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Modeling the chemistry of the dense interstellar clouds. I - Observational constraints for the chemistryA search for correlations arising from molecular line data is made in order to place constraints on the chemical models of interstellar clouds. At 10 to the 21st H2/sq cm, N(CO) for dark clouds is a factor of six greater than the value for diffuse clouds. This implies that the strength of the UV radiation field where CO shields itself from dissociation is about one-half the strength of the average Galactic field. The dark cloud data indicate that the abundance of CO continues to increase with A(V) for directions with A(V) of 4 mag or less, although less steeply with N(H2) than for diffuse clouds. For H2CO, a quadratic relationship is obtained in plots versus H2 column density. The data suggest a possible turnover at the highest values for A(V). NH3 shows no correlation with H2, C(O-18), HC3N, or HC5N; a strong correlation is found between HC5N and HC3N, indicating a chemical link between the cyanopolyynes.
Document ID
19900047461
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Federman, S. R.
(JPL, Pasadena, CA; Toledo, University OH, United States)
Huntress, W. T., Jr.
(JPL Pasadena, CA, United States)
Prasad, S. S.
(JPL, Pasadena; Southern California, University Los Angeles, CA, United States)
Date Acquired
August 14, 2013
Publication Date
May 10, 1990
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 354
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
90A34516
Distribution Limits
Public
Copyright
Other

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