On the collapse dynamics of cold stars with a phase transition in the interior

Cold stars can become unstable due to a phase transition in the centre. By small perturbations the collapse is triggered toward a new stable configuration. The features of the collapse are studied by means of a parameter-independent model with piece by piece uniform density. Possible consequences of such a collapse for neutron stars are: extreme speed-up, heating and a supernova-like release of binding energy. The dynamical stability properties of the model are considered in the framework of General Relativity. In particular the very beginning of the collapse can be treated by analytical means. In a certain range relativistic effects can prevent a configuration to collapse. (author)