Article (Scientific journals)
Contribution to spectral line formation in moving stellar envelopes - Radiation field and statistical equilibrium equations
Surdej, Jean
1977In Astronomy and Astrophysics, 60, p. 303-311
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Keywords :
RADIATIVE TRANSFER; STELLAR ENVELOPES; STELLAR MOTIONS; STELLAR SPECTRA; GRADIENTS; LINE SPECTRA; PROBABILITY DISTRIBUTION FUNCTIONS; VELOCITY DISTRIBUTION; LINE SHAPE
Abstract :
[en] The escape probability method introduced by Sobolev (1947) is used to derive the mean intensity of the radiation field at any point of an envelope which expands spherically with a positive or negative radial-velocity gradient. When considering outward-decelerating envelopes, an additional contribution to the mean intensity of the radiation field must be taken into account when compared with the results obtained by Castor (1970) in the case of outward-accelerating envelopes. A general discussion of the net radiative rates which populate the levels of an atom relates the problem of spectral-line formation in a moving medium to the one in a transparent atmosphere at rest. Namely, it is shown that dilution effects are expected to play an important role in envelopes where very large velocity gradients occur.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Surdej, Jean  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Language :
English
Title :
Contribution to spectral line formation in moving stellar envelopes - Radiation field and statistical equilibrium equations
Publication date :
1977
Journal title :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Publisher :
EDP Sciences, Les Ulis, France
Volume :
60
Pages :
303-311
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 02 August 2009

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