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Carbon Chemistry in Dense Molecular Clouds: Theory and Observational Constraints

Blake, Geoffrey A. (1990) Carbon Chemistry in Dense Molecular Clouds: Theory and Observational Constraints. In: Carbon in the galaxy: studies from earth and space. NASA conference publication. No.3061. NASA , Washington, DC, pp. 159-179. ISBN 21554672.

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For the most part, gas phase models of the chemistry of dense molecular clouds predict the abundances of simple species rather well. However, for larger molecules and even for small systems rich in carbon these models often fail spectacularly. We present a brief review of the basic assumptions and results of large scale modeling of the carbon chemistry in dense molecular clouds. Particular attention will be paid to the influence of the gas phase C/O ratio in molecular clouds, and the likely role grains play in maintaining this ratio as clouds evolve from initially diffuse objects to denser cores with associated stellar and planetary formation. Recent spectral line surveys at centimeter and millimeter wavelengths along with selected observations in the submillimeter have now produced an accurate "inventory" of the gas phase carbon budget in several different types of molecular clouds, though gaps in our knowledge clearly remain. The constraints these observations place on theoretical models of interstellar chemistry can be used to gain insights into why the models fail, and show also which neglected processes must be included in more complete analyses. Looking toward the future, larger molecules are especially difficult to study both experimentally and theoretically in such dense, cold regions, and some new methods are therefore outlined which may ultimately push the detectability of small carbon chains and rings to much heavier species.

Item Type:Book Section
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Blake, Geoffrey A.0000-0003-0787-1610
Additional Information:© 1990 National Aeronautics and Space Administration.
Series Name:NASA conference publication
Issue or Number:3061
Record Number:CaltechAUTHORS:20120918-093420406
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34165
Deposited By: Tony Diaz
Deposited On:19 Sep 2012 18:36
Last Modified:03 Oct 2019 04:16

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