Supernova theory

This is a general survey of the development of a supernova. The energy is supplied by the neutrinos from the core, as proposed by Wilson. An entropy maximum is formed at about 120 km, The region between this maximum and the shock is in convection. On the other hand, in the region between neutron star and entropy maximum, dS/dr > 0, which impedes further accretion to the neutron star, and makes infalling matter assemble outside the maximum. The shock moves slowly outward until it reaches about 300 km. There it breaks out, propelled by the recombination energy of nucleons into alpha-particles. A high rate of accretion is desirable for obtaining a high supernova energy. A high neutrino luminosity is necessary for the supernova to work. Ni-56 is formed from infalling material, probably O-16, when the shock hits it. The mass of Ni-56 is accurately predicted by existing computations. The matter which originally accumulated the shock energy probably is in a freeze-out, so perhaps only a fraction of it will combine into heavy nuclei; some may be ejected as He. It is likely that in SN 1987A there was considerable fallback. Fallback increases the mass of the neutron star, but is difficult to predict reliably.