EVOLUTIONARY SEQUENCES OF STELLAR MODELS OF INTERMEDIATE AND HIGH MASS INCLUDING CONVECTIVE CORE OVERSHOOTING

Stellar evolution with parameterized overshooting from the convective core has been studied for the stellar mass range M/M. = 3-30 and for the initial chemical composition range X(e) = 0.650-0.739 (hydrogen) and Z(e) = 0.021-0.044 (metals). Evolutionary sequences run from the zero-age main sequence to the end of core helium burning, but emphasis is placed here on the core helium-burning phase. Convective core overshooting during the previous main-sequence phase leads, in most cases, to a shortening of the blue loop on the H-R diagram that forms when helium is being depleted in the core. On the other hand, convective overshooting from the helium-burning core has the opposite effect. A larger initial metals abundance also tends to shorten the blue loop. In an extreme case the blue loop can be fully suppressed, but in a marginal case the normal trend can be reversed. The fraction of the core helium-burning lifetime that is spent in the blue phase is generally very sensitive to the physical input parameters. Detailed tables and plots of evolutionary tracks on the H-R diagram are provided.