THE BOLOMETRIC LIGHT-CURVE OF SN1993J AND THE NATURE OF ITS PROGENITOR

We have constructed the bolometric light curve of SN1993J bawd on UBVR I(JHK) photometric data obtained from various sources and assuming A(v ) = 0 and a distance modulus of 27.6. Effective temperatures and photo sphere radius at various times have been obtained from detailed blackb ody fits. The bolometric light curve shows two maxima. The short rise time to the second maximum, and the luminosities at the minimum and th e second maximum are used to constrain the properties of the progenito r star. The total mass of the hydrogen envelope M(H), in the star is f ound to be less than or similar to 0.2 M. at the time of explosion, an d the explosion ejected about 0.05 M. of Ni-56. Thin hydrogen envelope combined with a sufficient presupernova luminosity suggest that the e xploding star was in a binary with a probable period range of 5yr less -than-or-equal-to P(orb) less-than-or-equal-to 11 yr.