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Astron. Astrophys. 354, 1062-1070 (2000)

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Hydrocarbons in diffuse and translucent clouds

S. Viti, D.A. Williams and P.T. O'Neill

Department of Physics and Astronomy, UCL, Gower St., London, WC1E 6BT, UK

Received 18 October 1999 / Accepted 29 November 1999


We investigate the consequences on hydrocarbon chemistry in diffuse and translucent clouds of including an interaction between gaseous C+ ions and dust grains. In general, we find that models in which much of the carbon is deposited and retained on grain surfaces within the cloud lifetime represent a poor match to observations. Conversely, models in which carbon is efficiently converted to methane generally provide satisfactory agreement with the observed chemistry of translucent clouds. Such models also predict that the hydrocarbons C2H, [FORMULA] and H2CO may be detectable in diffuse clouds.

Key words: molecular processes – ISM: abundances – ISM: molecules

Send offprint requests to: sv@star.ucl.ac.uk

© European Southern Observatory (ESO) 2000

Online publication: February 25, 2000