The collapse of rotating stellar cores

The collapse of the rotating cores of massive stars (M >= 15Msub(sun)) is considered. The dynamical evolution of the core is followed by an explicit two-dimensional hydrodynamic code. A realistic, finite-temperature equation of state is used in the calculations. Rigidly and differentially rotating initial models are both studied. We find that in all cases considered the collapse proceeds up to nearly nuclear matter density before it is stopped. In none of the examined models is the core-bounce followed by an explosion. The dynamical behaviour of the slowly rotating models is very similar to that of non-rotating models. The rapidly rotating cores already show large non-spherical effects before core bounce. In these models, a high entropy blob is formed near the axis of rotation, which, while trying to rise and expand, is rapidly destroyed by the onset of circulation. A flattened, nearly hydrostatic central condensation builds up with relatively low central density (Q approx. equal to 5 1013 g cm-3) on which the matter of the envelope is further accreted. (orig.)