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Hydrogen Emission Lines from Extended Pulsating Atmospheres

Published online by Cambridge University Press:  15 February 2018

P. de Laverny  and
C. Magnan
P. de Laverny
Affiliation:
GRAAL, cc72, Université Montpellier II, F-34095 Montpellier cedex05, France Institut d'Astrophysique de Paris, France
C. Magnan
Affiliation:
GRAAL, cc72, Université Montpellier II, F-34095 Montpellier cedex05, France Institut d'Astrophysique de Paris, France College de France, Paris, France

Abstract

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In order to study the basic radiative mechanisms in the extended envelopes of evolved stars (e.g. Long Period Variables), we determine the spectrum emerging from a very optically thick Non-LTE hydrogen layer surrounding a core of high temperature (see figure 1). Such a model was first proposed by Sobolev (1960) and Menzel (1946). It is consistent with the fact that LPVs are likely evolving toward planetary nebulae. The main parameters of the model are the temperature of the illuminating star (Tr), the dilution factor (ω) and the Lyman continuum optical depth of the envelope (τ1c). We examine their influence upon the emerging intensities in the lines and in the continua.

The model could explain some observations related to evolved stars and especially the presence of emission features in an otherwise cold environment. Furthermore atmospheric pulsation phenomena produce large variations in the emerging spectra: reddening, emission/absorption transition of the hydrogen lines, profile deformations…

Type
Theoretical Breakthroughs
Information
International Astronomical Union Colloquium , Volume 139: New Perspectives on Stellar Pulsation and Pulsating Variable Stars , 1993 , pp. 281 - 282
Copyright
Copyright © Cambridge University Press 1993

References

Gros, M., Magnan, C., 1981, A&A, 93, 150.Google Scholar
de Laverny, P., Magnan, C., 1992, in preparation for A&A.Google Scholar
Magnan, C., 1992, submitted to A&A.Google Scholar
Menzel, D.H., 1946, Physica, XII, n.9-10, 768.Google Scholar
Sobolev, V.V., 1960, in “Moving Envelopes of Stars”, Harvard University Press.CrossRefGoogle Scholar