Nucleosynthesis and evolution of massive stars with mass loss and overshooting

The evolution of mass-losing stars that have M(ZAMS)/solar-M in the 50-100 range is examined. The stellar models used in this study include: (1) mass loss formalism for O, Of, and W-R stars; (2) the Roxburgh criterion for the convective core; and (3) a nuclear reaction network of 28 nuclides from H to Si-30 for analysis of energy production and chemical evolution during the H- and He-burning phases. The internal evolution of stars with solar masses of 50, 60, 80, and 100 is described by observing time variations of the stellar and convective core masses, and central temperature and density fluctuation during the H- and He-burning phases; the evolution of the models in the Hertzsprung-Russell diagram is studied. The formation of the chemical abundances in the convective core and surface of the stars is investigated. The composition of the stellar ejecta of the W-R stars is discussed. The data reveal that the computed evolutionary tracks and core and surface abundances correlate well with the observational data.