suggesting that the disk wind is launched from alarger distance. The inferred excitation temperatures for all molecules suggest that CO originates from the highest
atmospheric layers close to the host star, followed by HCN and C2 H2 , which emit, together with 13 CO, from slightly
deeper layers, whereas the CO2 originates from even deeper inside or further out in the disk. Additional analysis of
the 12 CO line wings hint at a misalignment between the inner (i 20 degrees) and outer disk (i 5 degrees). Finally,
we emphasise the need for complementary high-resolution CO observations, as in combination with the JWST-MIRI
observations they can be used to characterise the CO kinematics and the physical and chemical conditions of the otherobserved molecules with respect to CO.

The Epoch of Giant Planet Migration Planet Search Program. II. A Young Hot Jupiter
69. Candidate around the AB Dor Member HS Psc
Quang H. Tran, Brendan P. Bowler, William D. Cochran, Samuel Halverson, Suvrath Mahadevan, Joe P.
Ninan, Paul Robertson, Guðmundur Stefánsson, Ryan C. Terrien F We report the discovery of a hot Jupitercandidate orbiting HS Psc, a K7 (≈0.7 M ) member of the ≈130 Myr AB Doradus moving group. Using radial
velocities over 4 years from the Habitable-zone Planet Finder spectrograph at the Hobby-Eberly Telescope, we finda periodic signal at Pb = 3.986+0.044−0.003 d. A joint Keplerian and Gaussian process stellar activity model fit to the RVs
yields a minimum mass of mp sin i = 1.5+0.6−0.4 MJup . The stellar rotation period is well constrained by the Transiting
Exoplanet Survey Satellite light curve (Prot = 1.086 ± 0.003 d) and is not an integer harmonic nor alias of the orbital
period, supporting the planetary nature of the observed periodicity. HS Psc b joins a small population of young,close-in giant giant planet candidates with robust age and mass constraints and demonstrates that giant planets caneither migrate to their close-in orbital separations by 130 Myr or form in situ. Given its membership in a young
moving group, HS Psc represents an excellent target for follow-up observations to further characterize this young hot
Jupiter, refine its orbital properties, and search for additional planets in the system.

24

70. Formation and Structure of Circumplanetary Disks and Envelopes during the Late
Stages of Giant Planet Formation
Aster G. Taylor, Fred C. Adams F Giant planets are expected to form within circumstellar disks, which shape

their formation history and the local environment. Here, we consider the formation and structure of circumplanetarydisks that arise during the late stages of giant planet formation. During this phase, when most of the final mass isaccumulated, incoming material enters the Hill sphere and falls toward the planet. In the absence of torques, the fallingparcels of gas conserve their specific angular momentum and collect into a circumplanetary disk. Generalizing previous
work, we consider a range of possible geometries for the flow entering the sphere of influence of the planet. Specifically,
we consider five geometric patterns for the inward flow, ranging from concentration toward the rotational poles of thesystem to isotropic flow to concentration along the equatorial plane. For each case, we derive analytic descriptions
for the density field of the infall region, the disk surface density in the absence of viscosity, and steady-state solutions
for viscous disks. These results, in turn, specify the luminosity contributions of the planet, the circumplanetary disk,
and the envelope. These power sources, in conjunction with the surrounding material, collectively determine theobservational appearance of the forming planet. We conclude with an approximate determination of these radiative
signatures.

Fragmentation of Dense Rotation-Dominated Structures Fed by Collapsing Gravomagneto71. Sheetlets and Origin of Misaligned 100 au-Scale Binaries and Multiple Systems
Yisheng Tu, Zhi-Yun Li, Zhaohuan Zhu, Chun-Yen Hsu F The majority of stars are in binary/multiple sys-tems. How such systems form in turbulent, magnetized cores of molecular clouds in the presence of non-ideal MHD
effects remains relatively under-explored. Through ATHENA++-based non-ideal MHD AMR simulations with ambipolar diffusion, we show that the collapsing protostellar envelope is dominated by dense gravomagneto-sheetlets, aturbulence-warped version of the classic pseuodisk produced by anisotropic magnetic resistance to the gravitational
collapse, in agreement with previous simulations of turbulent, magnetized single-star formation. The sheetlets feed
mass, magnetic fields, and angular momentum to a Dense ROtation-Dominated (DROD) structure, which fragments
into binary/multiple systems. This DROD fragmentation scenario is a more dynamic variant of the traditional disk
fragmentation scenario for binary/multiple formation, with dense spiral filaments created by inhomogeneous feedingfrom the highly structured larger-scale sheetlets rather than the need for angular momentum transport, which isdominated by magnetic braking. Collisions between the dense spiraling filaments play a key role in pushing the local
magnetic Toomre parameter Qm below unity, leading to gravitational collapse and stellar companion formation provided that the local material is sufficiently demagnetized, with a plasma-β of order unity or more. This mechanism cannaturally produce in situ misaligned systems on the 100-au scale, often detected with high-resolution ALMA observations. Our simulations also highlight the importance of non-ideal MHD effects, which affect whether fragmentation
occurs and, if so, the masses and orbital parameters of the stellar companions formed.

72. The SPHERE view of the Orion star-forming region
P. -G. Valegard, C. Ginski, A. Derkink, A. Garufi, C. Dominik, A. Ribas, J. P. Williams, M. Benisty, T.
Birnstiel, S. Facchini, G. Columba, M. Hogerheijde, R. G. Van Holstein, J. Huang, M. Kenworthy, C. F.
Manara, P. Pinilla, Ch. Rab, R. Sulaiman, A. Zurlo F We present SPHERE/IRDIS H-band data for a sample of

23 stars in the Orion Star forming region observed within the DESTINYS (Disk Evolution Study Through Imaging
of Nearby Young Stars) program. We use polarization differential imaging in order to detect scattered light fromcircumstellar dust. From the scattered light observations we characterize the disk orientation, radius and contrast.
We analyse the disks in context of the stellar parameters and the environment of the Orion star-forming region. We
use ancillary X-shooter spectroscopic observations to characterize the central stars in the systems. We furthermore
use a combination of new and archival ALMA mm-continuum observations to characterize the dust masses present
in the circumstellar disks. Within our sample we detect extended circumstellar disks in 10 of 23 systems. Of these,
three are exceptionally extended (V351 Ori, V599 Ori and V1012 Ori) and show scattered light asymmetries which
may indicate perturbations by embedded planets or (in the case of V599 Ori) by an outer stellar companion. Ourhigh resolution imaging observations are also sensitive to close (sub)stellar companions and we detect 9 such objects
in our sample of which 5 were previously unknown. We find in particular a possible sub-stellar companion (either
a very low mass star or a high mass brown dwarf) 137 au from the star RY Ori. We find a strong anti-correlation
between disk detection and multiplicity, with only 2 of our 10 disk detections located in stellar multiple systems. We
also find a correlation between scattered light contrast and the millimetre flux suggesting that disks that have a high25

dust content are typically bright in near-infrared scattered light. Conversely we do not find significant correlations
between scattered light contrast of the disks and the stellar mass or age.

Polarization Holes as an Indicator of Magnetic Field-Angular Momentum Alignment I.
73. Initial Tests
Lijun Wang, Zhuo Cao, Xiaodan Fan, Hua-bai Li F The formation of protostellar disks is still a mystery, largely

due to the difficulties in observations that can constrain theories. For example, the 3D alignment between the rotationof the disk and the magnetic fields (B-fields) in the formation environment is critical in some models, but so far
impossible to observe. Here, we study the possibility of probing the alignment between B-field and disk rotation
using “polarization holes” (PHs). PHs are widely observed and are caused by unresolved B-field structures. With
ideal magnetohydrodynamic (MHD) simulations, we demonstrate that different initial alignments between B-field andangular momentum (AM) can result in B-field structures that are distinct enough to produce distinguishable PHs.
Thus PHs can potentially serve as probes for alignments between B-field and AM in disk formation.

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

75. Discovery of widespread non-metastable ammonia masers in the Milky Way
Y. T. Yan, C. Henkel, K. M. Menten, T. L. Wilson, A. Wootten, Y. Gong, F. Wyrowski, W. Yang, A.
Brunthaler, A. Kraus, B. Winkel F We present the results of a search for ammonia maser emission in 119 Galactic

high-mass star-forming regions (HMSFRs) known to host 22 GHz H2 O maser emission. Our survey has led to thediscovery of non-metastable NH3 inversion line masers toward 14 of these sources. This doubles the number of known
non-metastable ammonia masers in our Galaxy, including nine new very high excitation (J, K) = (9,6) maser sources.
These maser lines, including NH3 (5,4), (6,4), (6,5), (7,6), (8,6), (9,6), (9,8), (10,8), and (11,9), arise from energy levelsof 342 K, 513 K, 465 K, 606 K, 834 K, 1090 K, 942 K, 1226 K, and 1449 K above the ground state. Additionally, we
tentatively report a new metastable NH3 (3,3) maser in G048.49 and an NH3 (7,7) maser in G029.95. Our observations
reveal that all of the newly detected NH3 maser lines exhibit either blueshifted or redshifted velocities with respect tothe source systemic velocities. Among the non-metastable ammonia maser lines, larger velocity distributions, offset
from the source systemic velocities, are found in the ortho-NH3 (K = 3n) than in the para-NH3 (K 6= 3n) transitions.
13

76. The First Spatially-resolved Detection of CN in a Protoplanetary Disk and Evidence
for Complex Carbon Isotope Fractionation
Tomohiro C. Yoshida, Hideko Nomura, Kenji Furuya, Richard Teague, Charles J. Law, Takashi Tsukagoshi,
Seokho Lee, Christian Rab, Karin I. Öberg, Ryan A. Loomis F Recent measurements of carbon isotope ratios inboth protoplanetary disks and exoplanet atmospheres have suggested a possible transfer of significant carbon isotope
fractionation from disks to planets. For a clearer understanding of the isotopic link between disks and planets, it isimportant to measure the carbon isotope ratios in various species. In this paper, we present a detection of the 13 CN
N = 2−1 hyperfine lines in the TW Hya disk with the Atacama Large Millimeter/submillimeter Array. This is the first
spatially-resolved detection of 13 CN in disks, which enables us to measure the spatially resolved 12 CN/13 CN ratio for
the first time. We conducted non-local thermal equilibrium modeling of the 13 CN lines in conjunction with previously
26observed 12 CN lines to derive the kinetic temperature, H2 volume density, and column densities of 12 CN and 13 CN.
The H2 volume density is found to range between (4 − 10) × 107 cm−3 , suggesting that CN molecules mainly residein the disk upper layer. The 12 CN/13 CN ratio is measured to be 70+9
−6 at 30 < r < 80 au from the central star, which
is similar to the 12 C/13 C ratio in the interstellar medium. However, this value differs from the previously reported
values found for other carbon-bearing molecules (CO and HCN) in the TW Hya disk. This could be self-consistently
explained by different emission layer heights for different molecules combined with preferential sequestration of 12 C
into the solid phase towards the disk midplane. This study reveals the complexity of the carbon isotope fractionation
operating in disks.

77.

Relative velocities between 13 CO structures within 12 CO Molecular clouds
Lixia Yuan, Ji Yang, Xuepeng Chen, Yang Su, Shaobo Zhang, Xin Zhou, Zhiwei Chen, Qing-Zeng Yan, Min
Fang, Fujun Du, Yan Sun, Hongchi Wang, Ye Xu F Velocity fields of molecular clouds (MCs) can provide crucial

information on the merger and split between clouds, as well as their internal kinematics and maintenance, energy
injection and redistribution, even star formation within clouds. Using the CO spectral lines data from the Milky
Way Imaging Scroll Painting (MWISP) survey, we measure the relative velocities along the line of sight (∆VLOS )between 13 CO structures within 12 CO MCs. Emphasizing MCs with double and triple 13 CO structures, we find thatapproximately 70% of ∆VLOS values are less than ∼ 1 km s−1 , and roughly 10% of values exceed 2 km s−1 , with amaximum of ∼ 5 km s−1 . Additionally, we compare ∆VLOS with the internal velocity dispersion of 13 CO structures(σ13 CO,in ) and find that about 40% of samples in either double or triple regime display distinct velocity discontinuities,
i.e. the relative velocities between 13 CO structures are larger than the internal linewidths of 13 CO structures. Amongthese 40% samples in the triple regime, 33% exhibit signatures of combinations through the two-body motion, whereas
the remaining 7% show features of configurations through the multiple-body motion. The ∆VLOS distributions for
MCs with double and triple 13 CO structures are similar, as well as their ∆VLOS /σ13 CO,in distributions. This suggeststhat relative motions of 13 CO structures within MCs are random and independent of cloud complexities and scales.

The environment around young eruptive stars. SPHERE/IRDIS polarimetric imaging
78. of 7 protostars
A. Zurlo, P. Weber, S. Pérez, L. Cieza, C. Ginski, R. G. van Holstein, D. Principe, A. Garufi, A. Hales, J.
Kastner, E. Rigliaco, G. Ruane, M. Benisty, C. Manara F Eruptive stars are a class of young stellar objects thatshow an abrupt increase in their luminosity. These burst-like episodes are thought to dominate the stellar accretion
process during the class 0/class I stage. We present an overview of a survey of seven episodically accreting protostars
aimed at studying their potentially complex circumstellar surroundings. The observations were performed with the
instrument SPHERE, mounted at the VLT. We observed the eruptive stars in H-band with the near-infrared imager
IRDIS and used the polarimeter to extract the polarized light scattered from the stars’ surroundings. We produced
polarized light images for three FUor objects, Z CMa, V960 Mon, and FU Ori, and four EXor objects, XZ Tau, UZ
Tau, NY Ori, and EX Lup. We calculated the intrinsic polarization fraction for all the observed stars. In all systems weregistered scattered light from around the primary star. FU Ori and V960 Mon are surrounded by complex structures
including spiral-like features. In Z CMa, we detected a point source 0.7 arcsec to the northeast of the primary. Basedon the astrometric measurements from archival Keck/NIRC2 data, we find this source to be a third member of thesystem. Further, Z CMa displays an outflow extending thousands of au. Unlike the other EXor objects in our sample,
XZ Tau shows bright, extended scattered light structures, also associated with an outflow on a scale of hundreds of au.
The other EXors show relatively faint disk-like structures in the immediate vicinity of the coronagraph. Asymmetricarms were only found around FUor objects, while faint disks seem to predominantly occur around EXors. Importantly,
for Z CMa the detection of the faint extended structure questions previous interpretations of the system’s dynamic
state. The streamer which was associated with a fly-by object turned out to be part of a huge outflow extending 6000
au.

79. Gas inflows from cloud to core scales in G332.83-0.55: Hierarchical hub-filament structures and tide-regulated gravitational collapse
J. W. Zhou, S. Dib, M. Juvela, P. Sanhueza, F. Wyrowski, T. Liu, K. M. Menten F The massive star-forming

region G332.83-0.55 contains at least two levels of hub-filament structures. The hub-filament structures may form
through the "gravitational focusing" process. High-resolution LAsMA and ALMA observations can directly trace the27gas inflows from cloud to core scales. We investigated the effects of shear and tides from the protocluster on the surrounding local dense gas structures. Our results seem to deny the importance of shear and tides from the protocluster.
However, for a gas structure, it bears the tidal interactions from all external material, not only the protocluster. To
fully consider the tidal interactions, we derived the tide field according to the surface density distribution. Then, weused the average strength of the external tidal field of a structure to measure the total tidal interactions that areexerted on it. For comparison, we also adopted an original pixel-by-pixel computation to estimate the average tidal
strength for each structure. Both methods give comparable results. After considering the total tidal interactions, theslope of the σ − N ∗ R relation changes from 0.20 to 0.52, close to 0.5 of the pure free-fall gravitational collapse, andthe correlation also becomes stronger. Thus, the deformation due to the external tides can effectively slow down thepure free-fall gravitational collapse of gas structures. The external tide tries to tear up the structure, but the externalpressure on the structure prevents this process. The counterbalance between the external tide and external pressure
hinders the free-fall gravitational collapse of the structure, which can also cause the pure free-fall gravitational collapse
to be slowed down. These mechanisms can be called "tide-regulated gravitational collapse."

80. The Multilayer Nature of Molecular Gas toward the Cygnus Region
Shiyu Zhang, Yang Su, Xuepeng Chen, Min Fang, Qingzeng Yan, Shaobo Zhang, Yan Sun, Xiaolong Wang,
Haoran Feng, Yuehui Ma, Miaomiao Zhang, Zi Zhuang, Xin Zhou, Zhiwei Chen, Ji Yang F We study thephysical properties and 3D distribution of molecular clouds (MCs) toward the Cygnus region using the MWISP CO
survey and Gaia DR3 data. Based on Gaussian decomposition and clustering for 13 CO lines, over 70% of the fluxes arerecovered. With the identification result of 13 CO structures, two models are designed to measure the distances of themolecular gas in velocity crowding regions. The distances of more than 200 large 13 CO structures are obtained toward
the 150 square degree region. Additionally, tens of the identified MC structures coincide well with masers and/or
intense mid-IR emission. We find multiple gas layers toward the region: (1) the extensive gas structures composing
the Cygnus Rift from 700 pc to 1 kpc across the whole region; (2) the ∼ 1.3 kpc gas layer mainly in the Cygnus X
South region; and (3) the 1.5 kpc dense filament at the Cygnus X North region and many cometary clouds shaped by
Cygnus OB2. We also note that the spatial distribution of YSO candidates is generally consistent with the molecular
gas structures. The total molecular mass of the Cygnus region is estimated to be ∼ 2.7 × 106 M assuming an X-factor
ratio XCO = 2 × 1020 cm−2 (K · km · s−1 )−1 . The foreground Cygnus Rift contributes ∼25% of the molecular mass inthe whole region. Our work presents a new 3D view of the MCs’ distribution toward the Cygnus X region, as well as
the exact molecular gas mass distribution in the foreground Cygnus Rift.

Surveys of clumps, cores, and condensations in Cygnus X: Temperature and nonthermal
81. velocity dispersion revealed by VLA NH3 observations
Xu Zhang, Keping Qiu, Qizhou Zhang, Yue Cao, Yu Cheng, Junhao Liu, Yuwei Wang, Xing Lu, Xing Pan

F The physical properties, evolution, and fragmentation of massive dense cores (MDCs, ∼ 0.1 pc) are fundamental
pieces in our understanding of high-mass star formation. We aim to characterize the temperature, velocity dispersion,and fragmentation of the MDCs in the Cygnus X giant molecular cloud and to investigate the stability and dynamics
of these cores. We present the Karl G. Jansky Very Large Array (VLA) observations of the NH3 (J,K) = (1,1)
and (2,2) inversion lines towards 35 MDCs in Cygnus X, from which we calculated the temperature and velocity
dispersion. We extracted 202 fragments (∼ 0.02 pc) from the NH3 (1,1) moment-0 maps with the GAUSSCLUMPS
algorithm. We analyzed the stability of the MDCs and their NH3 fragments through evaluating the corresponding
kinetic, gravitational potential, and magnetic energies and the virial parameters. The MDCs in Cygnus X have atypical mean kinetic temperature TK of ∼ 20 K. Our virial analysis shows that many MDCs are in subvirializedstates, indicating that the kinetic energy is insufficient to support these MDCs against their gravity. The calculated
nonthermal velocity dispersions of most MDCs are at transonic to mildly supersonic levels, and the bulk motions makeonly a minor contribution to the velocity dispersion. Regarding the NH3 fragments, with TK ∼ 19 K, their nonthermalvelocity dispersions are mostly trans-sonic to subsonic. Unless there is a strong magnetic field, most NH3 fragments
are probably not in virialized states. We also find that most of the NH3 fragments are dynamically quiescent, while
only a few are active due to star formation activity.

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