We review critical physics affecting the observational characteristics of those supernovae that occur in massive stars. Particular emphasis is given to 1) how mass loss, either to a binary companion or by a radiatively driven wind, affects the type and light curve of the supernova, and 2) the interaction of the outgoing supernova shock with regions of increasing ρr3 in the stellar mantle. One conclusion is that Type II-L supernovae may occur in mass exchanging binaries very similar to the one that produced SN 1993J, but with slightly larger initial separations and residual hydrogen envelopes (∼1 M⊙ and radius ∼ several AU). The shock interaction, on the other hand, has important implications for the formation of black holes in explosions that are, near peak light, observationally indistinguishable from ordinary Type II-p and Ib supernovae.

Some Generalities

There is broad agreement regarding the qualitative evolution of single stars sufficiently massive to ignite carbon burning non-degenerately (e.g., Woosley & Weaver 1986; Weaver & Woosley 1993; Nomoto & Hashimoto 1986, 1988). Given the usual, relevant caveats about the treatment of convective mixing, convective overshoot, and semiconvection, it is agreed that stars of approximately 8 to 12 M⊙(±1 M⊙ depending upon initial helium abundance and convective parameters) will not proceed to silicon burning in hydrostatic equilibrium, but will stop prior to central neon ignition and experience a complicated subsequent evolution in which degenerate flashes play an important role.