We review the fundamental classification scheme and statistical analysis of supernovae, emphasizing recently introduced subtypes, SN 1987K, and SN 1993J. Type Ib/Ic and Type II supernovae are of interest for starburst galaxies. We discuss possible progenitors of SNIb and SN Ic, and the possibility that they may be Wolf-Rayet stars.

Introduction

Up to May 1, 1993, 890 supernovae have been discovered, of which 480 have been classified. Today, with data of increasing quantity and precision, we have categorized supernovae into several groups, not just Types I and II, but Types Ia, Ib/Ic, II-L, IIp, 87A, and probably more to come. But, except for SNIIp and SN1987A, we are still unclear as to the evolution of the progenitor star (or stars). As the rich diversity of supernovae becomes more evident, we are increasingly challenged to ask: what are the stellar progenitors and the explosion mechanisms of the various types and subtypes of supernovae? What makes a SN Ia and what would a progenitor system look like? Are the progenitors of SN Ib/Ic all Wolf-Rayet stars? Here we attempt a brief overview of these questions. For more extensive discussions of issues bearing on supernova progenitors, see recent reviews by Wheeler(1990, 1991) and Branch et al. (1990).

We have reached a basic understanding of how the observable properties of SNe depends on the characteristics of the immediate presupernova stars and their explosion parameters.