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Photon dominated regions: Observations of [C I] and CO

Published online by Cambridge University Press:  25 May 2016

Jocelyn Keene
Affiliation:
California Institute of Technology, 320-47, Pasadena, CA 91125, USA
D. C. Lis
Affiliation:
California Institute of Technology, 320-47, Pasadena, CA 91125, USA
T. G. Phillips
Affiliation:
California Institute of Technology, 320-47, Pasadena, CA 91125, USA
P. Schilke
Affiliation:
Universität zu Köln, I. Physikalisches Institut, Zülpicher Str. 77, D-50937, Köln, Germany

Abstract

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Since the construction of the first specialized submillimeter telescopes nearly a decade ago, there has been extensive mapping of astronomical sources in the previously difficult to observe ground-state fine-structure transition of [C I] at 492 GHz. We discuss recent CSO observations of [C I] and 13CO (2 → 1) lines toward bright photon-dominated regions (PDRs). These observations have revealed an interesting effect. In many sources and over a broad range of column densities, the observed intensity of the [C I] line is proportional to that of the 13CO (2 → 1) line with exceptions mainly in dense, active star-forming regions, where C I appears to be under-abundant relative to 13CO. In this paper we quantitatively display this effect.

Type
Star Formation
Copyright
Copyright © Kluwer 1997 

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