REACTIVE DESORPTION AND RADIATIVE ASSOCIATION AS POSSIBLE DRIVERS OF COMPLEX MOLECULE FORMATION IN THE COLD INTERSTELLAR MEDIUM

The recent discovery of terrestrial-type organic species such as methyl formate and dimethyl ether in the cold interstellar gas has proved that the formation of organic matter in the Galaxy begins at a much earlier stage of star formation than was previously thought. This discovery represents a chal...

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Bibliographic Details
Published in:The Astrophysical journal 2013-05, Vol.769 (1), p.1-9
Main Authors: Vasyunin, A I, Herbst, Eric
Format: Article
Language:English
Subjects:
ABUNDANCE
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Cold working
CONVERSION
DESORPTION
Ejection
Formations
GALAXIES
Grains
Interstellar gas
INTERSTELLAR GRAINS
Interstellar matter
INTERSTELLAR SPACE
METHYL ETHER
MOLECULES
ORGANIC MATTER
PRECURSOR
Star formation
STARS
SURFACES
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Summary:The recent discovery of terrestrial-type organic species such as methyl formate and dimethyl ether in the cold interstellar gas has proved that the formation of organic matter in the Galaxy begins at a much earlier stage of star formation than was previously thought. This discovery represents a challenge for astrochemical modelers. The abundances of these molecules cannot be explained by the previously developed "warm-up" scenario, in which organic molecules are formed via diffusive chemistry on surfaces of interstellar grains starting at 30 K, and then released to the gas at higher temperatures during later stages of star formation. In this article, we investigate an alternative scenario in which complex organic species are formed via a sequence of gas-phase reactions between precursor species formed on grain surfaces and then ejected into the gas via efficient reactive desorption, a process in which non-thermal desorption occurs as a result of conversion of the exothermicity of chemical reactions into the ejection of products from the surface. The proposed scenario leads to reasonable if somewhat mixed results at temperatures as low as 10 K and may be considered as a step toward the explanation of abundances of terrestrial-like organic species observed during the earliest stages of star formation.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/769/1/34