Pulsational Pair Instability Supernovae
The final evolution of stars in the mass range 70 140 solar masses is explored. Depending upon their mass loss history and rotation rates, these stars will end their lives as pulsational pair instability supernovae producing a great variety of observational transients with total durations ranging from weeks to millennia and luminosities from 10${41} to over 10${44} erg s$ 1} No non rotating model radiates more than $5 \times 10^{50} erg of light or has a kinetic energy exceeding $5 \times 10^{51} erg, but greater energies are possible, in principle, in magnetar powered explosions which are explored. Many events resemble Type Ibn, Icn, and IIn supernovae, and some potential observational counterparts are mentioned. Some PPISN can exist in a dormant state for extended periods, producing explosions millennia after their first violent pulse. These dormant supernovae contain bright Wolf Rayet stars, possibly embedded in bright x ray and radio sources. The relevance of PPISN to supernova impostors like Eta Carinae, to super luminous supernovae, and to sources of gravitational radiation is discussed. No black holes between 52 and 133 solar masses are expected from stellar evolution in close binaries.