The silicon chemistry of IRC+10 degrees 216

MacKay, D.D.S. and Charnley, S.B. (1999) The silicon chemistry of IRC+10 degrees 216. Monthly Notices of the Royal Astronomical Society, 302 (4). pp. 793-800. ISSN 0035-8711. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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We have modelled the circumstellar chemistry of SiC, SiC2, SiC4, SiH2, SiH4, HNSi and SiN in the carbon-rich envelope of the variable star IRC + 10 degrees 216. We find, in agreement with previous work, that SiC2 must be a parent and that neutral-neutral reactions are necessary to form SiC4. Our inclusion of many more neutral-neutral reactions has a limited influence on the calculated distributions of the Si-C compounds. In particular, the suggestion of Lucas et al. - that the SiC2 distribution peaks by almost an order of magnitude in the outer envelope relative to its inner envelope abundance - cannot be explained in any of our models. This enhancement is most likely to arise from a density peak or peaks along the line of sight. We show that the presence of SiH2 and the Si-N chemistry require that SiH4 supplies the bulk of available silicon in the photochemical region. The column densities and radial distributions of all the observed Si species are compared with their observed values, and column densities are given for several molecules predicted to be detectable in IRC + 10 degrees 216 - Sill, SiH3, SiC2H, HCSi, HNSi and SiC3.

Item Type: Article
Uncontrolled keywords: molecular processes; circumstellar matter; stars : individual : IRC+10 degrees 216; stars : late-type
Subjects: Q Science > Q Science (General)
Divisions: Faculties > Science Technology and Medical Studies > School of Engineering and Digital Arts
Depositing User: I.T. Ekpo
Date Deposited: 11 Aug 2009 10:04
Last Modified: 11 Aug 2009 10:04
Resource URI: (The current URI for this page, for reference purposes)
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