Suchergebnisse

We give here a derivation of the general relativistic non adiabatic radial pulsation equation for spherically symmetric non rotating stars.
The influence of general relativistic corrections on the non adiabatic terms is treated up to the first order in the relativistic parameter. This implies that the unperturbed model must be considered in a state of "quasi-equilibrium" in the sense that its physical characteristics are slowly varying functions of time, due to the conversion of proper mass into energy, caused by the thermonuclear reactions.
Eckart's formalism is used to take into account the presence of a radiative or convective flux but the influence of the radiative viscosity terms is neglected in the derivation of the structure and pulsation equations.
Relativistic expressions are given for the vibrational stability coefficient and the secular root, the last one being used to recover and clarify the general relativistic secular instability of supermassive stars above a certain critical mass, found by Appenzeller and Kippenhahn.