astrochemistry: from nanometers to megaparsecs – a ...€¦ · astrochemistry: from nanometers to...

Astrochemistry: From nanometers to megaparsecs – A symposium in honour of

John H. Black

This symposium is organised jointly by the divisions Astronomy andPlasma Physics and Onsala Space Observatory at the departmentof Space, Earth and Environment, Chalmers.

This event has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreementNo 730562 [RadioNet].

The symposium has also received funding from the Swedish Research Council (Vetenskapsrådet), dnr. 2018-06786.

BE GREENKEEP IT ON

THE SCREEN

The scientific organising committee (SOC)

Susanne Aalto

Maryvonne Gerin Eric Herbst

Gunnar Nyman

Amiel Sternberg

Ewine van Dishoeck Naoki Watanabe

Eva Wirström (Chair)

The local organising committee (LOC)

Susanne Aalto

Per Bjerkeli

Sabine König

Boy Lankhaar

Gunnar Nyman

Sandra P. Treviño-Morales

Eva Wirström (Chair)Robin Garnham

Chalmers University of Technology

LERMA-LRA

University of Virginia

Gothenburg University

Tel Aviv University

Leiden Observatory

Hokkaido University

Chalmers University of Technology

Onsala Space Observatory. Credit: S. Treviño-Morales

Participants

Thomas Ayres University of ColoradoPaul Barklem Uppsala UniversityShmuel Bialy Harvard Center for AstrophysicsJohn Black Chalmers University of TechnologyPer Bjerkeli Chalmers University of TechnologyLaure Bouscasse Max-Planck-Institut für

RadioastronomieAndrew Burkhardt Harvard & SmithsonianHannah Calcutt Chalmers University of TechnologyNuria CalvetPaola Caselli Max-Planck-Institut für

extraterrestrische PhysikSteven Charnley NASA Goddard Space Flight CenterIgor Chernykh Institute of Computational Mathematics and Mathematical GeophysicsIlse Cleeves University of Virginia Laura Colzi Università degli Studi di FirenzeCarla Maria Coppola Università degli Studi "Aldo Moro"

di BariTaïssa Danilovich KU Leuven Elvire De Beck Chalmers University of TechnologyDavid Dubois NASA Ames Research Center

/BAER Institute Juan Enrique Romero Universitat Autònoma de BarcelonaEdith Falgarone Ecole Normale SupérieureMalcolm Fridlund LeidenMaryvonne Gerin LERMA, CNRS and Observatoire de

Paris Caroline Gieser Max Planck Institute for Astronomy Barbara Michela Giuliano Max-Planck-Institut für

extraterrestrische PhysikJavier Goicoechea CSIC Isabelle Grenier Université de Paris and CEA SaclayNanase Harada ASIAALee Hartmann University of MichiganAarto Heikkilä Chalmers University of TechnologEric Herbst University of Virginia

Åke Hjalmarson Chalmers University of TechnologyCathy Horellou Chalmers University of TechnologyLiv Hornekar Aarhus University Martin Houde University of Western Ontario Chia-Jung Hsu Chalmers University of TechnologyMaria S. Kirsanova Russian Academy of Sciences Sabine König Chalmers University of Technology Maciej Koprowski University of Nicolaus CopernicusSergiy Krasnokutskiy MPI for Astronomy & Jena

UniversityLars E. Kristensen Niels Bohr Institute

Copenhagen University Charles Lada Harvard & Smithsonian Boy Lankhaar Chalmers University of TechnologySofie Liljegren Stockholm UniversityBrett McGuire NRAOBrendan McLaughlin Queen’s University of BelfastChiara Mininni University of Florence - INAFAyane Miyazaki Hokkaido University Sebastien Muller Chalmers University of TechnologyZsofia Nagy Max-Planck-Institute for

Extraterrestrial Physics David Neufeld Johns Hopkins UniversityGunnar Nyman Gothenburg UniversityHans Olofsson Chalmers University of TechnologyHenrik Ottosson Uppsala UniversityMarco Padovani INAF-Osservatorio Astrofisico di

Arcetri - Italy Carina Persson Chalmers university of technologyFereshteh Rajabi University of Waterloo Elena Redaelli Max Planck Institute for

Extraterrestrial Physics Evelyne Roueff LERMA, Observatoire de ParisMaryam Saberi Chalmers University of TechnologyHilda Sandström Chalmers University of Technology Stephan Schlemmer Universitaet zu KoelnChristopher Shingledecker Max-Planck-Institut für

extraterrestrische PhysikSigurd Sigersen Jensen Centre for Star and Planet

Formation and Niels Bohr Institute

Olli Sipilä Max-Planck-Institut fürExtraterrestrische Physik

Amiel Sternberg Tel Aviv UniversityCCA Flatiron Institute

Benoît Tabone Leiden UniversityLinda Tacconi Max-Planck-Institut für

Extraterrestrische PhysikKotomi Taniguchi University of VirginiaJulia Tjus Ruhr-University Bochum, GermanySandra P. Treviño-Morales Chalmers University of TechnologyFloris van der Tak SRON / U Groningen, NL Charl van der Walt Niels Bohr Institute

Copenhagen UniversityEwine van Dishoeck Leiden Observatory / MPELuis Velilla Prieto Chalmers University of TechnologyGeronimo Villanueva NASA Goddard Space Flight CenterWouter Vlemmings Chalmers University of TechnologyNaoki Watanabe Hokkaido UniversityRaphael WickerEva Wirström Chalmers University of TechnologyMark Wolfire University of Maryland Hans Zinnecker Universidad Autonoma de Chile

Programme

Monday, June 24

9:00 Registration & Coffee

10:30 Eva Wirström Welcome and logistics10:40 John H. Black Opening talk

Photon-dominated processes

11:10 Linda Tacconi Cold molecular extragalactic medium11:50 Amiel Sternberg The atomic to molecular (HI- to-H2)

transition in Galaxy star-forming regions

12:10 Lunch & registration

14:00 Nanase Harada Models of extragalactic astrochemistry

14:40 Evelyne Roueff Photon-driven chemistry15:20 Maria S. Kirsanova Merged H/H2 and C+/C/CO transitions in the

Orion Bar PDR

15:40 Coffee/Tea

16:10 Sandra Treviño-Morales Probing the HI/H2 layer around the ultracompact HII region MonR2

16:30 Ewine van Dishoeck Isotope selective photodissociation 17:10 Laura Colzi Enhanced nitrogen fractionation at core scales:

the high-mass star-forming region IRAS 05358+3543

17:30 Welcome to the City of Gothenburg

17:40 City of Gothenburg reception

Tuesday, June 25

Simple molecules

9:00 David Neufeld Small molecules observed at high spectral resolution with SOFIA: recent results from EXES and GREAT observations of two molecules, H2

and HeH+

9:40 Floris van der Tak Water in star formation10:20 Olli Sipilä Modeling deuterium chemistry in dense cores:

full scrambling versus proton hop

10:40 Coffee

11:00 Liv Hornekar Polycyclic Aromatic Hydrocarbons as catalysts for H2 formation

11:40 Brendan McLaughlin Formation of dicarbon in collisions of two carbon atoms

12:00 Steve Charnley Formation of Complex Organic Molecules in Dark Clouds

12:20 Taissa Danilovich The circumstellar sulphur chemistry of AGB stars

12:20 Lunch

14:00 Carla Coppola State-to-state and non-equilibrium phenomena in the chemistry of the early Universe

14:40 Paul S. Barklem A final-state resolved merged-beam experiment of mutual neutralization of Li+ and D− at stellar photospheric temperatures with DESIREE

15:20 Sebastien Müller Molecules towards QSOs

15:40 1-minute poster flash presentations

16:00 Poster session and refreshments

Wednesday, June 26

Spectroscopy and Radiative transfer

8:20 Stephan Schlemmer Lab spectroscopy for astrochemistry9:00 Brett McGuire Detecting Complex (Polycyclic?) Aromatic

Molecules in the ISM9:40 Geronimo Villanueva The delivery and evolution of water within the

solar system studied via the D/H

10:20 Coffee

10:40 Elvire de Beck Spectroscopy of evolved stars11:20 Hans Olofsson Heavy element recombination lines towards

an evolved star: In the footsteps of John Black11:40 Fereshteh Rajabi Dicke’s Superradiance and Maser Flares12:20 Martin Houde Non-Zeeman Circular Polarization of Rotational

Molecular Spectral Lines

12:40 Takeaway lunch for pick-up

13:00 Bus departs for Excursion to Marstrand

Marstrand archipelago. Credit: Philippe Salgarolo

Thursday, June 27

Cosmic rays and Energetic interactions

8:20 Eric Herbst Cosmic-ray driven chemistry

9:00 Marco Padovani Cosmic rays: the ubiquitous probe for the interstellar medium

9:20 Shmuel Bialy The Multiphased HI Gas – from Solar to Low

Metallicities

9:40 Poster session + Coffee

10:40 Isabelle Grenier Cosmic rays and the dark neutral medium

11:20 Julia Becker Tjus Ionization signatures and gamma-rays from

supernova remnants11:40 Christopher N. Simulating Ion-Irradiation Experiments using

Shingledecker Astrochemical Models

Transient and non-equilibrium processes

12:00 Edith Falgarone Cold molecular gas around high-z starbursts

12:40 Lunch

13:40 Paola Caselli Isotopic Fractionation in Star-Forming Regions

14:20 Andrew Burkhardt Using Shocked Outflows to Probe Interstellar Ice Chemistry

14:40 Javier Goicoechea Reactive molecular ions as tracers of harsh

interstellar environments

15:20 Coffee

15:50 Ilse Cleeves Transient chemistry in disks16:30 David Dubois Laboratory, modeling and observational study of

benzene condensation on Titan’s stratospheric

aerosols16:50 Thomas Ayres Carbon Monoxide in the Solar Atmosphere: from

Photosphere to COmosphere

17:10 Lee Hartmann Special talk

18:30 Celebratory Dinner at Universeum, including guided tours

Friday, June 28

Gas/Solid interactions

9:00 Naoki Watanabe The ortho-to-para ratio of hydrogen and water molecules desorbed from ice dust: experimental approach

9:40 Ayane Miyazaki Detection of OH radicals on amorphous solid water

10:00 Juan Enrique Romero Reactivity of HCO with CH3 and NH2 on Water Ice Surfaces. A Comprehensive Accurate Quantum Chemistry Study

10:20 Coffee

11:00 Serge Krasnokutski Experimental Characterization of Low-temperature Surface Reactions

11:20 Barbara Giuliano Direct measurements of the optical properties of CO ice in the THz range and opacity calculation

11:40 TBD Closing remarks

12:30 End of meeting

Astrochemistry: from nanometers to megaparsecs - List of posters

# Name Poster title1 Laure Bouscasse Chemical diversity in early massive protostellar objects2 Daria Burdakova Radiative association of small molecules3 Hannah Calcutt The stacking revolution: searching for the seeds of life4 Igor Chernykh Supercomputer simulation of astrochemical problems5 David Dubois The Fundamental Vibrational Frequencies and Spectroscopic

Constants of the Dicyanoamine Anion: Quantum Chemical Anal-ysis of a Likely Planetary Anion, NCNCN (C2N3)

6 Maryvonne Gerin Large scale mapping of the Orion B molecular cloud7 Caroline Gieser Physical and chemical complexity in high-mass star-forming re-

gions8 Ake Hjalmarson Odin and Herschel observations of H2O, CH and CH+ in the

barred spiral galaxy NGC 1365 - bar induced activity in the cir-cumnuclear torus region

9 Chia-Jung Hsu Mixing of the First Supernovae Metals10 Chia-Jung Hsu Simulating deuterium fractionation in massive pre-stellar cores11 Maciej Koprowski Determining star formation rates in high-redshift galaxies from

IRX-β relation12 Maciej Koprowski IRX-β relation at high redshifts13 Serge Krasnokutski Fullerene oligomers and polymers as carriers of unidentified IR

emission bands14 Charles Lada CO Depletion and the X-Factor on Subparsec Scales Across the

California Molecular Cloud15 Boy Lankhaar The polarization and molecular Zeeman effect of masers16 Chiara Mininni GUAPOS: G31.41+0.31 Unbiased ALMA sPectral Observational

Survey17 Zsofia Nagy The chemical structure of the starless core L1521E18 Elena Redaelli Deuteration of N2H+ and HCO+ in the prestellar core L1544 and

first evidence of N2D+ depletion19 Hilda Sandstrom Quantum Chemical Evaluation of Polarity-Inverted Membranes

and Polymers on the Surface of Titan20 Benoıt Tabone Molecule formation in dust-free irradiated jets21 Kotomi Taniguchi Cyanopolyyne Chemistry around Massive Young Stellar Objects22 Charl van der Walt Nature vs. Nurture: What sets the chemical complexity in star-

forming regions?23 Luis Velilla Prieto Molecular complexity in the envelopes of evolved stars

Oral contributions

Astrochemistry: From nanometers to megaparsecs- A symposium in honour of John H. Black

Gothenburg, Sweden, June 24-28, 2019

Title: Carbon Monoxide in the Solar Atmosphere: from Photosphere to COmospherePresenting author: Thomas AyresContact: [email protected]: University of Colorado, Center for Astrophysics & Space Astronomy

Carbon monoxide is Nature’s most durable molecule; able to survive the harshconditions of the Sun’s photosphere; even into the low chromosphere, which,paradoxically, should be too hot to support molecules. The unexpected high-altitude CO – revealed by anomalous limb-darkening and off-limb emissions ofthe strong 5µm bands – has been dubbed the “COmosphere.” It could be causedby a “molecular cooling catastrophe,” driven by CO itself. Or, it might representpockets of cold gas in overshooting convective plumes. Beyond the curious pres-ence of CO in the low chromosphere, the photospheric isotopologues are keytracers of isotopic ratios in the solar mixture, which carry hints concerning theformation of the Sun from the pre-solar nebula. Pilot analyses, based on classi-cal 1D solar reference models, suggested that the Sun was isotopically “heavier”than the Earth, quite at odds with the volatile fractionation processes thoughtto operate during the condensation of the rocky planets. More recently, thatconclusion has been challenged by 3D convection models. The large point-to-

point thermal fluctuations in such simulations apparently have disproportionate influence on the CO formation.Based on 3D CO spectral synthesis, the Sun now has been found to be lighter than the Earth, isotopicallyspeaking. Further, the CO-derived O abundance is trending upward toward the helioseismic-favored value,thus averting, perhaps, what has come to be called the “solar oxygen crisis.” Looking forward, soon-to-be-commissioned 4-m Daniel K. Inouye Solar Telescope on Haleakala, Maui, finally will achieve the high spatialresolution in the thermal-IR needed to resolve the solar – and broader astrophysical – issues raised by CO.

Figure 1: Right– 3D “Baseline” model: light= upflows; dark= downflows; red arrows= horizontal velocities (grayscale saturates at ±2 km s�1). Left– Blue dashed curve is 3D average T profile; red dot-dashed is FALC 1Dsemi-empirical solar reference model, slightly warmer in upper layers. Gray shading is power-density mapof temperature variations. Green dot marks white-light continuum surface. Hatched curves are relative COconcentrations: blue– Baseline 3D model; black– 3D +�T in outer layers to match 1D profile; red– 1D FALC.1D and 3D +�T have same < T >, but latter produces more CO, thanks to thermal fluctuations.



Title: A final-state resolved merged-beam experiment of mutual neutralization of Li+ andD− at stellar photospheric temperatures with DESIREE

Presenting author: Paul S. BarklemContact: [email protected]: Department of Physics and Astronomy, Uppsala University, SwedenCo-author: Jon Grumer, Gustav Eklund, Stefan Rosen, Najeeb Punnakayathil, Henrik Ced-

erquist, Henning Zettergren, Henning Schmidt

Measurement of Li abundances in stars is an important problem in astrophysics.For example, as primordial Li was produced in the Big Bang, the relationshipbetween the amount of Li observed in old, metal-poor stars and the primordialabundance is important to understand. Accurate stellar Li abundances tell usabout the Big Bang, stellar evolution, and physical processes in stars. Thesemeasured abundances are, however, sensitive to modelling of Li+H collisions andthese collisions have been an uncertainty in the modelling of the Li resonanceline, early work being based on a classical atomic collision model known as the“Drawin formula” (Steenbock & Holweger 1984). It has since been demonstratedthat quantum models differ from these by orders of magnitude, and that mutualneutralization (MN) of Li+ and H− is the most important process, which cannotbe described by the classical model (Barklem et al. 2003).

We report on a merged beam experiment on the MN of Li+/D−, equivalent to Li+/H−, at low energies (0− 0.6

eV), performed at the new double electrostatic storage ring national facility DESIREE in Sweden (Thomas etal. 2011). The only previous measurements of this process (Peart & Hayton 1994), though providing absolutemeasurements, were performed for collision energies higher than what is of interest in cool stellar atmospheres,and the final states were not resolved. The experimental resolution at DESIREE is sufficient to resolve the 3sfrom the 3p+3d states, which is shown in Figure 1. Calculations have predicted that the cross section for the3s final state is approximately a factor of 3 larger than for 3p, and a factor of 10 larger than for 3d (Belyaev& Barklem 2003). The experimental results indicate that the branching ratio between the 3s and the 3p+3dchannels are more equal than predicted by calculations. A precise quantitative conclusion on the branchingratio awaits further detailed analysis.

Figure 1: Histogram of the distances between the MN products at the time of arrival on the detector for collisionsat centre-of-mass energies close to 0 eV. The 3s final state, corresponding to the right peak, and the 3p+3dfinal state, corresponding to the left peak, are clearly distinguishable.

Our eventual goal is to map the absolute, final-state resolved, MN cross sections from meV energies to afew eV. This would provide strong constraints on both the theoretical modelling of electron transfer in atomiccollisions, as well as the astrophysical modelling and ultimately on the Li abundance in old stars.

References:• Barklem P S, Belyaev A K, and Asplund M (2003) A&A 409 L1 • Belyaev A K and Barklem P S (2003) Phys.Rev. A 68(6) 062703 • Peart B and Hayton D A (1994) J. Phys. B 27 2551 • Steenbock W and Holweger H(1984) A&A 130 319 • Thomas R D et al. (2011). Rev. Sci. Inst., 82(6), 065112



Title: The Multiphased HIGas – from Solar to Low MetallicitiesPresenting author: Shmuel BialyContact: [email protected]: Harvard-Smithsonian Center for AstrophysicsCo-author: Amiel Sternberg

The neutral atomic ISM is found to be multiphased, composed of the cold neu-tral medium (CNM, T ⇠ 100 K) and the warm neutral medium (WNM, T ⇠ 104

K), which coexist at approximately the same thermal pressure, P/kB ⇠ 3000cm�3 K. Such a multiphase structure is predicted by models of heating-coolingthermal balance[1�2], where heating is dominated by photoelectric heating fromdust-grains (and/or cosmic-ray heating), and cooling by Ly↵ line emission (for theWNN, T ⇠ 104 K) and [C II] and [O I] line-emission (for the CNM, T ⇠ 100 K). Inter-mediate temperatures are thermally unstable. The multiphase phenomena andthe thermal instability zone, may play a key role in regulating the star-formationproperties in galaxies.

I will present recent results[3] discussing the thermal properties of HIgas, asfunctions of the UV intensity, the cosmic-ray ionization rate, and gas metallicity,from solar to primordial metallicities. I will discuss the importance of the residualH2 in controlling the thermal structure of the predominantly HI gas. Despite itslow equilibrium abundance (H2/HI ⇠ 10�6), we find that H2 cooling and heating

mechanisms (dominated by H2 ro-vibrational cooling, UV pumping heating, and H2 formation heating) stronglyaffect (or totally dominate) the phase structure at low metallicities and/or when the UV intensity to cosmic-rayionization rate ratio is low.

Figure 1: Figure adopted from Bialy & Sternberg (in prep.). The thermal pressure as a function of gas den-sity for various metallicities. The solid (dashed) curves are for models that include (exclude) the H2 heatingand cooling processes. As the metallicity decreases, the WNM-to-CNM transition moves to higher densitiesand pressures, as metal line cooling becomes less efficient. The H2 cooling and heating processes start todominate and smooth out the multiphase structure.

References: [1] Field, Goldsmith & Habing, 1969, ApJ. 155 L14 [2] Wolfire, McKee, Hollenbach & Tielens,2003, ApJ. 587 278 [3] Bialy & Sternberg, in prep.



Title: Using Shocked Outflows to Probe Interstellar Ice ChemistryPresenting author: Andrew BurkhardtContact: [email protected]: Center for Astrophysics | Harvard & SmithsonianCo-author: Christopher N. Shingledecker, Romane Le Gal, Brett A. McGuire, Anthony J. Remi-

jan, Eric Herbst

It is believed that many of the most complex, and potentially prebiotic, moleculesknown in the interstellar medium are formed within the ice mantles on dustgrains [Herbst & van Dishoeck 2009]. While infrared absorption of vibrationalfeatures has allowed us to detect the solid-phase population for a limited num-ber of molecules, the majority of ice chemistry remains observationally uncon-strained (Boogert et al. 2015). However, low-velocity astrophysical shocksmay prove to be crucial probes of this phase of astrochemistry. Due to non-thermal desorption in these regions, the chemically-rich ices can be temporar-ily lifted into the gas phase, where they can be detected with rotational spec-troscopy, before redepositing onto the dust grains (Arce et al. 2007). Here, wediscuss recent interferometric observational and modeling efforts to study thechemical evolution within shocked regions within protostellar outflows. In par-ticular, we find certain gas-phase molecules are solely enhanced by this non-thermal desorption, while others undo significant post-shock gas-phase chem-istry.

Through recent observations with the Atacama Compact Array and the Submillimeter Array, weperformeda series chemical surveys for a handful of known chemically-rich molecular outflows to study the radial de-pendence of shock chemistry, as well as how this regime of chemistry varies over astrophysical environments.The derived abundances and morphologies are then compared to gas-grain chemical models which have beenadapted to simulate shock chemistry, which is able to predict which species either are useful probes for un-derlying ice chemistry or undergo significant post-shock gas-phase chemistry [4]. Both of these classes arespecies are found to be useful to disentangle the complex physico-chemical processes in these sources.

References: • Herbst, & van Dishoeck 2009, ARA&A, 47, 427 • Boogert et al. 2015, ARA&A, 53, 541 • Arceet al. 2007, Protostars and Planets V, 245 • Burkhardt et al. 2019, ApJ, in Review



Title: Isotopic Fractionation in Star-Forming RegionsPresenting author: Paola CaselliContact: [email protected]: Center for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics

Deuterium and 15-Nitrogen fractionation of interstellar molecules is known to oc-cur in star forming regions spanning a large range of evolutionary stages, fromstarless cloud cores to low- and high-mass protostellar environments, to proto-planetary disks. Primitive material in our Solar System as well as our Earth’soceans and atmosphere show evidence of isotopic fractionation, possible relicof the chemical processes happening in the proto-Solar Nebula. In this talk, Ishall review isotopic fraction measurements and our current understanding ofthe processes behind them.



Title: Formation of Complex Organic Molecules in Dark CloudsPresenting author: Steven CharnleyContact: [email protected]: NASA Goddard Space Flight CenterCo-author: Eva Wirstrom, Vianney Taquet

Understanding interstellar organic chemistry can yield important insights intothe chemical conditions prevalent at the birth of the Solar System (see Ehrenfre-und & Charnley 2000). Interstellar complex organic molecules (COMs: CH3OH,CH2CO, CH3CHO, C2H5OH, HNCO, NH2CHO, HCOOH, CH3OCH3, HCOOCH3)have plausible formation pathways on grain surfaces and have been found pri-marily in protostellar environments - hot cores and hot corinos - where ice man-tles have been evaporated from dust grains (e.g. Herbst & van Dishoeck 2009).However, gas phase ion-molecule chemistry, triggered by the sublimation of themain ice components at Tdust > 100 K, is likely to be a significant contributor tothe formation of many COMs in hot cores/corinos (Taquet et al. 2016).

Recent observations of cold molecular clouds (e.g. L1698B, Bacmann etal. 2012; Cernicaro et al. 2012; L1544, Vastel et al 2014; Taquet et al. 2017)

demonstrate that, although the actual desorption mechanism is unclear, grain mantles in dark clouds alreadycontain many large COMs. The inventory of these ’cold’ COMs is very similar to that of hot cores and theirmolecular abundances are comparable amongst the sources: ∼ few×10−10, about 100 times lower than that ofmethanol. These observations raise serious problems for theories of COM formation, particularly for CH3OCH3

and HCOOCH3. For Tdust ∼ 10 K recombination of photo-generated radicals induced by grain heating is inef-fective and thermal desorption cannot occur; for Tgas ∼ 10 K and at the low abundances of injected mantlematerial ion-molecule reactions are inefficient (Garrod et al. 2008; Vasyunin & Herbst 2013).

In this presentation we describe a new gas-grain model for COM formation in cold gas.

References: • Bacmann, A., Taquet, V., Faure, A., Kahane, C., & Ceccarelli, C., 2012, A&A, 541, L12 •Cernicharo, J., Marcelino, N., Roueff, E. et al. 2012, ApJ, 759, L43 • Ehrenfreund P, Charnley S.B. 2000.Annu. Rev. Astron. Astrophys., 38, 427 • Garrod, R. et al. 2008, ApJ, 682, 283 • Herbst, E. & van Dishoeck.E.F. 2009, Ann. Rev. Astron. Astrophys., 47, 427 • Taquet, V., Wirstrom, E. S., Charnley, S. B. 2016, ApJ, 821,46 • Taquet, V., Wirstrom, E. S., Charnley, S. B., et al. 2017, A&A, 607, A20 • Vastel, C. et al. 2014, ApJL 795,L2 • Vasyunin, A., Herbst, E. 2013, ApJ, 769, 34



Title: Transient chemistry in disksPresenting author: Ilse CleevesContact: [email protected]: University of VirginiaCo-author: Abygail Waggoner (University of Virginia), Edwin Bergin (University of Michigan),

Karin Oberg (CfA), Sean Andrews (CfA), David Wilner (CfA), Ryan Loomis (NRAO),Chunhua Qi (CfA), Bradford Snios (CfA), Edward McClain (CfA)

The chemistry of protoplanetary disks sets the initial composition of newly formedplanets and may regulate the efficiency by which planets form. Disk chemicalabundances typically evolve over timescales spanning thousands if not millions ofyears. Consequently, it was a surprise when ALMA observations taken over thecourse of a single year showed significantly variable emission in H13CO+ relativeto the otherwise constant thermal dust emission in the IM Lup protoplanetarydisk. HCO+ is a known X-ray sensitive molecule, and one possible explanationis that stellar activity is perturbing the chemical ”steady state” of the disk [1]. Ifconfirmed, simultaneous observations may provide a new tool to measure (andpotentially map) fundamental disk parameters, such as electron density, as the

light from X-ray flares propagates across the disk. Simulations suggest that flares can impact the abundancesof many commonly observed molecules, both over short time periods (days to weeks) and extending overmuch longer times when taking into account the aggregate effect of flares over time [2]. These findings suggestdisks, and possibly other astrophysical regions with variable irradiation, are far more chemically dynamic thanpreviously assumed.

References: • [1] Cleeves et al. 2017, ApJL, 843, 3. • [2] Waggoner & Cleeves, 2019, ApJ, Submitted.



Title: Enhanced nitrogen fractionation at core scales: the high-mass star-forming regionIRAS 05358+3543

Presenting author: Laura ColziContact: [email protected]: Universita degli Studi di FirenzeCo-author: F. Fontani, P. Caselli, S. Leurini, L. Bizzocchi, G. Quaia

It is well known that the 14N/15N isotopic ratio found for the proto-Solar nebula(PSN), 440 (Marty et al. 2010), is significantly higher than that measured in pris-tine Solar System materials, like comets (⇠140, Hily-Blant et al. 2017 and ref-erences therein). This suggests a local chemical enrichment of 15N during theSun formation process. However, the cause of this enrichment and its relationwith the natal clump are still uncertain. Since there is growing evidence point-ing out that our Sun was born in a rich cluster containing massive stars (e.g.Lichtenberg et al. 2019), we have studied the 14N/15N ratio in a large sample ofhigh-mass star forming regions. In this talk I will first show the overall behaviourof the 14N/15N ratio across the Galaxy (Colzi et al., 2018a, Colzi et al., 2018b).We have confirmed, based on a solid statistics for the first time, that the 14N/15Nratio increases with the Galactocentric distance as a consequence of the Galacticchemical evolution. Moreover, we have estimated that the 14N/15N ratio in the lo-cal interstellar medium is about 400, i.e. very close to the PSN value. Then, I willzoom-in into the massive star-forming protocluster IRAS 05358+3543, where wehave obtained the first interferometric maps of N-fractionation combining single-

dish and high-resolution interferometric observations of the 15N isotopologues of N2H+ (Colzi et al. 2019). Theanalysis yields 14N/15N ratios of 100-200 in the cores, and higher values of �200 in the diffuse clump gas.This result, which strongly suggests a local chemical enrichment of 15N at core-scales, helps us to understandhow the chemical inventory evolves from the parental molecular reservoir to smaller-scale objects, in whichstar-formation occurs. It suggests also that the 15N-enrichment measured in the pristine Solar System materialcould occur locally, in the environment in which the Sun was born, during the protocluster evolution.

Figure 1: Left panel: Averaged map of N2H+(1–0) at 93.1734 GHz. The contour levels are 4, 7, 10, 13, 16and 18 times the 1� rms of the map, equal to ⇠6 mJy/beam. Right panel: Averaged map of 15NNH+(1–0) at90.26 GHz. The black contour levels are 3, 5 and 7 times the 1� rms of the map, equal to ⇠0.5 mJy/beam. Inboth panels, the blue contours correspond to the 5� level of the averaged maps, from which we have definedthe ”core-scales” and derived the 14N/15N ratios. In both panels, the black squares indicate the position of thecontinuum sources. The dashed circle represents the NOEMA field of view and the synthesized beam is theellipse indicated in the lower left corner.

References: • Colzi, L., et al., 2018a, A&A 609, A129 • Colzi, L., et al., 2018b, MNRAS, 478, 3, p.3693-3720• Colzi, L., et al., 2019, arXiv:1903.06567 • Hily-Blant, P., et al., 2017, A&A 603, L6 • Lichtenberg et al., 2019,arXiv:1902.0402 • Marty B. et al., 2010, Geoch Cosmoch. Acta, 74, 340



Title: State-to-state and non-equilibrium phenomena in the chemistry of the early UniversePresenting author: Carla Maria CoppolaContact: [email protected]: Dipartimento di Chimica - Universita degli Studi “Aldo Moro” di Bari - Italy

The chemistry of the early Universe is usually considered as relatively simple andeasy to implement, due to the presence of few chemical ingredients. Most of theadopted models lie on the hypothesis of local thermal equilibrium and the timeevolution of atomic and molecular species is eventually dependent only on theinitial conditions and the cosmological framework, together with few key reactionrates. In this contribution, an overview on a state-to-state approach to the earlyUniverse chemistry is presented, together with the inclusion of non-equilibriumfeatures in the description of the interaction between matter and the cosmic mi-crowave background (CMB). In particular, the case of molecular internal statesfor the hydrogen molecule, its cation and its deuterated variant is described andthe effects of such a resolution is commented, based on the results on the evo-lution of the fractional abundances of atomic and molecular species. The effectson the thermal balance of the gas is also described and an extension to thesimulations of early star formation is provided. As a result, the need for state-to-state data and the urge for a proper description of the chemistry of the internalmolecular levels are described.

Figure 1: Typical chemical network for the early Universe chemistry (from Coppola & Galli 2019)

References:• Galli, D., Palla, F., Astron.Astrophys., 1998, 335, 403-420• Lepp, S. et al., J. Phys. B: At. Mol. Opt. Phys., 2002, 35, R57• Coppola, C. M. et al., ApJSS, 2011, 193, 7•Walker, Kyle M. et al., 2018, ApJ, 867, 152• Coppola, C. M. & Galli, D., 2019, in “Gas-Phase Chemistry in Space”, IOP Publishing, 2514-3433, 1-26



Title: The circumstellar sulphur chemistry of AGB starsPresenting author: Taıssa DanilovichContact: [email protected]: KU Leuven

Sulphur is the tenth most abundant element in the universe and its behaviour interms of what molecules it forms in circumstellar envelopes has been seen tovary for different types of AGB stars. There are clear differences across chemi-cal types, with CS forming more readily in the circumstellar envelopes of carbonstars, while SO and SO2 have only been detected in oxygen-rich stars. How-ever, we have also discovered differences in sulphur chemistry based on thedensity of the circumstellar envelope (Danilovich et al., 2016, Danilovich et al.,2017, Danilovich et al., 2019). For example, the radial distribution of SO is drasti-cally different between AGB stars with lower and higher density circumstellar en-velopes. H2S can be found in high abundances towards higher density oxygen-rich stars, whereas SiS accounts for a significant portion of the circumstellarsulphur for higher density carbon stars and is present in higher abundances forhigher density oxygen-rich stars. I will discuss these differences across AGBstars and what this implies for the chemical evolution of the circumstellar enve-lope. Studies of post-AGB stars show us that sulphur is not significantly depletedonto dust during the AGB phase (Waelkens et al. 1991, Reyniers & van Winckel2007), making it a good tracer of changing circumstellar chemistry.

Figure 1: R Dor SO and SO2 channel maps for the central three velocity channels, showing the co-location ofthese two molecules in the circumstellar envelope. The background colours show the SO (88 ! 77) transition,with the beam for those observations indicated in white in the lower left corners of each channel plot. The blackcontour plots show flux levels at 3, 5, 10, and 20 times the rms noise for the SO2 (201,19 ! 192,18) transition,with the beam for those observations shown in black in the bottom left hand corner of each channel plot.

References: • Danilovich T., et al., 2016, A&A, 588, A119 • Danilovich T., et al., 2017, A&A, 606, A124 •Danilovich T., et al., 2019, MNRAS, 484, 494 • Waelkens C., et al., 1991, A&A, 251, 495 • Reyniers M., vanWinckel H., 2007, A&A, 463, L1



Title: Spectroscopy of evolved starsPresenting author: Elvire De BeckContact: [email protected]: Department of Space, Earth and Environment, Chalmers University of TechnologyCo-author: –

Evolved stars can feed more than half of their mass into the interstellarmedium through steady outflows carrying gas and dust. As such, they enrichtheir host galaxies with newly formed elements and dust grains, affecting the for-mation of new generations of stars and planets. The chemical composition of thestar and its outflow influences the efficiency of the mass loss and this, in turn,dramatically affects the stellar evolution itself.

Molecular emission from such an outflow was first traced by Solomon etal. (1971) who observed the CO (J = 1 � 0) transition towards the carbon-richstar CW Leo, a.k.a. IRC +10 216, the brightest source at 5 µm outside theSolar System. To date, we have detected emission from around 80 differentmolecules towards similar stars, including water, carbon chains, phosphorus-bearing molecules, and polycyclic aromatic hydrocarbons (PAHs).

The outflows present an enormous range of densities (102 � 1012 cm�3) and temperatures (5 � 3000 K) and,given their relatively simple, nearly spherical structures, these outflows are excellent astrochemical test beds.The location of matter in the outflow can be translated into an age since ejection, allowing us to investigate thetemporal evolution of the chemical processes in the gas and dust. To probe the span of physical and chemicalconditions from the onset of the outflows out to the interaction region with the interstellar medium, we observea large variety of molecular species and excitation conditions. We use them to image the motions of the stellarsurface of giants, to derive mass-loss rates, to understand dust formation, and to trace high-speed jets piercingthe surrounding medium.

An unbiased inventory of molecules in the outflows of a representative variety of galactic evolved stars,based on sample surveys and spectral scans, provides strong empirical constraints to chemical models thatdescribe the processes governing gas, dust, and gas-dust chemistry. I will present the chemical richness inoutflows from red giants, supergiants, and planetary nebulae and discuss some of the open questions in thefield.

Figure 1: Left: CO(J = 1 � 0) emission measured by Solomon et al. (1971) towards CW Leo at 115 GHz; right:spectral scan towards AGB star R Dor from De Beck & Olofsson (2018) at 159 – 368 GHz.

References: • Solomon, P., Jefferts, K. B., Penzias, A. A., Wilson, R. W. 1971, ApJ, 163, L53 • De Beck, E.& Olofsson, H. 2018, A&A, 615, A8



Title: Laboratory, modeling and observational study of benzene condensation on Titan’sstratospheric aerosols

Presenting author: David DuboisContact: [email protected]: NASA Ames Research Center/Bay Area Environmental Research InstituteCo-author: E. Sciamma-O’Brien, L. T. Iraci, E. L. Barth, F. Salama, S. Vinatier

Aerosol particles in Titan’s atmosphere impact its thermal structure andcan act as condensation nuclei for the formation of clouds. Follow-ing the northern spring equinox in August 2009, Titan’s global atmo-spheric circulation reversed within two years. This event also increasedthe mixing ratios of benzene (C6H6) and other species at the Southpole. Simultaneously, a strong cooling with temperatures dropping be-low 120 K favored the condensation of organic molecules at unusuallyhigh altitudes (>250 km). C6H6 ices have been detected during theCassini mission by the Composite Infrared Spectrometer (CIRS), in theSouth polar cloud system, but the existing laboratory data is insufficientto allow models to reproduce the formation of the observed cloud sys-tem.

Here, we present the first results of combined laboratory, modeling and observational studies to investigatethe equilibrium vapor pressure and ice nucleation of C6H6 on Titan’s aerosols as an important component ofthe cloud system that appeared during the autumn at 300 km above Titan’s South pole. We have performedexperimental measurements of vapor pressure of C6H6 at Titan-relevant temperatures using the Ames Atmo-spheric Chemistry Laboratory (Iraci et al., 2010) and are studying the conditions required for condensation ofbenzene on laboratory-produced Titan aerosol analogs using the Titan Haze Simulation experiment developedon the NASA Ames COSmIC facility (Sciamma-O’Brien et al., 2017 & Salama et al., 2017). The experimentaldata has been used to constrain nucleation and condensation in microphysical models (Barth 2017). This isperformed in order to determine expected cloud altitudes and particle sizes, in synergy with observations fromCIRS in the 9-17 µm spectral region (Vinatier et al., 2018) and to better understand the molecular compositionof this cloud system.

References: • Iraci, L. T. et al., Icarus 210(2), 985-991, 2010. • Sciamma-OBrien, E. et al., Icarus 289, 214-226, 2017. • Salama, F. et al., Proceedings IAU No. 332, 2017. • Barth E. L., Planet. Space Sci. 127, 20-31,2017. • Vinatier, S. et al., Icarus 310, 89-104, 2018.



Title: Reactivity of HCO with CH3 and NH2 on Water Ice Surfaces. A Comprehensive Ac-curate Quantum Chemistry Study

Presenting author: Juan ENRIQUE ROMEROContact: [email protected]: Institut de Planetologie et d’Astrophysique de Grenoble (IPAG)Co-author: Cecilia CECCARELLI, Albert RIMOLA

Interstellar complex organic molecules (iCOMs) [Herbst & van Dishoeck 2009;Ceccarelli et al. 2018] have a great importance for the astronomical communityfor several reasons, including that they can contain an important fraction of car-bon in a molecular form easy to be used to synthesise more complex, even bioticmolecules. Moreover, they have gained a lot of attention since the discoveryof iCOMs in solar-type protostars [Cazaux et al. 2003; Bottinelli et al. 2004].Indeed, iCOMs formed in the protostellar phase could have been inherited fromthe small bodies of the Solar System, e.g. carbonaceous chondrites and comets,and played a role in the origin of life on Earth [e.g. Caselli & Ceccarelli 2012].

Thus, understanding how iCOMs are formed and destroyed is of high im-portance to predict the ultimate organic complexity reached in the interstellarmedium (ISM). Two paradigms are invoked in the literature. Both argue thatsimple molecules and atoms are hydrogenated on the interstellar grain surfaces

during the cold prestellar phase. Following this first step, one paradigm assumes that iCOMs appear as a resultof gas-phase chemical processes, whereas the other predicts that radical-radical reactivity on the grain sur-faces is the major responsible for the observed chemical complexity. The latter is nowadays the most popularamong astrochemical models, even though some basic assumptions of the paradigm are still a topic of debate.Among them, the assumed radical-radical reactivity on grains is extremely difficult to simulate and prove experi-mentally. Here we propose a complementary and, possibly, alternative method: theoretical quantum chemistrycalculations, which can provide a precious atomistic perspective from which to study such processes [e.g.Enrique-Romero et al. 2016; Rimola et al. 2018].

In this contribution, we present our recent quantum chemical study on the surface reactivity of two radicalcouples: CH3 + HCO and NH2 + HCO. According to observational evidences, the icy mantles that coverinterstellar dust grains are dominated by water [Boogert et al. 2015]. We, therefore, use two cluster-likemodels made of 18 and 33 water molecules, respectively, to simulate the grain surface where the radical-radicalreaction occurs. We then study the reactivity of the two biradical systems by means of static quantum chemicalcalculations to verify the formation of acetaldehyde (CH3CHO) and formamide NH3CHO), respectively. Besidesthe formation of the two iCOM, we also observe competitive processes leading back to simpler species, forexample to CH4 and CO in the first system. The occurrence of one process or the other could entirely dependon the relative orientation of the radicals upon encounter, namely on the water ice structure and interactionwith the two radicals. These results indicate that the fraction of iCOMs generated in the current astrochemicalmodels is certainly overestimated since the competitive reactions are not included.

References: • Herbst, E. & Van Dishoeck, E. F. 2009, Annual Review of Astronomy and Astrophysics, 47,427-480. • Ceccarelli, C., Viti, S., Balucani, N. et al. 2018, Monthly Notices of the Royal Astronomical Society,476(1), 1371-1383. • Cazaux, S., Tielens, A. G. G. M., Ceccarelli, C. et al. 2003, The Astrophysical Journal,593(1), 51-55. • Bottinelli, S., Ceccarelli, C., Lefloch, B. et al. 2004, The Astrophysical Journal, 615(1), 354-358. • Caselli, P. & Ceccarelli, C. 2012, The Astronomy and Astrophysics Review, 20(1), 56. • Enrique-Romero,J., Rimola, A., Ceccarelli, C. et al. 2016, Monthly Notices of the Royal Astronomical Society: Letters, 459(1),6-10. • Rimola, A., Skouteris, D., Balucani, N. et al. 2018, ACS Earth and Space Chemistry, 2(7), 720-734.• Boogert, A. A., Gerakines, P. A., & Whittet, D. C. 2015, Annual Review of Astronomy and Astrophysics, 53,541-581.



Title: Cold molecular gas around high-z starburst galaxiesPresenting author: Edith FalgaroneContact: [email protected]: Ecole Normale Superieure, ParisCo-authors: M.A. Zwaan, B. Godard, A. Vidal-Garcia, C. Herrera, E. Bergin, R. J. Ivison, A.

Omont, F. Walter, P. M. Andreani, F. Bournaud, D. Elbaz, and I. Oteo

Starburst galaxies at redshifts z ∼ 2 - 4 are among the most intensely star-forminggalaxies in the universe. The way they accrete their gas to form stars at such highrates is still a controversial issue. ALMA has detected the CH+(1-0) line in emis-sion and/or absorption in all the gravitationally lensed starburst galaxies targetedso far at 1.6 < z < 4.2 with star-formation rates in the range 300 to 1400 M⊙yr−1. The unique conjunction of its spectroscopic and chemical properties allowsCH+(1-0) to highlight the sites of most intense dissipation of mechanical energy.The absorption lines reveal highly turbulent reservoirs of low-density moleculargas, extending far out of the galaxies. The emission lines, of widths up to 1400km s−1, much broader than those of CO, arise in myriad molecular shocks pow-ered by star formation and possibly active galactic nuclei. The CH+(1-0) linestherefore probe the fate of prodigious energy releases, primarily stored in tur-bulence before being radiated away. The turbulent reservoirs act as sustainedmass and energy buffers over timescales up to a few hundreds of Myr. Theirmass supply involves gas inflows from galaxy mergers and/or cold stream ac-cretion, as supported by Keck/KCWI Lyα observations of one of these starburstgalaxies.

Figure 1: Subset of ALMA continuum-subtracted CH+(1-0) spectra. Green curves show fits to the spectraobtained with one Gaussian for the emission and one (or two) Gaussian(s) for the absorption (dashed curves).The velocity scale is in the galaxy restframe obtained through accurate redshift measurements. The redshiftand the lens magnification of each galaxy are given in the bottom left corners.

References: • Falgarone, Zwaan, Godard, et al. 2017, Nature 548 430 • Godard, Pineau des Forets, Lesaffre,et al. 2019, A&A 622, A100 • Li, Cai, Prochaska, et al. 2019, ApJ 875 130



Title: Direct measurements of the optical properties of CO ice in the THz range and opacitycalculation

Presenting author: Barbara M. GiulianoContact: [email protected]: Max Planck Institute for Extraterrestrial PhysicsCo-author: A. A. Gavdush, B. Muller, K. I. Zaytsev, T. Grassi, A. V. Ivlev, M. E. Palumbo, G. A.

Baratta, C. Scire, G. A. Komandin, S. O. Yurchenko, P. Caselli

Reliable, directly measured optical properties of astrophysical ice analogs in thefar infrared and terahertz range are missing. These parameters are of greatimportance to model the dust continuum radiative transfer in dense and coldregions, where thick ice mantles are present, and are necessary for the inter-pretation of future observations planned in the far-IR region. Coherent THz ra-diation allows direct measurement of the complex dielectric function (refractiveindex) of astrophysically relevant ice species in the THz range. The time-domainwaveforms and the frequency-domain spectra of reference samples of CO iceat different thicknesses, have been recorded. A new algorithm is developed toreconstruct the real and imaginary parts of the refractive index from the time-domain THz data. The developed algorithm enables, for the first time, the directdetermination of optical properties of astrophysical ice analogs. The obtaineddata provide a benchmark to interpret the observational data from current groundbased facilities as well as future space telescope missions, and allow to calculatethe opacities of the dust grains more accurately.

Figure 1: Optical properties of CO ice. (a) Real part of the refractive index, (b) power absorption coefficient,(c) real and (d) imaginary parts of the dielectric permittivity for the different deposition intervals of �tdep = 4, 5and 6 min.



Title: Reactive molecular ions as tracers of harsh interstellar environmentsPresenting author: Javier R. GoicoecheaContact: [email protected]: Instituto de Fisica Fundamental, CSIC, Madrid, Spain.

Reactive ions are transient species for which the timescale of reactive collisions(leading to a chemical reaction) with H2, H, or e� is comparable to, or shorterthan, that of inelastic collisions (Black et al. 1998). The formation of reactive ionssuch as CH+ and SH+ depends on the availability of C+ and S+ (i.e., of UV pho-tons, thus high ionization fractions xe = n(e�) / nH) and on the presence of excitedH2 (either UV-pumped or hot and thermally excited). This allows overcomingthe high endothermicity (and sometimes barrier) of their formation (Sternberg &Dalgargo 1995; Agundez et al. 2010). The reaction C+ + H2(v)! CH+ + H (1),for example, is endothermic by �E/k ' 4300 K if v=0, but exothermic and fast forv�1 (Hierl et al. 1997). The reaction S+ + H2(v)! SH+ + H (endothermic by�E/k'9860 K when v=0) becomes exothermic when v�2 (Zanchet et al. 2019).

CH+ was one of the first molecules detected in the 1930s. Due to the highendothermicity of reaction (1), explaining the presence of CH+ absorption lines

in diffuse clouds has been a long standing problem in astrochemistry (e.g. Godard, Falgarone et al. 2012).Herschel and now ALMA, have allowed us to image the emission from CH+ and SH+ rotational lines towardinterstellar and circumstellar sources irradiated by strong stellar UV fields (see Gerin et al. 2016 for a review).In dense gas, nH & 105 cm�3, the lifetime of CH+ is so short, a few hours, that the molecule may form and be de-stroyed without experiencing non-reactive collisions with other species. Contrary to most interstellar molecules,this implies that CH+ does not have time to thermalize, by elastic collisions, its translational motions to a ve-locity distribution at Tk. Hence, CH+ rotational lines are expected to show broad line shapes related to theenergy excess upon formation (thousands of K) and not to the actual Tk nor to an enhanced gas turbulence.Hence, CH+ can be excited by radiation many times during its its mean-free-time for non-reactive collisions, sothat it remains kinetically hot (large velocity dispersion) and rotationally warm (high Trot) while it emits. Reac-tive ions can thus “retain some memory of the energetics of the formation process” . This “formation pumping”was anticipated by John Black in his eloquent Faraday Discussion’s paper (1998) and explicitly modelled af-ter Herschel’s detections (Nagy et al. 2013; Godard & Cernicharo 2013). Today, CH+ (J = 1–0) emission hasmapped at parsec scales along Orion star-forming region (Goicoechea et al. 2019) and SH+ emission has beenspatially resolved at the edge of the Orion Bar PDR with ALMA at . 10�2 pc resolution (Goicoechea et al. 2017).Research on reactive ions is active and offers a common ground to study fundamental processes by as-tronomers and chemists (both in the lab and by ab initio quantum calculations).

Figure 1: IR image of Orion andCH+ (J = 1–0) emission in contours.

References: • Agundez, M., Goicoechea, J. R., Cernicharo, J., Faure,A., & • Black, J. H. 1998, Faraday Discussions, 109, 257 • Gerin, M.,Neufeld, D. A., & Goicoechea, J. R. 2016, ARAA, 54, 181 • Godard, B.,et al. 2012, A&A 540, A87 • Godard, B., & Cernicharo, J. 2013, A&A,550, A8 • Goicoechea, J. R., et al. 2017, A&A, 601, L9 • Goicoechea,J. R., et al. 2019, A&A, 622, A91 • Hierl, P. M., Morris, R. A., & Viggiano,A. A. 1997, JCP, 106, 10145 • Nagy, Z., et al. 2013, A&A, 550, A96 •Sternberg, A., & Dalgarno, A. 1995, ApJS, 99, 565 Roueff, E. 2010, ApJ,713, 662 • Zanchet, A., et al. 2019, A&A, in press.



Title: Cosmic rays and the dark neutral mediumPresenting author: Isabelle GrenierContact: [email protected]: AIM, Universite de Paris & CEA Saclay

GeV to TeV cosmic rays rather uniformly pervade the local interstellar medium.They penetrate deeply into clouds and produce gamma rays from hadronic in-teractions with the gas nuclei along their path, thereby revealing the total gascolumn densities independently of its state or chemistry. They serve to gaugethe molecular mass in the CO-bright regions (to scale the N(H2)/W(CO) con-version factor) and they reveal large quantities of ”dark” gas at the translucentH-H2 interface [1,2]. Preliminary constraints on the dark-gas composition pointto a large abundance of diffuse H2 and other molecules (HCO+, C2H) with onlylittle CO at the onset of CO formation [3], as predicted by Ewine van Dishoeckand John Black in 1988 [4]. An interesting relation between the H2-dark andCO-bright mass needs confirmation [2]. These results pave the way to searchfor means to observe this elusive phase in and beyond the solar neighbourhoodand to study the conditions that lead to this dark phase.

References: • [1] Planck Collaboration, Fermi Collaboration et al., 2015, A&A,582, A31 • [2] Remy Q., Grenier I. A., Marshall D. J., Casandjian J. M., 2018, A&A, 611, A51 • [3] Liszt H.,Gerin M., Grenier I., 2019, arXiv e-prints, arXiv:1905.05369 • [4] van Dishoeck E. F., Black J. H., 1988, ApJ,334, 771



Title: Models of extragalactic astrochemistryPresenting author: Nanas HaradaContact: [email protected]: ASIAA

Some galactic centers host energetic activities such as starburst or active galac-tic nuclei, which can alter their chemical composition from what is known in thespiral arm clouds in the Galaxy. Possible driving forces of the chemistry includeUV-radiation, cosmic rays, X-rays, shocks, as well as the high density. To identifydiagnostic molecular abundances or ratios of each mechanism, several types ofmodels have been constructed. I will review previous modeling work and discussfuture challenges.



Title: An appreciation of the career of JJ CharfmanPresenting author: Lee HartmannContact: [email protected]: University of Michigan

JJ Charfman was one of John Black’s closest, not to say intimate, collabora-tors. He first shot to fame due to the spectacular detection of interstellar BoronSulphide in astronomical associations. Even though he has long been retired,residing at the Bora-Bora Radio Observatory, there have been occasional contri-butions from new collaborators centered at the Steward Observatory. Charfmaneven has a Twitter feed, though posting is quite sporadic. I shall review some ofCharfman’s old achievements, with special emphasis on my own personal obser-vations of Charfman’s effort in the early 1980s to become Director of A Centerfor Astrophysics.

References: • Detection of Interstellar BS in the Cirrus Dark Cloud of the Num-bum Association - Part One - an Intuitive Model and its Subsequent Observation,JJ Charfman, 1980, IAU Symposium 87, p. 645. •On the Utter Irrelevance of LPLGraduate Students: An Unbiased Survey by Steward Observatory Graduate Stu-dents, JJ Charfman et al. Somewhere on the web. • The Effects of Moore’s Lawand Slacking on Large Computations, Gotbrath et al., https://arxiv.org/abs/astro-

ph/9912202 • The Super Huge Interferometric Telescope: A New Paradigm In Optical Interferometry. Rudnick,Charfman et al., http://adsabs.harvard.edu/abs/1999AAS...195.8713R • https://twitter.com/jjcharfman



Title: Cosmic Ray Driven ChemistryPresenting author: Eric HerbstContact: [email protected]: University of VirginiaCo-author: Christopher N. Shingledecker

Cosmic rays play a very important role in the chemistry of the interstellar medium.They are energetic enough to ionize molecular hydrogen in dense interstellarclouds, leading to the production of the simplest polyatomic molecule H3

+, andhelping to start a chain of ion-molecule reactions leading eventually to carbon-chain molecules and deuterated species among other species. Moreover, theyare the major source of visible and ultra-violet radiation in regions of high ex-tinction into which external photons cannot penetrate. The well-known mecha-nism for the production of radiation is the excitation of H2 followed by emissionof Lyman and Werner photons with the radiation important for photodissociationprocesses in both the gas and on dust particle mantles. In addition to photodisso-ciation, cosmic rays sputter material from grain mantles into the gas and heat thegrains to temperatures high enough to enhance the rate of thermal desorptionconsiderably. In addition to these processes, cosmic rays are energetic enough

to ionize and excite components of interstellar ice mantles, which lead to a chain of non-thermal reactions thateventually can produce organic molecules known as COMs. Although this sequence of solid phase reactions,known as irradiation, produces COMs in laboratory experiments of energetic protons and electrons bombard-ing ices with some source of carbon, it has not been studied until recently in theoretical detail, especially in theinterstellar medium, where the production of COMs at low temperature can enhance the abundances achievedby current chemical simulations not enhanced by other exotic processes.

In a recent series of papers, Shingledecker et al. developed an approach to the chemistry occurring inirradiation by high energy protons. The theory they developed can be utilized by itself, or can be guidedby experimental determination of needed parameters such as G values (molecules produced or destroyedper 100 eV of incoming radiation) and determination of so-callled “stopping” cross sections of elastic andinelastic processes, which help to relax the system and lead to a number of highly excited neutral radicalsknown as “suprathermal” molecules. These molecules have sufficient electronic-vibrational energy to reactwith neutral species no matter how high the activation energy for the processes is. This non-thermal chemistrydistinguishes irradiation from other non-thermal processes including photolysis, which occurs at much lowerand better defined energies. The processes involved in irradiation can be treated by a detailed Monte Carloapproach for simple systems, such as the bombardment of oxygen ice to produce a steady-state abundanceof ozone. Inclusion of a large number of processes into current chemical simulation networks requires a moreapproximate rate equation approach. A parallel attempt to reproduce experiments involving the bombardmentof water ice has also been undertaken.

Figure 1: A high-energy proton producing tracks ofhigh-energy electrons, which can undergo reactionsto produce ions and excited neutrals.

In a preliminary approach to using irradiation in con-junction with other chemical processes to study thechemistry of cold prestellar cores, it was found that en-hanced abundances of the gas-phase COM methyl for-mate do occur, leading to better agreement with obser-vations. A model with a more complete set of reac-tions that synthesize COMs involving the production ofsuprathermal neutrals and their subsequent reactionsis underway.References: • Shingledecker, C.N., & Herbst, E. 2018,PCCP, 20, 5359 • Shingledecker, C. N., Tennis, J., LeGal, R., & Herbst, E. 2018, ApJ, 861:20



Title: Polycyclic Aromatic Hydrocarbons as catalysts for H2 formationPresenting author: Liv HornekaerContact: [email protected]: Dept. Physics and Astronomy, Aarhus UniversityCo-author: The names of the Co-authors

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellarmedium, however, their impact on interstellar chemistry is still not thoroughly in-vestigated. Theoretical calculations and experimental measurements show thatPAHs react readily with atomic hydrogen to form superhydrogenated species- e.g. PAH molecules like pentacene and coronene can be fully superhydro-genated with one excess H atom pr. carbon atom in the molecule via H atom ad-dition. Once super-hydrogenated, PAH molecules have been shown to catalyzemolecular hydrogen formation and may also catalyze further reactions. Thesefindings may explain observations of increased molecular hydrogen formationrates in photodissociation regions with high PAH abundances. Here we presentresults on stable superhydrogenation configurations and cross-sections for theinitial H and D addition reactions for coronene and pentacene and discuss reac-tions towards more complex species via hydrogenation of pentacene-quinone.

Figure 1: Scanning Tunneling Microscopy Image of Superhydrogenated Coronene on Graphite

References: • E. Rauls and L. Hornekr. Astrophys. J. 679, 531 (2008) • J. D. Thrower et al. AstrophysicalJournal 750, 1, (2012) • V. Menella, L. Hornekr, J. Thrower and M. Accolla. Astrophys. J. Lett. 745, L2 (2012) •J. D. Thrower, E. E. Friis, A. L. Skov, B. Jrgensen and L. Hornekr. Phys. Chem. Chem. Phys. 16, 3381 (2014) •S. Cazaux et. al. Sci. Rep. 6, 19835 (2016) • P. Jensen et al. MNRAS (2018); doi.org/10.1093/mnras/stz1202• E. Habart et al. Astron. Astrophys. 397, 623 (2003) • E. Habart et al. Astron. Astrophys. 414, 531 (2004)



Title: Non-Zeeman Circular Polarization of Rotational Molecular Spectral LinesPresenting author: Martin HoudeContact: [email protected]: The University of Western OntarioCo-author: M. Chamma, T. Hezareh, F. Rajabi, S. Jones, J.-M. Girart, R. Rao

In this presentation I will discuss the recent discovery of circular polarizationsignals in the rotational line profiles of molecules that are negligibly sensi-tive to the Zeeman effect. Our initial findings obtained for CO in the OrionKL star-forming region with the Caltech Submillimeter Observatory [1] werefollowed with similar detections for two transitions of CO in an exhaustivestudy of the supernova remnant IC 443 (G), obtained with the IRAM 30m[2]. These new results have clearly established that circular polarizationarises, as predicted, from the conversion of linear polarization signals in-cident on the molecules responsible for the detected radiation. I will showhow the anisotropic resonant scattering model developed to explain theseobservations and others directly involves the ambient magnetic field [3].These results, and new ones using SMA archival data [4], suggest the pos-sibility of starting a whole new subfield of more incisive studies of magneticfields in the interstellar medium.

Figure 1: Circular polarization spectrum of the12CO (J = 2 ! 1) observations made at the peakposition of Orion KL at the Caltech Submillime-ter Observatory with the Four-Stokes-ParameterSpectral Line Polarimeter (FSPPol). Top: StokesI spectrum, uncorrected for telescope efficiency,and circular polarization levels (symbols with un-certainty, using the scale on the right). Bottom:the Stokes V spectrum, also uncorrected for tele-scope efficiency. The frequency resolution of theStokes I spectrum is 61 kHz (0.08 km s�1), whilethe Stokes V spectrum was smoothed by a factorof 20. Taken from [1].

References: • [1] Houde et al. 2013, ApJ, 764, 24 • [2] Hezareh et al. 2013, A&A, 558, A45 • [3] Houde, M.2014, ApJ, 795, 27 • [4] Chamma et al. 2018, MNRAS, 480, 3123



Title: Merged H/H2 and C+/C/CO transitions in the Orion Bar PDRPresenting author: Maria S. KirsanovaContact: [email protected]: Institute of Astronomy, Russian Academy of SciencesCo-author: Dmitri S. Wiebe

High-resolution ALMA images towards the Orion Bar show no discernible off-set between the peak of H2 emission in the photodissociation region (PDR) andthe 13CO(3–2) and HCO+(4–3) emission in the molecular region (Goicoecheaet al., 2016). This implies that positions of H2 and CO dissociation fronts areindistinguishable in the limit of ALMA resolution (1 arcsec). We use the chemo-dynamical model MARION (Kirsanova et al., 2009; Akimkin et al., 2015) to showthat the ALMA view of the Orion Bar, namely, no appreciable offset betweenthe 13CO(3–2) and HCO+(4–3) peaks, merged H2 and CO dissociation fronts,and high intensity of HCO+(4–3) emission, can only be explained by the ongoingpropagation of the dissociation fronts through the molecular cloud, coupled to thedust motion driven by the stellar radiation pressure, and are not reproduced inthe model where the dissociation fronts are assumed to be stationary. Modellingline intensities, we demonstrate that after the fronts have merged, the angularseparation of the 13CO(3–2) and HCO+(4–3) peaks is indeed unresolvable withthe ALMA observations. Our model predictions are consistent with the results ofthe ALMA observations about the relation of the bright HCO+(4–3) emission to

the compressed gas at the border of the PDR in the sense that the theoretical HCO+(4–3) peak does corre-spond to the gas density enhancement, which naturally appears in the dynamical simulation, and is locatednear the H2 dissociation front at the illuminated side of the CO dissociation front.

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Figure 1: Results of the time-dependent calculations for the Orion Bar. The horizontal axis shows the distancer from the origin of the computational domain. The source of UV photons is supposed to be located to theleft of the computational domain. Left: theoretical spatial distributions of gas temperature (Tgas) and density(ngas). Right: peak intensity of the 13CO(3–2) emission line and integrated intensity of the HCO+(4–3) emissionline. Red and green dashed lines show theoretical locations of the CO and H2 dissociation fronts, respectively.Hatched rectangles of both panels indicate observational values of the abundances, Tgas and ngas with the errorbars obtained by Goicoechea et al., 2016.

References: • Akimkin V. V. et al., MNRAS, 449, 440, 2015 • Goicoechea J. R. et al., Nature, 537, 207, 2016• Kirsanova M. S. et al., ARep, 53, 611, 2009



Title: Experimental Characterization of Low-temperature Surface ReactionsPresenting author: Serge KrasnokutskiContact: [email protected]: Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the

Friedrich Schiller University JenaCo-author: Thomas Henning

Low-temperature reactions on the surface of cosmic solid particles (dust) arethought to be responsible for the formation of complex organic molecules ob-served inside dark molecular clouds and planet-forming disks. These moleculescould later be delivered to planets and facilitate the formation of biopolymers.However, there is a lack of quantitative experimental data on the relevant sur-face reactions. We describe an experimental technique, which can be used tomeasure the energy released in reactions of a single pair of reactants. Thesedata can be directly compared with the results of quantum chemical computa-tions leading to unequivocal conclusions regarding the reaction pathways, thepresence of energy barriers, and the final reaction products. Schematic rep-resentation of the experimental technique is given in Figure 1. In the experi-ment superfluid He nanodroplets are used as a nanocalorimeter and as a thirdbody. Therefore, reactions investigated inside superfluid He nanodroplets areanalogues to those occurring on chemically inert surfaces, for example, waterice surfaces. The new method was applied to study the reactions of C atomswith H2, CO2, NH3 and C2H2 molecules. The formation of HCH, C2O2, CNH3,

and triplet cyclic-C3H2 products has been revealed. The method has applications beyond laboratory astro-physics in studying surface reactions.

R1

R2

Hen

Figure 1: Schematic representation of the chemical reactions occurring inside He droplets. R1 and R2 arethe two different reactants. Reactants are incorporated sequentially into He droplets. In less than 1 µs theymeet inside the droplets. Exothermic reactions with zero energy barriers in the entrance channel proceedspontaneously on encounters. The reaction energy is transferred to the droplets leading to a size reduction.Each evaporated He atom removes about 5 cm�1 of energy. By measuring the size of He droplets before andafter the evaporation, we can calculate the amount of energy released in the reaction.

References: • T. Henning and S. A. Krasnokutski, to appear in Nature Astronomy, 2019. http://dx.doi.org/10.1038/s41550-019-0729-8



Title: Detecting Complex (Polycyclic?) Aromatic Molecules in the ISMPresenting author: Brett A. McGuireContact: [email protected]: National Radio Astronomy Observatory and Center for Astrophysics | Har-

vard & SmithsonianCo-author: Andrew M. Burkhardt, Ryan A. Loomis, Kin Long Kelvin Lee, Christopher N. Shin-

gledecker, Ci Xue, Eric R. Willis, Steven B. Charnley, Martin A. Cordiner, Eric Herbst,Sergei Kalenskii, Anthony J. Remijan, and Michael C. McCarthy

Despite the widespread acceptance of the existence of a large reservoir of aro-matic carbon in the ISM for many decades, likely polycyclic aromatic hydrocar-bons (PAHs), no individual PAHs have been detected to date (McGuire 2018),and detailed observational studies of aromatic chemistry in general have beenlacking. Motivated by our discovery of benzonitrile (cyanobenzene; C6H5CN) inthe dark cloud TMC-1 (McGuire et al. 2018), we have undertaken two large ob-servational follow-ups with the GBT: GOTHAM and ARKHAM. Here, I will presentthe first science results of both projects. GOTHAM aims to explore the extent ofaromatic chemistry in TMC-1, where we detected C6H5CN, using a deep spectralline survey. Our detections of six new interstellar molecules from this work, in-cluding the first individually detected PAH molecules in the ISM, will be described.ARKHAM seeks to understand how widespread detectable aromatic chemistry is

at the earliest stages of star formation. From ARKHAM, we will present our detections of benzonitrile in sourcesoutside TMC-1, including those in which collapse toward protostellar formation, and a protostellar source itself,are included.

References: • McGuire 2018 ApJS 239, 17 • McGuire et al. 2018 Science 359, 202

Astrochemistry: From nanometers to megaparsecs

- A symposium in honour of John H. Black


Title: Formation of dicarbon in collisions of two carbon atoms

Presenting author: Brendan M McLaughlin

Contact: [email protected]

Institute: School of Mathematics and Physics, Queen’s University of Belfast (QUB)

Co-authors: Ryan T Smyth (QUB) and James F Babb (Center for Astrophysics, Harvard & Smith-

sonian)

Radiative association cross sections and rates are computed, using a quantum

approach, for the formation of C2 molecules (dicarbon) during the collision of

two ground state C(3P) atoms. We find that transitions originating in the C 1⇧g,

d 3⇧g, and 1 5⇧u states are the main contributors to the process (Babb et al.2019). The results are compared and contrasted with previous results obtained

from a semi-classical approximation. New ab initio potential curves and transi-

tion dipole moment functions have been obtained for the present work using the

multi-reference configuration interaction approach with the Davidson correction

(MRCI+Q) and aug-cc-pCV5Z basis sets. Applications of the current computa-

tions to various astrophysical environments and laboratory studies are briefly discussed focusing on these

rates. We also discuss recent calculations on collisions of a carbon atom and a carbon ion.

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C2 molecule. Results are shown for the dominant singlet, triplet, and quintet transitions with their appropriate

statistical factor included. The total quantal rate (brown line) is seen to lie above the previous total semiclassical

rate (dashed black line: Andrezza and Singh 1997) at all but the highest temperatures.

References:

• Andreazza, C. M., & Singh, P. D. 1997, MNRAS, 287, 287

• Babb, J. F., Smyth, R. T, & McLaughlin, B. M., 2019, Astrophys. J, in press



Title: Detection of OH radicals on amorphous solid waterPresenting author: Ayane MiyazakiContact: [email protected]: Institute of Low Temperature Science, Hokkaido UniversityCo-author: N. Watanabe, WMC Sameera, T. Hama, H.Hidaka, A. Kouchi

Surface reactions on interstellar grains play an important role in molecular for-mation in dense clouds. Surface reactions proceed via elementary processes:adsorption, diffusion, and collision with another adsorbate. Therefore, diffusionprocess on dust grain surface is crucial to surface reactions and should be clari-fied experimentally. Recently, Watanabe et al. developed a method for detectingH atoms on amorphous solid water (ASW), using the combination of photostimu-lated desorption and resonance-enhanced multiphoton ionization (PSD-REMPI)[1-3]. They reported the surface diffusion mechanism and activation energy ofH-atom diffusion on ASW. In the present study, we focus on the detection of OHradicals on ASW, because surface reactions of OH radicals would contribute tothe formation of complex molecules or those precursors. However, there is noexperiment for the direct detection of OH radical on water ice because of intrinsictechnical difficulty. In an infrared absorption spectroscopy, an OH radical spec-trum can be hardly separated from H2O band in ice. Temperature-programmed

desorption little provides the information about behavior of OH radical on water ice surface.Using the PSD-REMPI method, we have first succeeded in monitoring OH radicals on the ice surface, which

were produced by UV photolysis of ASW. I present the experimental details on detection and behavior of OHradicals on ASW

References: • [1] N. Watanabe et al. ApJL 714, L233 (2010). • [2] T. Hama et al. ApJ 757, 185 (2012). • [3]Kuwahata et al. Phys. Rev. Lett. 115, 133201 (2015).



Title: Molecular absorbers against background quasars: the cosmic microscopesPresenting author: Sebastien MullerContact: [email protected]: Chalmers University of Technology

More than thirty orders of magnitude separate nanometers and megaparcsecs.The former traditionally requires powerful microscopes, the latter powerful tele-scopes. I will show that studying molecular absorption against backgroundquasars is equivalent to use a cosmic microscope. This simple but powerfultechnique allows us to scrutinize the interstellar medium and reveal the chemicalsetup of distant galaxies, without the distance dilution affecting studies in emis-sion. In turn, the molecules at high redshifts are privileged cosmological probes,giving us information on how is the Universe evolving.



Title: Small molecules observed at high spectral resolution with SOFIA: recent results fromEXES and GREAT observations of two molecules, H2 and HeH+

Presenting author: David NeufeldContact: [email protected]: Johns Hopkins University

Small molecules provide a valuable probe of fundamental processes in the inter-stellar medium. and provide unique information about the environment in whichthey are observed. In this talk, I will discuss recent observational studies of twomolecules, H2 and HeH+, which have been observed at high spectral resolutionusing the EXES and GREAT instruments on the SOFIA airborne observatory.These studies show the value of high spectral resolution spectroscopy in the mid-and far-infrared spectral regions conducted from altitudes where the atmosphereis largely transparent. The H2 observations (Neufeld et al. 2019), performedwith the EXES mid-IR spectrometer at a resolving power λ/∆λ ∼ 105, targetedthe S(4) - S(7) pure rotational lines of H2. Observations of warm gas in HH7,a classic bow shock, revealed small velocity shifts ∼ 3 km s−1 between the ob-served emission lines of ortho-H2 [S(5) and S(7)] and those of para-H2 [S(4) andS(6)]. These velocity shifts bear witness to the conversion of para-H2 to ortho-H2

within the shock front, and provide compelling evidence for “C”-type shocks in which the flow velocity variescontinuously. The HeH+ observations (Gusten et al. 2019), performed with the GREAT spectrometer, have ledto the first astrophysical detection of the helium hydride cation. Here, the R(0) transition at 2.01 THz (149µm)was detected toward the young planetary nebula NGC 7027. Thanks to the unprecedented spectral resolvingpower of GREAT at this frequency, the HeH+ line could be distinguished for the first time from a nearby CHtransition. The detection of HeH+ provides a beautiful demonstration of Nature’s tendency to form molecules;despite the unpromising ingredients (hydrogen and the noble gas element helium), and the harsh conditions(strong UV irradiation and temperatures of several thousand Kelvin), HeH+ forms within a thin shell near theStromgren radius where He+ and H coexist. More than four decades ago, with his 1978 paper on the sub-ject, John Black played a central role in the recognition that HeH+ was a potentially-detectable astrophysicalmolecule: it has now been found at last, precisely where he suggested looking.

Figure 1: Left panel: spectra of H2 rotational transitions obtained by EXES toward HH7 (Neufeld et al. 2019).Right panel: spectra of HeH+ J = 1 − 0 obtained by GREAT toward NGC 7027 (Gusten et al. 2019).

References: • Black, J. H. 1978, ApJ, 222, 125 • Neufeld, D. A., DeWitt, C., Lesaffre, P., et al. 2019, ApJ, inpress • Gusten, R., Wiesemeyer, H., Neufeld, D., et al. 2019, Nature, 568, 357



Title: Heavy element recombination lines towards an evolved star: In the footsteps of JohnBlack

Presenting author: Hans OlofssonContact: [email protected]: Space, Earth and Environment, ChalmersCo-author: J. Black, E. Humphreys, M. Lindqvist, M. Maercker, L.-A. Nyman, S. Ramstedt, D.

Tafoya, W. Vlemmings

The 26α and 30α recombination lines of a heavy element have been detectedusing ALMA towards an evolved low-mass star in a binary system, HD101584 [1].The star is classified as a post-RGB object, but post-AGB remains a possibility.The most likely carrier of the lines is Mg, but there may also be contributionsfrom Na, Al, Si, K, and Fe. The modest temperature of the star, about 8500 K,means that the corresponding lines from H, He, and C are not detectable. Asimple model for the immediate surroundings of the star has been developed toestimate the properties of the gas, including its elemental abundances. Opticalspectra have provided additional constraints. This is a potentially new methodof observing cool stars, such as AGB stars and the more massive counterparts,red supergiants and yellow hypergiants.

References: • Olofsson et al. A&A 623, A153, 2019



Title: Cosmic rays: the ubiquitous probe for the interstellar mediumPresenting author: Marco PadovaniContact: [email protected]: INAF-Osservatorio Astrofisico di Arcetri - ItalyCo-author: (in alphabetical order) P. Caselli, A. Ferrara, K. Ferriere, D. Galli, P. Hennebelle, A.

Ivlev, A. Marcowith

Galactic cosmic rays are an omnipresent source of ionisation and dissociationof the interstellar gas, competing with UV and X-ray photons as well as natu-ral radioactivity in determining the fractional abundance of electrons, ions, andcharged dust grains in molecular clouds and circumstellar discs. Cosmic raysactivate the rich chemistry that is observed in molecular clouds and also regu-late the cloud collapse timescale, determining the efficiency of star and planetformation. However, they cannot penetrate up to the densest part of a molec-ular cloud, where the formation of stars takes place, because of energy lossprocesses and magnetic field deflections. Cosmic rays can also be produced inprotostellar shocks, and this local source can explain energetic phenomena suchas the synchrotron emission observed in jets, and the associated unusually highionisation rates. In this talk I will present recent results on cosmic-ray physicsand chemistry in star-forming regions obtained by analytical and numerical mod-els, supplemented by dedicated observations together with predictions on thecapability of future instruments such as SKA in detecting synchrotron emissionin molecular clouds.

References:• Cosmic-ray acceleration in young protostars - Padovani et al. 2015, A&A, 582, L13• Protostars: Forges of cosmic rays? - Padovani et al. 2016, A&A, 590, A8• The plasma physics of cosmic rays in star-forming regions - Padovani et al 2017, PPCF, 59, 014002• Cosmic-ray ionisation in circumstellar discs - Padovani et al. 2018a, A&A, 614, A111• Production of atomic hydrogen by cosmic rays in dark clouds - Padovani et al. 2018b, A&A, 619, A144• Synchrotron emission in molecular cloud cores: the SKA view - Padovani et al. 2018c, A&A, 620, L4



Title: Dicke’s Superradiance and Maser FlaresPresenting author: Fereshteh RajabiContact: [email protected]: Perimeter Institute for Theoretical Physics and the Institute for Quantum ComputingCo-author: Martin Houde (University of Western Ontario)

Burst phenomena covering a wide range of timescales are ubiquitous inastrophysics (e.g., from less than a millisecond for Fast Radio Bursts toseveral years for some maser flares). Understanding their origin and un-derlying physical processes is an important goal of contemporary astro-physics.To this end, we have recently applied Dicke’s superradiance, a co-herent quantum mechanical radiation mechanism, to the physics of the in-terstellar medium (ISM) to explain some of these burst phenomena. Inthis presentation I will focus on so-called maser flares and show how un-der certain conditions a region initially hosting a maser can transition to asuperradiance regime. When superradiance sets in, individual molecules(or atoms) become entangled and do not emit independently but do soas a group. One important consequence is that a superradiance systemwill radiate through powerful bursts with a peak intensity proportional to thesquare of the number of molecules contained in the radiating gas. Althoughit was first discussed by R. H. Dicke in 1954 and has been studied in thelaboratory for several decades, superradiance remained unnoticed by as-

tronomers until recently. I will thus present observational evidence for superradiance in the ISM and describeour models developed to explain corresponding radiation flares seen in the 6.7-GHz methanol, 1612-MHz OH,and 22-GHz water spectral lines.

Figure 1: Superradiance model for theS255IR-NIRS3 flare. Top: The black dotsare for the data and the solid cyan curvefor the superradiance model fit as a func-tion of retarded time. Bottom: The solidblack and cyan curves, respectively, showthe temporal evolution of the invertedpopulation density and the pumping rate.The fit is produced using a single super-radiance sample of length L = 140 aucomposed of NSR ' 6 ⇥ 1019 inverted andentangled methanol molecules. The in-version level prior to the appearance ofthe pump pulse corresponds to approxi-mately 0.1 cm�3 for a molecular populationspanning a velocity range of 1 km s�1. Thecolumn density of the inverted populationis (nL)SR = 6.4 ⇥ 103 cm�2 and the SR fluxdensity is scaled to the data. Taken from[4].

References: • [1] Rajabi & Houde 2016a, ApJ, 826, 216 • [2] Rajabi & Houde 2016b, ApJ, 828, 57 • [3] Rajabi& Houde 2017, Science Advances, 3, e1601858 • [4] Rajabi et al. 2019, MNRAS, 484, 1590



Title: Photon-driven chemistryPresenting author: Evelyne RoueffContact: [email protected]: LERMA, Observatoire de ParisCo-authors: E. Bron, J. Le Bourlot, F. Le Petit

John Black and Alex Dalgarno [1] emphasized more than 40 years ago the po-tential diagnostics of the infrared response of molecular Hydrogen to ultravio-let radiation. These predictions have been beautifully confirmed a few monthslater by Gautier et al. [2] thanks to a Fourier transform spectrometer installed atthe Steward Observatory telescope towards the Kleinmann-Low nebula in Orion.The infrared spectrum of molecular hydrogen has been subsequently detectedin various UV illuminated regions by ISO, Spitzer in space but also on the groundby CFHT, Lowell Observatory, VLT, McDonald, ....

Photon dominated regions (PDRs) are recognized as key areas for under-standing the interface between molecular gas, where stars form, and the sur-rounding galactic environment [3]. The Herschel Space Observatory has recentlyopened the possibility to detect warm molecular gas present in galactic and ex-tragalactic sources by covering CO excitation lines from Jup = 4 to Jup ⇠ 20 [4].The derived CO spectral line energy distributions (SLEDs) including high-J levelsallow to highlight energetic processes occurring in these star-forming regions.

Constant density models fail to reproduce the corresponding emissivities; however isobaric models allowto successfully account for excited CO as well as other tracers including H2, HD, CH+, .... found at the edge ofPDRs. Indeed, a thin but extended layer of molecular emission emerging from the FUV-irradiated gas is foundwith the one arc second resolved observations provided by ALMA [5]. A strong correlation between the gaspressure and the impinging radiation field is derived both from galactic [4] and extragalactic [6] observations.

My talk will outline how these new results reveal the multiple physical and chemical processes at work, fromthe formation/photo-destruction of molecular Hydrogen and occurence of an endothermic chemistry triggeredby vibrationally excited H2 (following UV pumping and pointing to a state-to-state chemistry) to the radiativefeedback-induced gas dynamics. A bright future is foreseen for PDR modelling where new physical contraintssuch as surface chemistry combined to possible photodesorption as well as time-dependent thermo-chemicalevolution [7] deserve consideration.

References: • [1] J.H.Black & A. Dalgarno 1976, ApJ 203, 123, • [2] T.N. Gautier et al. 1976 ApJ 207, L129 •[3] D.J. Hollenbach & A.G.G.M. Tielens 1999, Rev. Mod. Phys. 71, 173 • [4] C. Joblin et al. 2018, A&A 615,A129, Parikka et al. 2018, A&A 617, A77, S. Cuadrado et al. 2019, Astron. Astrophys. 625, L3, Wu et al.2018, A&A 618, A53, A B. Mookerjea et al. 2019, arXiv:1905.03161 • [5] J. Goicoechea et al. 2016, Nature537, 207, J. Goicoechea et al. 2017, Astron. Astrophys. 601, L9 • [6] M.Y.-Lee et al. 2016, &A 596, A85 • [7]E. Bron et al. 2018, arXiv:1801.01547, Kirsanova and Wiebe 2019, MNRAS 486, 2525



Title: Lab spectroscopy for astrochemistryPresenting author: Stephan SchlemmerContact: [email protected]: Universitaet zu KoelnCo-author:



Title: Simulating Ion-Irradiation Experiments using Astrochemical ModelsPresenting author: Christopher N. ShingledeckerContact: [email protected]: Max-Planck-Institut fr extraterrestrische PhysikCo-author: Anton Vasyunin, Eric Herbst, Paola Caselli

The upcoming launch of JWST promises to usher in an astrochemical ”ice age”by allowing for the collection of an unprecedented amount of data regardingspecies frozen onto interstellar dust grains. Astrochemical models will surelyfigure prominently in both interpreting these data, as well as in informing futureobserving proposals. However, this great opportunity calls for models which areequal to the task and, unfortunately, there remain significant uncertainties re-garding the chemistry of dust grains and dust grain ice-mantles - a situation thathas given it the dubious reputation of ”the last refuge of the scoundrel.” Theseices are exposed to a constant ionizing radiation flux, typically in the form of cos-mic rays, stellar winds, and radionuclide emission. There is now a large bodyof experimental work showing that these kinds of radiation can trigger significantphysico-chemical changes in ices, including the dissociation of species (radioly-sis), sputtering of surface species, and ice heating (Hudson and Moore, 2001).

Even so, modeling the chemical effects that result from interactions between ionizing radiation and interstellardust-grain ice mantles has proven challenging due to the complexity and variety of the underlying physicalprocesses. Here, we review recent effort by us on this topic (Shingledecker et al., 2019), as well as somesurprising insights regarding the mechanisms underlying bulk chemistry that can by gained through the use ofsuch models.

References: • Hudson, R. L., Moore, M. 2001, J. Geophys. Res. 106 33,275 • Shingledecker, C. N., et al.2019, Ap.J. submitted



Title: Modeling deuterium chemistry in dense cores: full scrambling versus proton hopPresenting author: Olli SipilaContact: [email protected]: Max-Planck-Institute for Extraterrestrial Physics (MPE)Co-author: Paola Caselli, Jorma Harju

Deuterated molecules are excellent probes of the dense and cold centers ofmolecular cloud cores. This is because they appear in conditions where other-wise abundant tracer molecules such as CO are frozen onto dust grains. Deu-terium is transferred from the main molecular reservoir, HD, to other species viathe H

+3+ HD ! H2D

+ + H2 reaction followed by a variety of efficient deuteron-donation reactions such as H2D

+ +N2 ! N2D+ +H2. The efficiency of deuteration

is also very strongly influenced by spin-state chemistry, because certain forma-tion/destruction channels are forbidden by selection rules. An open question innumerical models of deuterium chemistry at low temperature is the nature of thereaction mechanism when protons/deuterons are exchanged. For the H

+3+ H2

system, there is evidence that the proton transfer proceeds through full scram-bling, in which several atom interchanges can take place in a relatively long-livedreaction complex (e.g., Suleimanov et al. 2018). On the other hand, Le Gal et al.(2017) demonstrated that the formation of H2Cl

+ is governed by direct proton ab-straction in HCl

+ +H2. Here we present new models for deuterium and spin-statechemistry (Sipila et al. 2019, in prep.) where all proton-donation reactions of the

form XH+ + Y ! YH

+ + X (and deuterated analogs), with the exception of the H+3+ H2 system, are treated as

either full scrambling or proton/deuteron hop reactions. We apply our model to the starless core H-MM1 wherewe recently found (Harju et al. 2017) that the observed D/H and spin-state abundance ratios of deuteratedammonia do not match the non-statistical ratios predicted by our previous chemical model (Sipila et al. 2015).We find that the hop model reproduces the observed D/H ratios better than the full scrambling model does.The spin-state ratios predicted by the two models are very similar because they are heavily dependent on theH+3+H2 system which we do not modify, and indeed we find that the back-effect of the various proton/deuteron-

transfer reactions on H+3

and its isotopologs is very small. Figure 1 shows some example results at constantdensity and temperature, highlighting the difference between the full scrambling and hop models.

Figure 1: D/H abundance ratios of ammonia (left), H+3

(middle), and water (right) at constant density (n(H2) =10

6cm�3) and temperature (Tdust = Tgas = 10 K). Solid lines represent the full scrambling model, and dashed

lines represent the proton/deuteron hop model.

References: • Harju, J., Daniel, F., Sipila, O. et al. 2017, A&A, 600, A61 • Le Gal, R., Xie, C., Herbst, E. et al.2017, A&A, 608, A96 • Sipila, O., Harju, J., Caselli, P., and Schlemmer, S. 2015, A&A, 581, A122 • Sipila, O.,Caselli, P., and Harju, J. 2019, in prep. • Suleimanov, Y., Aguado, A., Gomez-Carrasco, S., and Roncero, O.2018, J. Phys. Chem. Lett., 9, 2133



Title: The atomic to molecular (HI-to-H2) transition in Galaxy star-forming regionsPresenting author: Amiel SternbergContact: [email protected]: Flatiron InstituteCo-author:

As was emphasized in John Black’s famous PhD thesis, the atomic to molecu-lar hydrogen (HI-to-H2) phase transition is of fundamental importance for star-formation and the emergence of chemical complexity in the interstellar mediumof galaxies. I will present an overview, and discuss recent theoretical studies,numerical and analytic, of the HI-to-H2 transition in irradiated systems, with ap-plications to the multi-scale behavior observed in star-forming galaxy disks fromlow- to high-redshift.



Title: Cold molecular extragalactic mediumPresenting author: Linda TacconiContact: [email protected]: Max-Planck-Inst. fuer extraterrestrische PhysikCo-author:



Title: Ionization signatures and gamma-rays from supernova remnantsPresenting author: Julia Becker TjusContact: [email protected]: Ruhr-University Bochum, Bochum, Germany

The origin of cosmic rays is still one of the central open questions in physicsand astrophysics. Still, scientists have come closer to the answer in the pastdecades - three supernova remnants (SNRs) have been identified as cosmicray emitters via the identification of the so-called pion bump in their gamma-ray spectrum, which must be hadron-induced. While uncontontroversial in theresult, these detections do not grant that the entire spectrum of cosmic rays asobserved at Earth is produced by SNRs: The three SNRs in question are strongemitters at GeV energies, however, they barely produce any signal in the TeV -PeV range, which is necessary in order to explain the entire cosmic ray spectrum.The search for solid proof is therefore ongoing with high insistence. In particular,finding methods to identify more cases of cosmic-ray emitting SNRs is necessaryto prove the case.

This talk will address the method that I worked on together with John - we in-vestigated if cosmic-ray induced ionization can help to solve the question by look-ing for correlated signatures in molecular lines and gamma-rays. This talk sum-marizes the state-of-the-art on the topic of cosmic-ray ionization and gamma-rayemitting SNRs.



Title: Probing the HI/H2 layer around the ultracompact HII region MonR2Presenting author: Sandra P. Trevino-MoralesContact: [email protected]: Onsala Space Observatory/Chalmers University of TechnologyCo-author: A. Fuente, A. Sanchez-Monge, P. Pilleri, J. Goicoechea, V. Ossenkopf-Okada et al.

One of the first signposts of high-mass star formation is the presence of com-pact HII regions, surrounded by layers of photon-dominated regions (PDRs). Thestudy of the properties of these objects is of special interest because they pro-vide information on the dynamical and chemical evolution of forming high-massstars. Reactive ions are thought to be excellent PDR tracers. In particular, highfractional abundances of CO+ are expected in the HI/H2 transition layer of densePDRs. Our team has performed a study of the spatial distribution of the CO+

rotational emission toward the MonR2 star-forming region, where there exists aseries of PDRs surrounding an expanding UC HII region. The CO+ emissionpresents a clumpy ring-like morphology that surrounds the HII region (Figure 1).We compared the CO+ distribution with other species present in PDRs, suchas [CII], H2 S(3), polycyclic aromatic hydrocarbons (PAHs), and molecular gastracers (Trevino-Morales et al. 2014, 2016). We find that the CO+ emission is

spatially coincident with the PAHs and [CII] emission, confirming that the CO+ only survives in a narrow denselayer of the HI/H2 interface. We determine the CO+ fractional abundance relative to [CII] toward three positionsassociated with different PDRs. The abundances range from 0.1 to 1.9×10−10, and are in good agreementwith chemical model predictions for the physical conditions prevailing in this UC HII region. Moreover, the CO+

linewidth is larger than those found in molecular gas tracers, and their central velocity are blue-shifted with re-spect to the molecular gas velocity. We interpret this as a hint that the CO+ is probing photo-evaporating clumpsurfaces. Overall, the spatial distribution and the kinematics of the studied species suggest the presence ofphoto-evaporating clumps in the dense frontier between the HII region and the molecular cloud. This scenariosupports the idea of a fragmented ionization and photo-dissociated fronts that was previously suggested byYoung et al. (2000) and Goicoechea et al. (2016).

Figure 1: MonR2 star-forming region as seen with CO+ (in color). Black contours correspond to the PAH11.3 µm emission (Panel A); the H2 9.7 µm emission tracing the layer between the HII region and the moleculargas (Panel B); and the [CII] emission (Panel C, Pilleri et al. 2014). The red contours (Panel B) show the NeII

emission tracing the HII region (Berne et al. 2009). The blue square indicates the ionization front position.

References: • Berne, O., et al. 2009, ApJ, 706, L160 • Goicoechea, J., et al. 2016, Nature, 537, 207 • Pilleri,P. et al. 2014, A&A, 561, A69 • Trevino-Morales, S. P., et al. 2014, A&A, 569, A19 • Trevino-Morales, S. P., etal. 2016, A&A, 593, L12 • Young et al. 2000, ApJ, 540, 886



Title: Water in Star FormationPresenting author: Floris van der TakContact: [email protected]: SRON / University of Groningen

Water plays the double role of agent and tracer in the origin of stars, planets,and habitability. This talk reviews the role of water as a tracer of the star for-mation process, in particular the formation of high-mass stars. After discussingobservational advances from the ground (APEX, ALMA) and from air/space (Her-schel, SOFIA), I will emphasize the importance of radiative transfer calculations(RADEX, RATRAN) and molecular input data (LAMDA, Basecol) for interpretingobservational data. The talk concludes with an outlook into future opportunities,with instruments such as JWST/MIRI, ELT/METIS, and SPICA/SAFARI.



Title: Isotope selective photodissociationPresenting author: Ewine F. van DishoeckContact: [email protected]: Leiden Observatory, Leiden UniversityCo-authors:

Studying isotope selective photodissociation in space requires a detailed under-standing of microscopic processes at the molecular level. John’s most cited pa-pers are exactly on this topic, linking in-depth knowledge of photodissociationprocesses with astronomical applications. An overview will be presented of ourcurrent understanding of isotope selective photodissociation for the H2, CO andN2 isotopologs. Applications will range from individual diffuse and translucentclouds, to large scale collections of clouds, AGB stars, protoplanetary disks,comets and meteorites. Details do matter, but once they are well constrainedthey open up precision astrochemistry!



Title: The delivery and evolution of water within the solar system studied via the D/HPresenting author: Geronimo L. VillanuevaContact: [email protected]: NASA - Goddard Space Flight Center, Greenbelt, MD 20771, USA

The majority of our planet is covered with water (71%), while an ancient oceancovered at least 19% of the Martian surface and held more water than EarthsArctic Ocean, as recently revealed from water isotopic measurements. The in-ner planets in our solar system were thought to be formed within the frost-line,and should be in principal mostly devoid of water. Where does this water comefrom? Small bodies rich in water (e.g., comets, asteroids) have been proposedas vehicles for this delivery, yet alternative findings suggest that this water mayhave been primordially endowed to Earth and Mars.

The D/H is a powerful metric in order to address these questions. Not onlyit permits to understand about the origin and delivery of water to the inner solarsystem, but it also permits to characterize the evolution of the habitability onthese planets. For instance, ground-based observations of D/H on Mars revealedthat atmospheric water in the near-polar region was enriched by a factor of seven

relative to Earths ocean water, implying that water in Mars permanent ice caps is enriched by 8-fold. Mars musthave lost a volume of water 6.5 times larger than the present polar caps to provide such large enrichment,implying the existence of an ancient ocean on Mars.

Specifically, instruments and missions to characterize water and its isotopes across the solar system havereached an unprecedented level of sophistication and maturity, opening new windows in the astrobiological ex-ploration of our solar system. High-resolution infrared spectrometers with broad spectral coverage at ground-based observatories (e.g., Keck, IRTF, VLT) and arrays of radio telescopes with state-of-the-art receivers (e.g.,ALMA) now permit the investigation of the kinematics, composition and thermal structure of a broad rangeof these bodies with unprecedented precision. These, combined with the advent of comprehensive spectro-scopic databases containing billions of lines, accurate radiative transfer models, and unprecedented availablecomputational power, are transforming the way we investigate water in the solar system.

In this talk, I will present a review of our current understanding of water in the solar system, and how newcapabilities will provide unprecedented opportunities for studying the origin, delivery and evolution of water.



Title: The ortho-to-para ratio of hydrogen and water molecules desorbed from ice dust:experimental approach

Presenting author: Naoki WatanabeContact: [email protected]: Institute of Low Temperature Science, Hokkaido UniversityCo-author: T. Hama, H. Ueta, A. Kouchi

Hydrogen (H2) and water (H2O) molecules have two nuclear isomers, ortho andpara states for the total spin of 1 and 0, respectively. At thermal equilibrium, theortho/para nuclear spin ratios (OPRs) of H2 and H2O are the functions of temper-ature, which is so-called nuclear spin temperature. Because the ortho and paraspin isomers take rotational states with odd and even quantum numbers, respec-tively, observing the population of rotational states of those molecules gives theOPR, in other words, the nuclear spin temperature. Radiative transition betweenortho and para states is forbidden. Furthermore, ortho-para conversion in gasphase by spin exchange reactions with proton and ionic species like H+3 occurvery slowly [1], the OPR has been often used as a tool to investigate physicaland chemical condition of the birth place of molecules. For H2, the OPR stronglyaffects not only chemistry like deuterium fractionation [2] in the gas phase but

also gas dynamics of core formation [3] because the energy difference between the ortho and para states issignificant. For H2O, it has been often proposed that the spin temperature closely correlates to the temperatureeither at birthplace of H2O molecule, i.e. the cosmic dust surface, or the inner cometary nucleus [4].

Recent years, laboratory experiments have shaded light on the behaviors of the OPR of H2 and H2Omolecules on ice. For H2, it was found that the OPR of nascent H2 produced by H-H recombination is 3and gradually decreases if H2 stays on the ice surface [5]. The ortho-para conversion rate is accelerated whenO2 molecules coexist on the ice surface because of magnetic dipole interaction [6]. The combination of theStark effect and Fermi contact was first proposed as a conversion mechanism [7]. The conversion rate on icestrongly depends on the ice temperature, which can be explained by energy dissipation by phonon process[8]. Very recently, the theoretical explanation for the conversion has been updated [9]. For H2O, the ortho-paraconversion was observed in solid argon matrix[10]. However, the OPRs of water both thermally desorbed [11]and photodesorbed from ice at 10 K [12] indicate nearly 3 regardless of water formation processes. Last year,we further demonstrated that the OPR is also 3 for H2O photodesobed from ice which is produced from onlypara-H2O at around 11 K [13]. These findings clearly show the different behavior of the OPR between H2 andH2O on ice. In my presentation, I will make a brief review for experimental approach to the OPR of H2 and H2Ofrom ice and discuss what controls the OPRs of these molecules on ice.

References: • [1] D. Wilgenbus, S. Cabrit, G. Pineau des Forets, D. Flower, In Molecular Hydrogen in Space,p.123, ed. F. Combes & G. Pineau des Forets, Cambridge: Cambridge Univ. Press, 2000. • [2] L. Pagani,E. Roueff, and P. Lesaffre, ApJL. 739, L35 (2011). • [3] N. Vaytet et al. A&A 563, A85 (2014). • [4] W. M.Irvine, F. P. Schloerb, J. Crovisier, B. Jr. Fegley, M. J. Mumma, In Protostars and Planets IV, p.1159, ed. V.Mannings, A. P. Boss, & S. S. Russell, Tucson, AZ: Arizona Univ. Press, 2000. • [5] N. Watanabe et al. ApJL714, L233 (2010). • [6] M. Chehrouri et al. Phys. Chem. Chem. Phys. 13, 2172 (2011). • [7] T. Sugimoto andK. Fukutani, Nat. Phys. 7, 307 (2011). • [8] H. Ueta et al. Phys. Rev. Lett. 116, 253201 (2016). • [9] E. IliscaChem. Phys. Lett. 713, 289 (2018). • [10] L. Abouaf-Marguin et al. Chem. Phys. Lett. 447, 232 (2007). • [11]T. Hama, K. Kuwahata, N. Watanabe, et al. ApJ, 757, 185 (2012). • [12] T. Hama, A. Kouchi, N. Watanabe,Science, 351, 65 (2016). • [13] T. Hama, A. Kouchi, N. Watanabe, ApJL 857, L13 (2018)

Posters



Title: Chemical diversity in early massive protostellar objectsPresenting author: Laure BouscasseContact: [email protected]: Max-Planck-Institut fur RadiostronomieCo-author: Timea Csengeri, Karl M. Menten, Friedrich Wyrowski, Arnaud Belloche, Sylvain Bon-

temps, Rolf Gusten

The physical conditions in massive dense cores (MDCs) leading to high-massstar formation are poorly constrained. Observations are lacking to confront the-ory. From the 870 micron ATLASGAL survey of the inner Galaxy, in the frameof the SPARKS project (Survey for high-mass Protostars with ALMA Revealedup to Kpc Scales, PI: Csengeri), we performed an ALMA follow-up on the mostmassive mid-infrared quiet clumps within 5 kpc. We found 6 sources that staysingle from 0.3 pc to 2000 au scales. This makes them relatively easy targets forsingle-dish observations to study the early warm-up phase chemistry leading tothe appearance of classical hot-cores. In addition to the 8 GHz instantaneousbandwidth at 345 GHz obtained with SPARKS, we obtained a complete spec-tral survey covering the 2 mm, 1 mm and 0.8 mm atmospheric window with theAPEX telescope towards a handful of sources. We will present here the chemicalcomposition of the protostellar envelopes. We aim to pin down where differentmolecules are located within the envelope with a particular focus on the distribu-tion and diversity of complex organic molecules.



Title: The stacking revolution: searching for the seeds of lifePresenting author: Hannah CalcuttContact: [email protected]: Chalmers University of TechnologyCo-author: J. B. Jolly

Complex organic molecules (COMs) are readily detected in the inner regionsof the gaseous envelopes of forming protostars. Their detection is crucial tounderstanding the chemical evolution of the Universe. Particularly, to explorethe link between the early stages of star formation and the formation of solarsystem bodies, where complex organic molecules have been found in abun-dance.

In recent years, the astrochemical community has made significant progressin terms of surveying the chemical content of star forming regions. Several ofthe brightest and most well known regions have had whole band surveys per-formed (e.g. IRAS 16293–2422, Jørgensen et al. 2016, and Sgr B2, Bellocheet al. 2016), providing us with an array of new molecular detections, particularlyof the weakest molecules. Despite this, detections of some of the most com-plex molecules, such as amino acids, have remained elusive. Studying thesemolecules is important to link the chemical content of star forming regions to thepathway to life formation. Their low abundance in star-forming regions makestheir detection a particular challenge, even with the unprecedented sensitivity

provided by ALMA observations.

Fundamentally, to detect the weakest molecules, we need to improve the signal-to-noise of our observa-tions. This is a problem that has also been encountered in high-redshift galaxy studies, but can be mitigated byusing line stacking techniques, to overcome the intrinsic limitations in spectral observations (Jolly et al. in prep.,Stanley et al. 2019). In this talk, I present work which applies these techniques to the local universe. We takean average of a large sample of Galactic hot cores, with the aim of dramatically improving the signal-to-noiseand detecting several biologically significant molecules for the first time in the ISM.

References: • Belloche, A., Muller, H. S. P., Garrod, R. T., & Menten, K. M. 2016, A&A, 587, A91 • Jørgensen,J. K., van der Wiel, M. H. D., Coutens, A., et al. 2016, A&A, 595, A117 • Stanley, F., Jolly, J. B., Konig, Knudsen,K. K., 2019, A&A



Title: Supercomputer simulation of astrochemical problemsPresenting author: Igor ChernykhContact: [email protected]: Institute of Computational Mathematics and Mathematical Geophysics SB RAS,

Novosibirsk, RussiaCo-author: Igor Kulikov, Victor Protasov

Numerical simulation plays a key role in modern astrophysical researches be-cause the characteristic time scale for the most of the processes begins fromsplit seconds for some chemical processes and goes up to hundreds of mil-lions of years for galaxies collision processes. In our presentation we providea new approach for the numerical simulation of astrophysical and astrochemicalprocesses. This approach is based on combining of both distributed and paral-lel computing techniques with advanced code vectorization for modern proces-sors architectures such as Skylake-SP/Cascade Lake-SP. Our numerical codeis based on the hydrodynamics approach with using of Godunov’s scheme as abase of the solver. Astrochemical solver is based on chemical kinetics approach.In our presentation, we will show the result of the numerical simulation of sometermolecular chemical processes for the high gas temperatures and densities.This research was supported by the RSCF grant 18-11-00044.

References: • Kulikov I., Chernykh I., Tutukov A. A New Hydrodynamic Model forNumerical Simulation of Interacting Galaxies on Intel Xeon Phi Supercomputers.

Journal of Physics: Conference Series, Vol. 719, Article Number 012006, 2016. • Kulikov I.M., Chernykh I.G.,Glinskiy B.M., Protasov V.A. An Efficient Optimization of HLL Method for the Second Generation of Intel XeonPhi Processor. Lobachevskii Journal of Mathematics, Vol. 39, pp. 543–550, 2018. • Kulikov I.M., ChernykhI.G., Snytnikov A.V., Glinskiy B.M., Tutukov A.V. AstroPhi: A code for complex simulation of the dynamicsof astrophysical objects using hybrid supercomputers, Computer Physics Communications, Vol. 186, pp. 71–80, 2015. • Chernykh et al. Advanced vectorization of ppml method for Intel R⃝ Xeon R⃝ scalable processors.Communications in Computer and Information Science, Vol. 965, pp. 465–471, 2019.



Title: The Fundamental Vibrational Frequencies and Spectroscopic Constants of theDicyanoamine Anion: Quantum Chemical Analysis of a Likely Planetary Anion,NCNCN� (C2N3

�)Presenting author: David DuboisContact: [email protected]: NASA Ames Research Center/BAER InstituteCo-author: Ella Sciamma-O’Brien, Ryan Fortenberry

Since the first identification of anions in dense molecular clouds and cir-cumstellar envelopes (CSE) in 2006 (McCarthy et al., 2006), their detec-tion has remained difficult. The well-studied IRC +10216 CSE (e.g. Remi-jan et al., 2007) has nonetheless revealed the presence of CnH� carbon-chain as well as cyano molecular anions (e.g. Thaddeus et al., 2008)such as Cn�1N� (n = 2 � 6). Among these, C8H� (Brunken et al.,2007) represents the largest carbon-chain anion detected in the interstellarmedium (ISM). In addition, Saturn’s moon Titan also unveiled the presenceof large anions with masses up to 13,800 u/q which require further identifica-tions.

The effort in the detection of anions has relied on a strong collaboration be-tween theoretical and laboratory analyses to measure rotational spectra and

spectroscopic constants to high accuracy. The advent of improved quantum chemical tools operating athigher accuracy and reduced computational cost is a crucial solution for the fundamental characterizationof astrophysically-relevant anions and their detection in the interstellar medium. In this context, we have turnedtowards the quantum chemical analysis of the dicyanamide anion NCNCN� (C2N3

�), a structurally bent andpolar compound. We have performed computations of C2N3

� using a CcCR (for Complete basis set limit,core Correlation and Relativity) quartic force field (QFF) method, which satisfy both computational cost andaccuracy approaches (Fortenberry 2017). This ion displays a bright ⌫2 (2130.9 cm�1) and a lesser ⌫1 (2190.7cm�1) fundamental vibrational frequency, making for strong markers for upcoming infrared observations withthe James Webb Space Telescope. Such an ion could potentially be detected in nitrogen-rich environments ofthe ISM or in the atmosphere of Titan, where advanced N-based reactions may lead to its formation.

References: • McCarthy M. C., Gottlieb C. A., Gupta H., and Thaddeus P., 2006, The Astrophysical Journal,652:L141-144 • Thaddeus P., Gottlieb C. A., Gupta H., et al., 2008, The Astrophysical Journal, 677:1132-1139• Fortenberry R. C., 2017, International Journal of Quantum Chemistry, 117, 81-91



Title: Large scale mapping of the Orion B molecular cloudPresenting author: Maryvonne GerinContact: [email protected]: LERMA, Observatoire de ParisCo-author: J. Pety, S. Bardeau, V. de Souza Magalhaes, E. Bron, J.R. Goicoechea, P. Gratier,

V. Guzman, Hughes, A., Languignon D., F. Le Petit, F. Levrier, H. Liszt, K. Oberg,J.H.Orkisz, N. Peretto, E. Roueff, A. Sievers , P. Tremblin

Located at about 400 pc from the Sun, the Orion Giant Molecular clouds (GMCs)are the closest regions of massive stars formation. At large spatial scales, GMCsare known to exhibit a complex structure, shaped by turbulence, gravity and mag-netic fields. To better understand the impact of the environment onto the stellarformation efficiency, sensitive, wide-field, spectroscopic mapping of the molecu-lar gas is required. The ORION-B project (Outstanding Radio-Imaging of OrioNB) currently uses the IRAM-30m/EMIR 3mm receiver to image a field of 5 squaredegrees, located near the southern edge of the Orion B molecular cloud. A totalfrequency bandwidth of 40 GHz is being observed with a spectral resolution of195 kHz (0.6 km/s), a typical spatial resolution of 27” (i.e., 50 mpc or 104 AU at400 pc, the distance of Orion B), and a typical sensitivity of 0.1 K (Pety et al.2017). Using the 12CO and 13CO(1-0) lines, we characterized the ratio of com-pressive vs. solenoidal motions in the turbulent flow, and we related this to thestar formation efficiency in various regions of Orion B (Orkisz et al. 2017). TheC18O(1-0) line allows us to finely characterize the dynamics of the filamentarynetwork in the Orion B (Orkisz et al. 2019). Compared to previous studies, thefilament population is dominated by low-density, thermally sub-critical structures,

suggesting that most of the identified filaments are not collapsing to form stars. In fact, only 1% of the OrionB cloud mass covered by our observations can be found in super-critical, star-forming filaments, consistentwith the low star formation efficiency of the region. We have performed statistical analyses of the multi lineinformation acquired in the survey to use the diversity of information carried by the various molecular species.These first analyses performed on a subset of the whole map (Gratier et al. 2017, Bron et al. 2018) showthat accurate information on the gas column density, density and UV illumination can be extracted from themolecular line intensities, and that difference in chemical pattern can be related to differences in physical con-ditions. We are now working on a wider field of view and on more detailed analyses including comparison withpredictions from chemical models.

Image of the CO isotopologue emission in the Orion-B molecular cloud,12CO is shown in blue, 13CO in green and C18O in red (Pety et al. 2017).

References: • Bron et al. 2018 A&A 610, A12. doi:10.1051/0004-6361/201731833 • Gratier et al. 2017,A&A 599,A100. doi:10.1051/0004-6361/201629847 • Orkisz et al. 2017 A&A 599,A99. doi:10.1051/0004-6361/201629220 • Orkisz et al. 2019 , A&A in press, arxiv 1902.02077 • Pety et al. 2017 A&A 599, A98.doi:10.1051/0004-6361/201629862



Physical and chemical complexity in high-mass star-forming regionsPresenting author: Caroline GieserContact: [email protected]: Max Planck Institute for Astronomy HeidelbergCo-author: Henrik Beuther, Dmitry Semenov, Aida Ahmadi, Sumeyye Suri and the CORE team

The birthplaces of massive stars are ideal laboratories to study the formation anddestruction of molecules in the interstellar medium. Here, we present a detailedobservational analysis of the physical and chemical properties of 18 luminoushigh-mass star-forming regions. This study is part of the NOrthern ExtendedMillimeter Array (NOEMA) large program CORE (Beuther et al. 2018). Theobservations were carried out with NOEMA at 1.4 mm with an angular resolutionof ⇡ 0.400 and to include large-scale emission observations using the IRAM 30 mtelescope were complemented.

The 1.4 mm continuum of the sample shows a large diversity of fragmenta-tion properties (Beuther et al. 2018). In addition, the spectral line data (coveringemission lines from simple and complex organic molecules) reveal large differ-ences between the regions as well as nearby dense cores (Feng et al. 2016,Gieser et al. in prep.). In this study, we quantify the chemical content with re-spect to the physical properties and investigate the spatial extent of the molecularemission.

Figure 1: Each panel shows the integrated intensity map of the H2CO 30,3 � 20,2 transition. The white contourmarks the 5� level of the integrated intensity. The green contour is the 5� level of the 1.4 mm continuumemission. The beam size of the spectral line data is shown in the lower left corner. The tick spacing is set to500.

References: • Beuther, H., Mottram, J. C., Ahmadi, A., et al. 2018, A&A, 617, A100 • Feng, S., Beuther, H.,Semenov, D., et al. 2016, A&A, 593, A46 • Gieser et al. in prep.



Title: Odin and Herschel observations of H2O, CH and CH+ in the barred spiral galaxyNGC 1365 - bar induced activity in the circumnuclear torus region

Presenting author: Åke HjalmarsonContact: [email protected]: Dept of Space, Earth and Environment, Chalmers University of Technology, Onsala

Space Observatory, SE-439 92 Onsala, SwedenCo-author: Aage Sandqvist, Bengt Larsson, Per Olof Lindblad, Urban Frisk, Stefan Lundin and

Gustaf Rydbeck

NGC 1365 is a prominent barred spiral galaxy in Fornax cluster at a distance of18.6 Mpc (where 1′′ corresponds to 90 pc). The galaxy displays a wide rangeof activity phenomena, including a Seyfert 1.5 type nucleus, an ejection jet ofhot gas from the nucleus (black hole), and a circumnuclear torus containing anumber of bright hot super star clusters and their associated massive molecularcloud complexes.

The Odin satellite is now in its nineteenth year of operation, much surpassingits design life-time of two years. We have recently used Odin to search for watervapor in NGC 1365 and have obtained a tentative detection of the 557 GHzground state o-H2O line in the central region of the galaxy. Herschel SpaceObservatory has mapped the inner region of NGC 365 with the SPIRE and PACSinstruments and we have analyzed these mostly unpublished results, which areavailable in the Herschel Science Archive. A number of water lines were detectedby SPIRE and the SPIRE results at 557 GHz are supporting the Odin results.

The H2O emission is localized to a 15′′ size region near the north-easternpeak of the central molecular torus of NGC 1365 -a region displaying varioussigns of shocks and strong star formation triggered by the bar- driven inflow. We

study the ongoing physical processes by means of the aforementioned multi-transition H2O (and CO) obser-vations, and here make additional use of new Statistical Image Deconvolution applied to SEST observationsof the CO (3–2) line, yielding an effective resolution of 5′′. The atomic gas in the galaxy center is also studiedusing unpublished VLA HI observations.

A study of the ongoing chemical processes in the circumnuclear torus region is also performed-aimingat evaluating the most relevant excitation and formation scenarios for H2O, CH and CH+ (and also othermolecules) in this region of cloud-cloud collisions, increased turbulence, shocks, and extensive star formation(leading to outflows/shocks and PDRs). Here an increased ionization level caused by cosmic ray focussing (inthe observed, aligned magnetic field), and also by X-rays, may play an additional role.



Title: Simulating deuterium fractionation in massive pre-stellar coresPresenting author: Chia-Jung HsuContact: [email protected]: Chalmers University of TechnologyCo-author: Jonathan Tan

The degree of deuterium fractionation is thought to be an important indica-tor of the chemical ages of pre-stellar cores. The physical properties and thetimescale required to reach a high deuterium fraction of N2H+ are under de-bate. Here we utilize KROME to couple a sophisticated chemical network into athree-dimensional magnetohydrodynamical simulation run by ENZO. The chemi-cal network involves general three-atom species as well as H3O+ and its deuter-ated form, which could influence the timescale and the fraction at steady state.The improved model enables us to analyze the time evolution of N2D+ and H2D+more accurately and assess their role in observational studies of pre-stellarcores.

References:• S. Kong, P. Caselli, J. C. Tan, V. Wakelam, and O. Sipila. The DeuteriumFractionation Timescale in DenseCloud Cores: A Parameter Space Explo-ration.Astrophysical Journal, 804:98, May 2015.• M. D. Goodson, S. Kong, J. C. Tan, F. Heitsch, and P. Caselli. Structure, Dy-namics, and DeuteriumFractionation of Massive Pre-stellar Cores.AstrophysicalJournal, 833:274, Dec 2016



Title: Mixing of the First Supernovae MetalsPresenting author: Chia-Jung HsuContact: [email protected]: Chalmers University of TechnologyCo-author: Ke-Jung Chen, Daniel J. Whalen, Jonathan Tan

Metal enrichment by the first generation (PopIII) supernovae changes the abun-dance pattern in the early universe, and influences the next generation of starformation. The chemical enrichment highly depends on the mixing and fallbackprocesses behind supernovae explosions. We utilize two popular codes, FLASHand ZEUS, to simulate the explosion process of the first supernovae in miniha-los. Besides, we are interested in the influence of cooling processes and in-volve the physics by KROME. We investigate the mixing process triggered by acore-collapse supernova whose progenitor is a 15 M� metal-free star in a photo-evaporated minihalo. Our results provide an abundance pattern to discuss theastrochemistry and the formation of metal-poor stars in the early universe.

References:• Daniel Whalen, Bob van Veelen, Brian W. O’Shea, Michael L. Norman. TheDestruction of Cosmological Minihalos by Primordial Supernovae.AstrophysicalJournal, Jul 2008.• Ke-Jung Chen, Daniel J. Whalen, Katharina M. J. Wollenberg, Simon C. O.Glover, Ralf S. Klessen. How the First Stars Regulated Star Formation. II. En-richment by Nearby Supernovae, Aug 2017




Title: Determining star formation rates in high-redshift galaxies from IRX-beta relation

Presenting author: Maciej Koprowski


Institute: University of Nicolaus Copernicus

Co-author: Kristen Coppin, James Dunlop, Jim Geach, Michał Michałowski, et al.

Precise determination of star formation rates for many galaxies at high redshifts

is very difficult, as they often lack IR observations, sensitive to the starlight re-

processed by dust. In order to account for this, one has to, therefore, utilize

alternative methods, most popular of which involves estimating the energy re-

emitted in the IR based on the amount of reddening in the rest-frame UV via the

so-called IRX-� relationship (Meurer et al. 1999). Many works, however, seem

to indicate that this local relation may not necessarily hold at high redshifts (eg.

Capak et al. 2015). In this talk I will present the stacking analysis of a large sam-

ple of optically-selected Lyman-break galaxies (LBGs) in the JCMT SCUBA2 and

Herschel SPIRE bands that was done in order to re-calibrate the IRX-� relation-

ship at redshifts 3�5. I will show that at high redshifts, the average galaxy suffers

from the dust attenuation law which is characteristic of local sources (Calzetti et

al. 2000). I will also explain how different methods of estimating the UV slope, �, can cause the resulting rela-

tion appear flatter and therefore often consistent with the SMC-like attenuation law (eg. Reddy et al. 2018). In

addition, I will show how the individual values of the IRX and � were calculated for a sample of 41 z ⇠ 3 LBGs,

detected in the recently-finished ALMA follow-up survey of the UDS SCUBA2 sources (Stach et al. 2018). I

will explain how the apparent scatter in the IRX-� plane is driven by the relative distribution of the stars and

dust, as encoded in the shapes of the attenuation curves, as well as show how the shapes of the assumed

attenuation curves affect the resulting stellar masses, as estimated via SED fitting. The results presented in

this talk indicate that while, on average, star formation rates for high-redshift galaxies can be estimated from

UV data alone, the values for the individual sources cannot be trusted in the absence of the IR data.

Figure 1: IRX-� relation for z ⇠ 3 LBGs (black circles) compared with some of the recent literature results. The black solid and dashed

lines represent the Calzetti- and SMC-like dust curves. It is clear, while ours and McLure et al. (2018) data are consistent with the

Calzetti-like dust, others seem to be lying between two dust curves.

References: • Calzetti D., Armus L., Bohlin R. C., Kinney A. L., Koornneef J., Storchi-Bergmann T., 2000, ApJ,

533, 682 • Capak P. L. et al., 2015, Nature, 522, 455 • McLure R. J. et al., 2018, MNRAS, 476, 3991 • Meurer

G. R., Heckman T. M., Calzetti D., 1999, ApJ, 521, 64 • Reddy N. A. et al., 2018, ApJ, 853, 56 • Stach S. M. et

al., 2018, preprint (arXiv:1903.02602)



Title: Fullerene oligomers and polymers as carriers of unidentified IR emission bandsPresenting author: Serge KrasnokutskiContact: [email protected]: Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the

Friedrich Schiller University JenaCo-author: M. Gruenewald, C. Jager, F. Otto, R. Forker, T. Fritz, Th. Henning

Several unidentified IR emission bands (UIBs) have been assigned to neutralC60 molecules present in circumstellar and interstellar environments. However,due to the similarity of IR spectra of C60 in the solid state and in the gas phase,there is as yet no consensus on the aggregation state of C60. We will show thateven strong covalent chemical bonding might have very little influence on the IRspectrum of C60, and that therefore such chemically bonded C60 could be thecarrier of the same UIBs. It would best explain observations like the missingemission from C60 ions and a large variation of relative band intensities betweendifferent sources.

In our previous work, we demonstrated that C additions at low temperatureenhance the chemical activity of the surface of C60 by carbene formation. The lat-ter may pave the way toward a generation of a new class of fullerene derivatives.Reactive C60 carbene species may also be formed in interstellar and circumstel-lar environments containing C and C60, where they could add other molecules,to form variety of fullerene derivatives and even fullerene polymers C60(C=C60)n.In our recent study, we demonstrated that such a chemically bonded C60 poly-

mer can be produced by co-condensation of C atoms together with C60 molecules on the surface of refractorydust particles. The experiments were performed in UHV chamber focusing molecular beams of C60 moleculesand C atoms on SiO2 substrate. This leaded to the formation of a three-dimensional C60 polymer film. Suchpolymerized C60 molecules cannot easily desorb, while their spectral properties in the VIS and IR are almostundisturbed by polymerization. As can be seen in Figure 1, the IR spectrum of C60 polymer film demonstrateonly few new weak absorption bands, while the positions of the main absorption bands of C60 are not altered.

Figure 1: IR (a) and UV-VIS (b) absorption spectra of the film produced by deposition of C60 alone and togetherwith C atoms. Arrows point to the new IR bands appearing after the polymerization of C60 molecules. Panel(b) demonstrates that the electronic properties of C60 remain almost unaltered upon polymerization.

References: • S. A. Krasnokutski, M. Kuhn, A. Kaiser, A. Mauracher, M. Renzler, D. K. Bohme, and P. Scheier,JPCL 7 (2016) 1440. • S. A. Krasnokutski, M. Gruenewald, C. Jager, F. Otto, R. Forker, T. Fritz, Th. Henning,to appear in ApJ, 2019.



Title: CO Depletion and the X-Factor on Subparsec Scales Across the California MolecularCloud.

Presenting author: Charles J. LadaContact: [email protected]: Harvard-Smithsonian Center for AstrophysicsCo-author: John Lewis, John Bieging

We report the results of an extensive investigation into the relation betweendust and gas-phase CO column densities across the California Molecular Cloud(CMC), perhaps the largest and most massive GMC in the solar neighbor-hood. We compare dust emission maps derived from Herschel observationswith 12CO(2-1), 13CO (2-1) and C18O(2-1) emission obtained with the StewardObservatory’s SMT to make deep (2 AV 60 mags) and direct comparisonsof CO and dust column density measurements at matched sub-parsec resolu-tion across this GMC. We find that on these scales there is no single value ofthe X-factor that characterizes the gas in the cloud, confirming results from an

earlier study (Kong et al. 2015). Indeed, measured X-factors range between ⇡ 0.5-25 with XCO approximatelyproportional to AV for cold ( TD < 17 K) gas. We compare 13CO (LTE) column densities with dust column den-sities for each map pixel to derive and map the 13CO depletion factor across the CMC. We find this depletionfactor to range between ⇡ 1 in the warmer (TD > 17 K) and lower extinction regions of the cloud to >20 in thecolder (TD < 17 K), higher extinction regions of the cloud, consistent with expectations of chemical desorptionof gas-phase CO onto cold grains. We use our depletion factor maps to define the boundaries of dense coresand construct a corresponding catalog of ”depletion” cores. We derive the core masses from the dust columndensities and depletion measured sizes and compare the results to similar measurements based solely onextinction measurements. We use the 13CO and C18O observations to measure the virial parameters of thecores. We find a well behaved relation between the virial parameter and mass of a core that is consistent witha pressure confined sequence, similar to other clouds (e.g., Lada et al. 2008; Kirk et al. 2017). Only about halfthe cores appear to be bound solely by gravity.

W[1

2CO

(J=2

-1)]

(K k

m/s

)

Visual extinction (mag)

120

100

80

60

40

20

010 20 30 40 50 60

50

40

30

20

T dus

t (K

)

Gal

actic

Lat

itude

(b)

Dep

letio

n

Galactic Longitude (l)

Figure 1: Left panel shows the relation between W(12CO) and extinction for the CMC, clearly demonstratingthe lack of a unique X-factor for the cloud. The right panel is a map of the 13CO depletion factor in one regionof the CMC. Depletion contours are plotted on top of a gray scale map of the Herschel derived dust columndensity. At any point the measured depletion factor is a line-of-sight average and thus a lower limit to the truevalue in the depleted inner regions. The peak of depletion in this map corresponds to a depletion factor >>12.

References: • Kong et al. 2015, ApJ, 805, 58. • Lada et al., 2008, ApJ, 672, 410. • Kirk et al. 2017, ApJ, 846,144.




Title: The polarization and molecular Zeeman effect of masers

Presenting author: Boy Lankhaar


Institute: Chalmers University of Technology

Co-author: Wouter Vlemmings

Understanding the magnetic field strength and morphology of (high-mass) star

forming regions and proto-planetary disks is of great importance in understand-

ing their dynamics. A tracer for the magnetic field in the densest parts of star

forming regions are molecular masers. Molecular masers are often found to

be (highly) polarized, both linearly and circularly, and can therefore reveal in-

formation on both magnetic field strength and morphology of the regions they

occur in. In this talk, I will present recent work on the molecular Zeeman pa-

rameters of methanol, a maser specie which occurs in (high-mass) star forming-

regions. Computing methanols Zeeman parameters using quantum-chemical

methods allowed us to perform the proper (re-)analysis of 10 years of methanol

maser observations, which was not possible before due to the missing Zeeman

parameters. I will also present the resuls of a new radiative transfer code that

is concerned with maser polarization. We find that the most strongly polarized

maser emission must come from alternative polarization mechanisms such as

anisotropy in the pumping. Alternative polarization mechanisms could be revealing for the dynamics surround-

ing the maser region. We will also discuss the influence of higher order matter-radiation interactions, such as

anisotropic resonant scattering, on the maser polarization radiative transfer.

References: • B. Lankhaar, W.H.T. Vlemmings, G. Surcis et al., Characterization of methanol as a magnetic

field tracer in star-forming regions, NatAs 2 (2018) • B. Lankhaar, G.C. Groenenboom, A. van der Avoird

Hyperfine interactions and internal rotation in methanol, J Chem Phys 145 (2016)



Title: GUAPOS: G31.41+0.31 Unbiased ALMA sPectral Observational SurveyPresenting author: Chiara MininniContact: [email protected]: University of FlorenceCo-author: M. T. Beltran, A. Sanchez-Monge, V. M. Rivilla, R. Cesaroni, P. Schilke, F. Fontani,

S. Viti, I. Jimenez-Serra, L. Testi, T. Moller and L. Colzi

Some of the best sources to study the richness and complexity of chem-istry in the interstellar medium, are Hot Molecular Cores (HMCs), the birth-places of high mass stars. Spectra of these sources show a very high den-sity of molecular lines, including emission from hydrogenated species, O-bearingspecies, N-bearing species, deuterated molecules and interstellar Complex Or-ganic Molecules (iCOMs) (e.g. Belloche et al. 2013). This richness is due to theirtypical mass (M > 100M�), density (n ⇠ 107cm�3) and temperature (T > 100K),that allow the release in gas-phase, by thermal evaporation or due to shocksassociated with the high mass star formation process, of the products of thechemical reactions occurring on the surface of grain mantles. Moreover, the hightemperatures allow to activate the neutral-neutral reactions that cannot occur incolder material.Spectral surveys in HMCs have been carried out mostly towards Sgr B2

(Sanchez-Monge et al. 2017; Belloche et al. 2013), but this source can not be considered as a templatefor typical HMCs in the Galaxy, since its proximity to the Galactic Center leads to peculiar environmental condi-tions, that could indeed have an impact on the chemistry. Here we present the project GUAPOS (G31.41+0.31Unbiased ALMA sPectral Observational Survey), a full ALMA Band 3 spectral survey with a resolution of 1.2”towards G31.41+0.31 (G31), one of the most well-known and chemically-rich HMC in the Galaxy (Cesaroni etal. 2010; Beltran et al. 2018). G31 is located at 3.7 kpc, with a luminosity � 104L� (Beltran et al. 2005) andhas no UC HII region embedded on it (Cesaroni et al. 2010). The first detection of glycolaldehyde outside theGalactic Center has been obtained towards G31 (Beltran et al. 2009), and heavy complex molecules such asmethyl formate or ethylene glycol have also been prevoiusly observed in this source (Rivilla et al. 2017). Thespectrum of the GUAPOS project, covering the spectral interval ⇠ 84 - 116 GHz with a spectral resolution of⇠500 KHz, will allow us to identify the large number of molecules present in this source (including iCOMS suchas C2H5CN, CH3CHO, CH3OCHO, CH3OCH3 and CH3COCH3 - see Fig.1) and to unveil its chemistry.

Figure 1: In black: G31 spectrum from the GUAPOS project, between 98 and 101 GHz; in red: preliminarysynthetic spectrum obtained with XCLASS (Moller et al. 2017)

References: • Belloche et al. 2013, A&A 559, A47 • Sanchez-Monge et al. 2017, A&A 604, A6 • Beltran etal. 2018, A&A 615, A141 • Beltran et al. 2005, A&A 435, 901 • Cesaroni et al. 2010, A&A 509, A50 • Beltranet al. 2009, ApJ 690, L93 • Rivilla et al. 2017, A&A 598, A59 • Moller et al. 2017, A&A 598, A7



Title: The chemical structure of the starless core L1521EPresenting author: Zsofia NagyContact: [email protected]: Max-Planck-Institute for Extraterrestrial PhysicsCo-author: Silvia Spezzano, Paola Caselli, Anton Vasyunin, Mario Tafalla, Luca Bizzocchi,

Domenico Prudenzano, and Elena Redaelli

L1521E is a dense starless core in Taurus which was found to have relatively lowmolecular depletion (e.g. Tafalla & Santiago, 2004). We have obtained ∼2.5×2.5arcminute maps in transitions of key molecular species, including C17O, CH3OH,c-C3H2, CN, SO, H2CS, and CH3CCH, using the IRAM-30m telescope, to studythe chemical structure of L1521E. We compared the results to those obtainedtoward the more evolved and better characterized L1544 pre-stellar core (Spez-zano et al. 2017 and references therein). Based on the IRAM-30m C17O mapand N(H2) derived from Herschel/SPIRE data, CO depletion toward L1521E ismore significant than suggested by earlier studies, with a lower limit of 4.9±1.8 onthe CO depletion factor toward the dust peak. The abundances of most sulfur-bearing molecules such as C2S, HCS+, C34S, C33S, SO, and OCS are highertoward L1521E than toward L1544 by factors of ∼2-20, which suggests that sig-nificant sulfur depletion is taking place during the dynamical evolution of densecores, from the starless to pre-stellar stage. This is also confirmed by chemical

models.

10-2

10-1

100

101

102

SO 13 CSOCS

C 2S C33 S

C34 S

HCS+

H 2CS

HC 3N c-C 3H 2C 4H HN

13 CE-CH 3O

H

CH 3CCH

CH 3CN

HC18 O

+

H13 CN

HCOHCN

N(X

)/N(A

-CH

3OH

)

L1521E L1544

Figure 1: Comparison of the abundances of species observed toward the dust peak of both L1521E and L1544.

References: • Tafalla M. & Santiago J., 2004, A&A, 414, L53 • Spezzano, S.; Caselli, P.; Bizzocchi, L. et al.2017, A&A 606, 82




Title: Radiative association of small molecules

Presenting author: Daria Burdakova


Institute: Chemistry and molecular biology

Co-author: Gunnar Nyman, Magnus Gustafsson, Thierry Stoecklin

When new stars are born, matter is contracting towards their center of mass

during a so called gravitational collapse. The gravitational energy is then trans-

formed into kinetic energy, similar to a falling object. For the star formation to

continue efficiently, some of the kinetic energy must be removed, which can oc-

cur by emitting electromagnetic radiation [1]. Emission of electromagnetic radi-

ation can be efficiently done by molecules. Therefore knowing which molecules

are present in the interstellar media, how they are created and destroyed is of

importance when considering star formation.

This work focused on radiative association (RA) reactions to form the CH

and Na++H2 molecules. RA is the process where a molecule is formed, from

two atoms or smaller molecules, while emitting a photon. The CH molecule was

chosen for this study because of its occurrence in several chemical reactions

in the interstellar medium, the sun, and comets [2]. Since metal ions have been

observed in the envelope of IRC+10216 [3], studying molecules containing metal

ions has been of interest. This motivates this choice of the Na+H2 molecule.

The focus of the study was to calculate the reaction cross sections and reaction rates. The reaction cross

section is a measure of how frequently the atoms will collide and form a molecule. The cross section is then

used to obtain the reaction rate constant, thereby giving an understanding of the formation process of the

molecule.

Since RA is a very slow process it is hard or impossible to study experimentally and here we have studied

it numerically. Two different programs have been used to obtain the reaction rates. The CH molecule was

treated using a locally written program that calculates the reaction rates for the formation of diatomic molecules

through RA. That program uses a semiclassical (SCl) method the results of which are compared to the results

obtained using a method based on perturbation theory (PT). The advantage of the SCl method is that it is

computationally cheaper than the PT method. A program written by Thierry Stoecklin that calculates RA

reaction rates to form triatomic molecules was used to obtain the rate coefficients for Na+�H2 formation from

Na++H2. The program is using a method [4] developed using the photodissociation theory by Band et al. [5] and

Balint-Kurti et al. [6] together with the driven equations method by Heather et al. [7]. Since photodissociation

is the reverse process of RA some changes were made.

References: • Reference 1 D. Prialnik (2000). An Introduction to the Theory of Stellar Structure and Evolution.

Cambridge University Press. pp.198199. • Reference 2 B. D. Abdallah, et al (2008). Ab initio potential

energy surfaces for the study of rotationally inelastic CH(X2) + H(2S) Collisions, Chem.Phys. Lett. 456, 7-

12. • Reference 3 S. Petrie, R. C. Dunbar (2000), Radiative association reactions of Na+, Mg+, and Al+

with abundant interstellar molecules. variational transition state theory calculations, J. Chem. Phys. 104,

44804488. • Reference 4 T. Stoecklin, F. Lique, M. Hochlaf (2013), A new theoretical method for calculating

the radiative association cross section of a triatomic molecule: application to N2-H�, Phys. Chem. Chem. Phys.

15, 13818-3825. • Reference 5 Y. B. Band, K. F. Freed, D. J. Kouri (1981), Half-collision description of nal state

distributions of the photodissociation of polyatomic molecules, Journal of Chemical Physics 74, 43804394. •Reference 6 G. G. Balint-Kurti, M. Shapiro (1981), Photofragmentation of triatomic molecules.295 theory of

angular and state distribution of product fragments, Chem. Phys. 61, 137155. • Reference 7 R. W. Heather,

J. C. Light (1983), Photodissociation of triatomic molecules: Rotational scattering eects, J. Chem. Phys. 78,

55135530.



Title: Deuteration of N2H+ and HCO+ in the prestellar core L1544 and first evidence ofN2D+ depletion

Presenting author: Elena RedaelliContact: [email protected]: Max Planck Institute for Extraterrestrial PhysicsCo-author: P. Caselli, L. Bizzocchi, O. Sipila, et al.

The elemental abundance of deuterium is D/H = 1.5 10�5 (Linsky 2003), but inthe cold phase of the interstellar medium (ISM), molecules exhibit enhancementsup to four orders of magnitude with respect to this value (Ceccarelli et al. 2014).In fact, in cold and dense environments the production of H2D+, the progenitor ofall deuterated species, is greatly favored (Dalgarno & Lepp 1984). The deutera-tion fraction is thus considered a good diagnostic indicator of the star formationprocess, and it is linked to other important quantities such as the electron fraction(Caselli et al. 1998). L1544 is one of the most studied prestellar cores, whichrepresent the initial stages of low-mass star formation. In this work, we presentnew, high sensitivity and high spectral resolution maps of several molecular ions:N2H+ (1-0) and (3-2), N2D+ (1-0), (2-1) and (3-2), HC18O+ (1-0), and DCO+ (1-0),(2-1) and (3-2). Combining the physical model of the source (Keto et al. 2015)with the abundance profiles derived with a gas-grain chemical model (Sipila et al.in prep), we are able to perform a full non-LTE radiative transfer analysis at thecore’s dust peak, using the code MOLLIE (Keto 1990) This approach allows usto derive the excitation conditions of each molecule and to use this information

to compute reliable values for the molecular column densities and thus of the D/H ratios, shown in Figure 1.Our study confirms that the LTE assumption does not hold for the analyzed transitions. We compute peakvalues for the deuterium fraction of D/HN2H+ = (0.19± 0.02) and D/HHCO+ = (0.027± 0.003), respectively, in goodagreement with previous work. We are able to investigate the D/H ratio up to ⇡ 4500 (⇡ 6000 AU), where D/Hvalues drop to ⇡ 1% for HCO+ and ⇡ 7% for N2H+. The chemical code used to model the observations predictthe partial depletion at the core’s center for all the molecules, including N2D+. This is to our knowledge the firsttime that the freeze-out of N2D+ onto dust grains, often predicted by models, finds observational confirmations.

Figure 1: D/H ratios derived in L1544 for N2H+ (left panel) and HCO+ (right panel). The black cross representsthe position of the mm dust peak (Ward-Thompson et al., 1999). The beam sizes are shown with red circles.

References: • Caselli, P., et al. 1998, ApJ, 499, 234 • Ceccarelli, et al. 2014, in Protostars and Planets VI, ed.H. Beuther, R. S. Klessen, C. P. Dullemond, & T. Henning, 859 • Dalgarno, A. & Lepp, S. 1984, ApJ, 287, L47• Keto, E. R. 1990, ApJ, 355, 190 • Keto, E., Caselli, P., & Rawlings, J. 2015, MNRAS, 446, 3731 • Linsky, J.L. 2003, Space Sci. Rev., 106, 49 •Ward-Thompson, D., Motte, F., & Andre, P. 1999, MNRAS, 305, 143



Title: Quantum Chemical Evaluation of Polarity-Inverted Membranes and Polymers on theSurface of Titan

Presenting author: Hilda SandstromContact: [email protected]: Chalmers University of TechnologyCo-author: Martin Rahm

Saturn’s moon Titan is the only other body in our solar system, except Earth,that hosts a dynamic liquid cycle that supports lakes, rivers and rainfall on itssurface (Tokano et al., 2006). The lakes on Titan are predominately made out ofliquid methane and ethane (Stofan et al., 2007), and photochemistry in the atmo-sphere produces a rich a variety of organic compounds (Niemann et al., 2005).Titan has been proposed as a strict test case for the limits of life, and the possibil-ity for ”methanogenic” life has received much attention (Lunine, 2010). In 2015,Stevenson et al. (Stevenson et al., 2015) suggested the possible self-assemblyof cell membranes made from acrylonitrile under Titan’s cryogenic conditions,based on theoretical calculations. The membranes were referred to as azoto-

somes and were proposed to form due to an enthalpy driven self-assembly through the dipole-dipole interactionof the nitrogen containing groups. Azotosomes were found to be kinetically stable and of comparable flexibilityto lipid bilayer membranes on Earth. In 2017, acrylonitrile was detected in Titan’s atmosphere by the ALMAradio telescope (Palmer et al., 2017), further fuelling speculation of the molecule’s importance. To evaluatethese claims, we have performed quantum mechanical calculations to estimate the thermodynamic stability ofthe proposed azotosome membrane relative to the molecular crystal structure of acrylonitrile. Our calculationsstrongly suggest that azotosome self-assembly is unlikely. This contribution will include a brief update on ourcurrent research into cryogenic polymerization of hydrogen cyanide within the context of Titan.

References: • Tokano, T.; McKay, C. P.; Neubauer, F. M.; Atreya, S. K.; Ferri, F.; Fulchignoni, M.; Niemann,H. B. Nature 2006, 442, 432-435. • Stofan, E. R. et al. Nature 2007, 445, 61-64. • Niemann, H. B. et al.Nature 2005, 438, 779-784. • Lunine, J. I. Faraday Discuss 2010, 147, 405-18; discussion 527. • Stevenson,J.; Clancy, P.; Lunine, J. Sci Adv 2015, 1, e1400067. • Palmer, M. Y.; Cordiner, M. A.; Nixon, C. A.; Charnley,S. B.; Mumma, M. J.; Teanby, N. A.; Kisiel, Z.; Irwin, P. G. J. Sci Adv 2017, 3, e1700022.



Title: Molecule formation in dust-free irradiated jetsPresenting author: Benoıt TaboneContact: [email protected]: Leiden Observatory, Leiden UniversityCo-author: G. Pineau des Forets, B. Godard, S. Cabrit, E. van Dishoeck

Jets and outflows are ubiquitous in accreting young stars of all ages, with similar col-limation and dynamics indicating a universal connection (probably of magnetic origin)between accretion and ejection. However, jets appear to have a very different chem-istry evolving from molecular in the youngest protostars (Class 0) to purely atomic inlate stages of disk accretion (Class 2, a few Myr). Such a chemical richness in theyoungest jets is intriguing for a flow heated by ambipolar diffusion and irradiated bya strong FUV and X-ray field from the accreting protostar. The unique combinationof high angular and spectral resolution provided by ALMA allows us to reveal for thefirst time the complex chemical and kinematic structure of molecular protostellar jetsclose to their launching region. ALMA observations of the typical Class 0 HH212 jethave revealed a SO/SO2 rotating flow emanating from the disk, and well reproducedby a slow dusty MHD disk-wind model launched from 0.2 to 40 au (Tabone et al.2017, Tabone et al. submitted). These findings are consistent with Panoglou et al.

2012 who have shown that molecules can survive and be formed through warm formation routes in a Class 0disk-wind launched beyond the dust sublimation radius (⇠ 0.2au). ALMA has also unveiled a rotating SiO jetattributed to the inner dust-free streamlines of the same extended disk-wind, or to a dust-free X-wind (Lee etal. 2017, see Fig. 1-a, Tabone et al. 2017). This discovery, based on the flow kinematics is challenging astro-chemical models of these unusual environments (e.g. Glassgold et al. 1991 or Cabrit et al 2012) and invites usto design new complementary tests based on the chemical content of the jets to pinpoint their launching point.

In this contribution, we would like to review our recent ALMA study on the origin of molecular outflows andpresent our current modeling work on the formation of molecules in dust-free irradiated jets. We will show thatin absence of dust, molecules such as CO, SiO, H2O can be formed in short time scales (⇠ few yr) throughendothermic reactions from a small fraction of H2 formed by electronic catalysis (through H�). Our jet modelindicates that the FUV field can be efficiently attenuated by C close to the source (⇠ 10 au) and by S, Si andother atomic species further out (see Fig. 1-b). Preliminary shock models will also be presented and theinfluence of a small fraction of surviving dust will be emphasized. These results will be compared to availabledata and future JWST observations, that will probe the H2 and atomic content of jets, will be discussed.

N3

N2

N1

S1S2

S3

0

50

–50

a) b)

Distance from the source (cm)

Relativ

eabun

dances H2

H

CO

C+

SiSiO

H2O

C

Disk

SiO

Δδ(au) e-

0ContSiO

Figure 1: a) ALMA view of the HH212 rotating SiO jet at 8 au (0.0400) resolution (from Lee et al. 2017). b) Modelof a dust-free advective PDR illustrating the influence of the attenuation of the FUV field by the gas along thejet (Tabone et al. in prep). Shocks will enhance molecular abundances by increasing density and temperature.

References: • Glassgold et al., ApJ, 373, 254 • Cabrit et al., 2012, A&A, 548, L2 • Panoglou et al., 2012,A&A, 538, A2 • Lee et al., 2017, NatAs, 1, 0152 • Tabone et al. 2017, A&A, 607, L6 • Tabone et al., submitted



Title: Cyanopolyyne Chemistry around Massive Young Stellar ObjectsPresenting author: Kotomi TaniguchiContact: [email protected]: University of VirginiaCo-author: Eric Herbst, Paola Caselli, Alec Paulive, Dominique M. Maffucci, & Masao Saito

Recent observations reveal chemical complexity in both low- and high-mass star-forming regions. Unsaturated carbon-chain molecules, such as C2nH, CCS, andcyanopolyynes (HC2n+1N), had been thought to be abundant in young starlesscores and decrease in abundance in later stages of low-mass star formation[1].On the other hand, saturated complex organic molecules (COMs) are abun-dant around star-forming cores, so-called hot cores and hot corinos in high- andlow-mass star-forming regions, respectively[2]. In contrast to the above classi-cal picture, some low-mass protostellar cores rich in carbon-chain species havebeen found. In these sources, methane (CH4) sublimates from dust grains ata temperature of ∼ 25 K and reacts with ionic carbon (C+) in the gas phaseleading carbon-chain formation, which was named warm carbon chain chemistry(WCCC)[3]. However, it is unclear whether carbon-chain molecules are formedaround massive young stellar objects (MYSOs) and what factors bring chemical

diversity around star-forming cores.We found that HC5N is abundant around some MYSOs, using the Green Bank 100-m and Nobeyama

45-m radio telescopes[4]. Moreover, chemical diversity around MYSOs is suggested; organic-poor MYSOsare surrounded by a cyanopolyyne-rich lukewarm envelope, while organic-rich MYSOs, namely hot cores, aresurrounded by a CH3OH-rich lukewarm envelope[5].

n(H

C 5N

)/nH

5x105 1x106 2x106

Temperature[K

]

time [yr]

The lower limit of HC5N abundance in G28.28-0.36

Figure 1: The gas-phase HC5N abundance withthe three-phase model during the warm-up period.The different colors of lines indicate different heatingtimescales; red, green, and blue indicate Fast (5×104

yr), Medium (2×105 yr), and Slow (1×106 yr), respec-tively. The dashed lines indicate the temperature andtheir colors correspond to the heating timescales.

We conducted chemical simulations of hot-coremodels with a warm-up period using the astrochemicalcode Nautilus[6] in order to investigate cyanopolyynechemistry around MYSOs, motivated by the partic-ularly high abundance of HC5N in the G28.28–0.36MYSO[4]. The cyanopolyynes are produced by a com-bination of neutral-neutral and ion-neutral gas-phasereactions during the warm-up period (T > 25 K) andaccumulate on and in the dust mantles before thetemperature reaches their sublimation temperatures.The sublimation of first CN and secondly the C2nH2(n = 1, 2, 3) species enhances key reactions to form thecyanopolyynes, which partly accrete onto dust mantles.As the temperature rises, the pattern of enhancementsin the production of the gaseous cyanopolyynes fol-lowed by partial accretion onto grains leads to a charac-teristic spectral-type pattern (Figure 1). The lower limitof the HC5N abundance observed in G28.28–0.36 canbe reproduced only after HC5N sublimates from dustgrains with temperatures above 100 K. Future JWSTobservations will enable us to confirm such a relationship between gas-phase cyanopolyyne chemistry anddust-surface chemistry. Furthermore, we propose the different heating timescales as a possible origin ofchemical diversity around MYSOs. This timescale depends not only on stellar masses but also on the rela-tionship between the size of the warming region and the infall velocity. The size of the warming region and theinfall velocity relate to the various physical conditions in star-forming regions, and hence the chemical diversityaround MYSOs may reflect a variety of massive star formation processes.

References: • [1] Suzuki, H. et al. 1992, ApJ, 392, 551, • [2] Herbst, E. & van Dishoeck, E. F. 2009, ARA&A,47, 427 • [3] Sakai, N. & Yamamoto, S. 2013, Chemical Reviews, 113, 8981 • [4] Taniguchi, K. et al. 2017,ApJ, 844, 68 • [5] Taniguchi, K. et al. 2018b, ApJ, 866, 150 • [6] Ruaud, M. et al. 2016, MNRAS, 459, 3756



Title: Nature vs. Nurture: What sets the chemical complexity in star-forming regions?Presenting author: Charl van der WaltContact: [email protected]: Niels Bohr Institute, Copenhagen UniversityCo-author: Lars E. Kristensen, Jes K. Jørgensen, Hannah Calcutt, the PILS-Cygnus team

Understanding the origin of the rich chemistry observed in newly formed pro-tostars is one of the key questions facing astrochemistry. One of the unknownaspects is the role the external environment plays on this chemical complex-ity. To this end, we performed a systematic line survey of 10 intermediate-mass(102L⊙ < Lbol < 105L⊙) hot cores in the Cygnus X star-forming region (The Pro-tostellar Interferometric Line Survey: Cygnus X, or PILS-Cygnus). This surveyis unique in that it covers such a large frequency bandwidth toward so manysources. This is an important frequency range, since many complex organicmolecular line transitions fall in this range. The PILS-Cygnus sources are all lo-cated in the same cloud at the same distance, around 1.7 kpc, and were selectedfor their location with respect to massive O-type stars. This will determine whatrole the UV-radiation of the physical environment in which the sources are located

plays on the chemistry of newly formed stars. By comparing the spectra of the 10 sources, and consideringthis external radiative environment, we will address the question of nature vs. nurture.

We here present preliminary results from the survey, including a detailed study of the source Cygnus X-N30(N30). It is the brightest of the 10 sources from the PILS-Cygnus program, and is a system consisting of 4 hotcores, including a binary component with a separation of about 1700 AU, and two cores at larger distancesfrom the central binary. The spectra of the binary components, N30-MM1a and MM1b, have revealed ∼ 400

different line transitions from 28 different molecular species (van der Walt et al., in prep.). The spectra of thetwo components look strikingly similar, suggesting that the initial conditions, or nature, that sets the chemicalevolution, plays a bigger role than the external environment, or nurture.

Figure 1: Herschel 3-colour image of part of the Cygnus X star-forming region, showing 8 of the 10 sourcesof the PILS-Cygnus survey. The cut-out image centre-top is the SMA continuum image of Cygnus X-N30, withthe 4 cores marked. The spectrum of N30-MM1a is shown on the right, with the brightest lines marked.



Title: Molecular complexity in the envelopes of evolved starsPresenting author: Luis Velilla-PrietoContact: [email protected]: Chalmers University of TechnologyCo-author: C. Sanchez Contreras, J. Cernicharo, M. Agundez, J. Alcolea, V. Bujarrabal, and G.

Quintana-Lacaci

The death of a Sun-like star is a complex process that plays a key role in thechemical evolution of the Universe, particularly, in the formation of dust grains.At the end of their lives, low-to-intermediate mass stars undergo an intensemass-loss process that creates a surrounding circumstellar envelope composedof molecules and dust. Most of this material is ejected by the star during theasymptotic giant branch (AGB) stage. Eventually, all this material enriches theinterstellar medium, the base component for later cloud, stellar, planetary, and,maybe, life formation. After decades of research and observations, the physicalconditions in these objects, which span the properties of a variety of differentastrophysical environments, are relatively well-known. They thus present one ofthe best astronomical laboratories to investigate the formation and destruction ofmolecules and dust and the growth of molecular complexity.

The latest advances in the field of instrumentation are allowing us to observethe molecular content of the circumstellar envelopes of evolved stars in the mil-limeter wavelength range with an unprecedented sensitivity, spatial, and spectral

resolution. In particular, spectral line surveys are consolidated as excellent techniques to characterise themolecular inventory and the physico-chemical properties of circumstellar envelopes. Thanks to our recentwork, it has been shown that the chemistry of oxygen-rich objects is not as poor as it was previously thought,with the detection of species such as HNCO, HNCS, or SO+ among others. The analysis of the spectral linesurveys we have presented in Sanchez Contreras et al. 2015, Velilla-Prieto et al. 2015, and Velilla-Prieto et al.2017 support the idea that the chemistry of AGB envelopes can be substantially altered by high-speed shocks,probably caused by the interaction between the slow AGB wind and the fast (few 100 km s−1) highly collimatedbipolar winds that some more evolved objects (post-AGB) display. The impact that binarity or magnetic fieldshave on this evolution has to be understood yet, although, from the chemical point of view, it is clear thatnon-equilibrium processes increase the complexity of the molecular material in these circumstellar envelopes.

Figure 1: Spectral line surveys in the 2 mm-wavelength range of the O-rich circumstellar envelopesOH231.8+4.2 (top) and IK Tau (bottom) observed with the IRAM 30m telescope.

References: • Sanchez Contreras, C., Velilla Prieto, L., Agundez, M., et al. 2015, A&A, 577, A52 • VelillaPrieto, L., Sanchez Contreras, C., Cernicharo, J., et al. 2015, A&A, 575, A84 • Velilla Prieto, L., SanchezContreras, C., Cernicharo, J., et al. 2017, A&A, 597, A25

astrochemistry: from nanometers to megaparsecs – a ...€¦ · astrochemistry: from nanometers to...

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