NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Deviations from LTE in a stellar atmosphereDeviations for LTE are investigated in an atmosphere of hydrogen atoms with one bound level, satisfying the equations of radiative, hydrostatic, and statistical equilibrium. The departure coefficient and the kinetic temperature as functions of the frequency dependence of the radiative cross section are studied analytically and numerically. Near the outer boundary of the atmosphere, the departure coefficient is smaller than unity when the radiative cross section grows with frequency faster than with the square of frequency; it exceeds unity otherwise. Far from the boundary the departure coefficient tends to exceed unity for any frequency dependence of the radiative cross section. Overpopulation always implies that the kinetic temperature in the statistical-equilibrium atmosphere is higher than the temperature in the corresponding LTE atmosphere. Upper and lower bounds on the kinetic temperature are given for an atmosphere with deviations from LTE only in the optically shallow layers when the emergent intensity can be described by a radiation temperature.
Document ID
19790048105
Document Type
Reprint (Version printed in journal)
Authors
Kalkofen, W. (Harvard-Smithsonian Center for Astrophysics Cambridge, Mass., United States)
Klein, R. I. (Kitt Peak National Observatory Tucson, Ariz., United States)
Stein, R. F. (Michigan State University East Lansing, Mich., United States)
Date Acquired
August 9, 2013
Publication Date
April 1, 1979
Publication Information
Publication: Journal of Quantitative Spectroscopy and Radiative Transfer
Volume: 21
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NSG-7293
CONTRACT_GRANT: NSF AST-76-22479
Distribution Limits
Public
Copyright
Other