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New Opacities and the Beta Cephei Stars

Published online by Cambridge University Press:  15 February 2018

L.A. Balona
L.A. Balona*
Affiliation:
South African Astronomical Observatory, P.O.Box 9, Observatory 7935, Cape, South Africa

Abstract

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The recent revision of metal opacities has opened up the possibility that the long-sought mechanism for driving pulsations in these stars has at last, been found. This hypothesis makes a testable prediction — that no β Cep variables should exist among metal-poor B-type stars. We report on the results of an intensive CCD monitoring campaign to test this prediction. The question of the pulsation mode of β Cep stars and the consequence of a revision of the absolute magnitudes to accommodate the fundamental radial mode among these stars is also discussed. Pulsational instability due to driving by ionization of metals has many other repercussions for the incidence of pulsation among the B-type stars. A classification scheme for other intrinsically variable B-type stars is suggested. It is shown that if, as generally supposed, pulsation is common among B-type stars then at least two different mechanisms must be in operation.

Type
Beyond the Classical Instability Strip
Information
International Astronomical Union Colloquium , Volume 139: New Perspectives on Stellar Pulsation and Pulsating Variable Stars , 1993 , pp. 163 - 170
Copyright
Copyright © Cambridge University Press 1993

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