The non-linear evolution of strange-mode instabilities

Dr. Matthias Grott (Universitäts-Sternwarte Göttingen)

Donnerstag, den 22.1.2004 um 10 Uhr c.t., PN-114

Abstract:

Sufficiently luminous objects, such as LBVs, Wolf-Rayet stars, HdC stars, RCrB stars and AGB stars are known to suffer from strange mode instabilities with growth rates in the dynamical range. The high growth rates of the instabilities indicate a connection to the observed mass loss of the corresponding objects. To test this conjecture, the evolution of the instabilities has to be followed into the non-linear regime by direct numerical simulations. The instabilities are observed to lead to stellar pulsations with velocity amplitudes of the order of the escape velocities of the corresponding objects.

In the talk, the origin of strange-mode instabilites will be sketched briefly. A method to solve the set of non-linear equations governing the evolution of strange-mode instabilites as well as some example calculations will be presented. So far, the photosphere has been the outer boudary of the models. An extension to the optically thin regime, including additional opacity sources, will be discussed.