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The CO/SiO radiative instability in cool star atmospheres revisitedWe revisit the formation of radiative instabilities in cool star atmospheres and compare our results with those given by Muchmore, Nuth, & Stencel. We have considered the combined influence of CO and SiO molecules and have computed models for a grid of effective temperatures and geometrical dilution factors for the stellar radiation. Our results are based on the analysis of the energy balance of gas elements with prescribed thermodynamic properties. Our results show that radiative instabilities are most likely primarily caused by CO, whereas SiO is expected to play only a minor role, except when the CO density is reduced compared to Local Thermodynamic Equilibrium (LTE) values or the CO band can be assumed to be optically thick. The onset of radiative instabilities is expected to be strongly modified when dynamic phenomena such as stochastic shocks are present. Our results provide strong evidence that dust formation can most likely occur via a radiative instability alone. Therefore, we present a revised version of the Muchmore et al. dust formation paradigm, which also considers hydrodynamic cooling. The new paradigm is particularly relevant in cases where dust is formed relatively close to the stellar photosphere.
Document ID
19950038089
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Cuntz, M.
(NCAR, Boulder, CO United States)
Muchmore, D. O.
(Weedin Place, Seattle, WA United States)
Date Acquired
August 16, 2013
Publication Date
September 20, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 433
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A69688
Funding Number(s)
CONTRACT_GRANT: NAGW-2904
Distribution Limits
Public
Copyright
Other

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