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A Physical Mechanism for the Generation of Extended Stellar Atmospheres*

Published online by Cambridge University Press:  08 February 2017

R. W. Hillendahl
R. W. Hillendahl*
Affiliation:
Department of Astronomy, University of California at Berkeley Lockheed Palo Alto Research Laboratory, 3251 Hanover Street, Palo Alto, California

Abstract

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A physical mechanism that can result in the generation of extended expanding atmospheres is discussed. The process involves the unloading of stellar material following the arrival of a shock wave at the edge of the star. The basic principles are developed from a discussion of a simplified case that has been studied in the laboratory; they are then applied to the atmosphere of a star. A radiation-hydrodynamics computation of a model cepheid is then used to obtain quantitative atmospheric profiles. The computed continuum and spectral lines during the unloading process are then examined. A discussion of the possibility that the unloading process occurs in stars other than cepheids suggests the existence of a shock visibility factor associated with ionization or dissociation in the region behind the shock front and leads to a possible alternate interpretation of the variable star instability strips in the H-R diagram.

Keywords

extended atmosphereshock wavehydrodynamiccepheids
Type
Part C
Information
International Astronomical Union Colloquium , Volume 2: Spectrum Formation in Stars With Steady-State Extended Atmospheres , August 1970 , pp. 300 - 319
Copyright
Copyright © 1970

Footnotes

†

Now at Lockheed Palo Alto Research Laboratory, 3251 Hanover Street, Palo Alto, California 93404.

(*)

This work was made possible by a grant of computer time made available by the Berkeley Astronomy Department and by a Lockheed Independent Research Grant.

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