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Non-radial Pulsations of BA Supergiants and Be Stars

Published online by Cambridge University Press:  12 April 2016

Dietrich Baade
Dietrich Baade*
Affiliation:
European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching b. München, Germany

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If observing time and number of photons are not the limit, it will probably be very difficult to find any Be star or BA supergiant that is not variable. Moreover, there is hardly any major set of observations that is not tempting to explain at least partly in terms of nonradial (g-mode) pulsations. Since a few years ago, such conjectures are also theoretically permissible because improved opacity calculations have established the classical к-mechanism as a viable source of pulsation driving (cf. Pamyatnykh, these proceedings).

Contrary to Be stars, it can for any given BA supergiant nevertheless be arbitrarily difficult to diagnose nonradial pulsations (NRP’s) with certainty because they need to be detected against considerable background ‘noise’ of other physical processes, most of which are related to mass loss and/or rotation. To make things worse, there is some evidence that NRP’s can have some effect on the dynamics of the mass loss. On the other hand, variable and non-spherical winds is the subject of this Colloquium, and this paper is accordingly biased towards the interplay between pulsation and mass loss.

Type
Section V Pulsation
Information
International Astronomical Union Colloquium , Volume 169: Variable and Non-spherical Stellar Winds in Luminous Hot Stars , 1999 , pp. 312 - 319
Copyright
Copyright © Springer-Verlag 1999

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