The simulation of non-linear stellar pulsations

Abstract

Details of a method for the numerical simulation of stellar pulsations and instabilities in the non-linear regime are presented. Important properties of the method are intrinsic mass and energy conservation. These are indispensable if the connection between stellar pulsations and mass loss is to be investigated. A prescription for the construction of initial models is given, which allows for the study of the linear regime of exponential growth of instabilities and a comparison with independent linear stability analyses. The dependence on numerical parameters of the simulations is investigated in detail. As a result, the acoustic luminosity generated by strange mode instabilities in a massive star is found to depend sensitively on the numerical viscosity necessary to handle shock waves. The values derived have to be regarded as lower limits and reach the order of magnitude of the kinetic luminosities observed in the winds of corresponding objects. This result is taken as further indication for a connection between strange mode instabilities and stellar mass loss.