The Star Formation Newsletter
A community newsletter on Star and Planet Formation research
No. 351 — 31 March 2022
Editor: João Alveswww.starformation.news

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Cover image caption
The Orion OMC1 cloud core located just behind the Orion Nebula contains the nearest site of ongoing massive star formation. The outflow emerging from OMC1 exhibits a remarkable explosive morphology. Credit: Bally et al. 2017, ALMA
(ESO/NAOJ/NRAO)
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 to the different 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 or the SFN.

Abstracts
1. The Magnetic Field versus Density relation in Star-Forming Molecular Clouds
Sayantan Auddy, Shantanu Basu, Takahiro Kudoh F We study the magnetic field to density (B − ρ) relation in
turbulent molecular clouds with dynamically important magnetic fields using nonideal three-dimensional magnetohydrodynamic
simulations. Our simulations show that there is a distinguishable break density ρT between the relatively flat low density regime
and a power-law regime at higher densities. We present an analytic theory for ρT based on the interplay of the magnetic field,
turbulence, and gravity. The break density ρT scales with the strength of the initial Alfvén Mach number MA0 for sub-Alfvénic( MA0 < 1) and trans-Alfvénic (MA0 ∼ 1) clouds. We fit the variation of ρT for model clouds as a function of MA0 , set bydifferent values of initial sonic Mach number M0 and the initial ratio of gas pressure to magnetic pressure β0 . This implies that
ρT , which denotes the transition in mass-to-flux ratio from the subcritical to supercritical regime, is set by the initial turbulent
compression of the molecular cloud.

power of near-infrared data for the study of young clusters: Illustrative case of
2. Hidden
RCW 38
Joana Ascenso F Studies of star formation rely heavily on observations in the near-infrared, but they typically need information from other wavelengths for interpretation. We show that we can infer distances and estimate the membership of youngstellar objects for young clusters independently using (ground-based) near-infrared, J, H, and KS broadband data alone. We
also show that we can estimate a lower limit for the fraction of sources with 2.2 µm excess emission with a sensitivity comparable
to that of mid-infrared space data, but with better resolution and fewer biases. Finally, we show that the typical methods for
inferring masses from these data may produce substantially unreliable results. This method is applied to the young, massive
cluster RCW 38, for which we estimate a distance of 1.5 kpc and a KS -band excess fraction larger than 60%.

3. The chemical nature of Orion protostars: Are ORANGES different from PEACHES?
ORANGES II

M. Bouvier, C. Ceccarelli, A. López-Sepulcre, N. Sakai, S. Yamamoto, Y. -L. Yang F Understanding the chemical
past of our Sun and how life appeared on Earth is no mean feat. The best strategy we can adopt is to study newborn stars
located in an environment similar to the one in which our Sun was born and assess their chemical content. In particular, hot
corinos are prime targets since recent studies showed correlations between interstellar Complex Organic Molecules (iCOMs)
abundances from hot corinos and comets. The ORion ALMA New GEneration Survey (ORANGES) aims to assess the numberof hot corinos in the closest and best analogue to our Sun’s birth environment, the OMC-2/3 filament. In this context, weinvestigated the chemical nature of 19 solar-mass protostars and found that 26% of our sample sources shows warm methanol
emission indicative of hot corinos. Compared to the Perseus low-mass star-forming region, where the PErseus ALMA CHEmistry
Survey (PEACHES) detected ∼ 60% of hot corinos, the latter seem to be relatively scarce in the OMC-2/3 filament. While
this suggests that the chemical nature of protostars in Orion and Perseus is different, improved statistics are needed in order to2

consolidate this result. If the two regions are truly different, this would indicate that the environment is likely playing a role inshaping the chemical composition of protostars.

4. Optical and Near-infrared View of Planet-forming Disks and Protoplanets
M. Benisty, C. Dominik, K. Follette, A. Garufi, C. Ginski, J. Hashimoto, M. Keppler, W. Kley, J. Monnier
F In this chapter of the Protostars and Planets VII, we review the breakthrough progress that has been made in the field ofhigh-resolution, high-contrast optical and near-infrared imaging of planet-forming disks. These advancements include the direct
detection of protoplanets embedded in some disks, and derived limits on planetary masses in others. Morphological substructures,
including: rings, spirals, arcs, and shadows, are seen in all imaged infrared-bright disks to date, and are ubiquitous across spectral
types. These substructures are believed to be the result of disk evolution processes, and in particular disk-planet interactions.
Since small dust grains that scatter light are tightly bound to the disk’s gas, these observations closely trace disk structures
predicted by hydrodynamical models and serve as observational tests of the predictions of planet formation theories. We argue
that the results of current and next-generation high-contrast imaging surveys will, when combined with complementary datafrom ALMA, lead to a much deeper understanding of the co-evolution of disks and planets, and the mechanisms by whichplanets form.

5. The Central 1000 au of a Pre-stellar Core Revealed with ALMA. II. Almost Complete
Freeze-out

Paola Caselli, Jaime E. Pineda, Olli Sipilä, Bo Zhao, Elena Redaelli, Silvia Spezzano, Maria José Maureira,Felipe Alves, Luca Bizzocchi, Tyler L. Bourke, Ana Chacón-Tanarro, Rachel Friesen, Daniele Galli, Jorma
Harju, Izaskun Jiménez-Serra, Eric Keto, Zhi-Yun Li, Marco Padovani, Anika Schmiedeke, Mario Tafalla,
Charlotte Vastel F Pre-stellar cores represent the initial conditions in the process of star and planet formation. Their low
temperatures (<10 K) allow the formation of thick icy dust mantles, which will be partially preserved in the future protoplanetarydisks, ultimately affecting the chemical composition of planetary systems. Previous observations have shown that carbon- andoxygen-bearing species, in particular CO, are heavily depleted in pre-stellar cores due to the efficient molecular freeze-out onto
the surface of cold dust grains. However, N-bearing species such as NH3 and, in particular, its deuterated isotopologues, appear
to maintain high abundances where CO molecules are mainly in solid phase. Thanks to ALMA, we present here the first clear
observational evidence of NH2 D freeze-out toward the L1544 pre-stellar core, suggestive of the presence of a"complete-depletionzone" within a '1800 au radius, in agreement with astrochemical pre-stellar core model predictions. Our state-of-the-art
chemical model coupled with a non-LTE radiative transfer code demonstrates that NH2 D becomes mainly incorporated in icy
mantles in the central 2000 au and starts freezing-out already at '7000 au. Radiative transfer effects within the pre-stellar
core cause the NH2 D(111 -101 ) emission to appear centrally concentrated, with a flattened distribution within the central '3000
au, unlike the 1.3 mm dust continuum emission which shows a clear peak within the central '1800 au. This prevented NH2 D
freeze-out to be detected in previous observations, where the central 1000 au cannot be spatially resolved.

6. Star formation in two irradiated globules around Cygnus OB2

F. Comerón, N. Schneider, A. A. Djupvik F We investigate the young stellar populations associated with DR 18 andECX 6-21, which are two isolated globules irradiated by the O-type stars of the Cygnus OB2 association. Both are HII regions
containing obvious tracers of recent and ongoing star formation. We also study smaller isolated molecular structures in theirsurroundings. Both globules contain their own embedded populations, with a higher fraction of the less-evolved classes. Masses
and temperatures are estimated under the assumption of a common age of 1 Myr, which has been found to appropriately
represent the general Cygnus OB2 YSO population but is most probably an overestimate for both globules, especially ECX
6-21. The early-B star responsible for the erosion of DR 18 is found to be part of a small aggregate of intermediate-mass stars
still embedded in the cloud, which probably contains a second site of recent star formation, also with intermediate-mass stars.
We confirm the two main star forming sites embedded in ECX 6-21 described in previous works, with the southern site being
more evolved than the northern site. We also discuss the small globule ECX 6-21-W (= G79.8 + 1.2), and propose that its nonthermal radio spectrum is due to synchrotron emission from an embedded jet, whose existence is suggested by our observations.
The extreme youth of some of the YSOs suggests that star formation in both globules started after they became externally
irradiated. The populations of both globules are not found to be particularly rich, but they contain stars with estimated masses
similar or above that of the Sun in numbers that hint at some differences with respect to the star formation process taking
place in more quiescent regions where low-mass stars dominate, which deeper observations may confirm.

7. The Life and Times of Giant Molecular Clouds
Mélanie Chevance, Mark R. Krumholz, Anna F. McLeod, Eve C. Ostriker, Erik W. Rosolowsky, Amiel Sternberg F Giant molecular clouds (GMCs) are the sites of star formation and stellar feedback in galaxies. Their properties set theinitial conditions for star formation and their lifecycles determine how feedback regulates galaxy evolution. In recent years, the3advent of high-resolution telescopes has enabled systematic GMC-scale studies of the molecular interstellar medium in nearby
galaxies, now covering a wide range of physical conditions and allowing for the first studies of how GMC properties depend on
galactic environment. These observational developments have been accompanied by numerical simulations of improving resolution that are increasingly accurately accounting for the effects of the galactic-scale environment on GMCs, while simultaneously
improving the treatment of the small-scale processes of star-formation and stellar feedback within them. The combination ofthese recent developments has greatly improved our understanding of the formation, evolution, and destruction of GMCs. We
review the current state of the field, highlight current open questions, and discuss promising avenues for future studies.

8. The ALMA-PILS survey: First tentative detection of 3-hydroxypropenal (HOCHCHCHO) in the interstellar medium and chemical modeling of the C3 H4 O2 isomers

A. Coutens, J. -C. Loison, A. Boulanger, E. Caux, H. S. P. Müller, V. Wakelam, S. Manigand, J. K. Jørgensen F Characterizing the molecular composition of solar-type protostars is useful for improving our understanding of thephysico-chemical conditions under which the Sun and its planets formed. In this work, we analyzed the Atacama Large Millimeter/submillimeter Array (ALMA) data of the Protostellar Interferometric Line Survey (PILS), an unbiased spectral surveyof the solar-type protostar IRAS 16293–2422, and we tentatively detected 3-hydroxypropenal (HOCHCHCHO) for the firsttime in the interstellar medium towards source B. Based on the observed line intensities and assuming local thermodynamic
equilibrium, its column density is constrained to be ∼1015 cm−2 , corresponding to an abundance of 10−4 relative to methanol,
CH3 OH. Additional spectroscopic studies are needed to constrain the excitation temperature of this molecule. We included
HOCHCHCHO and five of its isomers in the chemical network presented in Manigand et al. (2021) and we predicted theirchemical evolution with the Nautilus code. The model reproduces the abundance of HOCHCHCHO within the uncertainties.
This species is mainly formed through the grain surface reaction CH2 CHO + HCO → HCOCH2 CHO, followed by the tautomerization of HCOCH2 CHO into HOCHCHCHO. Two isomers, CH3 COCHO and CH2 COHCHO, are predicted to be even moreabundant than HOCHCHCHO. Spectroscopic studies of these molecules are essential in searching for them in IRAS 16293–2422
and other astrophysical sources.

Planet Formation Theory in the Era of ALMA and Kepler: from Pebbles to Exoplanets

9. Joanna Drazkowska, Bertram Bitsch, Michiel Lambrechts, Gijs D. Mulders, Daniel Harsono, Allona Vazan,
Beibei Liu, Chris W. Ormel, Katherine Kretke, Alessandro Morbidelli F Our understanding of planet formation
has been rapidly evolving in recent years. The classical planet formation theory, developed when the only known planetarysystem was our own Solar System, has been revised to account for the observed diversity of the exoplanetary systems. At
the same time, the increasing observational capabilities of the young stars and their surrounding disks bring new constraints
on the planet formation process. In this chapter, we summarize the new information derived from the exoplanets populationand the circumstellar disks observations. We present the new developments in planet formation theory, from dust evolution to
the growth of planetary cores by accretion of planetesimals, pebbles, and gas. We review the state-of-the-art models for theformation of diverse planetary systems, including the population synthesis approach which is necessary to compare theoreticalmodel outcomes to the exoplanet population. We emphasize that the planet formation process may not be spatially uniform
in the disk and there are preferential locations for the formation of planetesimals and planets. Outside of these locations, asignificant fraction of solids is not growing past the pebble-sizes. The reservoir of pebbles plays an important role in the growthof planetary cores in the pebble accretion process. The timescale of the emergence of massive planetary cores is an important
aspect of the present models and it is likely that the cores within one disk form at different times. In addition, there is growing
evidence that the first planetary cores start forming early, during the circumstellar disk buildup process.

Radionuclides in Meteorites and the Sun’s Birth Environment
10. Short-Lived
Steven J. Desch, Edward D. Young, Emilie T. Dunham, Yusuke Fujimoto, Daniel R. Dunlap F The solar nebulacontained a number of short-lived radionuclides (SLRs) with half-lives of tens of Myr or less, comparable to the timescales forformation of protostars and protoplanetary disks. Therefore, determining the origins of SLRs would provide insights into starformation and the Sun’s astrophysical birth environment. In this chapter, we review how isotopic studies of meteorites reveal
the existence and abundances of these now-extinct radionuclides; and the evidence that the SLR 10 Be, which uniquely among
the SLRs is not produced during typical stellar nucleosynthesis, was distributed homogeneously in the solar nebula. We review
the evidence that the SLRs 26 Al, 53 Mn, and 182 Hf, and other radionuclides, were also homogeneously distributed and can beused to date events during the Solar System’s planet-forming epoch. The homogeneity of the SLRs, especially 10 Be, strongly
suggests they were all inherited from the Sun’s molecular cloud, and that production by irradiation within the solar nebula
was very limited, except for 36 Cl. We review astrophysical models for the origin of 10 Be, showing that it requires that theSun formed in a spiral arm of the Galaxy with higher star formation rate than the Galaxy-wide average. Likewise, we review
the astrophysical models for the origins of the other SLRs and show that they likely arose from contamination of the Sun’smolecular cloud by massive stars over tens of Myr, most likely dominated by ejecta from Wolf-Rayet stars. The other SLRs

4also demand formation of the Sun in a spiral arm of the Galaxy with a star formation rate as high as demanded by the Solar
System initial 10 Be abundance. We discuss the astrophysical implications, and suggest further tests of these models and future
directions for the field.

11. Astrochemical modelling of infrared dark clouds

Negar Entekhabi, Jonathan C. Tan, Giuliana Cosentino, Chia-Jung Hsu, Paola Caselli, Catherine Walsh,
Wanggi Lim, Jonathan D. Henshaw, Ashley T. Barnes, Francesco Fontani, Izaskun Jiménez-Serra F Infrareddark clouds (IRDCs) are cold, dense regions of the interstellar medium (ISM) that are likely to represent the initial conditions
for massive star formation. It is thus important to study the physical and chemical conditions of IRDCs to provide constraints
and inputs for theoretical models of these processes. We aim to determine the astrochemical conditions, especially cosmic
ray ionisation rate (CRIR) and chemical age, in different regions of the massive IRDC G28.37+00.07 by comparing observed
abundances of multiple molecules and molecular ions with the predictions of astrochemical models. We have computed aseries of single-zone astrochemical models with a gas-grain network that systematically explores the parameter space of density,
temperature, CRIR, and visual extinction. We have also investigated the effects of choices of CO ice binding energy andtemperatures achieved in transient heating of grains when struck by cosmic rays. We selected 10 positions across the IRDC thatare known to have a variety of star formation activity. We utilised mid-infrared (MIR) extinction maps and sub-mm emission
maps to measure the mass surface densities of these regions, needed for abundance and volume density estimates. The sub-mm
emission maps were also used to measure temperatures. We then used IRAM-30m observations of various tracers to estimate
column densities and thus abundances. Using estimates of the abundances of CO, HCO+ and N2 H+ we find consistency withastrochemical models that have relatively low CRIRs of ζ ∼ 10−18 to ∼ 10−17 s−1 , with no evidence for systematic variation
with the level of star formation activity. Astrochemical ages are found to be < 1 Myr. We discuss potential sources of systematic
uncertainties in these results and the overall implications for IRDC evolutionary history and astrochemical models.(abridged
for arXiv)

12. Accretion Variability as a Guide to Stellar Mass AssemblyWilliam J. Fischer, Lynne A. Hillenbrand, Gregory J. Herczeg, Doug Johnstone, Ágnes Kóspál, Michael M.
Dunham F Variable accretion in young stellar objects reveals itself photometrically and spectroscopically over a continuumof timescales and amplitudes. Most dramatic are the large outbursts (e.g., FU Ori, V1647 Ori, and EX Lup type events), butmore frequent are the less coherent, smaller burst-like variations in accretion rate. Improving our understanding of time-variableaccretion directly addresses the fundamental question of how stars gain their masses. We review variability phenomena, as characterized from observations across the wavelength spectrum, and how those observations probe underlying physical conditions.
The diversity of observed lightcurves and spectra at optical and infrared wavelengths defies a simple classification of outbursts
and bursts into well-defined categories. Mid-infrared and sub-millimeter wavelengths are sensitive to lower-temperature phenomena, and it is currently unclear if observed flux variations probe similar or distinct physics relative to the shorter wavelengths.
We highlight unresolved issues and emphasize the value of spectroscopy, multiwavelength studies, and ultimately patience inusing variable accretion to understand stellar mass assembly.

a spectroscopic survey of young eruptive variables (EXor and candidates)
13. EXORCISM:
T. Giannini, A. Giunta, M. Gangi, R. Carini, D. Lorenzetti, S. Antoniucci, A. Caratti o Garatti, L. Cassarà,
B. Nisini, A. Rossi, V. Testa, F. Vitali F We present an optical/near-IR survey of 11 variable young stars (EXors andEXor candidates) aimed at deriving and monitoring their accretion properties. About 30 optical and near-infrared spectra (<∼ 1500-2000) were collected between 2014-2019 with the Large Binocular Telescope (LBT). From the spectral analysis we havederived the accretion luminosity and mass accretion rate, the visual extinction, the temperature and density of the permitted line
formation region, and the signature of the outflowing matter. Two sources (ASASSN-13db and iPTF15afq) have been observedin outburst and quiescence, three during a high-level of brightness (XZ Tau, PV Cep, and NY Ori), and the others in quiescence.
These latter have accretion luminosity and mass accretion rates in line with the values measured in classical T Tauri stars ofsimilar mass. All sources observed more than once present accretion variability. The most extreme case is ASASSN-13db, forwhich the mass accretion rate decreases by two orders of magnitude from the outburst peak in 2015 to quiescence in 2017. Also,in NY Ori the accretion luminosity decreases by a factor 25 in one year. In 80% of the sample we detect the [OI]630 nm line,
a tracer of mass loss. From the variability of the Hα/[OI]630, ratio, we conclude that mass accretion variations are larger thanmass loss variations. From the analysis of the HI recombination lines a correlation is suggested between the density of the line
formation region and the level of accretion activity of the source.

514. Large amplitude periodic outbursts and long period variables in the VVV VIRAC2-βdatabase

Zhen Guo, P. W. Lucas, L. C. Smith, C. Clarke, C. Contreras Peña, A. Bayo, C. Briceño, J. Elias, R. G.
Kurtev, J. Borissova, J. Alonso-García, D. Minniti, M. Catelan, F. Nikzat, C. Morris, N. Miller F The VISTA
Variables in the Via Lactea (VVV) survey obtained near-infrared photometry toward the Galactic bulge and the southern discplane for a decade (2010 - 2019). We designed a modified Lomb-Scargle method to search for large-amplitude (∆Ks > 1.5 mag)mid to long-term periodic variables (P > 10 d) in the 2nd version of VVV Infrared Astrometric Catalogue (VIRAC2-β). In total,
1520 periodic sources were discovered, including 59 candidate periodic outbursting young stellar objects (YSOs), based on theunique morphology of the phase-folded light curves, proximity to Galactic HII regions and mid-infrared colours. Five sources
are spectroscopically confirmed as accreting YSOs. Both fast-rise/slow-decay and slow-rise/fast-decay periodic outbursts were
found, but fast-rise/slow-decay outbursts predominate at the highest amplitudes. The multi-wavelength colour variations are
consistent with a variable mass accretion process, as opposed to variable extinction. The cycles are likely to be caused bydynamical perturbations from stellar or planetary companions within the circumstellar disc. An additional search for periodic
variability amongst YSO candidates in published Spitzer-based catalogues yielded a further 71 candidate periodic accretors,
mostly with lower amplitudes. These resemble cases of pulsed accretion but with unusually long periods and greater regularity.
The majority of other long-period variables are pulsating dusty Miras with smooth and symmetric light curves. We find thatsome Miras have redder W 3 − W 4 colours than previously thought, most likely due to their surface chemical compositions.

15. Initial Conditions for Star Formation: A Physical Description of the Filamentary ISM

A. Hacar, S Clark, F. Heitsch, J. Kainulainen, G. Panopoulou, D. Seifried, R. Smith F The interstellar medium
contains filamentary structure over a wide range of scales. Understanding the role of this structure, both as a conduit of gas
across the scales and a diagnostic tool of local physics, is a major focus of star formation studies. We review recent progressin studying filamentary structure in the ISM, interpreting its properties in terms of physical processes, and exploring formationand evolution scenarios. We include structures from galactic-scale filaments to tenth-of-a-parsec scale filaments, comprising both
molecular and atomic structures, from both observational and theoretical perspectives. In addition to the literature overview,
we assemble a large amount of catalogue data from different surveys and provide the most comprehensive census of filamentary
structures to date. Our census consists of 22 803 filamentary structures, facilitating a holistic perspective and new insights.
We use our census to conduct a meta-analysis, leading to a description of filament properties over four orders of magnitudes inlength and eight in mass. Our analysis emphasises the hierarchical and dynamical nature of filamentary structures. Filaments
do not live in isolation, nor they generally resemble static structures close to equilibrium. We propose that accretion during
filament formation and evolution sets some of the key scaling properties of filaments. This highlights the role of accretion during
filament formation and evolution and also in setting the initial conditions for star formation. Overall, the study of filamentary
structures during the past decade has been observationally driven. While great progress has been made on measuring the basic
properties of filaments, our understanding of their formation and evolution is clearly lacking. In this context, we identify anumber of directions and questions we consider most pressing for the field.

16. Star Formation in the Central Molecular Zone of the Milky Way

Jonathan D. Henshaw, Ashley T. Barnes, Cara Battersby, Adam Ginsburg, Mattia C. Sormani, Daniel L.
Walker F The Central Molecular Zone (CMZ) is a ring-like accumulation of molecular gas in the innermost few hundred
parsecs of the Milky Way, generated by the inward transport of matter driven by the Galactic bar. The CMZ is the mostextreme star-forming environment in the Galaxy. The unique combination of large-scale dynamics and extreme interstellar
medium conditions, characterised by high densities, temperatures, pressures, turbulent motions, and strong magnetic fields,
make the CMZ an ideal region for testing current star and planet formation theories. We review the recent observational andtheoretical advances in the field, and combine these to draw a comprehensive, multi-scale and multi-physics picture of the cycleof matter and energy in the context of star formation in the closest galactic nucleus.

from Aligned Dust Grains in the β Pic Debris Disk
17. Polarization
Charles L. H. Hull, Haifeng Yang, Paulo C. Cortés, William R. F. Dent, Quentin Kral, Zhi-Yun Li, Valentin J.
M. Le Gouellec, A. Meredith Hughes, Julien Milli, Richard Teague, Mark C. Wyatt F We present 870 µm ALMA
polarization observations of thermal dust emission from the iconic, edge-on debris disk β Pic. While the spatially resolved map
does not exhibit detectable polarized dust emission, we detect polarization at the ∼3σ level when averaging the emission acrossthe entire disk. The corresponding polarization fraction is Pfrac = 0.51 ± 0.19%. The polarization position angle χ is alignedwith the minor axis of the disk, as expected from models of dust grains aligned via radiative alignment torques (RAT) withrespect to a toroidal magnetic field (B-RAT) or with respect to the anisotropy in the radiation field (k-RAT). When averaging
the polarized emission across the outer versus inner thirds of the disk, we find that the polarization arises primarily from theSW third. We perform synthetic observations assuming grain alignment via both k-RAT and B-RAT. Both models produce
polarization fractions close to our observed value when the emission is averaged across the entire disk. When we average the6models in the inner versus outer thirds of the disk, we find that k-RAT is the likely mechanism producing the polarized emissionin β Pic. A comparison of timescales relevant to grain alignment also yields the same conclusion. For dust grains with realistic
aspect ratios (i.e., s > 1.1), our models imply low grain-alignment efficiencies.

SKA as a prebiotic molecule detector
18. TheIzaskun Jimenez-Serra, Jesus Martin-Pintado, Aran Insausti, Elena R. Alonso, Emilio J. Cocinero, Tyler L.
Bourke F One of the theories for the origin of life proposes that a significant fraction of prebiotic material could have arrived
to Earth from outer space between 4.1 and 3.8 billion years ago. This suggests that those prebiotic compounds could haveoriginated in interstellar space, to be later on incorporated to small Solar-system bodies and planetesimals. The recent discovery
of prebiotic molecules such as hydroxylamine and ethanolamine in the interstellar medium, strongly supports this hypothesis.
However, some species such as sugars, key for the synthesis of ribonucleotides and for metabolic processes, remain to bediscovered in space. The unmatched sensitivity of the Square Kilometer Array (SKA) at centimeter wavelengths will be able todetect even more complex and heavier prebiotic molecules than existing instrumentation. In this contribution, we illustrate thepotential of the SKA to detect simple sugars with three and four carbon atoms, using a moderate investment of observing time.

of detecting and characterizing embedded low-mass giant planets in gaps in
19. Feasibility
the VIS/NIR wavelength range
A. Krieger, S. Wolf F High-contrast imaging in the visible and near-infrared (VIS/NIR) has revealed the presence of aplethora of substructures in circumstellar disks (CSDs). One of the most commonly observed substructures are concentric gapsthat may hint at the presence of embedded forming planets. However, direct detections of them are rare, and thus ambiguity
regarding the origin of most gap features remains. The aim of this study is to investigate the capabilities of high-contrast
VIS/NIR imaging of directly detecting and characterizing low-mass giant planets in gaps. To this end, a grid of models of
protoplanetary disks was generated. The models include a central T Tauri star surrounded by a face-on CSD harboring an
accreting planet, which itself is surrounded by a circumplanetary disk (CPD) and carves a gap. We use the Monte Carloradiative transfer code Mol3D to generate temperature distributions and synthetic observations. Based on these simulations,
we measured the impact the planet and its CPD have on contrast curves and quantified the impact of the observing wavelengthand of five key parameters on the determined signal strength. Then, we applied a detection criterion on our results and assess
the capabilities of SPHERE/VLT of detecting the embedded planets. We find that a part of the investigated parameter space
includes detectable planets, and we elaborate on the implications of a non-detection. Furthermore, we analyze the potential
loss of valuable information by the use of a too small coronagraphic mask. However, we find this outcome to be very unlikely.
Finally, within the VIS/NIR we identify for each of the investigated basic properties of the planets and the disks the mostpromising observing wavelengths that enable us to distinguish between different underlying parameter values. We find, that thedetectability and the characterization often benefit from different observing wavelengths.

collisions in globular clusters: the origin of multiple stellar populations
20. Stellar
Valery Kravtsov, Sami Dib, Francisco A. Calderon, Jose A. Belinchon F Two generations of stars, G1 and G2,
typically populate Galactic globular clusters (GCs). The origin of G2 stars is unclear. We uncover two empirical dependencies
between GC characteristics, which can be explained by the formation of G2 Main-Sequence (MS) stars due to collision of theirprimordial counterparts (G1). A similar genesis of both G2 stars and peculiar objects like LMXBs and millisecond pulsars is
also implied. Indeed, we find a significant (at a confidence level > 99,9%) anti-correlation between the fraction of G1 red giants(NG1 /Ntot ) and stellar encounter rates among 51 GCs. Moreover, a Milky Way-like initial mass function (IMF) requires at least∼ 50% of MS stars located in the mass range [0.1-0.5] Mo dot. Unlike cluster mass loss, stellar collisions retain these G1 stars
by converting them into more massive G2 ones, with mainly Mms > 0.5 Mo dot. This process coupled with a decreasing relative
mass loss with increasing GC masses implies a smaller (NG1 /Ntot ) in more massive GCs with a shallower present day MF. Fromdata for 35 GCs, we find that such an anti-correlation is significant at 98.3% confidence level (Spearman’s correlation) for 12
most massive GCs (MGC > 105.3 Mo dot) and it is at a confidence level of 89% for the 12 least massive GCs (MGC < 105.1
Mo dot). Other fractions of G1 and G2 stars observed at the bottom of the MS as compared with the red giant branch in a few
GCs are consistent with the scenario proposed.

Effect of Molecular Cloud Properties on the Kinematics of Stars Formed in the
21. TheTrifid Region
Michael A. Kuhn, Lynne A. Hillenbrand, Eric D. Feigelson, Ian Fowler, Konstantin V. Getman, Patrick S.
Broos, Matthew S. Povich, Mariusz Gromadzki F The dynamical states of molecular clouds may affect the propertiesof the stars they form. In the vicinity of the Trifid Nebula (d = 1180 ± 25 pc), the main star cluster (Trifid Main) lies within
an expanding section of the molecular cloud; however, 0.3 deg to the north (Trifid North), the cloud’s velocity structure ismore tranquil. We acquired a Chandra X-ray observation to identify pre-main-sequence stars in Trifid North, complementing

7

a previous observation of Trifid Main. In Trifid North, we identified 51 candidate pre-main-sequence stars, of which 13 arehigh-confidence Trifid members based on Gaia EDR3 parallaxes and proper motions. We also re-analyzed membership of Trifid
Main and separated out multiple background stellar associations. Trifid North represents a stellar population 10in a separate
part of the cloud. The 1D stellar velocity dispersion in Trifid North (0.6 ± 0.2 km/s) is three times lower than in Trifid Main
(1.9 ± 0.2 km/s). Furthermore, in Trifid Main, proper motions indicate that the portion of the star cluster superimposed on
the optical nebula is expanding. Expansion of the HII region around the O-star HD 164492A, and the resulting gas expulsion,can explain both the motions of the stars and gas in Trifid Main. Contrary to previous studies, we find no evidence that acloud-cloud collision triggered star formation in the region.

Habitability: Supply and Retention of Life’s Essential Elements During Planet
22. Chemical
Formation
Sebastiaan Krijt, Mihkel Kama, Melissa McClure, Johanna Teske, Edwin A. Bergin, Oliver Shorttle, Kevin J.
Walsh, Sean N. Raymond F Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur (CHNOPS) play key roles in
the origin and proliferation of life on Earth. Given the universality of physics and chemistry, not least the ubiquity of water
as a solvent and carbon as a backbone of complex molecules, CHNOPS are likely crucial to most habitable worlds. To help
guide and inform the search for potentially habitable and ultimately inhabited environments, we begin by summarizing the
CHNOPS budget of various reservoirs on Earth, their role in shaping our biosphere, and their origins in the Solar Nebula. We
then synthesize our current understanding of how these elements behave and are distributed in diverse astrophysical settings,
tracing their journeys from synthesis in dying stars to molecular clouds, protoplanetary settings, and ultimately temperate rocky
planets around main sequence stars. We end by identifying key branching points during this journey, highlighting instanceswhere a forming planets’ distribution of CHNOPS can be altered dramatically, and speculating about the consequences for thechemical habitability of these worlds.

in the Veil: Protostellar feedback in Orion
23. Dents
U. Kavak, J. Bally, J. R. Goicoechea, C. H. M. Pabst, F. F. S. van der Tak, A. G. G. M. Tielens F Interest in stellar
feedback has recently increased because new studies suggest that radiative and mechanical feedback from young massive stars
regulate the physical and chemical composition of the interstellar medium (ISM) significantly. Recent SOFIA [CII] 158 micron
observations of the Orion Veil revealed that the expanding bubble is powered by stellar winds and influenced by previously
active molecular outflows of ionizing massive stars. We aim to investigate the mechanical feedback on the whole Veil shell by
searching for jets/outflows interacting with the Veil shell and determining the origin/driving mechanisms of these collisions. In
the light of these findings, as well as the momenta of the dents and their dynamical timescales, we propose that the dents are
created by the interaction of collimated jets/outflows from protostars with luminosities ranging from 103 to 104 L indicating
B-type stars in the Orion star-forming cloud with the surrounding Veil shell. However, it is challenging to pinpoint the driving
stars as they may have moved from the original ejection points of the jets/outflows. We conclude that the dynamics of the
expanding Veil shell is influenced not just by the O-type stars in the Trapezium cluster, but also by less massive stars, especiallyB-type, in the Orion Nebula. Mechanical feedback from protostars with a range of masses appears to play an important role indetermining the morphology of [HII] regions and injecting turbulence into the medium.

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions-IX. A

24. pilot study towards IRDC G034.43+00.24 on multi-scale structures and gas kinematics

Hong-Li Liu, Anandmayee Tej, Tie Liu, Paul F. Goldsmith, Amelia Stutz, Mika Juvela, Sheng-Li Qin, FengWei Xu, Leonardo Bronfman, Neal J. Evans, Anindya Saha, Namitha Issac, Ken’ichi Tatematsu, Ke Wang,
Shanghuo Li, Siju Zhang, Tapas Baug, Lokesh Dewangan, Yue-Fang Wu, Yong Zhang, Chang Won Lee, XunChuan Liu, Jianwen Zhou, Archana Soam F We present a comprehensive study of the gas kinematics associated withdensity structures at different spatial scales in the filamentary infrared dark cloud, G034.43+00.24 (G34). This study makes
use of the H13CO+ (1-0) molecular line data from the ALMA Three-millimeter Observations of Massive Star-forming regions(ATOMS) survey, which has spatial and velocity resolution of 0.04 pc and 0.2 km/s, respectively. Several tens of dendrogram
structures have been extracted in the position-position-velocity space of H13CO+, which include 21 small-scale leaves and 20
larger-scale branches. Overall, their gas motions are supersonic but they exhibit the interesting behavior where leaves tend to beless dynamically supersonic than the branches. For the larger-scale, branch structures, the observed velocity-size relation (i.e.,
velocity variation/dispersion versus size) are seen to follow the Larson scaling exponent while the smaller-scale, leaf structures
show a systematic deviation and display a steeper slope. We argue that the origin of the observed kinematics of the branch
structures is likely to be a combination of turbulence and gravity-driven ordered gas flows. In comparison, gravity-driven
chaotic gas motion is likely at the level of small-scale leaf structures. The results presented in our previous paper and thiscurrent follow-up study suggest that the main driving mechanism for mass accretion/inflow observed in G34 varies at different
spatial scales. We therefore conclude that a scale-dependent combined effect of turbulence and gravity is essential to explain
the star-formation processes in G34.

8

Investigation of Dust and Gaseous CO in 12 Nearby Molecular Clouds
25. SystematicJohn Arban Lewis, Charles J. Lada, Thomas Dame F We report the first uniform and systematic study of dust andmolecular gas in nearby molecular clouds. We use surveys of dust extinction and emission to determine the opacity and map
the distribution of the dust within a dozen local clouds in order to derive a uniform set of basic cloud properties. We find: 1)
the average dust opacity hκd,353 i = 0.8 cm2 g−1 with variations of a factor of ∼ 2 between clouds, 2) cloud PDFs are exquisitely
2
described by steeply falling power-laws with a narrow range of slope, and 3) a tight MGMC ∼ RGMC
scaling relation for the cloud
sample, indicative of a cloud population with an exactingly constant average surface density above a common fixed boundary.
We compare these results to uniformly analyzed CO surveys. We measure the CO mass conversion factors and assess theefficacy of CO for tracing the physical properties of molecular clouds. We find hαCO i = 4.31 ± 0.67 M (K km s−1 pc2 )−1(corresponding to XCO = 1.97 × 1020 cm−2 (K km s−1 )−1 ). We demonstrate that CO observations are a poor tracer of column
density and structure on sub-cloud spatial scales. On cloud scales, CO observations can provide measurements consistent withthose of the dust, provided data are analyzed in a similar, self-consistent fashion. Measurements of average GMC surface density
are sensitive to choice of cloud boundary. Care must be exercised to adopt common fixed boundaries when comparing surface
densities for cloud populations within and between galaxies.

26. Hydro-, Magnetohydro-, and Dust-Gas Dynamics of Protoplanetary Disks

G. Lesur, B. Ercolano, M. Flock, M. -K. Lin, C. -C. Yang, J. A. Barranco, P. Benitez-Llambay, J. Goodman,
A. Johansen, H. Klahr, G. Laibe, W. Lyra, P. Marcus, R. P. Nelson, J. Squire, J. B. Simon, N. Turner, O. M.
Umurhan, A. N. Youdin F The building of planetary systems is controlled by the gas and dust dynamics of protoplanetarydisks. While the gas is simultaneously accreted onto the central star and dissipated away by winds, dust grains aggregate
and collapse to form planetesimals and eventually planets. This dust and gas dynamics involves instabilities, turbulence andcomplex non-linear interactions which ultimately control the observational appearance and the secular evolution of these disks.
This chapter is dedicated to the most recent developments in our understanding of the dynamics of gaseous and dusty disks,covering hydrodynamic and magnetohydrodynamic turbulence, gas-dust instabilities, dust clumping and disk winds. We show
how these physical processes have been tested from observations and highlight standing questions that should be addressed in
the future.

Geophysical Evolution During Rocky Planet Formation

27. Tim Lichtenberg, Laura K. Schaefer, Miki Nakajima, Rebecca A. Fischer F Progressive astronomical characterizationof planet-forming disks and rocky exoplanets highlight the need for increasing interdisciplinary efforts to understand the birthand life cycle of terrestrial worlds in a unified picture. Here, we review major geophysical and geochemical processes that shapethe evolution of rocky planets and their precursor planetesimals during planetary formation and early evolution, and how thesemap onto the astrophysical timeline and varying accretion environments of planetary growth. The evolution of the coupled
core-mantle-atmosphere system of growing protoplanets diverges in thermal, compositional, and structural states to first order,and ultimately shapes key planetary characteristics that can discern planets harboring clement surface conditions from thosethat do not. Astronomical campaigns seeking to investigate rocky exoplanets will require significant advances in laboratory
characterization of planetary materials and time- and spatially-resolved theoretical models of planetary evolution, to extend
planetary science beyond the Solar System and constrain the origins and frequency of habitable worlds like our own.

Collision of protostellar jets in the star-forming region IC 1396N. Analysis of knot

28. proper motions

Rosario López, Robert Estalella, María T. Beltrán, Fabricio Massi, José A. Acosta-Pulido, Josep M. Girart F
The bright-rimmed cloud IC 1396N is believed to host one of the few known cases where two bipolar CO outflows driven byyoung stellar objects actually collide. The CO outflows are traced by chains of knots of H2 emission, with enhanced emission at
the position of the possible collision. The aim of this work is to use the proper motions of the H2 knots to confirm the collision
scenario. A second epoch H2 image was obtained, and the proper motions of the knots were determined with a time baselineof 11 years. We also performed differential photometry on the images to check the flux variability of the knots. For each
outflow (N and S) we classified the knots as pre-collision or post-collision. The axes of the pre-collision knots, the position of
the possible collision point, and the axes of the post-collision knots were estimated. The difference between the proper motion
direction of the post-collision knots and the position angle from the collision point was also calculated. For some of the knots weobtained the 3D velocity by using the radial velocity derived from H2 spectra. The velocity pattern of the H2 knots in the areaof interaction (post-collision knots) shows a deviation from that of the pre-collision knots, consistent with being a consequenceof the interaction between the two outflows. This favours the interpretation of the IC 1396N outflows as a true collision between
two protostellar jets instead of a projection effect.

929. Virial Clumps in Central Molecular Zone Clouds

Philip C. Myers, H Perry Hatchfield, Cara Battersby F CMZoom survey observations with the Submillimeter Array are
analyzed to describe the virial equilibrium (VE) and star-forming potential of 755 clumps in 22 clouds in the Central MolecularZone (CMZ) of the Milky Way. In each cloud, nearly all clumps follow the column-density-mass trend N Ms , where s = 0.38
± 0.03 is near the pressure-bounded limit s=1/3. This trend is expected when gravitationally unbound clumps in VE have
similar velocity dispersion and external pressure. Nine of these clouds also harbor one or two distinctly more massive clumps.
These properties allow a VE model of bound and unbound clumps in each cloud, where the most massive clump has the VE
critical mass. These models indicate that 213 clumps have velocity dispersion 1-2 km s−1 , mean external pressure 0.5-4 x 108
cm−3 K, bound clump fraction 0.06, and typical virial parameter alpha=4-15. These mostly unbound clumps may be in VE
with their turbulent cloud pressure, possibly driven by inflow from the galactic bar. In contrast, most Sgr B2 clumps are boundaccording to their associated sources and N-M trends. When the CMZ clumps are combined into mass distributions, their
typical power-law slope is analyzed with a stopped accretion model. It also indicates that most clumps are unbound and cannot
grow significantly, due to their similar time scales of accretion and dispersal, 0.2 Myr. Thus, virial and dynamical analyses ofthe most extensive clump census available indicate that star formation in the CMZ may be suppressed by a significant deficitof gravitationally bound clumps.

Mass Stars as Tracers of Star and Cluster Formation
30. Low
S. T. Megeath, R. A. Gutermuth, M. A. Kounkel F We review the use of young low mass stars and protostars, oryoung stellar objects (YSOs), as tracers of star formation. Observations of molecular clouds at visible, infrared, radio and X-ray
wavelengths can identify and characterize the YSOs populating these clouds, with the ability to detect deeply embedded objects
and all evolutionary stages. Surveys with the Spitzer, Herschel, XMM-Newton and Chandra space telescopes have measured
the spatial distribution of YSOs within a number of nearby (< 2.5 kpc) molecular clouds, showing surface densities varying by
more than three orders of magnitude. These surveys have been used to measure the spatially varying star formation rates andefficiencies within clouds, and when combined with maps of the molecular gas, have led to the discovery of star-forming relations
within clouds. YSO surveys can also characterize the structures, ages, and star formation histories of embedded clusters, andthey illuminate the relationship of the clusters to the networks of filaments, hubs and ridges in the molecular clouds from which
they form. Measurements of the proper motions and radial velocities of YSOs trace the evolving kinematics of clusters from the
deeply embedded phases through gas dispersal, providing insights into the factors that shape the formation of bound clusters.
On 100 pc scales that encompass entire star-forming complexes, Gaia is mapping the young associations of stars that havedispersed their natal gas and exist alongside molecular clouds. These surveys reveal the complex structures and motions inassociations, and show evidence for supernova driven expansions. Remnants of these associations have now been identified by
Gaia, showing that traces of star-forming structures can persist for a few hundred million years.

Setting the Stage for Planet Formation: Measurements and Implications of the Funda-

31. mental Disk Properties

A. Miotello, I. Kamp, T. Birnstiel, L. I. Cleeves, A. Kataoka F The field of planet formation is in an exciting era, whererecent observations of disks around low- to intermediate-mass stars made with state of the art interferometers and high-contrast
optical and IR facilities have revealed a diversity of substructures, some possibly planet-related. It is therefore important tounderstand the physical and chemical nature of the protoplanetary building blocks, as well as their spatial distribution, tobetter understand planet formation. Since PPVI, the field has seen tremendous improvements in observational capabilities,
enabling both surveys of large samples of disks and high resolution imaging studies of a few bright disks. Improvements in data
quality and sample size have, however, opened up many fundamental questions about properties such as the mass budget ofdisks, its spatial distribution, and its radial extent. Moreover, the vertical structure of disks has been studied in greater detailwith spatially resolved observations, providing new insights on vertical layering and temperature stratification, yet also bringing
rise to questions about other properties, such as material transport and viscosity. Each one of these properties - disk mass,
surface density distribution, outer radius, vertical extent, temperature structure, and transport - is of fundamental interest as
they collectively set the stage for disk evolution and corresponding planet formation theories. In this chapter, we will review
our understanding of the fundamental properties of disks including the relevant observational techniques to probe their nature,modelling methods, and the respective caveats. Finally, we discuss the implications for theories of disk evolution and planet
formation underlining what new questions have since arisen as our observational facilities have improved.

Demographics of young stars and their protoplanetary disks: lessons learned on disk

32. evolution and its connection to planet formation

C. F. Manara, M. Ansdell, G. P. Rosotti, A. M. Hughes, P. J. Armitage, G. Lodato, J. P. Williams F Since
Protostars and Planets VI (PPVI), our knowledge of the global properties of protoplanetary and debris disks, as well as of youngstars, has dramatically improved. At the time of PPVI, mm-observations and optical to near-infrared spectroscopic surveys werelargely limited to the Taurus star-forming region, especially of its most massive disk and stellar population. Now, near-complete10

surveys of multiple star-forming regions cover both spectroscopy of young stars and mm interferometry of their protoplanetarydisks. This provides an unprecedented statistical sample of stellar masses and mass accretion rates, as well as disk masses andradii, for almost 1000 young stellar objects within 300 pc from us, while also sampling different evolutionary stages, ages, andenvironments. At the same time, surveys of debris disks are revealing the bulk properties of this class of more evolved objects.
This chapter reviews the statistics of these measured global star and disk properties and discusses their constraints on theoreticalmodels describing global disk evolution. Our comparisons of observations to theoretical model predictions extends beyond the
traditional viscous evolution framework to include analytical descriptions of magnetic wind effects. Finally, we discuss how
recent observational results can provide a framework for models of planet population synthesis and planet formation.

33. The Appearance of Vortices in Protoplanetary Disks in Near-Infrared Scattered Light
Metea Marr, Ruobing Dong F Azimuthally asymmetric structures have been discovered in millimeter continuum emission
from many protoplanetary disks. One hypothesis is that they are vortices produced by the Rossby wave instability, for example
at edges of planet-opened gaps or deadzones. Confirming the vortex nature of these structures will have profound implications
to planet formation. One way to test the hypothesis is to compare the observed morphology of vortex candidates in nearinfrared scattered light with theoretical expectations. To this end, we synthesize the appearance of vortices in H-band polarized
light by combining hydrodynamic and radiative transfer simulations of the Rossby wave instability at a deadzone edge. In adisk at 140 pc, at the peak in its evolution a vortex at 65 au may appear as a radially narrow arc 50an axisymmetric disk
model. The contrast depends on the inclination of the disk and the position angle of the vortex only weakly. Such contrast
levels are well detectable in imaging observations of bright disks using instruments such as VLT/SPHERE, Subaru/SCExAO,
and Gemini/GPI. A vortex also casts a shadow in the outer disk, which may aid its identification. Finally, at modest to highinclinations (e.g., 60 degrees) a vortex may mimic a one-armed spiral. In the HD 34282 disk, such a one-armed spiral with ashadowed region on the outside has been found in scattered light. This feature roughly coincides with an azimuthal asymmetryin mm continuum emission, signifying the presence of a vortex.

34. The Isotopic Links from Planet Forming Regions to the Solar System

H. Nomura, K. Furuya, M. A. Cordiner, S. B. Charnley, C. M. O’D. Alexander, C. A. Nixon, V. V. Guzman,
H. Yurimoto, T. Tsukagoshi, T. Iino F Isotopic ratios provide a powerful tool for understanding the origins of materials,
including the volatile and refractory matter within solar system bodies. Recent high sensitivity observations of molecularisotopologues, in particular with ALMA, have brought us new information on isotopic ratios of hydrogen, carbon, nitrogenand oxygen in star and planet forming regions as well as the solar system objects. Solar system exploration missions, suchas Rosetta and Cassini, have given us further new insights. Meanwhile, the recent development of sophisticated models forisotope chemistry including detailed gas-phase and grain surface reaction network has made it possible to discuss how isotope
fractionation in star and planet forming regions is imprinted into the icy mantles of dust grains, preserving a record of the initialisotopic state of solar system materials. This chapter reviews recent progress in observations of molecular isotopologues inextra-solar planet forming regions, prestellar/protostellar cores and protoplanetary disks, as well as objects in our solar system– comets, meteorites, and planetary/satellite atmospheres – and discusses their connection by means of isotope chemical models.

35. The Origin and Evolution of Multiple Star Systems

Stella S. R. Offner, Maxwell Moe, Kaitlin M. Kratter, Sarah I. Sadavoy, Eric L. N. Jensen, John J. Tobin
F Most stars are born in multiple stellar systems. Observational advances over the last decade have enabled high-resolution,interferometric studies of forming multiple systems, statistical surveys of multiplicity in star-forming regions, and new insights
into disk evolution and planetary architectures in these systems. In this review, we compile the results of observational andtheoretical studies of stellar multiplicity. We summarize the population statistics spanning system evolution from the protostellar
phase through the main-sequence phase and evaluate the influence of the local environment. We describe current models for theorigin of stellar multiplicity and review the landscape of numerical simulations and assess their consistency with observations.
We review the properties of disks and discuss the impact of multiplicity on planet formation and system architectures. Finally,
we summarize open questions and discuss the technical requirements for future observational and theoretical progress.

Structures in Planet-Forming Disks
36. Kinematic
Christophe Pinte, Richard Teague, Kevin Flaherty, Cassandra Hall, Stefano Facchini, Simon Casassus F The
past 5 years have dramatically changed our view of the disks of gas and dust around young stars. Observations with the
Atacama Large Millimeter/submillimeter Array (ALMA) and extreme adaptive optics systems have revealed that disks are
dynamical systems. Most disks contain resolved structures, both in gas and dust, including rings, gaps, spirals, azimuthal
dust concentrations, shadows cast by misaligned inner disks, as well as deviations from Keplerian rotation. The origin of thesestructures and how they relate to the planet formation process remain poorly understood. Spatially resolved kinematic studies
offer a new and necessary window to understand and quantify the physical processes (turbulence, winds, radial and meridional11

flows, stellar multiplicity, instabilities) at play during planet formation and disk evolution. Recent progress, driven mainly by
resolved ALMA observations, includes the detection and mass determination of embedded planets, the mapping of the gas flow
around the accreting planets, the confirmation of tidal interactions and warped disk geometries, and stringent limits on the
turbulent velocities. In this chapter, we will review our current understanding of these dynamical processes and highlight how
kinematic mapping provides new ways to observe planet formation in action.

37. Planet-Disk Interactions

Sijme-Jan Paardekooper, Ruobing Dong, Paul Duffell, Jeffrey Fung, Frederic S. Masset, Gordon Ogilvie,
Hidekazu Tanaka F Planet-disk interactions, where an embedded massive body interacts gravitationally with the protoplanetary disk it was formed in, can play an important role in reshaping both the disk and the orbit of the planet. Spiral density
waves are launched into the disk by the planet, which, if they are strong enough, can lead to the formation of a gap. Botheffects are observable with current instruments. The back-reaction of perturbations induced in the disk, both wave-like andnon-wavelike, is a change in orbital elements of the planet. The efficiency of orbital migration is a long-standing problem inplanet formation theory. We discuss recent progress in planet-disk interactions for different planet masses and disk parameters,in particular the level of turbulence, and progress in modeling observational signatures of embedded planets.

38. The Role of Disk Winds in the Evolution and Dispersal of Protoplanetary Disks
Ilaria Pascucci, Sylvie Cabrit, Suzan Edwards, Uma Gorti, Oliver Gressel, Takeru Suzuki F The assembly
and architecture of planetary systems strongly depend on the physical processes governing the evolution and dispersal of
protoplanetary disks. Since Protostars and Planets VI, new observations and theoretical insights favor disk winds as being oneof those key processes. This chapter provides a comprehensive review of recent observations probing outflowing gas launchedover a range of disk radii for a wide range of evolutionary stages, enabling an empirical understanding of how winds evolve.
In parallel, we review theoretical advancements in both magnetohydrodynamic and photoevaporative disk wind models andidentify predictions that can be confronted with observations. By linking theory and observations we critically assess the roleof disk winds in the evolution and dispersal of protoplanetary disks. Finally, we explore the impact of disk winds on planet
formation and evolution and highlight theoretical work, observations, and critical tests for future progress.

fields in star formation: from clouds to cores
39. Magnetic
Kate Pattle, Laura Fissel, Mehrnoosh Tahani, Tie Liu, Evangelia Ntormousi F In this chapter we review recent
advances in understanding the roles that magnetic fields play throughout the star formation process, gained through observations
and simulations of molecular clouds, the dense, star-forming phase of the magnetised, turbulent interstellar medium (ISM).
Recent results broadly support a picture in which the magnetic fields of molecular clouds transition from being gravitationallysub-critical and near equipartition with turbulence in low-density cloud envelopes, to being energetically sub-dominant indense, gravitationally unstable star-forming cores. Magnetic fields appear to play an important role in the formation of cloud
substructure by setting preferred directions for large-scale gas flows in molecular clouds, and can direct the accretion of material
onto star-forming filaments and hubs. Low-mass star formation may proceed in environments close to magnetic criticality;
high-mass star formation remains less well-understood, but may proceed in more supercritical environments. The interaction
between magnetic fields and (proto)stellar feedback may be particularly important in setting star formation efficiency. We also
review a range of widely-used techniques for quantifying the dynamic importance of magnetic fields, concluding that bettercalibrated diagnostics are required in order to use the spectacular range of forthcoming observations and simulations to quantify
our emerging understanding of how magnetic fields influence the outcome of the star formation process.
+hard: interstellar PO detection
40. Ionise
Víctor M. Rivilla, Juan García de la Concepción, Izaskun Jiménez-Serra, Jesús Martín-Pintado, Laura Colzi,
Belén Tercero, Andrés Megías, Álvaro López-Gallifa, Antonio Martínez-Henares, Sara Massalkhi, Sergio
Martín, Shaoshan Zeng, Pablo De Vicente, Fernando Rico-Villas, Miguel A. Requena-Torres, Giuliana Cosentino
F We report the first detection of the phosphorus monoxide ion (PO+ ) in the interstellar medium. Our unbiased and very
sensitive spectral survey towards the G+0.693−0.027 molecular cloud covers four different rotational transitions of this molecule,two of which (J=1−0 and J=2−1) appear free of contamination from other species. The fit performed, assuming Local Thermodynamic Equilibrium conditions, yields a column density of N =(6.0±0.7)×1011 cm−2 . The resulting molecular abundancewith respect to molecular hydrogen is 4.5×10−12 . The column density of PO+ normalised by the cosmic abundance of P islarger than those of NO+ and SO+ , normalised by N and S, by factors of 3.6 and 2.3, respectively. The N (PO+ )/N (PO) ratio
is 0.12±0.03, more than one order of magnitude higher than those of N (SO+ )/N (SO) and N (NO+ )/N (NO). These results
indicate that P is more efficiently ionised in the ISM than N and S. We have performed new chemical models that confirm
that the PO+ abundance is strongly enhanced in shocked regions with high values of cosmic-ray ionisation rates (10−15 −10−14s−1 ), as occurs in the G+0.693−0.027 molecular cloud. The shocks sputter the interstellar icy grain mantles, releasing into the12gas phase most of their P content, mainly in the form of PH3 , which is converted into atomic P, and then ionised efficiently
by cosmic rays, forming P+ . Further reactions with O2 and OH produce PO+ . The cosmic-ray ionisation of PO might also
contribute significantly, which would explain the high N (PO+ )/N (PO) observed. The relatively high gas-phase abundance of
PO+ with respect to other P-bearing species stresses the relevance of this species in the interstellar chemistry of P.

Precursors of the RNA-world in space: Detection of (Z)-1,2-ethenediol in the interstel41. larmedium, a key intermediate in sugar formation
Víctor M. Rivilla, Laura Colzi, Izaskun Jiménez-Serra, Jesús Martín-Pintado, Andrés Megías, Mattia Melosso,
Luca Bizzocchi, Álvaro López-Gallifa, Antonio Martínez-Henares, Sarah Massalkhi, Belén Tercero, Pablo deVicente, Jean-Claude Guillemin, Juan García de la Concepción, Fernando Rico-Villas, Shaoshan Zeng, Sergio Martín, Miguel A. Requena-Torres, Francesca Tonolo, Silvia Alessandrini, Luca Dore, Vincenzo Barone,
Cristina Puzzarini F We present the first detection of (Z)-1,2-ethenediol, (CHOH)2 , the enol form of glycolaldehyde, in theinterstellar medium towards the G+0.693-0.027 molecular cloud located in the Galactic Center. We have derived a column
density of (1.8±0.1)×1013 cm−2 , which translates into a molecular abundance with respect to molecular hydrogen of 1.3×10−10 .
The abundance ratio between glycolaldehyde and (Z)-1,2-ethenediol is ∼5.2. We discuss several viable formation routes throughchemical reactions from precursors such as HCO, H2 CO, HCOH or CH2 CHOH. We also propose that this species might be an
important precursor in the formation of glyceraldehyde (HOCH2 CHOHCHO) in the interstellar medium through combination
with the hydroxymethylene (CHOH) radical.

42. Cluster Formation in GGD12-15: Infall Motion with Rotation of the Natal Clump

Tomomi Shimoikura, Kazuhito Dobashi, Naomi Hirano, Fumitaka Nakamura, Tomoya Hirota, Tomoaki Matsumoto, Kotomi Taniguchi, Yoshito Shimajiri F We report results of observations of the GGD12-15 region, where cluster
formation is actively taking place, using various molecular emission lines. The C18O (J= 1-0) emission line reveals a massive
clump in the region with a mass of 2800 Mo distributed over 2 pc. The distribution of the C18O(J= 3-2) emission is similar
to that of a star cluster forming therein, with an elliptical shape of 1 pc in size. A bipolar molecular outflow driven by IRS
9Mc, a constituent star of the cluster, is blowing in a direction perpendicular to the elongated C18O (J= 3-2) distribution,
covering the entire clump. There is a massive core with a radius of 0.3 pc and a mass of 530 Mo in the center of the clump.
There are two velocity components around the core, which are prominent in a position-velocity (PV) diagram along the major
axis of the clump. In addition, a PV diagram along the minor axis of the clump, which is parallel to the outflow, shows avelocity gradient opposite to that of the outflow. The velocity structure strongly indicates the infalling motion of the clump.
Comparison of the observational data with a simple model of infalling oblate clumps indicates that the clump is undergoinggravitational contraction with rotation.

planet-driven dust spirals with ALMA
43. Observing
Jessica Speedie, Richard A. Booth, Ruobing Dong F ALMA continuum observations of thermal emission from thedust component of protoplanetary disks have revealed an abundance of substructures that may be interpreted as evidence
for embedded planets, but planet-driven spiral arms – perhaps one of the most compelling lines of evidence – have provencomparatively elusive. In this work, we test the capabilities of ALMA to detect the planet-driven spiral signal in continuum
emission. Carrying out hydrodynamic simulations and radiative transfer calculations, we present synthetic Band 7 continuum
images for a wide range of disk and observing conditions. We show that thermal mass planets at tens of au typically drive spirals
detectable within a few hours of integration time, and the detectable planet mass may be as low as ∼Neptune mass (0.3 Mth ).
The grains probed by ALMA form spirals morphologically identical to the underlying gas spiral. The temperature of the dust
spiral is crucial in determining its contrast, and spirals are easier to detect in disks with an adiabatic equation of state andlonger cooling times. Resolving the spiral is not necessary for its detection; with the help of residual maps, the optimal beam
size is a few times the spiral width at a constant noise level. Finally, we show how the presence of gaps and rings can impair ourability to recognize co-located spirals. Our work demonstrates the planet-finding potential of the current design specification of
ALMA, and suggests that observing capability is not the bottleneck in searching for spirals induced by thermal mass planets.

Mass ejection and time variability in protostellar outflows: Cep E. SOLIS XVI

44. A. de A. Schutzer, P. R. Rivera-Ortiz, B. Lefloch, A. Gusdorf, C. Favre, D. Segura-Cox, A. Lopez-Sepulcre,
R. Neri, J. Ospina-Zamudio, M. De Simone, C. Codella, S. Viti, L. Podio, J. Pineda, R. O’Donoghue, C.
Ceccarelli, P. Caselli, F. Alves, R. Bachiller, N. Balucani, E. Bianchi, L. Bizzocchi, S. Bottinelli, E. Caux, A.
Chacón-Tanarro, F. Dulieu, J. Enrique-Romero, F. Fontani, S. Feng, J. Holdship, I. Jiménez-Serra, A. Jaber
Al-Edhari, C. Kahane, V. Lattanzi, Y. Oya, A. Punanova, A. Rimola, N. Sakai, S. Spezzano, I. R. Sims, V.
Taquet, L. Testi, P. Theulé, P. Ugliengo, C. Vastel, A. I. Vasyunin, F. Vazart, S. Yamamoto, A. Witzel F
Protostellar jets are an important agent of star formation feedback, tightly connected with the mass-accretion process. The

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history of jet formation and mass-ejection provides constraints on the mass accretion history and the nature of the driving source.
We want to characterize the time-variability of the mass-ejection phenomena at work in the Class 0 protostellar phase, in order
to better understand the dynamics of the outflowing gas and bring more constraints on the origin of the jet chemical composition
and the mass-accretion history. We have observed the emission of the CO 2-1 and SO NJ =54 -43 rotational transitions withNOEMA, towards the intermediate-mass Class 0 protostellar system Cep E. The CO high-velocity jet emission reveals a centralcomponent associated with high-velocity molecular knots, also detected in SO, surrounded by a collimated layer of entrained
gas. The gas layer appears to accelerate along the main axis over a length scale delta0 700 au, while its diameter gradually
increases up to several 1000au at 2000au from the protostar. The jet is fragmented into 18 knots of mass 10−3 Msun, unevenly
distributed between the northern and southern lobes, with velocity variations up to 15 km/s close to the protostar, well below
the jet terminal velocities. The knot interval distribution is approximately bimodal with a scale of 50-80yr close to the protostar
and 150-200yr at larger distances > 12 arcsec. The mass-loss rates derived from knot masses are overall steady, with values of
2.7x10−5 Msun/yr (8.9x10−6 Msun/yr) in the northern (southern) lobe. The interaction of the ambient protostellar material
with high-velocity knots drives the formation of a molecular layer around the jet, which accounts for the higher mass-loss ratein the north. The jet dynamics are well accounted for by a simple precession model with a period of 2000yr and a mass-ejection
period of 55yr.

45. Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2

Ken’ichi Tatematsu, You-Ting Yeh, Naomi Hirano, Sheng-Yuan Liu, Tie Liu, Somnath Dutta, Dipen Sahu,
Neal J. Evans II, Mika Juvela, Hee-Weon Yi, Jeong-Eun Lee, Patricio Sanhueza, Shanghuo Li, David Eden,
Gwanjeong Kim, Chin-Fei Lee, Yuefang Wu, Kee-Tae Kim, L. Viktor T’oth, Minho Choi, Miju Kang, Mark
A. Thompson, Gary A. Fuller, 20 Di Li, Ke Wang, Takeshi Sakai, Ryo Kandori, Shih-Ying Hsu, Chau-Ching
Chiong, JCMT Large Program SCOPE collaboration, ALMASOP collaboration F In this study, 36 cores (30starless and 6 protostellar) identified in Orion were surveyed to search for inward motions. We used the Nobeyama 45 m radio
telescope, and mapped the cores in the J = 1 → 0 transitions of HCO+ , H13 CO+ , N2 H+ , HNC, and HN13 C. The asymmetry
parameter δV , which was the ratio of the difference between the HCO+ and H13 CO+ peak velocities to the H13 CO+ line width,
was biased toward negative values, suggesting that inward motions were more dominant than outward motions. Three starlesscores (10% of all starless cores surveyed) were identified as cores with blue-skewed line profiles (asymmetric profiles with more
intense blue-shifted emission), and another two starless cores (7identified as candidate blue-skewed line profiles. The peakvelocity difference between HCO+ and H13 CO+ of them was up to 0.9 km s−1 , suggesting that some inward motions exceeded
the speed of sound for the quiescent gas (∼ 10 − 17 K). The mean of δV of the five aforementioned starless cores was derived
to be −0.5±0.3. One core, G211.16−19.33North3, observed using the ALMA ACA in DCO+ J = 3 → 2 exhibited blue-skewed
features. Velocity offset in the blue-skewed line profile with a dip in the DCO+ J = 3 → 2 line was larger (∼ 0.5 km s−1 ) thanthat in HCO+ J = 1 → 0 (∼ 0.2 km s−1 ), which may represent gravitational acceleration of inward motions. It seems that thiscore is at the last stage in the starless phase, judging from the chemical evolution factor version 2.0 (CEF2.0).

46. OB Associations

Nicholas J. Wright, Simon Goodwin, Robin D. Jeffries, Marina Kounkel, Eleonora Zari F OB associations are
low-density groups of young stars that are dispersing from their birth environment into the Galactic field. They are importantfor understanding the star formation process, early stellar evolution, the properties and distribution of young stars and theprocesses by which young stellar groups disperse. Recent observations, particularly from Gaia, have shown that associations arehighly complex, with a high degree of spatial, kinematic and temporal substructure. The kinematics of associations have shown
them to be globally unbound and expanding, with the majority of recent studies revealing evidence for clear expansion patterns
in the association subgroups, suggesting the subgroups were more compact in the past. This expansion is often non-isotropic,
arguing against a simple explosive expansion, as predicted by some models of residual gas expulsion. The star formation
histories of associations are often complex, exhibit moderate age spreads and temporal substructure, but so far have failed toreveal simple patterns of star formation propagation (e.g., triggering). These results have challenged the historical paradigmof the origin of associations as the expanded remnants of dense star clusters and suggests instead that they originate as highly
substructured systems without a linear star formation history, but with multiple clumps of stars that have since expanded andbegun to overlap, producing the complex systems we observe today. This has wide-ranging consequences for the early formation
environments of most stars and planetary systems, including our own Solar System.

of Compact Multi-planet Systems: Diversity and Uniformity
47. Architectures
Lauren M. Weiss, Sarah C. Millholland, Erik A. Petigura, Fred C. Adams, Konstantin Batygin, Anthony M.
Bloch, Christoph Mordasini F One of the most important developments in exoplanet science in the past decade is thediscovery of multi-planet systems with sub-Neptune-sized planets interior to 1 AU. This chapter explores the architectures ofthese planetary systems, which often display a remarkable degree of uniformity: the planets have nearly equal sizes, regularorbital spacing, low eccentricities, and small mutual inclinations. This uniformity stands in sharp contrast to the diverse

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nature of the exoplanet sample considered as a whole (as well as our inner solar system). We begin with a critical review ofthe observations – including possible biases – and find that these peas-in-a-pod planetary systems are apparently a common
outcome of the planet formation process. Modest departures from exact uniformity suggest additional patterns, such as theplanet mass slowly increasing with semi-major axis. The star formation process naturally produces circumstellar disks withthe properties required to produce these planetary systems, although the solid material must move inward from its initial
location. We discuss primary modes of planetary assembly, the role of orbital migration, and post-nebular atmospheric loss.
Mature planetary systems are found to be near their minimum energy (tidal equilibrium) configurations; this finding provides apartial explanation for their observed properties and indicates that efficient energy dissipation must occur. Finally, we consider
population synthesis models and show that peas-in-a-pod patterns emerge with reasonable choices for the input parameters.
Nonetheless, interesting observational and theoretical challenges remain in order to understand how these surprisingly organizedplanetary systems arise from the disorder of their formation processes.

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