Evolution to Catastrophe

Abstract

In this chapter describes presupernova evolution. Single stars of zero-age main-sequence (ZAMS) mass up to at least 6 solar masses become white dwarfs that will not explode as supernovae. The evolution of stars of ZAMS mass 6–13 solar masses is exceedingly complex, involving degenerate cores, episodes of dredge-up of matter from their interiors, thermal pulses, off center ignition of neon and oxygen, mass loss, and more. At present, it is difficult to know which of these stars undergo collapse, and perhaps explode and whether they have carbon-oxygen or oxygen-neon-magnesium cores. Stars of ZAMS mass between 13 and about 70 solar masses undergo collapse of their iron cores. In this range, some stars explode by ejecting their envelopes while others may become black holes. More massive stars may undergo thermonuclear explosions owing to pair instabilities in their oxygen cores. A section of the chapter is devoted to the complex effects of rotation on single-star evolution. Another section addresses the equally complex topic of binary-star evolution, which is essential to understanding the origin of Type Ia supernovae and probably of most stripped-envelope supernovae (Types IIb, Ib, and Ic).