THE EVOLUTION AND EXPLOSION OF MASSIVE BINARY STARS AND TYPE IB-IC-IIB-IIL SUPERNOVAE

Supernovae are classified as Type I and Type II and further subdivided into Ia, Ib, Ic, II-P, II-L, and IIb. The origin of such an observational diversity has not been well understood. The recent nearby supernovae SN 1993J and SN 1994I have provided particularly useful material to clarify the supernova-progenitor connection. For a progenitor of Type IIb supernova 1993J, we propose that merging of two stars in a close binary is responsible for the formation of a thin H-rich envelope. For a progenitor of Type Ic supernova 1994I, we propose a bare C+O star that has lost both H and He envelope after common envelope phase. By generalizing these scenarios, we show that common envelope evolution in massive close binary stars leads to various degree of stripping of the envelope mass of massive star. This naturally can lead to the explanation of the origin of Type II-L, IIn, IIb, Ib, and Ic in a unified manner. The binary hypothesis to explain the diversity of supernovae can be substantiated with new information on SN IIb 1993J and SN Ic 1994I. Hydrodynamical and nucleosynthesis models for these supernovae (including Rayleigh-Taylor instabilities) and their light curves are compared with observations. Since extensive mass loss is essential for the binary scenario, circumstellar interactions are examined to compare X-ray observations.