SN 1987A - AN EMPIRICAL AND ANALYTIC APPROACH

Starting from Wilson's idea that the supernova gets its energy from neutrinos heating the mantle of the star, I use the neutrino observations to find the available neutrino flux. This agrees well with recent computations by Wilson and Mayle, using ''neutron fingers.'' In the mantle of the star, one can define a ''gain radius.'' outside this radius, the energy gain from neutrino absorption is greater than the energy loss by electron capture. The temperature and density are calculated from simple arguments for r > 100 km: In the region where free nucleons dominate, the entropy is assumed to be constant; in the region where nucleons and alpha-particles are mixed, the fraction of nucleons is determined from the internal energy. One can then calculate the fraction of neutrino energy which can be transferred to the region outside the gain radius; this turns out to be 1%-2%. With the observed neutrino flux, this gives a supernova energy of 0.8 foe (1 foe = 10(-51) ergs); nucleo-synthesis adds about 0.4 foe, for a total of 1.2 foe, compared with the observed energy of 1.4 +/- 0.4 foe. In this paper, I shall try to go as directly as possible to the calculation of the supernova energy. Other problems are discussed in sectional-sign 11-14. In particular, it is shown that, and why, the shock wave starts only after some delay.