Early Supernova Luminosity

The diffusion of radiant energy from spherical expanding matter has been analytically and numeri- cally calculated for masses and velocities of model supernova outbursts. The agreement with observation is satisfactory. The production of a large mass fraction of the radioactive isotope 56Ni, which has been predicted from calculations of supernova nucleosynthesis, appears to be critical for the formation of the observed light curves. The radioactive energy from 0 25 Mo of "Ni by the decay process 56Ni -+ ~~Co (6d01, Ec, 1.72 MeV of 7-rays per decay) supplies the radiant energy, 1O~~ ergs, during the "diffusive release" phase (5-20 days) of expansion near maximum. The subsequent decay process, 56Co -~ 56Fe (77 days, Ec, 3.59 MeV of 7-rays), in conjunction with progressive 7-ray transparency of the expanding matter, gives rise to the long-time exponential light decay of 35-65 days. The velocity distribution with the best fit (Type I supernovae) gives (V2) = (1.6 X 10~ cm sec-')2. For a pure thermonuclear super- nova requiring a minimum of 1.4 Mo of 12c, the implied kinetic energy is 3 times the maximum avail- able from 12C burning, and 6 times that available from the model calculated by Hansen. This implies the possibility that some supernovae originated from neutron stars