Stellar evolution at high mass with semiconvective mixing according to the Schwarzschild criterion

Abstract

view Abstract Citations (86) References (41) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Stellar evolution at high mass with semiconvective mixing according to the Schwarzschild criterion. Stothers, R. ; Chin, C. -W. Abstract Evolutionary sequences for stellar models with 10, 15, 30, and 60 solar masses, as well as four different initial chemical compositions, are calculated to the end of core helium burning using the Schwarzschild criterion for convection. The results are analyzed in terms of the modifications of interior structure and surface parameters induced by semiconvective mixing as a result of adopting the Schwarzschild criterion. It is found that the main differences from results based on the Ledoux criterion are the great extent of the convectively unstable layers in the intermediate zone and the eventual development of a fully convective zone at the base of the semiconvective one. It is shown that semiconvection develops outside the convective core just after the ZAMS stage for masses greater than 12 solar masses and just before the stage of central hydrogen exhaustion for masses greater than 6 solar masses. The present models are found to be insufficiently hot in comparison with the bulk of observed stable blue supergiants and to predict far too many red supergiants fro the range above 20 solar masses. It is concluded that something is fundamentally wrong with the models, the most likely suspects being the stellar opacities adopted and the neglect of mass loss. Publication: The Astrophysical Journal Pub Date: March 1976 DOI: 10.1086/154191 Bibcode: 1976ApJ...204..472S Keywords: Convective Heat Transfer; Stellar Evolution; Stellar Models; Stellar Structure; Chemical Composition; Helium; Hertzsprung-Russell Diagram; Hydrogen; Nuclear Reactions; Stellar Envelopes; Stellar Mass; Supergiant Stars; Astrophysics full text sources ADS |