Light Curve Studies of SN 1993J and SN 1994I

Numerical light curve calculations have been carried out to constrain the light-curve parameters of the recent SNs 1993J and 1994I. For SN 1993J the radius of the progenitor star is constrained to be in the range 2-4 × 10 13 cm which is consistent with the candidate progenitor star. The ejected mass is constrained to be in the range 1.9-3.5 M ☉ ; equating the ejected mass to the helium core mass of the progenitor implies a main-sequence mass in the range 12-17 M ☉ . Using the new Cepheid distance to M81, the ejected 56 Ni mass is found to be in the range 0.10-0.14 M ☉ . For SN 1994I the ejected mass is in the range 0.9-1.3 M ☉ ; equating the ejected mass to the carbon-oxygen core mass of the progenitor implies a main-sequence mass in the range 13-20 M ☉ . For a distance of 7 Mpc and an extinction A V = 1.4 mag, the ejected 56 Ni mass is found to be 0.07 M ☉ . Recent studies of galactic chemical evolution have suggested that the main-sequence masses and ejected 56 Ni masses of core collapse SNs may be inversely correlated. We examine this effect for 1993J, 1994I, and 1987A, but the small number of known nickel mass-main-sequence mass systems makes it too early to draw definitive conclusions.