Grids of Evolutionary Models of Massive Stars with Mass Loss and Overshooting. Properties of Wolf-Rayet Stars Sensitive to Overshooting

摘要

In order to establish a reference grid of massive star models, the evolution of stars of initial mass 120, 85, 60, 40, 25, 20, and 15 solar masses is followed from the 0 age sequence to the end of the C-burning phase. An overshooting parameter which reproduces at best the observed main sequence (MS) width as found by Mermilliod and Maeder (1986) for young clusters and associations is chosen. The overshooting, with the extent and the mass loss rates adopted, produces an MS narrowing for O-stars and a large MS widening for early B-type stars. When compared to other sets of models, the results allow the identification of observable properties sensitive to overshooting for a given mass loss. These are the mapping of surface C/N and O/N ratios for stars in the upper HR diagram, the mass limits for red supergiants and WR stars, and the slope of the mass-luminosity relation for WR stars.