THE EVOLUTION OF MASSIVE STARS INCLUDING MASS-LOSS - PRESUPERNOVA MODELS AND EXPLOSION

The evolution of massive stars of 35, 40, 60, and 85 M., is followed through all stages of nuclear burning to the point of iron core collapse. Critical nuclear reaction and mass-loss rates are varied. Efficient mass loss during the Wolf-Rayet stage is likely to lead to final masses as small as 4 M.. Indeed for a reasonable parameterization of the mass loss, there may be convergence of all Wolf-Rayet stars, both single and in binaries, to a narrow band of small final masses. Our representative model, a 4.25 M., Wolf-Rayet presupernova derived from a 60 M. star, is followed through a simulated explosion and its explosive nucleosynthesis and light curve determined. Its properties are similar to those observed in Type Ib supernovae. The effects of the initial mass and mass loss on the presupernova structure of small mass Wolf-Rayet models is also explored. We find that important properties of the presupernova star and its explosion can only be obtained by following the complete evolution starting on the main sequence. For example, the model examined differs substantially from a 4.25 M. helium core evolved at constant mass using the same physics.