The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 376 — 30 April 2024
Editor: João Alveswww.starformation.news

Cover image caption
NIR color composite image of M78 in Orion by ESA Euclid. Blue, green, and red channels represent 0.7, 1.1, and 1.7 microns.
Hot stars appear white-blue, excited hydrogen gas in blue, and regions with dust and molecular gas in a clear red hue.
Credits: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi

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.

Chandra X-ray Analysis of Herbig Ae/Be Stars
Hema Anilkumar, Blesson Mathew, V. Jithesh, Sreeja S. Kartha, P. Manoj, Mayank Narang, Mahathi Chavali⋆ Herbig Ae/Be (HAeBe) stars are intermediate-mass pre-main sequence stars, characterized by infrared excess andemission lines. They are observed to emit X-rays, whose origin is a matter of discussion and not settled yet. X-ray
emission is not expected in HAeBe stars, as they lack the sub-surface convective zone. In this study, we retrieved
observations from the Chandra archive for 62 HAeBe stars, among which 44 sources (detection fraction ∼71%) weredetected in X-rays, with 7 being new detections. We use this sample as a test bed to conduct a comparative analysis of
the X-ray properties of HAeBe stars and their low-mass counterparts, T Tauri Stars (TTSs). Further, we compare the
X-ray properties of HAeBe stars and TTSs with optical and IR properties to constrain the X-ray emission mechanism
in HAeBe stars. We found no correlation between X-ray emission and disk properties of HAeBe stars, confirming that
X-rays are not related to accretion shocks. About 56% of HAeBe stars without any known sub-arcsec companions
have lower plasma temperatures (kT ≤ 2 keV). We observe flaring/variability in HAeBe stars with confirmed low-masscompanions. These stars show plasma temperatures > 2 keV, similar to TTSs. Guided by this information we discuss
the role of a T Tauri companion for X-ray emission seen in our sample of HAeBe stars. From the results obtained inthis paper, we suggest that X-ray emission from HAeBe stars may not be related to accretion shocks or hidden TTS,
but rather can be due to magnetically driven coronal emission.

2.

Search and study of young infrared stellar clusters
Naira Azatyan ⋆ The main aim of this paper is to study both the Interstellar Medium (ISM) and the young stellar

population in the three star-forming regions, namely IRAS 05137+3919, 05168+3634, and 19110+1045. The study ofthe ISM includes determination of the hydrogen column density (N(H2 )) and dust temperature (Td ) in the regions
using Modified blackbody fitting. The main parameters of identified and classified young stellar objects (YSOs)
belonging to the regions were determined comparing with the radiation transfer models. We also constructed a colourmagnitude diagram to compare the parameters of the YSOs with the results of the radiative transfer models. The
three stellar populations appear to have formed under different scenarios. In the cases of IRAS 05137+3919 and
IRAS 05168+3634, the age spread is considerably wider, suggesting that the stellar population likely emerged fromindependent condensations. In contrast, the third region comprises a pair of ultra-compact HII regions (UCHIIs),
G45.12+0.13 and G45.07+0.13, with a notably smaller age spread. This hints at the possibility that these clusters
originated from a single triggering event.

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3. Extinction values towards embedded planets in protoplanetary disks estimated fromhydrodynamic simulations
Felipe Alarcón, Edwin Bergin, Gabriele Cugno ⋆ The upcoming new coronographs with deeper contrast limits,

together with planned and current high-contrast imaging campaigns will push the detectability limit of protoplanets.
These planet-hunting campaigns present a new opportunity to characterize protoplanets and their surrounding environments. However, there are clear uncertainties as to what are the extinction levels at different regions of protoplanetarydisks, which will impede our ability to characterize young planets. A correct understanding of the expected extinction
together with multiple photometric observations will lead to constraints on the extinction levels, dust growth, disk
evolution and protoplanetary accretion rates. In this work, we used hydrodynamic simulations and protoplanetary
disk observational constraints obtained from both dust and gas emission to explore the expected extinction maps forcontinuum filters associated with strong hydrogen lines as tracers of accretion and key broadband photometric filters.
We provide a scaling relationship for the extinction as a function of planetary separation and disk mass for three different gas giant masses. We also report values for a subset of disks of interest targetted by multiple imaging campaigns.
The described values will be useful for the optimal design of future planet-hunting surveys and for giving context
to non-detections in protoplanetary disks and the observed fluxes of point sources along with the birth conditions ofprotoplanets.

4.

Thermal Structure and Millimeter Emission of Protoplanetary Disk with embedded
protoplanets from radiative transfer modeling
Felipe Alarcón, Edwin Bergin ⋆ The discovery of protoplanets and circumplanetary disks provides a unique oppor-

tunity to characterize planet formation through observations. Massive protoplanets shape the physical and chemical
structure of their host circumstellar disk by accretion, localized emission, and disk depletion. In this work, we study thethermal changes induced within the disk by protoplanet accretion and synthetic predictions through hydrodynamical
simulations with post-processed radiative transfer with an emphasis on radio millimeter emission. We explored distinct
growth conditions and varied both planetary accretion rates and the local dust-to-gas mass ratios for a protoplanet
at 1200 K. The radiative transfer models show that beyond the effect of disk gaps, in most cases, the CPD and theplanet’s emission locally increase the disk temperature. Moreover, depending on the local dust-to-gas depletion andaccretion rate, the CPD presence may have detectable signatures in millimeter emission. It also has the power to generate azimuthal asymmetries important for continuum subtraction. Thus, if other means of detection of protoplanets
are proven, the lack of corresponding evidence at other wavelengths can set limits on their growth timescales througha combined analysis of the local dust-to-gas ratio and the accretion rate.

5.

Formation of low mass protostars and their circumstellar disks
Adnan Ali Ahmad, Matthias González, Patrick Hennebelle, Benoît Commerçon ⋆ The birth process of circumstellar disks remains poorly constrained due to observational and numerical challenges. Recent numerical works haveshown that the small-scale physics, often wrapped into a sub-grid model, play a crucial role in disk formation andevolution. This calls for a combined approach in which both the protostar and circumstellar disk are studied in concert.
We aim to elucidate the small scale physics and constrain sub-grid parameters commonly chosen in the literature byresolving the star-disk interaction. We carry out a set of very high resolution 3D radiative-hydrodynamics simulations
that self-consistently describe the collapse of a turbulent dense molecular cloud core to stellar densities. We study thebirth of the protostar, the circumstellar disk, and its early evolution (< 6 yr after protostellar formation). Following
the second gravitational collapse, the nascent protostar quickly reaches breakup velocity and sheds its surface material,
thus forming a hot (∼ 103 K), dense, and highly flared circumstellar disk. The protostar is embedded within the disk,
such that material can flow without crossing any shock fronts. The circumstellar disk mass quickly exceeds that ofthe protostar, and its kinematics are dominated by self-gravity. Accretion onto the disk is highly anisotropic, andaccretion onto the protostar mainly occurs through material that slides on the disk surface. The polar mass flux is
negligible in comparison. The radiative behavior also displays a strong anisotropy, as the polar accretion shock isshown to be supercritical whereas its equatorial counterpart is subcritical. We also find a remarkable convergence ofour results with respect to initial conditions. These results reveal the structure and kinematics in the smallest spatial
scales relevant to protostellar and circumstellar disk evolution.

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6.

JWST observations of the Horsehead photon-dominated region I. First results frommulti-band near- and mid-infrared imaging
A. Abergel, K. Misselt, K. D. Gordon, A. Noriega-Crespo, P. Guillard, D. Van De Putte, A. N. Witt, N.
Ysard, M. Baes, H. Beuther, P. Bouchet, B. R. Brandl, M. Elyajouri, O. Kannavou, S. Kendrew, P. Klassen,
B. Trahin ⋆ The JWST has captured the sharpest IR images ever taken of the Horsehead nebula, a prototypicalmoderately irradiated PDR that is fully representative of most of the UV-illuminated molecular gas in the Milky
Way and star-forming galaxies. We investigate the impact of FUV radiation of a molecular cloud and constrain the
structure of the edge of the PDR and its illumination conditions. We used NIRCam and MIRI to obtain 17 broadband
and 6 narrowband maps from 0.7 to 28 µm. We mapped the dust emission, scattered light, and several gas phase lines.
We also used HST-WFC3 maps at 1.1 and 1. 6 µm, along with HST-STIS spectroscopic observations of the Hα line.
We probed the structure of the edge of the Horsehead and resolved its spatial complexity. We detected a network offaint striated features extending perpendicularly to the PDR front into the H II region in filters sensitive to nano-grain
emission and light scattered by larger grains. This may indeed figure as the first detection of the entrainment of dust
particles in the evaporative flow. The map of the 1-0 S(1) line of H2 presents sharp sub-structures on scales as small as
1.5 arcsec. The ionization and dissociation fronts appear at distances 1-2 arcsec behind the edge of the PDR and seemto spatially coincide, indicating a thickness of the neutral atomic layer below 100 au. All broadband maps present
strong color variations which can be explained by dust attenuation. Deviations of the emissions in the Hα, Paα, andBrα lines also indicate dust attenuation. With a very simple model, we derive the main features of the extinction
curve. A small excess of extinction at 3 µm may be attributed to icy H2 O mantles onto grains. In all lines of sightcrossing the inner regions of the Horsehead, it appears that dust attenuation is non-negligible over the entire spectral
range.

7.

The Asymmetric Bipolar Fe II Jet and H2 Outflow of TMC1A Resolved with JWST’s
NIRSpec IFU
Korash Assani, Daniel Harsono, Jon Ramsey, Zhi-Yun Li, Per Bjerkeli, Klaus Pontoppidan, Łukasz Tychoniec,
Hannah Calcutt, Lars Kristensen, Jes Jorgensen, Adele Plunkett, Martijn van Gelder, Logan Francis ⋆(abridged) Protostellar outflows exhibit large variations in their structure depending on the observed gas emission. This
study analyzes the atomic jet and molecular outflow in the Class I protostar, TMC1A to characterize morphology andidentify previously undetected spatial features with JWST’s NIRSpec IFU. In addition to identifying a large numberof Fe II and H2 lines, we have detected the bipolar Fe jet by revealing, for the first time, the presence of a red-shifted
atomic jet. Similarly, the red-shifted component of the H2 slower wide-angle outflow is observed. Both Fe II and H2
red-shifted emission exhibit significantly lower flux densities compared to their blue-shifted counterparts. Additionally,
we report the detection of a collimated high-velocity (100 km s-1), blue-shifted H2 outflow, suggesting the presence ofa molecular jet in addition to the well-known wider angle low-velocity structure. The Fe II and H2 jets show multiple
intensity peaks along the jet axis, which may be associated with ongoing or recent outburst events. In addition to thevariation in their intensities, the H2 wide-angle outflow exhibits a "ring"-like structure. The blue-shifted H2 outflow
also shows a left-right brightness asymmetry likely due to interactions with the surrounding ambient medium andmolecular outflows. Using the Fe II line ratios, the extinction along the atomic jet is estimated to be between Av =10-30 on the blue-shifted side, with a trend of decreasing extinction with distance from the protostar. A similar Av is
found for the red-shifted side, supporting the argument for an intrinsic red-blue outflow lobe asymmetry rather thanenvironmental effects such as extinction. This intrinsic difference revealed by the unprecedented sensitivity of JWST,
suggests that younger outflows already exhibit the red-blue side asymmetry more commonly observed towards jets
associated with Class II disks.

8.

EL meteorites do date the giant planet instability
Chrysa Avdellidou, Marco Delbo, David Nesvorny, Kevin J. Walsh, Alessandro Morbidelli ⋆ In our recent work,
we combined dynamical simulations, meteoritic data and thermal models as well as asteroid observations to argue thatthe current parent body of the EL meteorites was implanted into the asteroid belt not earlier than 60 Myr after the
beginning of the Solar System and that the most likely capture mechanism was the giant planet orbital instability. In
the study "The link between Athor and EL meteorites does not constrain the timing of the giant planet instability"that appeared in arXiv, Izidoro and collaborators argue that the implantation of Athor into the asteroid belt does notnecessarily require that the giant planet orbital instability occurred at the implantation time. Here we provide further
arguments that, in the end, the giant planet instability is still the most likely dynamical process to implant asteroid

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Athor into the asteroid main belt between 60 and 100 Myr after the beginning of the Solar System.

9.

First detection in space of the high-energy isomer of cyanomethanimine: H2CNCNDavid San Andrés, Víctor M. Rivilla, Laura Colzi, Izaskun Jiménez-Serra, Jesús Martín-Pintado, Andrés
Megías, Álvaro López-Gallifa, Antonio Martínez-Henares, Sarah Massalkhi, Shaoshan Zeng, Miguel Sanz-Novo,
Belén Tercero, Pablo de Vicente, Sergio Martín, Miguel A. Requena-Torres, Germán Molpeceres, Juan Garcíade la Concepción ⋆ We report the first detection in the interstellar medium of N -cyanomethanimine (H2 CNCN),

the stable dimer of HCN of highest energy, and the most complex organic molecule identified in space containing
the prebiotically relevant NCN backbone. We have identified a plethora of a-type rotational transitions with 3≤ Jup ≤ 11 and Ka ≤ 2 that belong to this species towards the Galactic Center G+0.693-0.027 molecular cloud,the only interstellar source showing the three cyanomethanimine isomers (including the Z- and E- isomers of Ccyanomethanimine, HNCHCN). We have derived a total column density for H2 CNCN of (2.9 ± 0.1)×1012 cm−2 , whichtranslates into a total molecular abundance with respect to H2 of (2.1 ± 0.3)×10−11 . We have also revisited theprevious detection of E- and Z-HNCHCN, and found a total C/N -cyanomethanimine abundance ratio of 31.8 ± 1.8
and a Z/E-HNCHCN ratio of 4.5 ± 0.2. While the latter can be explained on the basis of thermodynamic equilibrium,chemical kinetics are more likely responsible for the observed C/N -cyanomethanimine abundance ratio, where thegas-phase reaction between methanimine (CH2 NH) and the cyanogen radical (CN) arises as the primary formationroute.

10. The role of magnetic fields in disc galaxies: spiral arm instability
Raghav Arora, Christoph Federrath, Robi Banerjee, Bastian Körtgen ⋆ Context. Regularly-spaced, star-forming
regions along the spiral arms of nearby galaxies provide insight into the early stages and initial conditions of starformation. The regular separation of these star-forming regions suggests spiral arm instability as their origin. Aims.
We explore the effects of magnetic fields on the spiral arm instability. Methods. We use three-dimensional global
magnetohydrodynamical simulations of isolated spiral galaxies, comparing three different initial plasma β values (ratiosof thermal to magnetic pressure) of β = ∞, 50, and 10. We perform Fourier analysis to calculate the separation of theover-dense regions formed from the spiral instability. We then compare the separations with observations. Results.
We find that the spiral arms in the hydro case (β = ∞) are unstable, with the fragments initially connected by gas
streams, reminiscent of Kelvin-Helmholtz instability. In the β = 50 case, the spiral arms fragment, but the fragments
separate earlier and tend to be elongated in the direction perpendicular to the spiral arms. However, in the β = 10 run
the arms are stabilised against fragmentation by magnetic pressure. The spiral arms in the unstable cases fragment
into regularly-spaced, over-dense regions. We determine their separation to be ∼ 0.5 kpc in the hydro and ∼ 0.65
kpc in the β = 50 case, both in agreement with the observations of nearby galaxies. We find a smaller median+0.49
characteristic wavelength of the over-densities to be 0.73+0.31−0.36 kpc in the hydro case, compared to 0.98−0.46 kpc in the
β = 50 case. Moreover, we find a higher growth rate of the over-densities in the β = 50 run compared to the hydrorun. We observe magnetic hills and valleys along the fragmented arms in the β = 50 run, which is characteristic of
the Parker instability.

11. How common can the origin of clusters Cha I, Cha II, epsilon Cha and eta Cha be?
Vadim V. Bobylev, Anisa T. Bajkova ⋆ The trajectories of the clusters η Cha, ϵ Cha and Cha I, Cha II, constructedbackward in time, have been studied. We concluded that the hypothesis about the joint formation of all four of theseclusters from one molecular cloud cannot be completely excluded. However, 10-15 Myr ago, all these four clusters
were located at approximately the same height above the plane of the Galaxy. Thus, the gas-dust clouds from which
all these four clusters were formed were located on one broad front. It is possible that the appearance of the Cha
I, Cha II, ϵ Cha and η Cha clusters may be associated with the impact on such a front of shock waves formed after
supernova explosions in the Scorpius-Centauri association. New estimates of the kinematic ages of the clusters Cha I
and Cha II are obtained as 0.12 ± 0.19 and 0.05 ± 0.15, respectively. It is shown that the minimum size of the Cha
I-north and Cha I-south clusters corresponded to the time of 0.55 ± 0.24 Myr and 0.04 ± 0.18 Myr ago, respectively,
and approximately 1.5 Myr ago the distance between the trajectories of these two groupings was minimal.

512. Impacts of Energetic Particles from T Tauri Flares on Inner Protoplanetary Discs
Valentin Brunn, Christian Rab, Alexandre Marcowith, Christophe Sauty, Marco Padovani, Chadi Meskini ⋆T Tauri stars are known to be magnetically active stars subject to strong flares observed in X-rays. These flares arelikely due to intense magnetic reconnection events during which a part of the stored magnetic energy is converted into
kinetic energy of supra-thermal particles. Since T Tauri stars are surrounded by an accretion disc, these particles may
influence the disc dynamics and chemistry. This work continues on a previous stationary model, which showed thatenergetic particles accelerated during flares can produce a strong ionisation rate at high column densities in the inneraccretion disc. The present model includes non-stationary sequences of flaring events sampled by a Chandra X-ray
survey of nearby young stellar objects. We calculate the averaged ionisation rate expected in a radius range from 0.08
to 0.6 au from the central star. We confirm that energetic particles produced by the flares dominate the ionisationof the disc up to column densities of 1025 cm−2 . We further study the main consequences of this additional sourceof ionisation on the viscosity, the accretion rate, the volumetric heating rate and the chemical complexity of innerprotoplanetary discs.

13. Inefficient star formation in high Mach number environments. II. Numerical simulations
and comparison with analytical models
Noé Brucy, Patrick Hennebelle, Tine Colman, Ralf S. Klessen, Corentin Le Yhuelic ⋆ Predicting the starformation rate (SFR) in galaxies is crucial to understand their evolution and morphology. To do so requires a fineunderstanding of how dense structures of gas are created and collapse. In that, turbulence and gravity play a major
role. Within the gravo-turbulent framework, we assume that turbulence shapes the ISM, creating density fluctuations
that, if gravitationally unstable, will collapse and form stars. The goal of this work is to quantify how different
regimes of turbulence, characterized by the strength and compressibility of the driving, shape the density field. We
are interested in the outcome in terms of SFR and how it compares with existing analytical models for the SFR. We
run a series of hydrodynamical simulations of turbulent gas. The simulations are first conducted without gravity, sothat the density and velocity are shaped by the turbulence driving. Gravity is then switched on, and the SFR ismeasured and compared with analytical models. The physics included in these simulations is very close to the one
assumed in the classical gravo-turbulent SFR analytical models, which makes the comparison straightforward. We
found that the existing analytical models convincingly agree with simulations at low Mach number, but we measure
a much lower SFR in the simulation with a high Mach number. We develop, in a companion paper, an updated
physically-motivated SFR model that reproduces well the inefficient high Mach regime of the simulations. Our work
demonstrates that accurate estimations of the turbulent-driven replenishment time of dense structures and the dense
gas spatial distribution are necessary to correctly predict the SFR in the high Mach regime. The inefficient high-Machregime is a possible explanation for the low SFR found in dense and turbulent environments such as the centers of our
Milky Way and other galaxies.

14. The magnetic field in the Flame nebula
Ivana Bešlić, Simon Coudé, Dariusz C. Lis, Maryvonne Gerin, Paul F. Goldsmith, Jerome Pety, Antoine Roueff,
Karine Demyk, Charles D. Dowell, Lucas Einig, Javier R. Goicoechea, Francois Levrier, Jan Orkisz, Nicolas
Peretto, Miriam G. Santa-Maria, Nathalie Ysard, Antoine Zakardjian ⋆ Star formation is essential in galaxy

evolution and the cycling of matter. The support of interstellar clouds against gravitational collapse by magnetic (B-)
fields has been proposed to explain the low observed star formation efficiency in galaxies and the Milky Way. Despite thePlanck satellite providing a 5-15’ all-sky map of the B-field geometry in the diffuse interstellar medium, higher spatial
resolution observations are required to understand the transition from diffuse gas to gravitationally unstable filaments.
NGC 2024, the Flame Nebula, in the nearby Orion B molecular cloud, contains a young, expanding HII region and adense filament that harbors embedded protostellar objects. Therefore, NGC 2024 is an excellent opportunity to study
the role of B-fields in the formation, evolution, and collapse of filaments, as well as the dynamics and effects of young
HII regions on the surrounding molecular gas. We combine new 154 and 216 micron dust polarization measurements
carried out using the HAWC+ instrument aboard SOFIA with molecular line observations of 12CN(1-0) and HCO+(10) from the IRAM 30-meter telescope to determine the B-field geometry and to estimate the plane of the sky magnetic
field strength across the NGC 2024. The HAWC+ observations show an ordered B-field geometry in NGC 2024 that
follows the morphology of the expanding HII region and the direction of the main filament. The derived plane of thesky B-field strength is moderate, ranging from 30 to 80 micro G. The strongest B-field is found at the northern-westedge of the HII region, characterized by the highest gas densities and molecular line widths. In contrast, the weakest
6field is found toward the filament in NGC 2024. The B-field has a non-negligible influence on the gas stability atthe edges of the expanding HII shell (gas impacted by the stellar feedback) and the filament (site of the current starformation).

15. Self-similarity of the magnetic field at different scales: the case of G31.41+0.31
M. T. Beltrán, M. Padovani, D. Galli, N. Áñez-López, J. M. Girart, R. Cesaroni, D. Dall’Olio, G. Anglada,
C. Y. Law, A. Lorenzani, L. Moscadelli, Á. Sánchez-Monge, M. Osorio, Q. Zhang ⋆ Context. Dust polarization

observations of the massive protocluster G31.41+0.31 carried out at 1” ( 3750 au) resolution with the SMA at 870
microm have revealed one of the clearest examples to date of an hourglass-shaped magnetic field morphology in thehigh-massregime. Additionally, 0.24” ( 900 au) resolution observations with ALMA at 1.3 mm have confirmed theseresults. The next step is to investigate whether the magnetic field maintains its hourglass-shaped morphology down
to circumstellar scales. Aims. To study the magnetic field morphology toward the four (proto)stars A, B, C, and D
contained in G31.41+0.31 and examine whether the self-similarity observed at core scales (1” and 0.24” resolution)
still holds at circumstellar scales, we carried out ALMA observations of the polarized dust continuum emission at
1.3 mm and 3.1 mm at an angular resolution of 0.068” ( 250 au), sufficient to resolve the envelope emission of theembedded protostars. Methods. We used ALMA to perform full polarization observations at 233 GHz (Band 6) and97.5 GHz (Band 3) with a synthesized beam of 0.072” x 0.064”. We carried out polarization observations at two
different wavelengths to confirm that the polarization traces magnetically aligned dust grains and is not due to dust
self-scattering. Results. The polarized emission and the direction of the magnetic field obtained at the two wavelengths
are basically the same, except for an area between the embedded sources C and B. In such an area, the emission at
1.3 mm could be optically thick and affected by dichroic extinction. ...

16. SOFIA/HAWC+ Far-InfraRed Polarimetric Large Area CMZ Exploration (FIREPLACE)
Survey I: General Results from the Pilot Program
Natalie O. Butterfield, David T. Chuss, Jordan A. Guerra, Mark R. Morris, Dylan Pare, Edward J. Wollack,
C. Darren Dowell, Matthew J. Hankins, Kaitlyn Karpovich, Javad Siah, Johannes Staguhn, Ellen Zweibel ⋆We present the first data release (DR1) of the Far-Infrared Polarimetric Large Area CMZ Exploration (FIREPLACE)
survey. The survey was taken using the 214-micron band of the HAWC+ instrument with the SOFIA telescope (19.6′
resolution; 0.7 pc). In this first data release we present dust polarization observations covering a 0.5deg region of the
Galactic Center’s Central Molecular Zone (CMZ), approximately centered on the Sgr B2 complex. We detect 25,000
Nyquist-sampled polarization pseudovectors, after applying the standard SOFIA cuts for minimum signal-to-noise in
fractional polarization and total intensity of 3 and 200, respectively. Analysis of the magnetic field orientation suggests a bimodal distribution in the field direction. This bimodal distribution shows enhancements in the distributionof field directions for orientations parallel and perpendicular to the Galactic plane, which is suggestive of a CMZ
magnetic field configuration with polodial and torodial components. Furthermore, a detailed analysis of individualclouds included in our survey (i.e., Sgr B2, Sgr B2-NW, Sgr B2-Halo, Sgr B1, and Clouds-E/F) shows these clouds
have fractional polarization values of 1–10% at 214-micron, with most of the emission having values <5%. A few
of these clouds (i.e., Sgr B2, Clouds-E/F) show relatively low fractional polarization values toward the cores of thecloud, with higher fractional polarization values toward the less dense periphery. We also observe higher fractionalpolarization towards compact HII regions which could indicate an enhancement in the grain alignment in the dust
surrounding these sources.

SOFIA/HAWC+ Far-Infrared Polarimetric Large Area CMZ Exploration (FIREPLACE)
17. II: Detection of a Magnetized Dust Ring in the Galactic Center
Natalie O. Butterfield, Jordan A. Guerra, David T. Chuss, Mark R. Morris, Dylan Pare, Edward J. Wollack,
Allison H. Costa, Matthew J. Hankins, Johannes Staguhn, Ellen Zweibel ⋆ We present the detection of a magne-

tized dust ring (M0.8-0.2) in the Central Molecular Zone (CMZ) of the Galactic Center. The results presented in thispaper utilize the first data release (DR1) of the Far-Infrared Polarimetric Large Area CMZ Exploration (FIREPLACE)
survey (i.e., FIREPLACE I; Butterfield et al. 2023). The FIREPLACE survey is a 214 µm polarimetic survey of the
Galactic Center using the SOFIA/HAWC+ telescope. The M0.8-0.2 ring is a region of gas and dust that has a circularmorphology with a central depression. The dust polarization in the M0.8-0.2 ring implies a curved magnetic field that
traces the ring-like structure of the cloud. We posit an interpretation in which an expanding shell compresses and7

concentrates the ambient gas and magnetic field. We argue that this compression results in the strengthening of themagnetic field, as we infer from the observations toward the interior of the ring.

18. INvestigations of massive Filaments ANd sTar formation (INFANT). I. Core Identification and Core Mass Function
Yu Cheng, Xing Lu, Patricio Sanhueza, Hauyu Baobab Liu, Qizhou Zhang, Roberto Galván-Madrid, Ke Wang,
Fumitaka Nakamura, Tie Liu, Siyi Feng, Shanghuo Li, Sihan Jiao, Kei E. I. Tanaka, Xunchuan Liu, Pak Shing
Li, Qiuyi Luo, Qilao Gu, Yuxin Lin, András E. Guzmán ⋆ Filamentary structures are ubiquitously found in

high-mass star-forming clouds. To investigate the relationship between filaments and star formation, we carry out the
INFANT (INvestigations of massive Filaments ANd sTar formation) survey, a multi-scale, multi-wavelength survey ofmassive filamentary clouds with ALMA band 3/band 6 and VLA K band. In this first paper, we present the ALMA
band 6 continuum observations toward a sample of 8 high-mass star forming filaments. We covered each target withapproximately rectangular mosaic field of view with two 12-m array configurations, achieving an angular resolutionof ∼0.6" (2700 AU at 4.5 kpc) and a continuum rms of ∼0.1 mJy/beam (∼0.06 Msun in gas mass assuming 15 K).
We identify cores using the getsf and astrodendro and find the former is more robust in terms of both identificationand measuring flux densities. We identify in total 183 dense cores (15–36 cores in each cloud) and classify their starformation states via outflow and warm gas tracers. The protostellar cores are statistically more massive than theprestellar cores, possibly indicating further accretion onto cores after formation of protostars. For the high-mass end(Mcore > 1.5 Msun) of the core mass function (CMF) we derive a power-law index of −1.15 ± 0.12 for the wholesample, and −1.70 ± 0.25 for the prestellar population. We also find a steepening trend in CMF with cloud evolution(−0.89 ± 0.15 for the young group v.s. −1.44 ± 0.25 for the evolved group) and discuss its implication for cluster
formation.

19. Mid-Infrared Spectrum of the Disk around the Forming Companion GQ Lup B Revealed
by JWST/MIRI
Gabriele Cugno, Polychronis Patapis, Andrea Banzatti, Michael Meyer, Felix A. Dannert, Tomas Stolker,
Ryan J. MacDonald, Klaus M. Pontoppidan ⋆ GQ Lup B is a forming brown dwarf companion (M ∼ 10 − 30 MJ )showing evidence for an infrared excess associated with a disk surronding the companion itself. Here we present
mid-infrared (MIR) observations of GQ Lup B with the Medium Resolution Spectrograph (MRS) on JWST, spanning
4.8 − 11.7 µm. We remove the stellar contamination using reference differential imaging based on principal component
analysis (PCA), demonstrating that the MRS can perform high-contrast science. Our observations provide a sensitive
probe of the disk surrounding GQ Lup B. We find no sign of a silicate feature, similar to other disk surrounding
very low mass objects, which likely implies significant grain growth (amin ≳ 5 µm), and potentially dust settling.
Additionally, we find that if the emission is dominated by an inner wall, the disk around the companion might have an
inner cavity larger than the one set by sublimation. Conversely, if our data probe the emission from a thin flat disk,
we find the disk to be very compact. More observations are required to confirm this finding and assess the verticalstructure of the disk. This approach paves the path to the future study of circumplanetary disks and their physicalproperties. Our results demonstrate that MIR spectroscopic observations can reveal the physical characteristics ofdisks around forming companions, providing unique insights into the formation of giant planets, brown dwarfs andtheir satellites.

20. JWST/NIRCam Imaging of Young Stellar Objects. II. Deep Constraints on Giant
Planets and a Planet Candidate Outside of the Spiral Disk Around SAO 206462
Gabriele Cugno, Jarron Leisenring, Kevin R. Wagner, Camryn Mullin, Roubing Dong, Thomas Greene, Doug
Johnstone, Michael R. Meyer, Schuyler G. Wolff, Charles Beichman, Martha Boyer, Scott Horner, Klaus
Hodapp, Doug Kelly, Don McCarthy, Thomas Roellig, George Rieke, Marcia Rieke, John Stansberry, Erick
Young ⋆ We present JWST/NIRCam F187N, F200W, F405N and F410M direct imaging data of the disk surrounding

SAO 206462. Previous images show a very structured disk, with a pair of spiral arms thought to be launched by one ormore external perturbers. The spiral features are visible in three of the four filters, with the non-detection in F410M
due to the large detector saturation radius. We detect with a signal-to-noise ratio of 4.4 a companion candidate (CC1)that, if on a coplanar circular orbit, would orbit SAO 206462 at a separation of ∼ 300 au, 2.25σ away from the predicted
separation for the driver of the eastern spiral. According to the BEX models, CC1 has a mass of MCC1 = 0.8 ± 0.3 MJ .

8

No other companion candidates were detected. At the location predicted by simulations of both spirals generated
by a single massive companion, the NIRCam data exclude objects more massive than ∼ 2.2 MJ assuming the BEX
evolutionary models. In terms of temperatures, the data are sensitive to objects with Teff ∼ 650 − 850 K, whenassuming planets emit like blackbodies (Rp between 1 and 3RJ ). From these results, we conclude that if the spirals
are driven by gas giants, these must be either cold or embedded in circumplanetary material. In addition, the NIRCamdata provide tight constraints on ongoing accretion processes. In the low extinction scenario we are sensitive to massaccretion rates of the order Ṁ ∼ 10−9 MJ yr−1 . Thanks to the longer wavelengths used to search for emission lines,
we reach unprecedented sensitivities to processes with Ṁ ∼ 10−7 MJ yr−1 even towards highly extincted environments(AV ≈ 50 mag).

Climbing the Cliffs: Classifying YSOs in the Cosmic Cliffs JWST Data using a Proba21. bilistic Random Forest
B. L. Crompvoets, J. Di Francesco, H. Teimoorinia, T. Preibisch ⋆ Among the first observations released to the
public from the James Webb Space Telescope (JWST) was a section of the star-forming region NGC 3324 known
colloquially as the "Cosmic Cliffs." We build a photometric catalog of the region and test the ability of using theProbabilistic Random Forest machine learning method to identify its Young Stellar Objects (YSOs). We find 450 candidate YSOs (cYSOs) out of 19 497 total objects within the field, 413 of which are cYSOs not found in previous works.
These classifications are verified with several different metrics, including recall and precision. Using the obtained
probabilities of objects being YSOs, we employ a Monte Carlo approach to determine the surface density of cYSOs in
the Cosmic Cliffs, which we find to be largely coincident with column densities derived from Herschel data, up to acolumn density of 1.37 × 1022 cm−2 . The newly determined number and spatial distribution of YSOs in the Cosmic
Cliffs demonstrate that JWST is far more capable of detecting YSOs in dusty regions than Spitzer. Comparisons of
the observed colors and brightness of faint cYSOs with those of pre-main-sequence models suggest JWST has detecteda significant population of sub-stellar YSOs in the Cosmic Cliffs. The size of this population further suggests previous
estimates of star formation efficiencies in molecular clouds have been systematically low.

22. Full orbital solutions in pre-main sequence high-order multiple systems: GG Tau Ab
and UX Tau B
Gaspard Duchêne, Jean-Baptiste LeBouquin, François Ménard, Nicolás Cuello, Claudia Toci, Maud Langlois⋆ High-order multiple (triple and beyond) systems are relatively common. Their interaction with circumstellar andcircumbinary material can have a large impact on the formation and evolution of planetary systems and depends
on their orbital properties. GG Tau and UX Tau are two pre-main sequence high-order multiple systems in which
the tightest pair has a projected separation of ≈ 5–20 au. Characterizing precisely their orbits is crucial to establish
their long-term stability, to predict the dynamics and evolution of circumstellar matter, and to evaluate the potential
for planet formation in such systems. We combine existing astrometric measurements with previously unpublishedhigh-resolution observations of the GG Tau Ab and UX Tau B pairs and perform Keplerian orbital fits. For GG Tau Ab
the data presented here represent the first detection of orbital motion. For both systems they yield dramatic increases
in orbital coverage (≳ 60% and ≈ 100% for UX Tau B and GG Tau Ab, for orbital periods of ≈ 32 and ≈ 8 yr,
respectively) and allow us to obtain well-constrained orbital fits, including dynamical masses with ≲ 10% and ≲ 7%
random and systematic uncertainties. We find that both GG Tau A and UX Tau A–B likely form stable hierarchicalsystems, although one possible deprojection solution for GG Tau is strongly misaligned and could experience vonZeipel-Lidov-Kozai oscillations. We further find that the UX Tau B orbit is much more eccentric than the GG Tau Ab
one, possibly explaining the lack of circumstellar material in the former. The newly-determined orbits revive thequestion of the dynamical fate of gas and dust in these two hierarchical systems and should spur new dedicatedsimulations to assess the long-term evolution of the systems and the dynamical perturbations imposed by the close
binaries they host.

23. Planet Formation by Gas-Assisted Accretion of Small Solids
Gennaro D’Angelo, Peter Bodenheimer ⋆ We compute the accretion efficiency of small solids, with radii 1 cm ≤Rs ≤ 10 m, on planets embedded in gaseous disks. Planets have masses 3 ≤ Mp ≤ 20 Earth masses (Me) and orbit
within 10 AU of a solar-mass star. Disk thermodynamics is modeled via three-dimensional radiation-hydrodynamic
calculations that typically resolve the planetary envelopes. Both icy and rocky solids are considered, explicitly modeling9their thermodynamic evolution. The maximum efficiencies of 1 ≤ Rs ≤ 100 cm particles are generally ≲ 10%, whereas
10 m solids tend to accrete efficiently or be segregated beyond the planet’s orbit. A simplified approach is applied tocompute the accretion efficiency of small cores, with masses Mp ≤ 1 Me and without envelopes, for which efficiencies
are approximately proportional to Mp( 2/3). The mass flux of solids, estimated from unperturbed drag-induced drift
velocities, provides typical accretion rates dMp/dt ≲ 1e-5 Mearth/yr. In representative disk models with an initial
gas-to-dust mass ratio of 70-100 and total mass of 0.05-0.06 Msun, solids’ accretion falls below 1e-6 Mearth/yr after
1-1.5 million years (Myr). The derived accretion rates, as functions of time and planet mass, are applied to formation
calculations that compute dust opacity self-consistently with the delivery of solids to the envelope. Assuming dustto-solid coagulation times of approximately 0.3 Myr and disk lifetimes of approximately 3.5 Myr, heavy-element
inventories in the range 3-7 Me require that approximately 90-150 Me of solids cross the planet’s orbit. The formation
calculations encompass a variety of outcomes, from planets a few times the Earth mass, predominantly composed ofheavy elements, to giant planets. The peak luminosities during the epoch of solids’ accretion range from ≈ 1e-7 to ≈1e-6 times the solar luminosity.

24. The jet of BP Tau
A. V. Dodin, S. A. Potanin, M. A. Burlak, D. V. Cheryasov, N. P. Ikonnikova, S. A. Lamzin, B. S. Safonov, N.
I. Shatskii, A. M. Tatarnikov ⋆ A strong global magnetic field of young low-mass stars and a high accretion rate

are the necessary conditions for the formation of collimated outflows (jets) from these objects. But it is still unclear
whether these conditions are also sufficient. We aim to check whether BP Tau, an actively accreting young star witha strong magnetic field, has a jet. We carried out narrowband SII 672 nm imaging and spectroscopic observations of
BP Tau and its vicinity. We find that BP Tau is a source of a Herbig-Haro flow (assigned number HH 1181), which
includes two HH objects moving from the star in opposite directions and a micro- (counter-) jet of 1" projected
length. The flow is oriented along position angle 59 ± 1 degree.

25. The stability of dense cores near the Serpens South protocluster

Rachel K. Friesen, Emma Jarvis ⋆ Most stars form in clusters and groups rather than in isolation. We present≲ 5′′ angular resolution (∼ 2000 au, or 0.01 pc) Very Large Array NH3 (1,1), (2,2), and (3,3) and 1.3 cm continuum
emission observations of the dense gas within the Serpens South protocluster and extended filaments to the north andsouth. We identify 94 dense cores using a dendrogram analysis of the NH3 (1,1) integrated intensity. Gas temperatures
TK and non-thermal linewidths σNT both increase towards the centre of the young stellar cluster, in the dense gas
generally and in the cores specifically. We find that most cores (54%) are super-virial, with gravitationally bound cores
located primarily in the filaments. Cores in the protocluster have higher virial parameters by a factor ∼ 1.7, driven
primarily by the increased core σNT values. These cores cannot collapse to form stars unless they accrete additional
mass or their core internal motions are reduced. The southern filament shows a significant velocity gradient previouslyinterpreted as mass flow toward the cluster. We find more complex kinematics in the northern filament. We finda strong correlation between σNT and TK , and argue that the enhanced temperatures and non-thermal motions are
due to mechanical heating and interaction between the protocluster-driven outflows and the dense gas. Filament-led
accretion may also contribute to the increased σNT values. Assuming a constant fraction of core mass ends up in theyoung stars, future star formation in the Serpens South protocluster will shift to higher masses by a factor ∼ 2.

26. MINDS: Mid-infrared atomic and molecular hydrogen lines in the inner disk around a
low-mass star
Riccardo Franceschi, Thomas Henning, Benoît Tabone, Giulia Perotti, Alessio Caratti o Garatti, Giulio Bettoni,
Ewine F. van Dishoeck, Inga Kamp, Olivier Absil, Manuel Güdel, Göran Olofsson, L. B. F. M. Waters,
Aditya M. Arabhavi, Valentin Christiaens, Danny Gasman, Sierra L. Grant, Hyerin Jang, Donna Rodgers-Lee,
Matthias Samland, Kamber Schwarz, Milou Temmink, David Barrado, Anthony Boccaletti, Vincent Geers,
Pierre-Olivier Lagage, Eric Pantin, Tom P. Ray, Silvia Scheithauer, Bart Vandenbussche, Gillian Wright ⋆ This

work aims to measure the mass accretion rate, the accretion luminosity, and more generally the physical conditionsof the warm emitting gas in the inner disk of the very low-mass star 2MASS-J16053215-1933159. We investigate
the source mid-infrared spectrum for atomic and molecular hydrogen line emission. We present the full James Webb
Space Telescope (JWST) Mid-InfraRed Instrument (MIRI) Medium Resolution Spectrometer (MRS) spectrum of
the protoplanetary disk around the very low-mass star 2MASS-J16053215-1933159 from the MINDS GTO program,10

previously shown to be abundant in hydrocarbon molecules. We analyzed the atomic and molecular hydrogen lines
in this source by fitting one or multiple Gaussian profiles. We then built a rotational diagram for the H2 lines toconstrain the rotational temperature and column density of the gas. Finally, we compared the observed atomic line
fluxes to predictions from two standard emission models. We identify five molecular hydrogen pure rotational lines and
16 atomic hydrogen recombination lines. The spectrum indicates optically thin emission for both species. We use themolecular hydrogen lines to constrain the mass and temperature of the warm emitting gas. The HI (7-6) recombinationline is used to measure the mass accretion rate and luminosity onto the central source. HI recombination lines canalso be used to derive the physical properties of the gas using atomic recombination models. The JWST-MIRI MRS
observations for the very low-mass star 2MASS-J16053215-1933159 reveal a large number of emission lines, many
originating from atomic and molecular hydrogen because we are able to look into the disk warm molecular layer.
Their analysis constrains the physical properties of the emitting gas and showcases the potential of JWST to deepen
our understanding of the physical and chemical structure of protoplanetary disks

27. An ALMA search for substructure and fragmentation in starless cores in Orion B North
Samuel Fielder, Helen Kirk, Michael Dunham, Stella Offner ⋆ We present Atacama Large Millimeter/submillimeter
Array (ALMA) Cycle 3 observations of 73 starless and protostellar cores in the Orion B North molecular cloud. We
detect a total of 34 continuum sources at 106 GHz, and after comparisons with other data, 4 of these sources appear to
be starless. Three of the four sources are located near groupings of protostellar sources, while one source is an isolated
detection. We use synthetic observations of a simulation modeling a collapsing turbulent, magnetized core to computethe expected number of starless cores that should be detectable with our ALMA observations and find at least two(1.52) starless core should be detectable, consistent with our data. We run a simple virial analysis of the cores to
put the Orion B North observations into context with similar previous ALMA surveys of cores in Chamaeleon I and
Ophiuchus. We conclude that the Chamaeleon I starless core population is characteristically less bounded than theother two populations, along with external pressure contributions dominating the binding energy of the cores. These
differences may explain why the Chamaeleon I cores do not follow turbulent model predictions, while the Ophiuchus
and Orion B North cores are consistent with the model.

A self-consistent model for dust settling and the vertical shear instability in protoplan28. etary disks
Yuya Fukuhara, Satoshi Okuzumi ⋆ The spatial distribution of dust particles in protoplanetary disks affects dust

evolution and planetesimal formation processes. The vertical shear instability (VSI) is one of the candidate hydrodynamic mechanisms that can generate turbulence in the outer disk region and affect dust diffusion. Turbulence driven
by the VSI has a predominant vertical motion that can prevent dust settling. On the other hand, the dust distribution controls the spatial distribution of the gas cooling rate, thereby affecting the strength of VSI-driven turbulence.
Here, we present a semi-analytic model that determines the vertical dust distribution and the strength of VSI-driven
turbulence in a self-consistent manner. The model uses an empirical formula for the vertical diffusion coefficient in
VSI-driven turbulence obtained from our recent hydrodynamical simulations. The formula returns the vertical diffusion
coefficient as a function of the vertical profile of the cooling rate, which is determined by the vertical dust distribution.
We use this model to search for an equilibrium vertical dust profile where settling balances with turbulent diffusion
for a given maximum grain size. We find that if the grains are sufficiently small, there exists a stable equilibrium dust
distribution where VSI-driven turbulence is sustained at a level of alphaz 10−3 , where alphaz is the dimensionlessvertical diffusion coefficient. However, as the maximum grain size increases, the equilibrium solution vanishes because
the VSI can no longer stop the settling of the grains. This runaway settling may explain highly settled dust rings
found in the outer part of some protoplanetary disks.

29. Gaia23bab : a new EXor

T. Giannini, E. Schisano, P. Abraham, S. Antoniucci, K. Biazzo, F. Cruz-Saenz de Miera, E. Fiorellino, M.
Gangi, A. Kospal, M. Kuhn, E. Marini, Z. Nagy, D. Paris ⋆ On March 6 2023, the Gaia telescope has alerted

a 2-magnitude burst from Gaia23bab, a Young Stellar Object in the Galactic plane. We observed Gaia23bab with
the Large Binocular Telescope obtaining optical and near-infrared spectra close in time to the peak of the burst, andcollected all public multi-band photometry to reconstruct the historical light curve. This latter shows three bursts
in ten years (2013, 2017 and 2023), whose duration and amplitude are typical of EXor variables. We estimate that,11due to the bursts, the mass accumulated on the star is about twice greater than if the source had remained quiescentfor the same period of time. Photometric analysis indicates that Gaia23bab is a Class,II source with age < 1 Myr,
spectral type G3-K0, stellar luminosity 4.0 Lsun, and mass 1.6 Msun. The optical/near infrared spectrum is rich inemission lines. From the analysis of these lines we measured the accretion luminosity and the mass accretion rateLacc(burst)=3.7 Lsun, Macc(burst) 2.0 10( − 7) Msun/yr, consistent with those of EXors. More generally, we derive
the relationships between accretion and stellar parameters in a sample of EXors. We find that, when in burst, theaccretion parameters become almost independent of the stellar parameters and that EXors, even in quiescence, aremore efficient than classical T Tauri stars in assembling mass.

30. Reduction of dust radial drift by turbulence in protoplanetary disks
Fabiola Antonietta Gerosa, Jérémie Bec, Héloïse Méheut, Anand Utsav Kapoor ⋆ Dust particles in protoplanetary disks, lacking support from pressure, rotate at velocities exceeding those of the surrounding gas. Consequently,
they experience a head-wind from the gas that drives them toward the central star. Radial drift occurs on timescales
much shorter than those inferred from disk observations or those required for dust to aggregate and form planets.
Additionally, turbulence is often assumed to amplify the radial drift of dust in planet-forming disks when modeled
through an effective viscous transport. However, the local interactions between turbulent eddies and particles are
known to be significantly more intricate than in a viscous fluid. Our objective is to elucidate and characterize thedynamic effects of Keplerian turbulence on the mean radial and azimuthal velocities of dust particles. We employ 2D
shearing-box incompressible simulations of the gas, which is maintained in a developed turbulent state while rotating
at a sub-Keplerian speed. Dust is modeled as Lagrangian particles set at a Keplerian velocity, therefore experiencing aradial force toward the star through drag. Turbulent eddies are found to reduce the radial drift, while simultaneously
enhancing the azimuthal velocities of small particles. This dynamic behavior arises from the modification of dust
trajectories due to turbulent eddies.

Trajectory of Infalling Particles in Streamers around Young stars. Dynamical
31. TIPSY:
analysis of the streamers around S CrA and HL Tau
Aashish Gupta, Anna Miotello, Jonathan P. Williams, Til Birnstiel, Michael Kuffmeier, Hsi-Wei Yen ⋆ Context.

Elongated trails of infalling gas, often referred to as "streamers," have recently been observed around young stellar
objects (YSOs) at different evolutionary stages. This asymmetric infall of material can significantly alter star andplanet formation processes, especially in the more evolved YSOs. Aims. In order to ascertain the infalling nature ofobserved streamer-like structures and then systematically characterize their dynamics, we developed the code TIPSY(Trajectory of Infalling Particles in Streamers around Young stars). Methods. Using TIPSY, the streamer molecularline emission is first isolated from the disk emission. Then the streamer emission, which is effectively a point cloudin three-dimensional (3D) position-position-velocity space, is simplified to a curve-like representation. The observed
streamer curve is then compared to the theoretical trajectories of infalling material. The best-fit trajectories are used
to constrain streamer features, such as the specific energy, the specific angular momenta, the infall timescale, andthe 3D morphology. Results. We used TIPSY to fit molecular-line ALMA observations of streamers around a Class
II binary system, S CrA, and a Class I/II protostar, HL Tau. Our results indicate that both of the streamers are
consistent with infalling motion. TIPSY results and mass estimates suggest that S CrA and HL Tau are accreting
material at a rate of ≳ 27 Mjupiter Myr−1 and ≳ 5 Mjupiter Myr−1 , respectively, which can significantly increase
the mass budget available to form planets. Conclusions. TIPSY can be used to assess whether the morphology andkinematics of observed streamers are consistent with infalling motion and to characterize their dynamics, which is
crucial for quantifying their impact on the protostellar systems.

32. Maser Flares Driven by Isothermal Shock Waves
M. D. Gray, S. Etoka, B. Pimpanuwat, A. M. S. Richards ⋆ We use 3D computer modelling to investigate thetimescales and radiative output from maser flares generated by the impact of shock-waves on astronomical unit-scale
clouds in interstellar and star-forming regions, and in circumstellar regions in some circumstances. Physical conditions
are derived from simple models of isothermal hydrodynamic (single-fluid) and C-type (ionic and neutral fluid) shockwaves, and based on the ortho-H2 O 22-GHz transition. Maser saturation is comprehensively included, and we findthat the most saturated maser inversions are found predominantly in the shocked material. We study the effect on theintensity, flux density and duration of flares of the following parameters: the pre-shock level of saturation, the observer’s

12viewpoint, and the shock speed. Our models are able to reproduce observed flare rise times of a few times 10 days,
specific intensities of up to 105 times the saturation intensity and flux densities of order 100(R/d)2 Jy from a source ofradius R astronomical units at a distance of d kiloparsec. We found that flares from C-type shocks are approximately
5 times more likely to be seen by a randomly placed observer than flares from hydrodynamically shocked clouds ofsimilar dimensions. We computed intrinsic beaming patterns of the maser emission, finding substantial extension of
the pattern parallel to the shock front in the hydrodynamic models. Beaming solid angles for hydrodynamic models
can be as small as 1.3 × 10−5 sr, but are an order of magnitude larger for C-type models.

33. Radial and vertical constraints on the icy origin of H2 CO in the HD 163296 Protoplanetary Disk
Claudio Hernández-Vera, Viviana V. Guzmán, Elizabeth Artur de la Villarmois, Karin I. Öberg, L. Ilsedore
Cleeves, Michiel R. Hogerheijde, Chunhua Qi, John Carpenter, Edith C. Fayolle ⋆ H2 CO is a small organic

molecule widely detected in protoplanetary disks. As a precursor to grain-surface formation of CH3 OH, H2 CO isconsidered an important precursor of O-bearing organic molecules that are locked in ices. Still, since gas-phase reactions can also form H2 CO, there remains an open question on the channels by which organics form in disks, andhow much the grain versus the gas pathways impact the overall organic reservoir. We present spectrally and spatiallyresolved Atacama Large Millimeter/submillimeter Array observations of several ortho- and para-H2 CO transitions
toward the bright protoplanetary disk around the Herbig Ae star HD 163296. We derive column density, excitation
temperature, and ortho-to-para ratio (OPR) radial profiles for H2 CO, as well as disk-averaged values of NT ∼ 4 × 1012
cm−2 , Tex ∼ 20 K, and OPR ∼ 2.7, respectively. We empirically determine the vertical structure of the emission,
finding vertical heights of z/r ∼ 0.1. From the profiles, we find a relatively constant OPR ∼ 2.7 with radius, but still
consistent with 3.0 among the uncertainties, a secondary increase of NT in the outer disk, and low Tex values that
decrease with disk radius. Our resulting radial, vertical, and OPR constraints suggest an increased UV penetration
beyond the dust millimeter edge, consistent with an icy origin but also with cold gas-phase chemistry. This Herbig
disk contrasts previous results for the T Tauri disk, TW Hya, which had a larger contribution from cold gas-phasechemistry. More observations of other sources are needed to disentangle the dominant formation pathway of H2 CO inprotoplanetary disks.

34. The Physical Origin of the Stellar Initial Mass Function
Patrick Hennebelle, Michael Y. Grudić ⋆ Stars are amongst the most fundamental structures of our Universe.

They comprise most of the baryonic and luminous mass of galaxies, synthethise heavy elements, and injec t mass,
momentum, and energy into the interstellar medium. They are also home to the planets. Since stellar properties areprimarily decided by their mass, the so-called stellar initial mass function (IMF) is critical to the structuring of ourUniverse. We review the various physical processes, and theories which have been put forward as well as the numericalsimulations which have been carried out to explain the origin of the stellar initial mass function. Key messages fromthis review are: (1) Gravity and turbulence most likely determine the power-law, high-mass part of the IMF. (2)Depending of the Mach number and the density distribution, several regimes are possible, including ΓIM F ≃ 0, -0.8, -1
or -1.3 where dN/d log M ∝ M ΓIM F . These regimes are likely universal, however the transition between these regimes
is not. (3) Protostellar jets can play a regulating influence on the IMF by injecting momentum into collapsing clumps
and unbinding gas. (4) The peak of the IMF may be a consequence of dust opacity and molecular hydrogen physics atthe origin of the first hydrostatic core. This depends weakly on large scale environmental conditions such as radiation,
magnetic field, turbulence or metallicity. This likely constitutes one of the reason of the relative universality of the
IMF.

35. Protoplanetary Disk Polarization at Multiple Wavelengths: Are Dust Populations Diverse?
Rachel E. Harrison, Zhe-Yu Daniel Lin, Leslie W. Looney, Zhi-Yun Li, Haifeng Yang, Ian Stephens, ManuelFernández-López ⋆ Millimeter and sub-millimeter observations of continuum linear dust polarization provide insight

into dust grain growth in protoplanetary disks, which are the progenitors of planetary systems. We present the resultsof the first survey of dust polarization in protoplanetary disks at 870 µm and 3 mm. We find that protoplanetarydisks in the same molecular cloud at similar evolutionary stages can exhibit different correlations between observing
wavelength and polarization morphology and fraction. We explore possible origins for these differences in polarization,

13

including differences in dust populations and protostar properties. For RY Tau and MWC 480, which are consistent
with scattering at both wavelengths, we present models of the scattering polarization from several dust grain size
distributions. These models aim to reproduce two features of the observational results for these disks: (1) both disks
have an observable degree of polarization at both wavelengths and (2) the polarization fraction is higher at 3 mm thanat 870 µm in the centers of the disks. For both disks, these features can be reproduced by a power-law distribution of
spherical dust grains with a maximum radius of 200 µm and high optical depth. In MWC 480, we can also reproduce
features (1) and (2) with a model containing large grains (amax = 490 µm ) near the disk midplane and small grains(amax = 140 µm) above and below the midplane.

Inefficient star formation in high Mach number environments I. The turbulent support
36. analytical model
Patrick Hennebelle, Noé Brucy, Tine Colman ⋆ The star formation rate (SFR), the number of stars formed per unitof time, is a fundamental quantity in the evolution of the Universe. While turbulence is believed to play a crucial rolein setting the SFR, the exact mechanism remains unclear. Turbulence promotes star formation by compressing the gas,
but also slows it down by stabilizing the gas against gravity. Most widely-used analytical models rely on questionableassumptions, including: i) integrating over the density PDF, a one-point statistical description that ignores spatial
correlation, ii) selecting self-gravitating gas based on a density threshold that often ignores turbulent dispersion, iii)
assuming the freefall time as the timescale for estimating SFR without considering the need to rejuvenate the density
PDF, iv) assuming the density PDF to be lognormal. Improving upon the only existing model that incorporates thespatial correlation of the density field, we present a new analytical model. We calculate the time needed to rejuvenate
density fluctuations of a given density and spatial scale, revealing that it is generally much longer than the freefall time,rendering the latter inappropriate for use. We make specific predictions regarding the role of the Mach number, M ,and the driving scale of turbulence divided by the mean Jeans length. At low to moderate Mach numbers, turbulence
does not reduce and may even slightly promote star formation by broadening the PDF. However, at higher Mach
numbers, most density fluctuations are stabilized by turbulent dispersion, leading to a steep drop in the SFR as theMach number increases.

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

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

14

38.

Dynamics Near the Inner Dead-Zone Edges in a Proprotoplanetary Disk
Kazunari Iwasaki, Kengo Tomida, Shinsuke Takasao, Satoshi Okuzumi, Takeru K. Suzuki ⋆ We perform threedimensional global non-ideal magnetohydrodynamic simulations of a protoplanetary disk containing the inner deadzone edge. We take into account realistic diffusion coefficients of the Ohmic resistivity and ambipolar diffusion basedon detailed chemical reactions with a single-size dust grains. We found that the conventional dead zone identified
by the Elsässer numbers of the Ohmic resistivity and ambipolar diffusion is divided into two regions: "the transitionzone" and "the coherent zone". The coherent zone has the same properties as the conventional dead zone, and extends
outside of the transition zone in the radial direction. Between the active and coherent zones, we discover the transitionzone whose inner edge is identical to that of the conventional dead-zone. The transition zone extends out over theregions where thermal ionization determines diffusion coefficients. The transition zone has completely different physicalproperties than the conventional dead zone, the so-called undead zone, and zombie zone. Combination of amplificationof the radial magnetic field owing to the ambipolar diffusion and a steep radial gradient of the Ohmic diffusivity causes
the efficient evacuation of the net vertical magnetic flux from the transition zone within several rotations. Surface gas
accretion occurs in the coherent zone but not in the transition zone. The presence of the transition zone prohibits
mass and magnetic flux transport from the coherent zone to the active zone. Mass accumulation occurs at both edgesof the transition zone as a result of mass supply from the active and coherent zones.

39. Meteorites and Planet Formation
Rhian H. Jones ⋆ Meteorites are a remarkable resource. They capture the imagination of people worldwide with theirspectacular entry through Earth’s atmosphere as fireballs, and their exotic character of being pieces of other worlds.
Scientifically, they are critical to interpreting the early stages of formation of the Solar System, as well as the geologicalevolution of asteroids, the Moon, and Mars, and they are vital to understanding planetary formation processes. With
the burgeoning exploration of extrasolar planetary systems, knowledge of the fundamental process of planetary growthfrom protoplanetary disks has taken on a new significance. Meteorites provide essential and detailed insight into theformation of planetary systems, although we must bear in mind that they only represent one reference point (our own
Solar System) in what is clearly a wide spectrum of possible chemical and physical parameters governing the diverse
realm of extrasolar planets. This chapter summarises the nature of our meteorite collections, and the ways in which
meteorites contribute to our understanding of the formation and evolution of our own Solar System, with broader
implications for planetary systems in general.

40. The CO-to-H2 Conversion Factor in the Central Molecular Zone of the Milky Way using
CO isotopologues
Mikito Kohno, Yoshiaki Sofue ⋆ We performed correlation analyses between the 12 CO and 13 CO J =1-0 line

intensities in order to derive the variability of the CO-to-H2 conversion factor (XCO,iso ) in the central molecular zone
(CMZ) of our Galaxy. New high-resolution XCO,iso maps at a resolution of ∼ 30" and the longitude-velocity diagram(LVD) at resolution ∼ 30" × 2 km s−1 are presented using the 12 CO and 13 CO archival survey data obtained by
the Nobeyama 45 m telescope. We revealed the variation of XCO,iso in the CMZ within the range of XCO,iso ∼(0.2 − 1.3) × 1020 cm−2 (K km s−1 )−1 , if we assume the normalization value of 0.59 × 1020 cm−2 (K km s−1 )−1 . The
mean value is obtained as XCO,iso = (0.48 ± 0.15) × 1020 cm−2 (K km s−1 )−1 in the CMZ of our Galaxy.

41. Scales of Stability and Turbulence in the Molecular ISM
Eric Keto ⋆ From the archival data of the BU-FCRAO 13 CO GRS, we measure the radial profiles of column density

and turbulent velocity dispersion from the centers of molecular clouds outward into the surrounding diffuse molecular
ISM. Averaged across spatial scales, the profiles are consistent with turbulence that is on average in hydrostatic
equilibrium. We measure the turbulent kinetic energy (KE) and the gravitational potential energy (GE) within
and the pressure energy (PE) outside the clouds. The distribution of the sum 2KE-|GE|-PE has a mean near zero
indicating approximate virial equilibrium. The average pressure energy is consistent with estimates of the pressure of
the multiphase ISM at the Galactic mid-plane. If the dynamical time scale of the turbulence scales with its crossing
time, this apparent equilibrium may result from the rapid virialization of the KE and GE with respect to changes in
PE. In a snapshot, the clouds appear to be in virial equilibrium within a confining pressure. However, the durationof the equilibrium is approximately the crossing time. An analysis of Larson’s scaling relationships of line width andcolumn density finds no correlation. Tthe inference of constant column density with cloud size is a misinterpretation15

of this lack of correlation.

42. Kinematic age of the β-Pictoris moving group
Jinhee Lee, Inseok Song ⋆ Accurate age estimation of nearby young moving groups (NYMGs) is important asthey serve as crucial testbeds in various fields of astrophysics, including formation and evolution of stars, planets,
as well as loose stellar associations. The β-Pictoris moving group (BPMG), being one of the closest and youngest
NYMGs, has been extensively investigated, and its estimated ages have a wide range from ∼10 to 25 Myr, dependingon the age estimation methods and data used. Unlike other age dating methods, kinematic traceback analysis offersa model-independent age assessment hence the merit in comparing many seemingly discordant age estimates. In thisstudy, we determine the kinematic ages of the BPMG using three methods: probabilistic volume calculation, mean
pairwise distance calculation, and covariance matrix analysis. These methods yield consistent results, with estimatedages in the range of 14 to 20 Myr. Implementing corrections to radial velocities due to gravitational redshift andconvectional blueshift increases the ages by ∼ 2 − 4 Myr. Conversely, considering data uncertainties decreases theestimated ages by 1 to 2 Myr. Taken together, our analysis determined the kinematic age of BPMG to be 16.3+3.4−2.1
Myr. This age is significantly younger than the commonly accepted age of the BPMG (∼24 Myr) determined primarily
from the lithium depletion boundary analysis. This younger kinematic age may point to the discrepancy between theluminosity evolution and lithium depletion models or the presence of unaccounted systematic error in the method.
This result underscores the necessity for systematic reevaluations of age-dating methods for nearby, young moving
groups.

43. Formation of the four terrestrial planets in the Jupiter-Saturn chaotic excitation scenario: fundamental properties and water delivery
Patryk Sofia Lykawka, Takashi Ito ⋆ The Jupiter-Saturn chaotic excitation (JSCE) scenario proposes that the

protoplanetary disk was dynamically excited and depleted beyond 1-1.5 au in a few Myr, offering a new and plausible explanation for several observed properties of the inner solar system. Here, we expanded our previous work byconducting a comprehensive analysis of 37 optimal terrestrial planet systems obtained in the context of the JSCE
scenario. Each optimal system harbored exactly four terrestrial planets analogs to Mercury, Venus, Earth, and Mars.
We further investigated water delivery, feeding zones, and accretion history for the planet analogs, which allowed us tobetter constrain the water distribution in the disk. The main findings of this work are as follows: 1) the formation offour terrestrial planets with orbits and masses similar to those observed in our solar system in most of our sample, as
evidenced by the dynamically colder and hotter orbits of Venus-Earth and Mercury-Mars analogs, and the high successrates of similar mutual orbital separations ( 40-85%) and mass ratios of the planets ( 70-90%) among the 37 systems;
and 2) water was delivered to all terrestrial planets during their formation through the accretion of water-bearing
disk objects from beyond 1-1.5 au. The achievement of Earth’s estimated bulk water content required the disk tocontain sufficient water mass distributed within those objects initially. This requirement implies that Mercury, Venus,
and Mars acquired water similar to the amount on Earth during their formation. Several of our planet analogs also
matched additional constraints, such as the timing of Moon formation by a giant impact, Earth’s late accretion massand composition, and Mars’s formation timescale.

44. Disk dissipation, giant planet formation and star-formation-rate fluctuations in the past
three-million-year history of Gould’s Belt
Mingchao Liu, Jinhua He, Jixing Ge, Tie Liu, Yuping Tang, Xuzhi Li ⋆ Although episodic star formation (SF) had

been suggested for nearby SF regions, a panoramic view to the latest episodic SF history in the solar neighborhood
is still missing. By uniformly constraining the slope α of infrared spectral energy distributions (SEDs) of youngstellar objects (YSOs) in the 13 largest Gould’s Belt (GB) protoclusters surveyed by Spitzer Space Telescope, wehave constructed a cluster-averaged histogram of α representing YSO evolution lifetime as a function of the α value.
Complementary to the traditional SED classification scheme (0, I, F, II, III) that is based on different α values, astaging scheme (A,B,C,D,E) of SED evolution is advised on the basis of the α statistical features that can be better
matched to the physical stages of disk dissipation and giant planet formation. This has also allowed us to unravel
the fluctuations of star formation rate (SFR) in the past three-million-year (3 Myr) history of these GB protoclusters.
Diverse evolutionary patterns such as single peak, double peaks and on-going acceleration of SFR are revealed. The
SFR fluctuations are between 20% ∼ 60% (∼ 40% on average) and no dependence on the average SFR or the number of16

SFR episodes is found. However, spatially close protoclusters tend to share similar SFR fluctuation trends, indicatingthat the driving force of the fluctuations should be at size scales beyond the typical cluster sizes of several parsec.

Can near-to-mid infrared spectral energy distribution quantitatively trace protoplane45. tary disk evolution?
Mingchao Liu, Jinhua He, Zhen Guo, Jixing Ge, Yuping Tang ⋆ Infrared (IR) spectral energy distribution (SED)
is the major tracer of protoplanetary disks. It was recently proposed to use the near-to-mid IR (or K-24) SED slope
α defined between 2-24µm as a potential quantitative tracer of disk age. We critically examine the viability of thisidea and confront it with additional statistics of IR luminosities and SED shapes. We point out that, because thestatistical properties of most of the complicated physical factors involved in disk evolution are still poorly understoodin a quantitative sense, the only viable way is to assume them to be random so that an idealized ‘average disk’ can be
defined, which allows the α histogram to trace its age. We confirm that the statistics of the zeroth order (luminosity),
first order (slope α) and second order characteristics (concavity) of the observed K-24 SEDs indeed carry useful information upon the evolutionary processes of the ‘average disk’. We also stress that intrinsic diversities in K-24 SED
shapes and luminosities are always large at the level of individual stars so that the application of the evolutionary
path of the ‘average disk’ to individual stars must be done with care. The data of most curves in plots are provided
on GitHub.

46. New Herbig-Haro Objects associated with Embedded Sources

T. A. Movsessian, T. Yu. Magakian, B. Reipurth, H. R. Andreasyan ⋆ We continue to present the results of the
Byurakan Narrow Band Imaging Survey (BNBIS). The main goal of this survey is to search for Herbig-Haro (HH)
objects and jets in Galactic dark clouds. In this work we present the results of the search in the vicinity of infrared
sources that are bright in the WISE survey and embedded in the dark clouds. The survey is performed with the
1 m Schmidt telescope of Byurakan Observatory, lately equipped with a new CCD detector, which allows to obtain
one square degree images of the sky in various filters. Narrow-band filters were used to obtain Halpha and [S II]
images, and a medium-width filter was used for the continuum imaging. New HH flows and knots were found near six
embedded IR sources, which constitutes a significant proportion of the objects observed. At least two of the newly
found HH flows (HH 1226 and HH 1227) lie in isolated dark clouds, thus pointing to active star formation in theseregions. Other flows are also located in detached and dense globules or filaments. The length of the HH 1228 flow
is about 1 pc; it has also a molecular hydrogen counterpart of the same extension. Coordinates, charts, detailed
descriptions and distance estimates are provided. The lower limits of bolometric luminosities of the source stars are
typical for low-mass young stellar objects.

47. Delivery of Dust Particles from Protoplanetary Disks onto Circumplanetary Disks ofGiant Planets
Natsuho Maeda, Keiji Ohtsuki, Ryo Suetsugu, Yuhito Shibaike, Takayuki Tanigawa, Masahiro N. Machida ⋆Principal regular satellites of gas giants are thought to be formed by the accumulation of solid materials in circumplanetary disks (CPDs). While there has been significant progress in the study of satellite formation in CPDs, details of the
supply of satellite building blocks to CPDs remain unclear. We performed orbital integration of solid particles in the
protoplanetary disk (PPD) approaching a planet, considering the gas drag force using the results of three-dimensionalhydrodynamical simulations of a local region around the planet. We investigated planetary-mass dependence of thecapture positions and capture rates of dust particles accreting onto the CPD. We also examined the degree of dust
retention in accreting gas onto the CPD, which is important for determining the ratio of dust-to-gas inflow rates, a
key parameter in satellite formation. We found that the degree of dust retention increases with increasing planetary
mass for a given dust scale height in the PPD. In the case of a small planet (Mp = 0.2MJup ), most particles withinsufficient initial altitudes in the PPD are isolated from the gas in the accreting region. On the other hand, in thecase of a massive planet (Mp = 1MJup ), dust particles can be coupled to the vertically accreting gas, even when the
dust scale height is about 10 − 30% of the gas scale height. The results of this study can be used for models of dustdelivery and satellite formation in the CPDs of gas giants of various masses, including exoplanets.

17

48. Core to ultracompact HII region evolution in the W49A massive protocluster
T. Nony, R. Galván-Madrid, N. Brouillet, G. Suárez, F. Louvet, C. G. De Pree, M. Juárez-Gama, A. Ginsburg,
K. Immer, Y. Lin, H. B. Liu, C. G. Román-Zúñiga, Q. Zhang ⋆ We aim to identify and characterize cores in thehigh-mass proto-cluster W49, determine their evolutionary stages and measure the associated lifetimes. We built a
catalog of 129 cores extracted from an ALMA 1.3 mm continuum image at 0.26" (2900 au) angular resolution. The
association between cores and Hyper/Ultra Compact HII (H/UC HII) regions was established from the analysis of
VLA 3.3 cm continuum and H30α line observations. We also looked for emission of hot molecular cores (HMCs)
using the methyl formate doublet at 218.29 GHz. We identified 40 cores associated with an H/UC HII region and 19
HMCs over the ALMA mosaic. The 52 cores with an H/UC HII region and/or a HMC are assumed to be high-mass
protostellar cores, while the rest of the core population likely consists in prestellar cores and low-mass protostellar
cores. We found a good agreement between the two tracers of ionized gas, with 23 common detections and only fourcores detected at 3.3 cm and not in H30α. The spectral indexes from 3.3 cm to 1.3 mm range from 1, for the youngest
cores with partially optically thick free-free emission, to about -0.1, that is optically thin free-free emission obtainedfor cores likely more evolved. Using as a reference the H/UC HII regions, we found the statistical lifetimes of the
HMC and massive protostellar phases in W49N to be about 6 × 104 yr and 1.4 × 105 yr, respectively. We also showedthat HMC can co-exist with H/UC HII regions during a short fraction of the core lifetime, about 2 × 104 yr. This
indicates a rapid dispersal of the inner molecule envelope once the HC HII is formed.

49. PROJECT-J: JWST observations of HH46 IRS and its outflow. Overview and first
results
B. Nisini, M. G. Navarro, T. Giannini, S. Antoniucci, P. J. Kavanagh, P. Hartigan, F. Bacciotti, A. Caratti oGaratti, A. Noriega Crespo, E. van Dishoek, E. Whelan, H. G. Arce, S. Cabrit, D. Coffey, D. Fedele, J. Eisloeffel,
M. E. Palumbo, L. Podio, T. P. Ray, M. Schultze, R. G. Urso, J. M. Alcala’, M. A. Bautista, C. Codella, T.
G. Greene, C. F. Manara ⋆ We present the first results of the JWST program PROJECT-J (PROtostellar JEts

Cradle Tested with JWST ), designed to study the Class I source HH46 IRS and its outflow through NIRSpec and
MIRI spectroscopy (1.66 to 28 micron). The data provide line-images ( 6.6" in length with NIRSpec, and up to 20"
with MIRI) revealing unprecedented details within the jet, the molecular outflow and the cavity. We detect, for the
first time, the red-shifted jet within 90 au from the source. Dozens of shock-excited forbidden lines are observed,
including highly ionized species such as [Ne III] 15.5 micron, suggesting that the gas is excited by high velocity (>80 km/s) shocks in a relatively high density medium. Images of H2 lines at different excitations outline a complex
molecular flow, where a bright cavity, molecular shells, and a jet-driven bow-shock interact with and are shaped by theambient conditions. Additional NIRCam 2 micron images resolve the HH46 IRS 110 au binary system and suggestthat the large asymmetries observed between the jet and the H2 wide angle emission could be due to two separate
outflows being driven by the two sources. The spectra of the unresolved binary show deep ice bands and plenty ofgaseous lines in absorption, likely originating in a cold envelope or disk. In conclusion, JWST has unraveled for the
first time the origin of the HH46 IRS complex outflow demonstrating its capability to investigate embedded regions
around young stars, which remain elusive even at near-IR wavelengths.

50. JWST/MIRI detection of suprathermal OH rotational emissions: probing the dissociation of the water by Lyman alpha photons near the protostar HOPS 370
David A. Neufeld, P. Manoj, Himanshu Tyagi, Mayank Narang, Dan M. Watson, S. Thomas Megeath, Ewine F.
Van Dishoeck, Robert A. Gutermuth, Thomas Stanke, Yao-Lun Yang, Adam E. Rubinstein, Guillem Anglada,
Henrik Beuther, Alessio Caratti o Garatti, Neal J. Evans II, Samuel Federman, William J. Fischer, Joel Green,
Pamela Klaassen, Leslie W. Looney, Mayra Osorio, Pooneh Nazari, John J. Tobin, Lukasz Tychoniec, Scott
Wolk ⋆ Using the MIRI/MRS spectrometer on JWST, we have detected pure rotational, suprathermal OH emissions

from the vicinity of the intermediate-mass protostar HOPS 370 (OMC2/FIR3). These emissions are observed fromshocked knots in a jet/outflow, and originate in states of rotational quantum number as high as 46 that possess excitation energies as large as EU /k = 4.65 × 104 K. The relative strengths of the observed OH lines provide a powerful
diagnostic of the ultraviolet radiation field in a heavily-extinguished region (AV ∼ 10 − 20) where direct UV observations are impossible. To high precision, the OH line strengths are consistent with a picture in which the suprathermal
OH states are populated following the photodissociation of water in its B̃ − X band by ultraviolet radiation producedby fast (∼ 80 km s−1 ) shocks along the jet. The observed dominance of emission from symmetric (A′ ) OH states overthat from antisymmetric (A′′ ) states provides a distinctive signature of this particular population mechanism. More18

over, the variation of intensity with rotational quantum number suggests specifically that Lyα radiation is responsible
for the photodissociation of water, an alternative model with photodissociation by a 104 K blackbody being disfavoredat a high level of significance. Using measurements of the Brα flux to estimate the Lyα production rate, we findthat ∼ 4% of the Lyα photons are absorbed by water. Combined with direct measurements of water emissions in theν2 = 1 − 0 band, the OH observations promise to provide key constraints on future models for the diffusion of Lyαphotons in the vicinity of a shock front.

SOFIA/HAWC+ Far-Infrared Polarimetric Large-Area CMZ Exploration (FIREPLACE)
51. Survey III: Full Survey Data Set
Dylan Paré, Natalie O. Butterfield, David T. Chuss, Jordan A. Guerra, Jeffrey I. Iuliano, Kaitlyn Karpovich,Mark R. Morris, Edward Wollack ⋆ We present the second data release (DR2) of the Far-Infrared Polarimetric

Large-Area CMZ Exploration (FIREPLACE) survey. This survey utilized the Stratospheric Observatory for Infrared
Astronomy (SOFIA) High-resolution Airborne Wideband Camera plus (HAWC+) instrument at 214 µm (E-band) toobserve dust polarization throughout the Central Molecular Zone (CMZ) of the Milky Way. DR2 consists of observations that were obtained in 2022 covering the region of the CMZ extending roughly from the Brick to the Sgr C
molecular clouds (corresponding to a roughly 1◦ × 0.75◦ region of the sky). We combine DR2 with the first FIREPLACE data release to obtain full coverage of the CMZ (a 1.5◦ ×0.75◦ region of the sky). After applying total andpolarized intensity significance cuts on the full FIREPLACE data set we obtain ∼65,000 Nyquist-sampled polarization
pseudovectors. The distribution of polarization pseudovectors confirms a bimodal distribution in the CMZ magnetic
field orientations, recovering field components that are oriented predominantly parallel or perpendicular to the Galactic plane. These magnetic field orientations indicate possible connections between the previously observed parallel andperpendicular distributions. We also inspect the magnetic fields toward a set of prominent CMZ molecular clouds (theBrick, Three Little Pigs, 50 km s−1 , Circum-nuclear Disk, CO 0.02-0.02, 20 km s−1 , and Sgr C), revealing spatiallyvarying magnetic fields that generally trace the morphologies of the clouds. We find evidence that compression fromstellar winds and shear from tidal forces are prominent mechanisms influencing the structure of the magnetic fields
observed within the clouds.

52. Probing the eccentricity in protostellar discs – Modeling kinematics and morphologies
Enrico Ragusa, Elliot Lynch, Guillaume Laibe, Cristiano Longarini, Simone Ceppi ⋆ Protostellar discs are mostly

modelled as circular structures of gas and dust orbiting a protostar. However, a number of physical mechanisms, e.g.
the presence of a (sub)stellar companion or initial axial asymmetry, can cause the gas and dust orbital motion to become
eccentric. Theoretical studies have revealed that, when present, disc eccentricity is expected to occur with predictableprofiles that can be long-lasting and potentially observable in protostellar systems. We construct an analytical model
predicting the typical features of the kinematics and morphology of eccentric protostellar discs, with the final goal ofcharacterising the observational appearance of eccentricity in discs. We validate the model using a numerical simulationof a circumbinary disc (where the binary makes the disc eccentric). We finally post-process the simulation with Monte
Carlo Radiative Transfer to study how eccentric features would appear through the "eyes" of ALMA. Besides the
motion of the material on eccentric Keplerian orbits in the disc orbital plane, the most characteristic eccentric featureemerging from the analytical model is strong vertical motion with a typical anti-symmetric pattern (with respect tothe disc line of pericentres). A circumbinary disc with a ≈ 40 au eccentric cavity (ecav = 0.2), carved by an abin = 15
au binary, placed at a distance d = 130 pc, is expected to host in its upper emission surface vertical oscillations up tovz ∼ 400 ms−1 close to the cavity edge, i.e. well within ALMA spectral and spatial resolution capabilities. A residual
spiral pattern in the vertical velocity ∆vz ∼ 150 ms−1 of the simulation cannot be captured by the theoretical model,
we speculate it to be possibly linked to the presence of a companion in the system.

53. Quasi-equilibrium chemical evolution in starless cores
Jonathan Rawlings, Eric Keto, Paola Caselli ⋆ The chemistry of H2O, CO and other small molecular species in

an isolated pre-stellar core, L1544, has been assessed in the context of a comprehensive gas-grain chemical model,
coupled to an empirically constrained physical/dynamical model. Our main findings are (i) that the chemical network
remains in near equilibrium as the core evolves towards star formation and the molecular abundances change in
response to the evolving physical conditions. The gas-phase abundances at any time can be calculated accurately withequilibrium chemistry, and the concept of chemical clocks is meaningless in molecular clouds with similar conditions

19and dynamical time scales, and (ii) A comparison of the results of complex and simple chemical networks indicatesthat the abundances of the dominant oxygen and carbon species, H2O, CO, C, and C+ are reasonably approximatedby simple networks. In chemical equilibrium, the time-dependent differential terms vanish and a simple network
reduces to a few algebraic equations. This allows rapid calculation of the abundances most responsible for spectralline radiative cooling in molecular clouds with long dynamical time scales. The dust ice mantles are highly structured
and the ice layers retain a memory of the gas-phase abundances at the time of their deposition. A complex (gas-phaseand gas-grain) chemical structure therefore exists, with cosmic-ray induced processes dominating in the inner regions.
The inferred H2O abundance profiles for L1544 require that the outer parts of the core and also any medium exterior
to the core are essentially transparent to the interstellar radiation field.

54. Unveiling very young O stars. Two Galactic O2V((f*))z in Westerlund 2
A. Roman-Lopes ⋆ O-type stars are known to significantly contribute to both the dynamics and evolution of galaxies.

Massive and luminous, they probably control and regulate the galaxies star formation rates. For this work I performed
a redetermination of the spectral types and effective temperatures of the Galactic O-type stars MSP182, MSP183,
MSP199, VPHAS-01338, and VPHAS-01273. From a careful examination of the spectral features present in the blue
optical spectral region, it was possible to identify several nitrogen lines usually only seen in the blue optical spectra of
O2-O3 stars. From the nitrogen ionic equivalent width ratios measured in the spectra of MSP182, MSP183, MSP199,
VPHAS-01338, and VPHAS-01273, and in those of standard stars of the O2-O4 spectral types, earlier spectral types
and hotter effective temperature values were derived. Two O2V, together with three new O3V stars, are now firmly
identified in the Westerlund 2 region. Besides RFS1 in NGC3603, the O2 stars found in Westerlund 2 are the only
other exemplars known to date in the Milky Way. From the nitrogen equivalent width line ratios measured in the
spectra of standard stars of the O2-O4 spectral types, linear relations between the NIV4058-NIII4640 ratio and theeffective temperature in the 47000K-51000K range were derived. Based on my spectroscopic analysis of the sciencetargets and the use of a HRD, a mean heliocentric distance of 5kpc to Westerlund 2 was computed, a result thatis in line with the mean heliocentric distance of 5.3(1.5) kpc obtained from the associated Gaia DR3 parallaxes anddistances. The Westerlund 2 massive stars studied in this work probably share a common evolutionary process thatmight be representative of the evolutionary ages of a large fraction of the cluster’s O-type stellar population, which
seems to be much younger than 1 Myrs.

Accretion Funnel Reconfiguration during an Outburst in a Young Stellar Object: EX
55. Lupi
Koshvendra Singh, Joe P. Ninan, Marina M. Romanova, David A. H. Buckley, Devendra K. Ojha, Arpan
Ghosh, Andrew Monson, Malte Schramm, Saurabh Sharma, Daniel E. Reichart, Joanna Mikolajewska, Juan
Carlos Beamin, J. Borissova, Valentin D. Ivanov, Vladimir V. Kouprianov, Franz-Josef Hambsch, Andrew
Pearce ⋆ EX Lupi, a low-mass young stellar object, went into an accretion-driven outburst in March of 2022. The

outburst caused a sudden phase change of 112◦ ± 5◦ in periodically oscillating multiband lightcurves. Our highresolution spectra obtained with HRS on SALT also revealed a consistent phase change in the periodically varying
radial velocities, along with an increase in the radial velocity amplitude of various emission lines. The phase change andincrease of radial velocity amplitude morphologically translates to a change in the azimuthal and latitudinal location of
the accretion hotspot over the stellar surface, which indicates a reconfiguration of the accretion funnel geometry. Our
3D MHD simulations reproduce the phase change for EX Lupi. To explain the observations we explored the possibilityof forward shifting of the dipolar accretion funnel as well as the possibility of an emergence of a new accretion funnel.
During the outburst, we also found evidence of the hotspot’s morphology extending azimuthally, asymmetrically witha leading hot edge and cold tail along the stellar rotation. Our high cadence photometry showed that the accretion
flow has clumps. We also detected possible clumpy accretion events in the HRS spectra, that showed episodicallyhighly blue-shifted wings in the Ca II IRT and Balmer H lines.

on PDS 70 b and c from the dust continuum emission of the circumplanetary
56. Constraints
discs considering in situ dust evolution
Yuhito Shibaike, Christoph Mordasini ⋆ The young T Tauri star PDS 70 has two gas accreting planets sharing
one large gap in a pre-transitional disc. Dust continuum emission from PDS 70 c has been detected by Atacama
Large Millimeter/submillimeter Array (ALMA) Band 7, considered as the evidence of a circumplanetary disc, but the20

emission from PDS 70 b has not. We constrain the planet mass and the gas accretion rate of the planets by introducing
a model of dust evolution in the CPDs and reproducing the detection and non-detection. We first develop a 1D steadygas disc model of the CPDs reflecting the planet properties. We then calculate the radial distribution of the dust
profiles considering the dust evolution in the gas disc and calculate the total flux density of dust thermal emission
from the CPDs. We find positive correlations between the flux density and three planet properties, the planet mass,
gas accretion rate, and their product called "MMdot". We then find that the MMdot of PDS 70 c is larger than 0.4
MJ2 /Myr, and the planet mass and the gas accretion rate are larger than 5MJ and 0.02 MJ/Myr, respectively. This is
the first case to succeed in obtaining constraints on planet properties from the flux density of dust continuum from a
CPD. We also find some loose constraints on the properties of PDS 70 b from the non-detection. We propose possible
scenarios for the planets explaining the non-detection respectively detection of the dust emission. The first explanationis that planet c has larger planet mass and/or larger gas accretion rate than planet b. The other possibility is that
the CPD of planet c has a larger amount of dust supply and/or weaker turbulence than that of planet b. If the dust
supply to planet c is larger than b due to its closeness to the outer dust ring, it is also quantitatively consistent withthat planet c has weaker H-alpha line emission than planet b considering the dust extinction effect.

57. JWST detections of amorphous and crystalline HDO ice toward massive protostars
Katerina Slavicinska, Ewine F. van Dishoeck, Łukasz Tychoniec, Pooneh Nazari, Adam E. Rubinstein, Robert
Gutermuth, Himanshu Tyagi, Yuan Chen, Nashanty G. C. Brunken, Will R. M. Rocha, P. Manoj, Mayank
Narang, S. Thomas Megeath, Yao-Lun Yang, Leslie W. Looney, John J. Tobin, Henrik Beuther, Tyler L.
Bourke, Harold Linnartz, Samuel Federman, Dan M. Watson, Hendrik Linz ⋆ This work aims to utilize theincreased sensitivity and resolution of the JWST to quantify the HDO/H2 O ratio in ices toward young stellar objects(YSOs) and to determine if the HDO/H2 O ratios measured in the gas phase toward massive YSOs (MYSOs) arerepresentative of the ratios in their ice envelopes. Two protostars observed in the Investigating Protostellar Accretion(IPA) program using JWST NIRSpec were analyzed: HOPS 370, an intermediate-mass YSO (IMYSO), and IRAS
20126+4104, a MYSO. The HDO ice toward these sources was detected above the 3σ level and quantified via its 4.1µm band. The contributions from the CH3 OH combination modes to the observed optical depth in this spectral region
were constrained via the CH3 OH 3.53 µm band to ensure that the integrated optical depth of the HDO feature was
not overestimated. H2 O ice was quantified via its 3 µm band. From these fits, ice HDO/H2 O abundance ratios of
4.6±1.8×10−3 and 2.6±1.2×10−3 are obtained for HOPS 370 and IRAS 20126+4104, respectively. The simultaneous
detections of both crystalline HDO and crystalline H2 O corroborate the assignment of the observed feature at 4.1 µm
to HDO ice. The ice HDO/H2 O ratios are similar to the highest reported gas HDO/H2 O ratios measured toward
MYSOs as well as the hot inner regions of isolated low-mass protostars, suggesting that at least some of the gas
HDO/H2 O ratios measured toward massive hot cores are representative of the HDO/H2 O ratios in ices. The need foran H2 O-rich CH3 OH component in the CH3 OH ice analysis supports recent experimental and observational resultsthat indicate that some CH3 OH ice may form prior to the CO freeze-out stage in H2 O-rich ice layers.

A broken debris cascade as a possible source of hot dust emission in transitioning planet58. forming disks
Niels Swinkels, Carsten Dominik ⋆ Planet-forming disks turn from gas-rich, massive disks made of dust and gas

into planetary systems containing only small amounts dust produced by collisions between smaller planetary objects
like planetesimals, asteroids, or comets. Traditionally we talk about protoplanetary (age ∼1 Myr), transitional (∼5-10 Myr), and debris disks (∼ 10-hundreds of Myr), even though the overlap between these phases may be relevant.
We aim to show that in the transition phase of a disk, when gas surface densities are reduced but not yet negligible,
a seemingly small amount of collisional activity may lead to the production of dust on a level that is observationally
relevant by creating regions of optical depth 1 or above. In particular, we aim to show that the hot dust emission
component of transitional disks may in fact be debris dust produced in such collisions. We develop an analytical model
to derive the conditions under which observationally relevant amounts of dust can be produced. We focus on the effectof the gas surface density during the transition phase of a disk from fully gas-dominated to the gas-poor debris stage.
We show that the decrease of the gas surface density has an important effect. It allows smaller planetesimals to become
collisional, starting a cascade. At the same time, small particles are not destroyed by collisions. That interrupted
cascade is critical to preserve the produced dust for significant time intervals, allowing a seemingly minor amount ofplanetesimal collisions to be effective in producing detectable amounts of dust. The warm emission of low amounts ofdust in many transitional planet-forming disks might be caused entirely by second-generation dust, exposing planetary21

material at a time much earlier than the age of what are traditionally considered as debris disks.

The Nature of X-Rays from Young Stellar Objects in the Orion Nebula Cluster – A
59. Chandra HETGS Legacy Project
Norbert S. Schulz, David P. Huenemoerder, David A. Principe, Marc Gagne, Hans Moritz Günther, Joel
Kastner, Joy Nichols, Andrew Pollock, Thomas Preibisch, Paola Testa, Fabio Reale, Fabio Favata, Claude R.
Canizares ⋆ The Orion Nebula Cluster (ONC) is the closest site of very young (∼ 1 Myrs) massive star formation.

The ONC hosts more than 1600 young and X-ray bright stars with masses ranging from ∼ 0.1 to 35 M⊙ . The Chandra
HETGS Orion Legacy Project observed the ONC with the Chandra high energy transmission grating spectrometer(HETGS) for 2.1 Ms. We describe the spectral extraction and cleaning processes necessary to separate overlapping
spectra. We obtained 36 high resolution spectra which includes a high brilliance X-ray spectrum of θ1 Ori C with over
100 highly significant X-ray lines. The lines show Doppler broadening between 300 and 400 km s−1 . Higher spectral
diffraction orders allow us to resolve line components of high Z He-like triplets in θ1 Ori C with unprecedented spectral
resolution. Long term light curves spanning ∼20 years show all stars to be highly variable, including the massive stars.
Spectral fitting with thermal coronal emission line models reveals that most sources show column densities of up to a
few times 1022 cm−2 and high coronal temperatures of 10 to 90 MK. We observe a bifurcation of the high temperaturecomponent where some stars show a high component of 40 MK, while others show above 60 MK indicating heavy flaring
activity. Some lines are resolved with Doppler broadening above our threshold of ∼ 200 km s−1 , up to 500 km s−1 .
This data set represents the largest collection of HETGS high resolution X-ray spectra from young pre-MS stars in asingle star-forming region to date.

60. FAUST XV. A disk wind mapped by CH3 OH and SiO in the inner 300 au of the NGC
1333 IRAS 4A2 protostar
M. De Simone, L. Podio, L. Chahine, C. Codella, C. J. Chandler, C. Ceccarelli, A. Lopez-Sepulcre, L. Loinard,
B. Svoboda, N. Sakai, D. Johnstone, F. Menard, Y. Aikawa, M. Bouvier, G. Sabatini, A. Miotello, C. Vastel,
N. Cuello, E. Bianchi, P. Caselli, E. Caux, T. Hanawa, E. Herbst, D. Segura-Cox, Z. Zhang, S. Yamamoto ⋆Context. Understanding the connection between outflows, winds, accretion and disks in the inner protostellar regions
is crucial for comprehending star and planet formation process. Aims. We aim to we explore the inner 300 au of the
protostar IRAS 4A2 as part of the ALMA FAUST Large Program. Methods. We analysed the kinematical structuresof SiO and CH3 OH emission with 50 au resolution. Results. The emission arises from three zones: i) a very compact
and unresolved region (<50 au) dominated by the ice sublimation zone, at ±1.5 km s−1 with respect to vsys, traced
by methanol; ii) an intermediate region (between 50 au and 150 au) traced by both SiO and CH3 OH, between 2 and 6
km s−1 with respect to vsys, with an inverted velocity gradient (with respect to the large scale emission), whose origin
is not clear; iii) an extended region (>150 au) traced by SiO, above 7 km s−1 with respect to vsys, and dominated by
the outflow. In the intermediate region we estimated a CH3 OH/SiO abundance ratio of about 120-400 and a SiO/H2
abundance of 10−8 . We explored various possibilities to explain the origin of this region such as, rotating disk/innerenvelope, jet on the plane of the sky/precessing, wide angle disk wind. Conclusions. We propose that CH3 OH andSiO in the inner 100 au probe the base of a wide-angle disk wind. The material accelerated in the wind crosses theplane of the sky, giving rise to the observed inverted velocity gradient, and sputtering the grain mantles and cores
releasing CH3 OH and SiO. This is the first detection of a disk wind candidate in SiO, and the second ever in CH3 OH.

Discovery of thionylimide, HNSO, in space: the first N-, S- and O-bearing interstellar
61. 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 ⋆ 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 and22

SO2, 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.

62. Kinematics & Star Formation in the Hub-Filament System G6.55-0.1
Saurav Sen, Bhaswati Mookerjea, Rolf Guesten, Friedrich Wyrowski, C. H Ishwara Chandra ⋆ Hub-filament
systems (HFSs) being the potential sites of formation of star clusters and high mass stars, provide a test bed for thecurrent theories that attempt to explain star formation globally. It is thus important to study a large number of HFSs
using both intensity and velocity information to constrain these objects better observationally. We present here a studyof the hub-filament system associated with G6.55-0.1 using newly obtained observations of radio continuum and J=2–1
transition of CO, 13 CO, and C18 O. The radio continuum maps show multiple peaks that coincide with far-infrared dust
continuum peaks indicating the presence of more than one young massive stars in the hub of the HFS. We used thevelocity information from the C18 O(2–1) map to (a) show that the source G6.55-0.1 is not physically associated with
the SNR W28 and (b) disentangle and identify the velocity components genuinely associated with G6.55-0.1. Amongthe velocity-coherent structures identified, the two filaments at 13.8 and 17.3 km s−1 contribute a total mass accretion
rate of ∼3000 M⊙ Myr−1 to the hub. Both the filaments also show V-shaped structure, characteristic of gravitational
collapse, in their velocity profile at the location of the hub. Estimated mass per unit length of the segments of thefilaments are smaller than the critical line masses derived from virial equilibrium considerations. This suggests thatwhile the filaments are not gravitationally collapsing as a whole, the spectra from the hub indicate that the inner parts
are dynamically decoupled and collapsing to form stars.

63. First detection of the [CII] 158 micron line in the intermediate-velocity cloud Draco
N. Schneider, V. Ossenkopf-Okada, E. Keilmann, M. Roellig, S. Kabanovic, L. Bonne, T. Csengeri, B. Klein,
R. Simon, F. Comeron ⋆ High-latitude intermediate-velocity clouds (IVCs) are part of the Milky Way’s HI halo andoriginate from either a galactic fountain process or extragalactic gas infall. They are partly molecular and can mostof the time be identified in CO. Some of these regions also exhibit high-velocity cloud (HVC) gas, which is mostly
atomic, and gas at local velocities (LVCs), which is partly atomic and partly molecular. We conducted a study on the
IVCs Draco and Spider, both were exposed to a very weak UV field, using the receiver upGREAT on SOFIA. The 158
micron line of ionized carbon (CII) was observed, and the results are as follows: In Draco, the CII line was detected atintermediate velocities (but not at local or high velocities) in four out of five positions. No CII emission was found at
any velocity in the two observed positions in Spider. To understand the excitation conditions of the gas in Draco, we
analyzed complementary CO and HI data as well as dust column density and temperature maps from Herschel. The
observed CII intensities suggest the presence of shocks in Draco that heat the gas and subsequently emit in the CII
cooling line. These shocks are likely caused by the fast cloud’s motion toward the Galactic plane that is accompaniedby collisions between HI clouds. The nondetection of CII in the Spider IVC and LVC as well as in other low-density
clouds at local velocities that we present in this paper (Polaris and Musca) supports the idea that highly dynamic
processes are necessary for CII excitation in UV-faint low-density regions.

64. Gas kinematics and dynamics of Carina Pillars: A case study of G287.76-0.87
Ngo-Duy Tung, Le Ngoc Tram, Archana Soam, William T. Reach, Edwin Das, Ed Chambers, Blesson Mathew⋆ We study the kinematics of a pillar, namely G287.76-0.87, using three rotational lines of 12 CO(5-4), 12 CO(8-7),
CO(11-10), and a fine structure line of [OI] 63 µm Southern Carina observed by SOFIA/GREAT. This pillar isirradiated by the associated massive star cluster Trumpler 16, which includes η Carina. Our analysis shows that therelative velocity of the pillar with respect to this ionization source is small, ∼ 1 km s−1 , and the gas motion in the tailis more turbulent than in the head. We also performed analytical calculations to estimate the gas column density inlocal thermal equilibrium (LTE) conditions, which yields NCO as (∼ 0.2 − 5) × 1017 cm−2 . We further constrain thegas’s physical properties in non-LTE conditions using RADEX. The non-LTE estimations result in nH2 ≃ 105 cm−3
and NCO ≃ 1016 cm−2 . We found that the thermal pressure within the G287.76-0.87 pillar is sufficiently high to makeit stable for the surrounding hot gas and radiation feedback if the winds are not active. While they are active, stellar
winds from the clustered stars sculpt the surrounding molecular cloud into pillars within the giant bubble aroundη Carina.
12

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65. Orbital dynamics in the GG Tau A system: investigating its enigmatic disc
Claudia Toci, Simone Ceppi, Nicolás Cuello, Gaspard Duchêne, Enrico Ragusa, Giuseppe Lodato, Francesca
Farina, François Ménard, Hossam Aly ⋆ GG Tau is one of the most studied multiple young stellar systems: GG Tau

A is a hierarchical triple surrounded by a massive disc and its companion, GG Tau B, is also a binary. Despite numerous
observational attempts, an understanding of the geometry of the GG Tau A system is still elusive. We provide new
astrometric measures of the system and we run a set of hydrodynamical simulations with two representative orbits
to test how they impact a disc composed of dust and gas. We test the dynamical evolution of the two scenarios on
short and long timescales. We obtain synthetic flux emission from our simulations and we compare them with 1300
µm ALMA dust continuum emission and 1.67 µm SPHERE dust scattering images to infer the most likely orbital
arrangement. We extend the analysis of the binary orbital parameters using six new epochs from archival data, showingthat the current measurements alone are not capable of breaking the degeneracy between families of coplanar andmisaligned orbits. We found that the time-scale for the onset of the disc eccentricity growth, τecc , is a fundamental
time-scale for the morphology of the system. Results from numerical simulations show that the best match between
is obtained with the misaligned configuration (∆θ = 30◦ ) on timescales shorter than τecc . The results exhibit analmost circular cavity and dust ring. However, for both scenarios, the cavity size and its eccentricity quickly grow fortimescales longer than τecc and the models do not reproduce the observed morphology anymore. This implies thateither the age of the system is shorter than τecc or that the disc eccentricity growth is not triggered or dissipated. Thisfinding raises questions on the future evolution of the GG Tau A system and, more in general, on the time evolutionof eccentric binaries and their circumbinary discs.

Internal 1000 AU-scale Structures of the R CrA Cluster-forming Cloud – I: Filamentary
66. Structures
Kengo Tachihara, Naofumi Fukaya, Kazuki Tokuda, Yasumasa Yamasaki, Takeru Nishioka, Daisei Abe, Tsuyoshi
Inoue, Naoto Harada, Ayumu Shoshi, Shingo Nozaki, Asako Sato, Mitsuki Omura, Kakeru Fujishiro, Misato
Fukagawa, Masahiro N. Machida, Takahiro Kanai, Yumiko Oasa, Toshikazu Onishi, Kazuya Saigo, Yasuo Fukui⋆ We report on ALMA ACA observations of a high-density region of the Corona Australis cloud forming a young starcluster, and the results of resolving internal structures. In addition to embedded Class 0/I protostars in continuum,
a number of complex dense filamentary structures are detected in the C18O and SO lines by the 7m array. These are
sub-structures of the molecular clump that are detected by the TP array as the extended emission. We identify 101 and37 filamentary structures with a few thousand AU widths in C18O and SO, respectively, called as feathers. The typicalcolumn density of the feathers in C18O is about 1022 cm−2 , and the volume density and line mass are 105 cm−3 ,and a few times Msun pc−1 , respectively. This line mass is significantly smaller than the critical line mass expected
for cold and dense gas. These structures have complex velocity fields, indicating a turbulent internal property. The
number of feathers associated with Class 0/I protostars is only 10, indicating that most of them do not form stars
but rather being transient structures. The formation of feathers can be interpreted as a result of colliding gas flow as
the morphology well reproduced by MHD simulations, supported by the the presence of HI shells in the vicinity. The
colliding gas flows may accumulate gas and form filaments and feathers, and trigger the active star formation of the
R CrA cluster.

Co-evolution of dust grains and protoplanetary disks II: structure and evolution of
67. protoplanetary disks; an analytical approach
Yusuke Tsukamoto ⋆ In our previous study (Tsukamoto et al. 2023), we investigated formation and early evolutionof protoplanetary disks with 3D non-ideal magnetohydrodynamics simulations considering dust growth, and foundthat the modified equations of the conventional steady accretion disk model which consider the magnetic braking,dust growth and ambipolar diffusion reproduce the disk structure obtained from simulations very well. In this paper,
as a sequel of the our previous study, we analytically investigate the structure and evolution of protoplanetary disks
corresponding to Class 0/I young stellar objects using the modified steady accretion disk model combining an analyticalmodel of envelope accretion. We estimate that the disk radius is several AU at disk formation epoch and increases toseveral 100 AU at the end of the accretion phase. The disk mass is estimated to be 0.01M⊙ ≲ Mdisk ≲ 0.1M⊙ for a disk
with radius of several 10 AU and mass accretion rate of Ṁdisk ∼ 10−6 M⊙ yr−1 . We also found that, with typical disk
ionization rates and moderate mass accretion rate (Ṁdisk ≳ 10−8 M⊙ yr−1 ), magneto-rotational instability is suppressedin the disk because of low plasma β and efficient ambipolar diffusion. We argue that the radial profile of specific angularmomentum (or rotational velocity) at the disk outer edge should be continuously connected to that of the envelope if

24the disk evolves by magnetic braking, and should be discontinuous if the disk evolves by internal angular momentum
transport process such as gravitational instability or magneto-rotational instability. Future detailed observations of thespecific angular momentum profile around the disk outer edge are important for understanding the angular momentum
transport mechanism of protoplanetary disks.

The First Estimation of the Ambipolar Diffusivity Coefficient from Multi-Scale Obser68. vations of the Class 0/I Protostar, HOPS-370
Travis J. Thieme, Shih-Ping Lai, Yueh-Ning Lee, Sheng-Jun Lin, Hsi-Wei Yen ⋆ Protostars are born in mag-netized environments. As a consequence, the formation of protostellar disks can be suppressed by the magnetic fieldefficiently removing angular momentum of the infalling material. Non-ideal MHD effects are proposed to as one way toallow protostellar disks to form. Thus, it is important to understand their contributions in observations of protostellar
systems. We derive an analytical equation to estimate the ambipolar diffusivity coefficient at the edge of the protostellar disk in the Class 0/I protostar, HOPS-370, for the first time, under the assumption that the disk radius is set by
ambipolar diffusion. Using previous results of the protostellar mass, disk mass, disk radius, density and temperature19
2 −1
profiles and magnetic field strength, we estimate the ambipolar diffusivity coefficient to be 1.7+1.5.
−1.4 × 10 cm s
We quantify the contribution of ambipolar diffusion by estimating its dimensionless Elsässer number to be ∼ 1.7+1.0−1.0 ,
indicating its dynamical importance in this region. We compare to chemical calculations of the ambipolar diffusivity
coefficient using the Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library (NICIL), which is consistent
with our results. In addition, we compare our derived ambipolar diffusivity coefficient to the diffusivity coefficients for
Ohmic dissipation and the Hall effect, and find ambipolar diffusion is dominant in our density regime. These results
demonstrate a new methodology to understand non-ideal MHD effects in observations of protostellar disks. Moredetailed modeling of the magnetic field, envelope and microphysics, along with a larger sample of protostellar systems
is needed to further understand the contributions of non-ideal MHD.

69. Evidence of grain alignment by magnetically enhanced radiative torques from multiwavelength dust polarization modeling of HL Tau
Thang Nguyen Tat, Pham Ngoc Diep, Thiem Hoang, Le Ngoc Tram, Nguyen Bich Ngoc, Nguyen Thi Phuong,
Bao Truong ⋆ Atacama Large Millimeter/Submillimeter Array (ALMA) has revolutionized the field of dust polar-

ization in protoplanetary disks across multiple wavelengths. Previous observations and empirical modeling suggested
multiple mechanisms of dust polarization toward HL Tau, including grain alignment and dust scattering. However, adetailed modeling of dust polarization based on grain alignment physics is not yet available. Here, using our updated
POLARIS code, we perform numerical modeling of dust polarization arising from both grain alignment by MagneticallyEnhanced Radiative Torque (MRAT) mechanism and self-scattering to reproduce the HL Tau polarization observed atthree wavelengths 0.87, 1.3, and 3.1 mm. Our modeling results show that the observed multi-wavelength polarization
could be reproduced only when large grains contain embedded iron inclusions and those with slow internal relaxationmust have wrong internal alignment (i.e., the grain’s major axis parallel to its angular momentum). The abundanceof iron embedded inside grains in the form of clusters is constrained to be ≳ 16%, and the number of iron atoms per
cluster is Ncl ∼ 9 × 102 . Maximum grain sizes probed at wavelengths λ = 0.87, 1.3, and 3.1 mm are constrained at ∼60, 80, and 90 µm, respectively.

Probing the Physics of Star-Formation (ProPStar): II. The first systematic search for
70. streamers toward protostars
María Teresa Valdivia-Mena, Jaime E. Pineda, Paola Caselli, Dominique M. Segura-Cox, Anika Schmiedeke,
Silvia Spezzano, Stella Offner, Alexei V. Ivlev, Michael Küffmeier, Nichol Cunningham, Roberto Neri, María
José Maureira ⋆ The detection of narrow channels of accretion toward protostellar disks, known as streamers, haveincreased in number in the last few years. However, it is unclear if streamers are a common feature around protostars
that were previously missed, or if they are a rare phenomenon. Our goals are to obtain the incidence of streamers
toward a region of clustered star formation and to trace the origins of their gas, to determine if they originate within
the filamentary structure of molecular clouds or from beyond. We used combined observations of the nearby NGC 1333
star-forming region, carried out with the NOEMA interferometer and the IRAM 30m single dish. Our observations
cover the area between the IRAS 4 and SVS 13 systems. We traced the chemically fresh gas within NGC 1333 with
HC3N molecular gas emission and the structure of the fibers in this region with N2H+ emission. We fit multiple

25

velocity components in both maps and used clustering algorithms to recover velocity-coherent structures. We findstreamer candidates toward 7 out of 16 young stellar objects within our field of view. This represents an incidence ofapproximately 40% of young stellar objects with streamer candidates when looking at a clustered star forming region.
The incidence increases to about 60% when we considered only embedded protostars. All streamers are found in
HC3N emission. Given the different velocities between HC3N and N2H+ emission, and the fact that, by construction,
N2H+ traces the fiber structure, we suggest that the gas that forms the streamers comes from outside the fibers. Thisimplies that streamers can connect cloud material that falls to the filaments with protostellar disk scales.

Primordial dust rings, hidden dust mass, and the first generation of planetesimals in
71. gravitationally unstable protoplanetary disks
Eduard I. Vorobyov, Aleksandr M. Skliarevskii, Manuel Guedel, Tamara Molyarova ⋆ Aims. A new mechanismof dust accumulation and planetesimal formation in a gravitationally unstable disk with suppressed magnetorotational
instability is studied and compared with the classical dead zone in a layered disk model. Methods. We use numericalhydrodynamics simulations in the thin-disk limit FEOSAD code to model the formation and long-term evolutionof gravitationally unstable disks, including dust dynamics and growth. Results. We found that in gravitationallyunstable disks with a radially varying strength of gravitational instability a region of low mass and angular momentum
transport forms in the inner several astronomical units. This region is characterized by low effective αfGI and is similar
in characteristics to the dead zone in the layered disk model. As the disk forms and evolves, the GI-induced dead zone
accumulates a massive dust ring, which is susceptible to the development of the streaming instability. The model andobservationally inferred dust masses and radii may differ significantly in gravitationally unstable disks with massive
inner dust rings. Conclusions. The early occurrence of the GI-induced dust ring followed by the presumed developmentof the streaming instability suggest that this mechanism may form the first generation of planetesimals in the innerterrestrial zone of the disk. The proposed mechanism, however, crucially depends on the susceptibility of the disk togravitational instability and requires that the magnetorotational instability be suppressed.

72. CAI formation in the early Solar System
P. Woitke, J. Drażkowska, H. Lammer, K. Kadam, P. Marigo ⋆ Ca-Al-rich inclusions (CAIs) are the oldest dated

solid materials in the solar system, found as light-coloured crystalline ingredients in meteorites. Their formation time
is commonly associated with age zero of the Solar System. Yet, the physical and chemical processes that once led
to the formation of these sub-millimetre to centimetre-sized mineral particles in the early solar nebula are still amatter of debate. This paper proposes a pathway to form such inclusions during the earliest phases of disc evolution.
We combine 1D viscous disc evolutionary models with 2D radiative transfer, equilibrium condensation, and new
dust opacity calculations. We show that the viscous heating associated with the high accretion rates in the earliest
evolutionary phases causes the midplane inside of about 0.5 au to heat up to limiting temperatures of about 1500-1700
K, but no further. These high temperatures force all refractory material components of the inherited interstellar
dust grains to sublimate - except for a few Al-Ca-Ti oxides such as Al2O3, Ca2Al2SiO7, and CaTiO3. Once the
Mg-Fe silicates are gone, the dust becomes more transparent and the heat is more efficiently transported to the discsurface, which prevents any further warm-up. This thermostat mechanism keeps these minerals above their annealing
temperature for hundreds of thousands of years, which creates large, pure and crystalline particles. These particles
are dragged out by the viscously spreading disc. Beyond about 0.5 au, the silicates re-condense on the Ca-Al-richparticles, adding an amorphous silicate matrix. We estimate that this mechanism to produce CAIs works during thefirst 50000 years of disc evolution. These particles then continue to move outward and populate the entire disc up
to radii of about 50 au, before, eventually, the accretion rate subsides, the disc cools, and the particles start to drift
inwards.

73. Terrestrial planet formation from a ring: long-term simulations accounting for the giant
planet instability
J. M. Y. Woo, D. Nesvorny, J. Scora, A. Morbidelli ⋆ The process leading to the formation of the terrestrial

planet remains elusive. In a previous publication, we have shown that, if the first generation of planetesimals forms
in a ring at about 1 AU and the gas disk’s density peaks at the ring location, planetary embryos of a few martianmasses can grow and remain in the ring. In this work, we extend our simulations beyond the gas-disk stage, covering
200 Myr and accounting for the phase of giant planet instability, assumed to happen at different times. About half26

of the simulations form a pair of Venus and Earth analogues and, independently, about 10% form a Mars analogue.
We find that the timing of the giant planet instability affects statistically the terrestrial system’s excitation state andthe timing of the last giant impacts. Hence a late instability (about 60 to 100 Myr after the Solar system’s birth)
is more consistent with a late Moon-formation time, as suggested by radioactive chronometers. However, the lateveneer mass (LVM: mass accreted after the last giant impact) of Earth-sized planets suffering a giant impact after 80
My is usually an order of magnitude lower than the value inferred from geochemistry. In addition, the final angularmomentum deficit (AMD) of the terrestrial planets tends to be too high. We tested the effect on the final AMD of thegeneration of debris during collisions and found that it is too small to change these conclusions. We argue that thebest-case scenario is that the Moon-forming event occurred between 50 and 80 My, possibly just following the giant
planet instability.

ALMA 2D Super-resolution Imaging of Taurus-Auriga Protoplanetary Disks: Probing
74. Statistical Properties of Disk Substructures
Masayuki Yamaguchi, Takayuki Muto, Takashi Tsukagoshi, Hideko Nomura, Naomi Hirano, Takeshi Nakazato,
Shiro Ikeda, Motohide Tamura, Ryohei Kawabe ⋆ In the past decade, ALMA observations of protoplanetary disks

revealed various substructures including gaps and rings. Their origin may be probed through statistical studies on
the physical properties of the substructures. We present the analyses of archival ALMA Band 6 continuum data of
43 disks (39 Class II and 4 Herbig Ae) in the Taurus-Auriga region. We employ a novel 2D super-resolution imaging
technique based on sparse modeling to obtain images with high fidelity and spatial resolution. As a result, we haveobtained images with spatial resolutions comparable to a few au (0′′ .02 − 0′′ .1), which is two to three times better
than conventional CLEAN methods. All dust disks are spatially resolved, with the radii ranging from 8 to 238 au
with a median radius of 45 au. Half of the disks harbor clear gap structures, whose radial locations show a bimodal
distribution with peaks at ≲ 20 au and ≳ 30 au. We also see structures indicating weak gaps at all the radii in the disk.
We find that the widths of these gaps increase with their depths, which is consistent with the model of planet-disk
interactions. The inferred planet mass-orbital radius distribution indicates that the planet distribution is analogous
to our Solar System. However, planets with Neptune mass or lower may exist in all the radii.

75. Chemistry in Protoplanetary DisksKe Zhang ⋆ Planets are formed inside disks around young stars. The gas, dust, and ice in these natal disks are

the building materials of planets, and therefore their compositions fundamentally shape the final chemical compositions of planets. In this review, we summarize current observations of molecular lines in protoplanetary disks, fromnear-infrared to millimeter wavelengths. We discuss the basic types of chemical reactions in disks and the current
development of chemical modeling. In particular, we highlight the progress made in understanding snowline locations,abundances of main carriers of carbon, oxygen, and nitrogen, and complex organic molecules in disks. Finally, we discuss efforts to trace planet formation history by combining the understanding of disk chemistry and planet formation
processes.

76. Fine structure in the Sigma Orionis cluster revealed by Gaia DR3
M. Žerjal, E. L. Martín, A. Pérez-Garrido ⋆ Sigma Orionis is an open cluster in the nearest giant star formationsite - Orion. Its youth (3-5 Myr), low reddening, and relative vicinity make it an important benchmark cluster tostudy stellar and substellar formation and evolution. Young star-forming sites are complex and hierarchical. Precision
astrometry from Gaia DR3 enables the exploration of their fine structure. We used the modified convergent point
technique to kinematically re-evaluate the members in the Sigma Orionis cluster and its vicinity. We present clear
evidence for three kinematically distinct groups in the Sigma Orionis region. The second group, the RV Orionis
association, is adjacent to the Sigma Orionis cluster and is composed only of low-mass stars. The third group, theFlame association, whose age is comparable to that of Sigma Orionis, overlaps with the younger NGC 2024 in theFlame Nebula. In total, we have discovered 105 members of this complex not previously found in the literature (82 in
Sigma Orionis, 19 in the Flame association, and 4 in the RV Orionis association).

27