Pulsating Relativistic Stars

Pulsating stars have given important information in classical astronomy and are still an active research field, e.g. asteroseismology or helioseismology. By studying the rich oscillation stellar spectra, optical astronomy makes predictions for the stellar equations of state (EOS), the evolutionary age of the stars, and in the case of Cepheids one can make exact predictions for the distance of the object. For relativistic astrophysics the pulsations of relativistic stars are of great importance since through them one can discuss stability properties of compact objects and, moreover, pulsating stars can be a promising source of gravitational waves. It is expected that during the first few seconds which will follow a supernova explosion the newly formed neutron star will pulsate wildly and this pulsation will be mainly damped due to the emission of gravitational radiation which will carry away the characteristic signature of the collapsed object. The energy stored in the pulsation will be of the same order as the kinetic energy of the collapse and in this way a significant part of the original mass-energy of the newly formed neutron star will be radiated away as gravitational radiation. With the present sensitivity of the resonant detectors it is quite sure that the gravitational waves will be detected if a supernovae explosion takes place in