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Radiation Transfer and Photochemical Effects in Inhomogeneous Dense Clouds

Published online by Cambridge University Press:  07 August 2017

S. Aiello
Affiliation:
Dip. di Astronomia e Scienza dello Spazio, Università di Firenze, Italy
C. Cecchi Pestellini
Affiliation:
Dip. di Astronomia e Scienza dello Spazio, Università di Firenze, Italy Harvard-Smithsonian Institute of Astrophysics, Cambridge, Massachusetts, USA
S. Tiné
Affiliation:
Dip. di Astronomia e Scienza dello Spazio, Università di Firenze, Italy

Abstract

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UV radiation leads to photodissociation and photoionization of molecular species in diffuse clouds and in the extended envelopes of dark regions. In the inner part of heavily-obscured objects, the residual external field may be negligible; alternative mechanisms, such as cosmic-ray-induced H2 emission, appear to be efficient in photodestruction processes. We evaluate the relative importance of these radiation sources, and give some estimates of their effects on the mean lifetime of interstellar molecules, taking into account the cloud structure that significantly affects the penetration depth of UV radiation.

Type
Quiescent Clouds and Regions of Star Formation
Copyright
Copyright © Kluwer 1992 

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