Pair-Instability Supernova Models

Abstract

In this chapter presents models of pair-instability supernovae (PISN). During core oxygen burning, models are rendered dynamically unstable by electron-positron pair production in an offcenter shell. The infalling shell compresses and heats the oxygen core to the point of thermonuclear ignition and explosion of (usually) the entire star. The nominal oxygen core masses and zero-age main-sequence (ZAMS) masses for nonrotating, solar-abundance models are 60-130 and 140-260 solar masses, respectively, but these numbers, especially the ZAMS-mass range, depend on rotation, metallicity and mass loss. The ejected mass of radioactive nickel-56 varies from tens of solar masses at the upper end of the mass range to much smaller values at the lower end. The predicted observational features depend strongly on ZAMS mass and on whether or not the hydrogen envelope is retained until the time of explosion. Models of somewhat lower ZAMS mass than those of PISN models undergo pulsations (hence PPISN) induced by pair production that may eject multiple interacting shells; these interactions may themselves produce bright supernova-like displays. The PPISN phase is followed by core collapse or a PISN explosion.