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The relationship between carbon monoxide abundance and visual extinction in interstellar cloudsCarbon monoxide column densities are compared to visual extinctions toward field stars in the rho Oph and Taurus molecular cloud complexes. The relationship of C(0-18) column density to extinction is established, and new determinations for (C-13)O column densities are given for a range of visual extinctions extended to beyond 20 mag. A prescription for determining hydrogen column densities and masses of molecular clouds from observations of CO isotopes is presented and discussed critically. These measurements agree well with the predictions of gas phase chemistry models which include chemical fractionation and selective isotopic photodestruction. The functional dependence of the C(O-18) column density on extinction is characterized by two different regimes separated by a distinct transition observed to occur at 4 mag in both molecular cloud complexes, whereas the functional dependence of (C-13)O is quite different in the two regions. Some saturation is found to occur for C(O-18) emission at high visual extinction and use the rarer isotopic species C(O-17) and (C-13)(O-18) to correct for it.
Document ID
19830032974
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Frerking, M. A.
(California Institute of Technology, Jet Propulsion Laboratory, Pasadena, CA; Bell Telephone Laboratories, Inc. Holmdel, NJ, United States)
Langer, W. D.
(Bell Telephone Laboratories, Inc., Holmdel; Princeton University Princeton, NJ, United States)
Wilson, R. W.
(Bell Telephone Laboratories, Inc. Holmdel, NJ, United States)
Date Acquired
August 11, 2013
Publication Date
November 15, 1982
Publication Information
Publication: Astrophysical Journal
Subject Category
Astrophysics
Accession Number
83A14192
Distribution Limits
Public
Copyright
Other

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