Stellar Evolution. V. The Evolution of a 15 M_{sun} Star from the Main Sequence Through Core Helium

Abstract

view Abstract Citations (172) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Stellar Evolution. V. The Evolution of a 15 M_{sun} Star from the Main Sequence Through Core Helium Iben, Icko, Jr. Abstract The evolution of a 15 Mo star of population I composition is described and compared with the evolution of less massive stars presented in earlier papers of this series and with the evolution of a 15.6 Mo star calculated by Hayashi and his collaborators. During the core hydrogen-burning phase, the evolution of the 15 Mo star is qualitatively almost identical with the evolution of the lighter stars. In the 15 Mo star, during the phases of over-all contraction and hydrogen-shell development, matter becomes unstable against convection in a large region extending outward from the developing shell. The redistribution of composition variables in this region has an effect on the surface abundances when the star reaches the red-giant tip. Core helium burning in the 15 Afo star occurs at much higher surface temperatures than is the case with less massive stars and requires a significantly longer time interval than that found for the 15.6 Mo star. Contrary to the results of Hayashi and Cameron, the surface temperature of the 15 Mo star decreases throughout the core helium-burning phase. Passage across the observational Cepheid strip and motion along the red-giant branch do not occur until near the end of the core helium-burning phase of the 15 Mo star. Publication: The Astrophysical Journal Pub Date: February 1966 DOI: 10.1086/148530 Bibcode: 1966ApJ...143..516I full text sources ADS | Related Materials (6) Part 1: 1965ApJ...141..993I Part 2: 1965ApJ...142.1447I Part 3: 1966ApJ...143..483I Part 4: 1966ApJ...143..505I Part 6: 1967ApJ...147..624I Part 7: 1967ApJ...147..650I