Supernovae and Stellar Mass Loss

Abstract

AbstractType I supernovae can be modeled as the carbon deflagration of white dwarfs and Type II supernovae as the explosions of massive stars with hydrogen envelopes. The massive stars at the ends of their lives are expected to be red supergiants, which are observed to have slow, dense winds. The interaction of the supernova kinetic energy and radiation with the circumstellar gas gives rise to observational phenomena at a range of wavelengths. Additional phenomena, such as a scattered light echo, are predicted. While the light from a Type II supernova near maximum light is probably from energy deposited in the initial explosion, there is now good evidence that the radioactive decay of 56Co powers the emission at late times. It was been noted that the explosions of massive stars without hydrogen envelopes would be quite unlike normal Type II supernovae. There is now good evidence for such explosions – SN1985f and the class of peculiar Type I supernovae. It is suggested that these supernovae be called Type III with the spectroscopic definition of a) no H lines and b) broad [01] lines at late times. That not all very massive star explosions are of this type is indicated by SN1961v, which was probably a very massive explosion, but in which hydrogen was present.