Volume 445, Number 1, January I 2006
|Page(s)||197 - 204|
|Section||Interstellar and circumstellar matter|
|Published online||13 December 2005|
Astrochemistry of dimethyl ether
Leiden Institute of Chemistry, PO Box 9502, 2300 RA, Leiden, The Netherlands e-mail: email@example.com
2 Space Science and Astrobiology Division, NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035, USA
3 Université P. et M. Curie, Department of Physical Chemistry, Case 22, 4 place Jussieu, 75005 Paris, France
Accepted: 31 August 2005
Dimethyl ether (DME, CH3OCH3) is one of the largest organic molecules detected in the interstellar gas and shows high abundances in star-forming regions, known as hot molecular cores. The observed DME might be formed on grains or by secondary gas phase reactions from a precursor molecule, which in turn was sublimed into the gas phase from the grain surface. Studies on the stability and degradation pathways of DME therefore provide important constraints on the evolutionary cycle of large organic molecules and chemical pathways in the interstellar medium. We studied the UV photodestruction rate of DME in a solid argon matrix. DME was destroyed with a half-life of 54 seconds under laboratory conditions, which corresponds to years in a dense cloud. We discuss the UV photochemistry of DME in the context of two issues: its formation mechanism and its chemistry in hot cores. Chemical models of shielded hot core regions indicate that UV photodestruction is relatively unimportant for DME, even by the internally-generated radiation field. These models clearly show that gas phase processes are almost certainly responsible for the formation of interstellar DME.
Key words: astrochemistry / methods: laboratory / ISM: molecules
© ESO, 2005
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