The Star Formation Newsletter
A community newsletter on Star and Planet Formation research 22 August 2021
Editor: João Alves
No. 344www.starformation.news

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Cover image caption

Mid-Infrared color composite of the Galactic Center. Once Terra Incognita, the Galactic Center is becoming a major starformation target in recent years. For scale, the image's width, about 250 pc at a distance of 8.3 kpc, is about the size of theentire Orion star formation region. Over the last few years, major work has focused on, e.g., Sgr B2, the Brick, the Arches andQuintuplet clusters, and the enigmatic Galactic Center cluster. Credit: NASA, JPL-Caltech.
Note from the Editor

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

Abstracts
1. A Circumplanetary Disk Around PDS70c
Myriam Benisty, Jaehan Bae, Stefano Facchini, Miriam Keppler, Richard Teague, Andrea Isella, Nicolas T.
Kurtovic, Laura M. Perez, Anibal Sierra, Sean M. Andrews, John Carpenter, Ian Czekala, Carsten Dominik,
Thomas Henning, Francois Menard, Paola Pinilla, Alice Zurlo

PDS70 is a unique system in which two protoplanets, PDS70b and c, have been discovered within the dust-depleted cavityof their disk, at ∼22 and 34au respectively, by direct imaging at infrared wavelengths. Subsequent detection of the planetsin the Hα line indicates that they are still accreting material through circumplanetary disks. In this Letter, we present new
Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum emission at 855µm at high angularresolution (∼20mas, 2.3au) that aim to resolve the circumplanetary disks and constrain their dust masses. Our observations
conrm the presence of a compact source of emission co-located with PDS70c, spatially separated from the circumstellar disk
and less extended than ∼1.2au in radius, a value close to the expected truncation radius of the cicumplanetary disk at a thirdof the Hill radius. The emission around PDS70c has a peak intensity of ∼86±16 µJy beam−12.

models which follow the evolution of gas and solids in a protoplanetary disk. We focus on substructures in the distribution of
millimeter-sized and smaller solid particles produced by the vertical shear instability. We show that their characteristics arecompatible with some of the shallow gaps detected in recent observations at sub-mm/mm wavelengths, and present predictions
for future observations with better sensitivity and angular resolution with ALMA and a Next Generation Very Large Array.

3. Hourglass Magnetic Field from a Survey of Current Density ProlesGianfranco Bino, Shantanu Basu, Mahmoud Sharkawi, Indrani Das

Modelling the magnetic eld in prestellar cores can serve as a useful tool for studying the initial conditions of star formation.
The analytic hourglass model of Ewertowski and Basu (2013) provides a means to t observed polarimetry measurements andextract useful information. The original model does not specify any radial distribution of the electric current density. Here,
we perform a survey of possible centrally-peaked radial distributions of the current density, and numerically derive the fullhourglass patterns. Since the vertical distribution is also specied in the original model, we can study the eect of dierent
ratios of vertical to radial scale length on the overall hourglass pattern. Dierent values of this ratio may correspond to dierent
formation scenarios for prestellar cores. We demonstrate the exibility of our model and how it can be applied to a variety ofmagnetic eld patterns.

4. The STAR-MELT Python package for emission line analysis of YSOs
Justyn Campbell-White, Aurora Sicilia-Aguilar, Carlo F. Manara, Soko Matsumura, Min Fang, Antonio Frasca,
Veronica Roccatagliata

We introduce the STAR-MELT Python package that we developed to facilitate the analysis of time-resolved emission line
spectroscopy of young stellar objects. STAR-MELT automatically extracts, identies and ts emission lines. We summarise
our analysis methods that utilises the time domain of high-resolution stellar spectra to investigate variability in the line prolesand corresponding emitting regions. This allows us to probe the innermost disc and accretion structures of YSOs. Local
temperatures and densities can be determined using Boltzmann statistics, the Saha equation, and the Sobolev large velocity
gradient approximation. STAR-MELT allows for new results to be obtained from archival data, as well as facilitating timely
analysis of new data as it is obtained. We present the results of applying STAR-MELT to three YSOs, using spectra from
UVES, XSHOOTER, FEROS, HARPS, and ESPaDOnS. We demonstrate what can be achieved for data with disparate timesampling, for stars with dierent inclinations and variability types. For EX Lupi, we conrm the presence of a localised andstable stellar-surface hot spot associated with the footprint of the accretion column. For GQ Lupi A, we nd that the maximum
infall rate from an accretion column is correlated with lines produced in the lowest temperatures. For CVSO109 we investigate
the rapid temporal variability of a redshifted emission wing, indicative of rotating and infalling material in the inner disc. Our
results show that STAR-MELT is a useful tool for such analysis, as well as other applications for emission lines.

5. Core mass function of a single giant molecular cloud complex with 10 cores
4

Yue Cao, Keping Qiu, Qizhou Zhang, Yuwei Wang, Yuanming Xiao

Similarity in shape between the initial mass function (IMF) and the core mass functions (CMFs) in star-forming regions prompts
the idea that the IMF originates from the CMF through a self-similar core-to-star mass mapping process. To accurately
determine the shape of the CMF, we create a sample of 8,431 cores with the dust continuum maps of the Cygnus X giant
molecular cloud complex, and design a procedure for deriving the CMF considering the mass uncertainty, binning uncertainty,
sample incompleteness, and the statistical errors. The resultant CMF coincides well with the IMF for core masses from a few
M to the highest masses of 1300 M with a power-law of dN/dM ∝ M −2.30±0.04 , but does not present an obvious attened
turnover in the low-mass range as the IMF does. More detailed inspection reveals that the slope of the CMF steepens withincreasing mass. Given the numerous high-mass star-forming activities of Cygnus X, this is in stark contrast with the existing
top-heavy CMFs found in high-mass star-forming clumps. We also nd that the similarity between the IMF and the massfunction of cloud structures is not unique at core scales, but can be seen for cloud structures of up to several pc scales. Finally,
our SMA observations toward a subset of the cores do not present evidence for the self-similar mapping. The latter two results
indicate that the shape of the IMF may not be directly inherited from the CMF.

3

6. The GUAPOS project II. A comprehensive study of peptide-like bond molecules
L. Colzi, V. M. Rivilla, M. T. Beltrán, I. Jiménez-Serra, C. Mininni, M. Melosso, R. Cesaroni, F. Fontani, A.
Lorenzani, A. Sánchez-Monge, S. Viti, P. Schilke, L. Testi, E. R. Alonso, L. Kolesniková

Peptide-like bond molecules, which can take part to the formation of proteins in a primitive Earth environment, have been detected up to now only towards a few sources. We present a study of HNCO, HC(O)NH2 , CH3 NCO, CH3 C(O)NH2 , CH3 NHCHO,CH3 CH2 NCO, NH2 C(O)NH2 , NH2 C(O)CN, and HOCH2 C(O)NH2 towards the hot core G31.41+0.31. We have used the spectrum obtained from the ALMA 3mm spectral survey GUAPOS, with an angular resolution of 1.2"×1.2" (∼4500 au), to derivecolumn densities of all the molecular species, together with other 0.2"×0.2" (∼750 au) ALMA observations to study themorphology of HNCO, HC(O)NH2 and CH3 C(O)NH2 . We have detected HNCO, HC(O)NH2 , CH3 NCO, CH3 C(O)NH2 , andCH3 NHCHO, for the rst time all together outside the Galactic center. We have obtained molecular fractional abundanceswith respect to H2 from 10−7 down to a few 10−9 and with respect to CH3 OH from 10−3 to ∼4×10−2 . From the comparison
with other sources, we nd that regions in an earlier stage of evolution, such as pre-stellar cores, show abundances at least
two orders of magnitude lower than those in hot cores, hot corinos or shocked regions. Moreover, molecular abundance ratios
towards dierent sources are found to be consistent between them within ∼1 order of magnitude, regardless of the physicalproperties (e.g. dierent masses and luminosities), or the source position throughout the Galaxy. New correlations between
pairs of molecular abundances have also been found. These results suggest that all these species are formed on grain surfaces inearly evolutionary stages of molecular clouds, and that they are subsequently released back to the gas-phase through thermal
desorption or shock-triggered desorption.

A survey for variable young stars with small telescopes: IV  Rotation Periods of YSOs
7. in IC5070
Dirk Froebrich, Efthymia Derezea, Aleks Scholz, Jochen Eislöel, Siegfried Vanaverbeke, Alfred Kume, Carys
Herbert, Justyn Campbell-White, Niall Miller, Bringfried Stecklum, Sally V. Makin, Thomas Urtly, Francisco
C. Soldán Alfaro, Erik Schwendeman, Georey Stone, Mark Phillips, George Fleming, Rafael Gonzalez Farfán,
Tonny Vanmunster, Michael A. Heald, Esteban Fernández Mañanes, Tim Nelson, Heinz-Bernd Eggenstein,Franky Dubois, Ludwig Logie, Steve Rau, Klaas Wiersema, Nick Quinn, Diego Rodriguez, Rafael Castillo
García, Thomas Killestein, Tony Vale, Domenico Licchelli, Marc Deldem, Georg Piehler, Dawid Mo¹dzierski,
Krzysztof Kotysz, Katarzyna Kowalska, Przemysªaw Mikoªajczyk, Stephen R. L. Futcher, Timothy P. Long,
Mario Morales Aimar, Barry Merrikin, Stephen Johnstone, Pavol A. Dubovský, Igor Kudzej, Roger Pickard,
Samuel J. Billington, Lord Dover, Tarik Zegmott, Jack J. Evitts, Alejandra Traspas Munia, Mark C. Price

Studying rotational variability of young stars is enabling us to investigate a multitude of properties of young star-disk systems.
We utilise high cadence, multi-wavelength optical time series data from the Hunting Outbursting Young Stars citizen science
project to identify periodic variables in the Pelican Nebula (IC5070). A double blind study using nine dierent period-nding
algorithms was conducted and a sample of 59 periodic variables was identied. We nd that a combination of four period
nding algorithms can achieve a completeness of 85% and a contamination of 30% in identifying periods in inhomogeneous
data sets. The best performing methods are periodograms that rely on tting a sine curve. Utilising GaiaEDR3 data, we haveidentied an unbiased sample of 40 periodic YSOs, without using any colour or magnitude selections. With a 98.9% probability
we can exclude a homogeneous YSO period distribution. Instead we nd a bi-modal distribution with peaks at three andeight days. The sample has a disk fraction of 50%, and its statistical properties are in agreement with other similarly aged
YSOs populations. In particular, we conrm that the presence of the disk is linked to predominantly slow rotation and nd a
probability of 4.8×10−3 that the observed relation between period and presence of a disk has occurred by chance. In our sample
of periodic variables, we also nd pulsating giants, an eclipsing binary, and potential YSOs in the foreground of IC5070.

8. CRAFT (Cosmic Ray Acceleration From Turbulence) in Molecular Clouds
Brandt A. L. Gaches, Stefanie Walch, Alex Lazarian

Low-energy cosmic rays, in particular protons with energies below 1 GeV, are signicant drivers of the thermochemistry ofmolecular clouds. However, these cosmic rays are also greatly impacted by energy losses and magnetic eld transport eects
in molecular gas. Explaining cosmic ray ionization rates of 10−16 s−1 or greater in dense gas requires either a high external
cosmic ray ux, or local sources of MeV-GeV cosmic ray protons. We present a new local source of low-energy cosmic rays inmolecular clouds: rst order Fermi-acceleration of protons in regions undergoing turbulent reconnection in molecular clouds. We
show from energetic-based arguments there is sucient energy within the magneto-hydrodynamic turbulent cascade to produce
ionization rates compatible with inferred ionization rates in molecular clouds. As turbulent reconnection is a volume-lling
process, the proposed mechanism can produce a near-homogeneous distribution of low-energy cosmic rays within molecular
clouds.

4

9. Touching the Stars: Using High-Resolution 3D Printing to Visualize Stellar Nurseries
Nia Imara, John C. Forbes, James C. Weaver

Owing to their intricate variable density architecture, and as a principal site of star formation, molecular clouds represent oneof the most functionally signicant, yet least understood features of our universe. To unravel the intrinsic structural complexityof molecular clouds, here we leverage the power of high-resolution bitmap-based 3D printing, which provides the opportunity
to visualize astrophysical structures in a way that uniquely taps into the human brain's ability to recognize patterns suppressedin 2D representations. Using a new suite of nine simulations, each representing dierent physical extremes in the turbulent
interstellar medium, as our source data, our workow permits the unambiguous visualization of features in the 3D-printed
models, such as quasi-planar structures, that are frequently obscured in traditional renderings and animations. Our bitmapbased 3D printing approach thus faithfully reproduces the subtle density gradient distribution within molecular clouds in atangible, intuitive, and visually stunning manner. While laying the groundwork for the intuitive analysis of other structurally
complex astronomical data sets, our 3D-printed models also serve as valuable tools in educational and public outreach endeavors.

10. Dark cloud-type chemistry in PDRs with moderate UV eldMaria S. Kirsanova, Anna F. Punanova, Dmitry A. Semenov, Anton I. Vasyunin

We present a study of emission lines of small hydrocarbons C2 H and c-C3 H2 , and COMs precursors H2 CO and CH3 OH in order
to better understand the possible chemical link between the molecular abundances and UV radiation eld in photodissociation
regions (PDRs). We study two PDRs around extended and compact HII regions with G ≤ 50 Habings in the S235 star-forming
complex. We nd the highest abundances of both hydrocarbons on the edges of molecular clumps, while c-C3 H2 is also abundantin the low-density expanding PDR around compact HII region S235 A. We see the highest methanol column density towards
the positions with the UV eld G ≈ 20 − 30 Habings and explain them by reactive desorption from the dust grains. The
NC2 H /NCH3 OH ratio is lower by a factor of few or the order of magnitude in comparison with the Horsehead and Orion Bar
PDRs. The ratio is similar to the value observed in hot corinos in the Perseus cloud. We conclude that ion-molecular andgrain surface chemical routes rule the molecular abundances in the PDRs, and the PDRs inherit molecular abundances fromthe previous dark stage of molecular cloud evolution in spite of massive stars already emitting in optics.

rst interferometric survey in the K-band of massive YSOs. On the hot dust,
11. Theionised gas, and binarity at au scales
E. Koumpia, W. -J. de Wit, R. D. Oudmaijer, A. J. Frost, S. Lumsden, A. Caratti o Garatti, S. P. Goodwin,
B. Stecklum, I. Mendiguta, J. D. Ilee, M. Vioque

Circumstellar discs are essential for high mass star formation, while multiplicity, in particular binarity, appears to be an
inevitable outcome since the vast majority of massive stars (> 8 Msun) are found in binaries (up to 100%). We constrain thesizes of the dust and ionised gas (Brgamma) emission of the innermost regions towards a sample of six MYSOs, and provide
high-mass binary statistics of young stars at 2-300 au scales using VLTI (GRAVITY, AMBER) observations. We determine
the inner radius of the dust emission and place MYSOs with K-band measurements in a size-luminosity diagram for the rsttime, and compare our ndings to T Tauris and Herbig AeBes. We also compare the observed K-band sizes to the sublimation
radius predicted by three dierent disc scenarios. Lastly, we apply binary geometries to trace close binarity among MYSOs.
The inner sizes of MYSOs, Herbig AeBe and T Tauri stars appear to follow a universal trend at which the sizes scale with thesquare-root of the stellar luminosity. The Brgamma emission originates from somewhat smaller and co-planar area comparedto the 2.2 µm continuum emission. We discuss this new nding with respect to disc-wind or jet origin. Finally, we reportan MYSO binary fraction of 17-25% at milli-arcsecond separations (2-300 au). The size-luminosity diagram indicates that the
inner regions of discs around young stars scale with luminosity independently of the stellar mass. At the targeted scales (2-300au), the MYSO binary fraction is lower than what was previously reported for the more evolved main sequence massive stars,
which, if further conrmed, could implicate the predictions from massive binary formation theories. Lastly, we spatially resolve
the crucial star/disc interface in a sample of MYSOs, showing that au-scale discs are prominent in high-mass star formationand similar to their low-mass equivalents.

512. The IGRINS YSO Survey I. Stellar parameters of pre-main sequence stars in TaurusAuriga
Ricardo López-Valdivia, Kimberly R. Sokal, Gregory N. Mace, Benjamin T. Kidder, Maryam Hussaini, Larissa
No, L. Prato, Christopher M. Johns-Krull, Heeyoung Oh, Jae-Joon Lee, Chan Park, Jae Sok Oh, Adam
Kraus, Kyle F. Kaplan, Joe Llama, Andrew W. Mann, Hwihyun Kim, Michael A. Gully-Santiago, Hye-In Lee,
Soo jong Pak, Narae Hwang, Daniel T. Jae

We present fundamental parameters for 110 canonical K- & M-type (1.3−0.13M ) Taurus-Auriga young stellar objects (YSOs).
The analysis produces a simultaneous determination of eective temperature (Teff ), surface gravity (log g), magnetic eldstrength (B), and projected rotational velocity (v sin i). Our method employed synthetic spectra and high-resolution (R∼45,000)
near-infrared spectra taken with the Immersion GRating INfrared Spectrometer (IGRINS) to t specic K-band spectral regions
most sensitive to those parameters. The use of these high-resolution spectra reduces the inuence of distance uncertainties,
reddening, and non-photospheric continuum emission on the parameter determinations. The median total (t + systematic)
uncertainties were 170 K, 0.28 dex, 0.60 kG, 2.5 km s−1 for Teff , log g, B, and v sin i, respectively. We determined B for 41
Taurus YSOs (upper limits for the remainder) and nd systematic osets (lower Teff , higher log g and v sin i) in parameters when
B is measurable but not considered in the t. The average log g for the Class II and Class III objects diers by 0.23±0.05dex,
which is consistent with Class III objects being the more evolved members of the star-forming region. However, the dispersion
in log g is greater than the uncertainties, which highlights how the YSO classication correlates with age (log g), yet there are
exceptionally young (lower log g) Class III YSOs and relatively old (higher log g) Class II YSOs with unexplained evolutionary
histories. The spectra from this work are provided in an online repository along with TW Hydrae Association (TWA) comparison
objects and the model grid used in our analysis.

13. If you like C/O variations, you should have put a ring on it
Nienke van der Marel, Arthur Bosman, Sebastiaan Krijt, Gijs D. Mulders, Jennifer B. Bergner

The C/O-ratio as traced with C2 H emission in protoplanetary disks is fundamental for constraining the formation mechanismsof exoplanets and our understanding of volatile depletion in disks, but current C2 H observations show an apparent bimodal
distribution which is not well understood, indicating that the C/O distribution is not described by a simple radial dependence.
The transport of icy pebbles has been suggested to alter the local elemental abundances in protoplanetary disks, through settling,
drift and trapping in pressure bumps resulting in a depletion of volatiles in the surface and an increase of the elemental C/O.
We combine all disks with spatially resolved ALMA C2 H observations with high-resolution continuum images and constraints
on the CO snowline to determine if the C2 H emission is indeed related to the location of the icy pebbles. We report a possible
correlation between the presence of a signicant CO-icy dust reservoir and high C2 H emission, which is only found in diskswith dust rings outside the CO snowline. In contrast, compact dust disks (without pressure bumps) and warm transition disks(with their dust ring inside the CO snowline) are not detected in C2 H, suggesting that such disks may never have contained asignicant CO ice reservoir. This correlation provides evidence for the regulation of the C/O prole by the complex interplay of
CO snowline and pressure bump locations in the disk. These results demonstrate the importance of including dust transport inchemical disk models, for a proper interpretation of exoplanet atmospheric compositions, and a better understanding of volatile
depletion in disks, in particular the use of CO isotopologues to determine gas surface densities.

14. The Mass Budgets and Spatial Scales of Exoplanet Systems and Protoplanetary Disks
Gijs D. Mulders, Ilaria Pascucci, Fred J. Ciesla, Rachel B. Fernandes

Planets are born from disks of gas and dust, and observations of protoplanetary disks are used to constrain the initial conditionsof planet formation. However, dust mass measurements of Class II disks with ALMA have called into question whether they
contain enough solids to build the exoplanets that have been detected to date. In this paper, we calculate the mass and spatial
scale of solid material around Sun-like stars probed by transit and radial velocity exoplanet surveys, and compare those to theobserved dust masses and sizes of Class II disks in the same stellar mass regime. We show that the apparent mass discrepancy
disappears when accounting for observational selection and detection biases. We nd a discrepancy only when the planet
formation eciency is below 100%, or if there is a population of undetected exoplanets that signicantly contributes to themass in solids. We identify a positive correlation between the masses of planetary systems and their respective orbital periods,
which is consistent with the trend between the masses and the outer radii of Class II dust disks. This implies that, despite afactor 100 dierence in spatial scale, the properties of protoplanetary disks seem to be imprinted on the exoplanet population.

6

IMF and multiplicity of stars from gravity, turbulence, magnetic elds, radiation
15. Theand outow feedback
Sa jay Sunny Mathew, Christoph Federrath

We perform a series of three-dimensional, magnetohydrodynamical (MHD) simulations of star cluster formation including
gravity, turbulence, magnetic elds, stellar radiative heating and outow feedback. We observe that the inclusion of protostellar
outows (1) reduces the star formation rate by a factor of ∼ 2, (2) increases fragmentation, and (3) shifts the initial massfunction (IMF) to lower masses by a factor of 2.0 ± 0.2, without signicantly aecting the overall shape of the IMF. The
form of the sink particle (protostellar objects) mass distribution obtained from our simulations matches the observational IMFs
reasonably well. We also show that turbulence-based theoretical models of the IMF agree well with our simulation IMF in thehigh-mass and low-mass regime, but do not predict any brown dwarfs, whereas our simulations produce a considerable numberof sub-stellar objects, which are produced by dynamical interactions (ejections). We nd that these dynamical interactions also
play a key role for the binary separation distribution and stellar kinematics in general. Our numerical model of star cluster
formation also reproduces the observed mass dependence of multiplicity. Our multiplicity fraction estimates generally concurwith the observational estimates for dierent spectral types. We further calculate the specic angular momentum of all thesink particles and nd that the average value of 1.5 × 1019 cm2 s−1 is consistent with observational data. The specic angularmomentum of our sink particles lies in the range typical of protostellar envelopes and binaries. We conclude that the IMF iscontrolled by a combination of gravity, turbulence, magnetic elds, radiation and outow feedback.

the gap between protoplanetary and debris disks: separate evolution of mil16. Bridging
limeter and micrometer-sized dust
Arnaud Michel, Nienke van der Marel, Brenda Matthews

The connection between the nature of a protoplanetary disk and that of a debris disk is not well understood. Dust evolution,planet formation, and disk dissipation likely play a role in the processes involved. We aim to reconcile both manifestations of
dusty circumstellar disks through a study of optically thin Class III disks and how they correlate to younger and older disks.
In this work, we collect literature and ALMA archival millimeter uxes for 85 disks (8%) of all Class III disks across nearby
star-forming regions. We derive millimeter-dust masses Mdust and compare these with Class II and debris disk samples in thecontext of excess infrared luminosity, accretion rate, and age. The mean Mdust of Class III disks is 0.29 ± 0.19 M⊕ . We propose
a new evolutionary scenario wherein radial drift is very ecient for non-structured disks during the Class II phase resulting ina rapid decrease of Mdust . However, we nd long infrared protoplanetary disk timescales of ∼8 Myr, which are consistent withoverall slow disk evolution. In structured disks, the presence of dust traps allows for the formation of planetesimal belts at large
radii, such as those observed in debris disks. We propose therefore that the planetesimal belts in debris disks are the result of
dust traps in structured disks, whereas protoplanetary disks without dust traps decrease in dust mass through radial drift andare therefore undetectable as debris disks after the gas has dissipated. These results provide a hypothesis for a novel view of
disk evolution.

Statistics in Star Forming Regions: Is Star Formation Driven By Column Den17. Spatial
sity Alone?
Brendan Retter, Jennifer Hatchell, Tim Naylor

Star formation is known to occur more readily where more raw materials are available. This is often expressed by a 'KennicuttSchmidt' relation where the surface density of Young Stellar Objects (YSOs) is proportional to column density to some power,µ. The aim of this work was to determine if column density alone is sucient to explain the locations of Class 0/I YSOs
within Serpens South, Serpens Core, Ophiuchus, NGC1333 and IC348, or if there is clumping or avoidance that would point
to additional inuences on the star formation. Using the O-ring test as a summary statistic, 95 per cent condence envelopes
were produced for dierent values of µ from probability models made using the Herschel column density maps. The YSOs were
tested against four distribution models: the best-estimate of µ for the region, µ = 0 above a minimum column density thresholdand zero probability elsewhere, µ = 1, and the power-law that best represents the ve regions as a collective, µ = 2.05 ± 0.20.
Results showed that µ = 2.05 model was consistent with the majority of regions and, for those regions, the spatial distribution
of YSOs at a given column density is consistent with being random. Serpens South and NGC1333 rejected the µ = 2.05 model
on small scales of ∼ 0.15pc which implies that small-scale interactions may be necessary to improve the model. On scales above
0.15 pc, the positions of YSOs in all ve regions can be well described using column density alone.

718. An orbital release model for the Orion BN/KL ngers
A. C. Raga, P. R. Rivera-Ortiz, A. Rodriguez-Gonzalez, A. Castellanos-Ramirez

We present a simple model in which the bullets that produce the "Orion ngers" (ejected by the BN/KL object) are interpreted
as protoplanets or low mass protostars in orbit around a high mass star that has a supernova explosion. As the remnant of
the SN explosion has only a small fraction of the mass of the pre-supernova star, the orbiting objects then move away in free
trajectories, preserving their orbital velocity at the time of release. We show that a system of objects arranged in approximately
co-planar orbits results in trajectories with morphological and kinematical characteristics resembling the Orion ngers. We
show that, under the assumption of constant velocity motions, the positions of the observed heads of the ngers can be used toreconstruct the properties of the orbital structure from which they originated, resulting in a compact disk with an outer radiusof ∼ 2.4 AU.

19. A Core Mass Function Indistinguishable from the Salpeter Stellar Initial Mass Function
Using 1000 au Resolution ALMA Observations
Genaro Suárez, Roberto Galván-Madrid, Luis Aguilar, Adam Ginsburg, Sundar Srinivasan, Hauyu Baobab
Liu, Carlos G. Román-Zúñiga

We present the core mass function (CMF) of the massive star-forming clump G33.92+0.11 using 1.3 mm observations obtainedwith the Atacama Large Millimeter/submillimeter Array (ALMA). With a resolution of 1000 au, this is one of the highest
resolution CMF measurements to date. The CMF is corrected by ux and number incompleteness to obtain a sample that iscomplete for gas masses M & 2.0 M . The resulting CMF is well represented by a power-law function (dN/d log M ∝ M Γ ),whose slope is determined using two dierent approaches: i) by least-squares tting of power-law functions to the ux- andnumber-corrected CMF, and ii) by comparing the observed CMF to simulated samples with similar incompleteness. We provide
a prescription to quantify and correct a attening bias aecting the slope ts in the rst approach, which is caused by smallsample or edge eects when the data is represented by either classical histograms or a kernel density estimate, respectively. The
resulting slopes from both approaches are in good agreement each other, with Γ = −1.11+0.12−0.11 being our adopted value. Although
this slope appears to be slightly atter than the Salpeter slope Γ = −1.35 for the stellar initial mass function (IMF), we ndfrom Monte Carlo simulations that the CMF in G33.92+0.11 is statistically indistinguishable from the Salpeter representationof the stellar IMF. Our results are consistent with the idea that the form of the IMF is inherited from the CMF, at least at
high masses and when the latter is observed at high-enough resolution.

20. Optical Properties of Interstellar Dust around the Orion A Molecular Cloud
Hayato Uehara, Kazuhito Dobashi, Shingo Nishiura, Tomomi Shimoikura, Takahiro Naoi

We have studied optical properties of interstellar dust around the Orion A molecular cloud to investigate the size distribution
and the composition of dust grains. Orion A is one of the most studied molecular clouds in the solar vicinity (d ' 400 pc).
In this paper, we used optical and near-infrared photometric data. The optical data were obtained by BV RI bands imaging
observations. The near-infrared data consisting of JHKS bands were taken from 2MASS point source catalog. We produced
some color excess maps around Orion A, and measured their ratios such as E(R − I)/E(B − V ). In order to investigate dust
properties, we compared the observed ratios with results of simulation performed by Naoi T. et al. (2021) who calculated theextinction in the optical to near-infrared wavelengths based on a standard dust model; they assumed a power-law grain-size
distribution with an upper cuto radius and assumed graphite and silicate as dominant components. As a result, we foundthat the upper cuto radius around Orion A is ' 0.3 µm, and silicate predominates compared with graphite (with the fractionof silicate grater than 93 %). In addition, we further derived the total-to-selective extinction ratio RV from the observed
extinction of AV and the color excess E(B − V ), and compared it with the model calculations. Dust properties (i.e., the upper
cuto radius and the ratio of graphite/silicate) derived from RV is almost consistent with those derived from the color excess
ratios.

21. Probing Protoplanetary Disk Winds with C II Absorption
Ziyan Xu, Gregory J. Herczeg, Christopher M. Johns-Krull, Kevin France

We present an analysis of wind absorption in the C II λ1335 doublet towards 40 classical T Tauri stars with archival farultraviolet (FUV) spectra obtained by the Hubble Space Telescope. Absorption features produced by fast or slow winds arecommonly detected (36 out of 40 targets) in our sample. The wind velocity of the fast wind decreases with disk inclination,
consistent with expectations for a collimated jet. Slow wind absorption is detected mostly in disks with intermediate or highinclination, without a signicant dependence of wind velocity on disk inclination. Both the fast and slow wind absorption are8

preferentially detected in FUV lines of neutral or singly ionized atoms. The Mg II λλ2796, 2804 lines show wind absorption
consistent with the absorption in the C II lines. We develop simplied semi-analytical disk/wind models to interpret theobservational disk wind absorption. Both fast and slow winds are consistent with expectations from a thermal-magnetized disk
wind model and are generally inconsistent with a purely thermal wind. Both the models and the observational analysis indicatethat wind absorption occurs preferentially from the inner disk, oering a wind diagnostic in complement to optical forbiddenline emission that traces the wind in larger volumes.

22. TIMES II: Investigating the Relation Between Turbulence and Star-forming Environments in Molecular Clouds
Hyeong-Sik Yun, Jeong-Eun Lee, Neal J. Evans II, Stella S. R. Oner, Mark H. Heyer, Jungyeon Cho, Brandt
A. L. Gaches, Yao-Lun Yang, How-Huan Chen, Yunhee Choi, Yong-Hee Lee, Giseon Baek, Minho Choi, Jongsoo
Kim, Hyunwoo Kang, Seokho Lee, Ken'ichi Tatematsu

We investigate the eect of star formation on turbulence in the Orion A and Ophiuchus clouds using principal component analysis(PCA). We measure the properties of turbulence by applying PCA on the spectral maps in 13 CO, C18 O, HCO+ J =1−0, and
CS J =2−1. First, the scaling relations derived from PCA of the 13 CO maps show that the velocity dierence (δv) for a given
spatial scale (L) is the highest in the integral shaped lament (ISF) and L1688, where the most active star formation occurs in
the two clouds. The δv increases with the number density and total bolometric luminosity of the protostars in the sub-regions.
Second, in the ISF and L1688 regions, the δv of C18 O, HCO+ , and CS are generally higher than that of 13 CO, which implies
that the dense gas is more turbulent than the diuse gas in the star-forming regions; stars form in dense gas, and dynamical
activities associated with star formation, such as jets and outows, can provide energy into the surrounding gas to enhanceturbulent motions.

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