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A flux-limited treatment for the conductive evaporation of spherical interstellar gas cloudsIn this work, we present and analyze a new analytic solution for the saturated (flux-limited) thermal evaporation of a spherical cloud. This work is distinguished from earlier analytic studies by allowing the thermal conductivity to change continuously from a diffusive to a saturated form, in a manner usually employed only in numerical calculations. This closed form solution will be of interest as a computational benchmark. Using our calculated temperature profiles and mass-loss rates, we model the thermal evaporation of such a cloud under typical interstellar medium (ISM) conditions, with some restrictions. We examine the ionization structure of the cloud-ISM interface and evaluate column densities of carbon, nitrogen, oxygen, neon, and silicon ions toward the cloud. In accord with other investigations, we find that ionization equilibrium is far from satisfied under the assumed conditions. Since the inclusion of saturation effects in the heat flux narrows the thermal interface relative to its classical structure, we also find that saturation effects tend to lower predicted column densities.
Document ID
19930045201
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Dalton, William W. (NASA Headquarters Washington, DC United States)
Balbus, Steven A. (Virginia Univ. Charlottesville, United States)
Date Acquired
August 16, 2013
Publication Date
February 20, 1993
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 404
Issue: 2
ISSN: 0004-637X
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NSF AST-90-21348
CONTRACT_GRANT: NAGW-764
Distribution Limits
Public
Copyright
Other