Does stellar collapse produce supernovae or black holes

This article describes the most recent calculations on the model of supernova explosions. The author postulates that a supernova is produced by gravitational collapse of a star after it has burned all of its thermonuclear material. The end product of the burn is iron; thus, just before the star collapses, it has a central core composed of iron. During the collapse, the energy, released by the gravitational field is used to decompose the iron into lighter nuclei. Finally, the core consists of hot neutrinos, electrons, protons, neutrons, and helium nuclei. The pressure at the center of the star becomes sufficiently high to stop the collapse suddenly and to produce outwardly directed shock waves. It is thought that this shock wave may be strong enough to eject the outer material of the star. The new calculations produce explosions whose energy is slightly too low to explain most observed supernova. (SC)