BREAKOUT OF THE SUPERNOVA SHOCK

The shock in a supernova of Type II first moves slowly and then sudden ly breaks out with a velocity of order 10(9) cm s(-1). This breakout i s due to the recombination of nucleons into alpha-particles. It is sho wn that this recombination provides enough energy to lift the matter a gainst gravity. The net energy after escape from the star is about 4 x 10(18) ergs g(-1). Supernovae of Type II differ mainly in the binding energy of the mantle of the progenitor.