ANALYSIS OF THE EARLY SPECTRA AND LIGHT-CURVE OF SN-1987A

Numerical modeling of supernova spectra, light curves, and hydrodynami cs requires physical inputs, numerical techniques, approximations, and assumptions which must be thoroughly understood in order to study the details of supernova explosions. Here, we discuss some of these in th e context of the early evolution of supernova 1987A. Gray radiation-hy drodynamics is used to calculate the bolometric light curve and the hy drodynamic evolution of the supernova. Synthetic spectra are then obta ined for the resulting density and velocity structure. The spectrum ca lculations are performed using a special-relativistic treatment of the radiative transfer equation in the comoving frame, line blanketing by about 10(5) spectral lines, and departures from LTE for H I, He I Mg II, and Ca II. We find that we are able to simultaneously fit the earl y light curve and spectra reasonably well, using a progenitor model fr om Arnett (1991a), without fine-tuning the free parameters. Temperatur e structures and radiative equilibrium, non-LTE effects, homologous ex pansion, and mean opacities are discussed.