Review of the Theoretical Changes of Surface Chemistry during Massive Star Evolution

摘要

It is suggested that for main sequence stars, central nuclear processing generally has no effect on surface abundances. Later in the evolution, the newly synthetized elements may be revealed at the stellar surface by processes such as mass loss, convective dredge-up, overshooting, diffusion, and rotational and tidal mixing. Changes of CNO abundances are the most conspicuous and the easiest to observe spectroscopically; abundance ratios like C/N, O/N may undergo changes by more than 100. Surface chemistry is thus a most powerful diagnostics of stellar evolution, model assumptions, and nuclear cross sections.