Molecule formation in the interstellar gas

Dalgarno, A.; Black, J. H.

doi:10.1088/0034-4885/39/6/002

Cited by 272 publications

(84 citation statements)

References 205 publications

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“…As we mentioned above, this may not be the case on a dust-grain surface under particular conditions; hence, using the rate-equation approach to describe interstellar surface chemistry can lead to large errors when compared with results using more realistic stochastic techniques. The main reason why modelers persist with such a method is the convenience, stability, and the rather fast numerical performance of the pure chemical kinetics codes, even for reaction networks which consist of thousands of reactions involving hundreds of molecules (e.g., Dalgarno and Black 1976;Leung et al 1984;D'Hendecourt et al 1985;Brown and Charnley 1990;Hasegawa et al 1992;Bergin et al 1995;Millar et al 1997;Aikawa et al 1996;Willacy et al 1998;Semenov et al 2010;Agúndez and Wakelam 2013;Albertsson et al 2013;McElroy et al 2013;Grassi et al 2014). As an indication, rate equations require CPU time of ∼1-60 seconds.…”

Section: Outline Of a Generic Gas-grain Codementioning

confidence: 99%

Grain Surface Models and Data for Astrochemistry

et al. 2017

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The cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions.

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Section: Outline Of a Generic Gas-grain Codementioning

confidence: 99%

Grain Surface Models and Data for Astrochemistry

et al. 2017

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“…In this section, we give a very brief introduction to the basics of CO formation chemistry, but we refer readers in search of a more detailed and comprehensive treatment to the classic papers by Glassgold & Langer (1975), Langer (1976), Dalgarno & Black (1976), Tielens & Hollenbach (1985) and Sternberg & Dalgarno (1995).…”

Section: Transition From C + To C To Comentioning

confidence: 99%

Physical Processes in the Interstellar Medium

Klessen

Glover

2015

Saas-Fee Advanced Course

163

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Interstellar space is filled with a dilute mixture of charged particles, atoms, molecules and dust grains, called the interstellar medium (ISM). Understanding its physical properties and dynamical behavior is of pivotal importance to many areas of astronomy and astrophysics. Galaxy formation and evolution, the formation of stars, cosmic nucleosynthesis, the origin of large complex, prebiotic molecules and the abundance, structure and growth of dust grains which constitute the fundamental building blocks of planets, all these processes are intimately coupled to the physics of the interstellar medium. However, despite its importance, its structure and evolution is still not fully understood. Observations reveal that the interstellar medium is highly turbulent, consists of different chemical phases, and is characterized by complex structure on all resolvable spatial and temporal scales. Our current numerical and theoretical models describe it as a strongly coupled system that is far from equilibrium and where the different components are intricately linked together by complex feedback loops. Describing the interstellar medium is truly a multi-scale and multi-physics problem. In these lecture notes we introduce the microphysics necessary to better understand the interstellar medium. We review the relations between large-scale and small-scale dynamics, we consider turbulence as one of the key drivers of galactic evolution, and we review the physical processes that lead to the formation of dense molecular clouds and that govern stellar birth in their interior.

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“…A photochemical origin is considered to be one of the viable mechanisms. Photochemistry plays a significant role in shaping the chemical reaction network in the solar nebula and interstellar clouds (5,10,(20)(21)(22)(23)(24)(25)(26). Laboratory-based photochemistry experiments have provided some verification that the isotopic fractionation during photolysis of various sulfur-containing molecules by UV photons is massindependent (27)(28)(29).…”

Section: Sulfur In Achondritic Meteoritesmentioning

confidence: 99%

Sulfur isotopic fractionation in vacuum UV photodissociation of hydrogen sulfide and its potential relevance to meteorite analysis

Chakraborty

Jackson

Ahmed

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Select meteoritic classes possess mass-independent sulfur isotopic compositions in sulfide and organic phases. Photochemistry in the solar nebula has been attributed as a source of these anomalies. Hydrogen sulfide (H 2 S) is the most abundant gas-phase species in the solar nebula, and hence, photodissociation of H 2 S by solar vacuum UV (VUV) photons (especially by Lyman-α radiation) is a relevant process. Because of experimental difficulties associated with accessing VUV radiation, there is a paucity of data and a lack of theoretical basis to test the hypothesis of a photochemical origin of mass-independent sulfur. Here, we present multiisotopic measurements of elemental sulfur produced during the VUV photolysis of H 2 S. Mass-independent sulfur isotopic compositions are observed. The observed isotopic fractionation patterns are wavelengthdependent. VUV photodissociation of H 2 S takes place through several predissociative channels, and the measured mass-independent fractionation is most likely a manifestation of these processes. Meteorite sulfur data are discussed in light of the present experiments, and suggestions are made to guide future experiments and models.chondrites | achondrites | isotope

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Molecule formation in the interstellar gas

Cited by 272 publications

References 205 publications

Grain Surface Models and Data for Astrochemistry

Grain Surface Models and Data for Astrochemistry

Physical Processes in the Interstellar Medium

Sulfur isotopic fractionation in vacuum UV photodissociation of hydrogen sulfide and its potential relevance to meteorite analysis

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