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Shielding of CO from dissociating radiation in interstellar cloudsThe paper investigates the photodissociation of CO in interstellar clouds in the light of recent laboratory studies which suggest that line rather than continuum processes dominate its dissociation by ultraviolet radiation. Using a simple radiative transfer model, the shielding of representative dissociating bands is estimated, including self-shielding, mutual shielding between different isotopes, and near coincidences with strong lines of H2. Each of these processes materially affects the photodestruction rates of the various isotopic species in the transition regions of molecular clouds. These results are combined with an appropriate gas phase chemical model to determine how the abundances of the CO isotopes vary with depth into the cloud. It is found that self-shielding and mutual shielding cause significant variations in isotopic ratios. In addition, fractionation enhances species containing C-13. The relationship between the column densities of CO and H2 is found to vary for the different isotopes and to be sensitive to local conditions.
Document ID
19850048749
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Glassgold, A. E.
(New York Univ. New York, NY, United States)
Huggins, P. J.
(New York University New York, NY, United States)
Langer, W. D.
(AT&T Bell Laboratories Holmdel, NJ, United States)
Date Acquired
August 12, 2013
Publication Date
March 15, 1985
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 290
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
85A30900
Funding Number(s)
CONTRACT_GRANT: NGR-33-016-196
CONTRACT_GRANT: NSF AST-82-16484
Distribution Limits
Public
Copyright
Other

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