Late Phases of Evolution of a 1.1M[sun] Star Composed of 12C.

Abstract

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Late Phases of Evolution of a 1.1M⊙ Star Composed of 12C. Kutter, G. S. ; Savedoff, M. P. Abstract The late phases of evolution of a 1.1 Mo star, consisting of `2C, are followed. The initial stellar radius exceeds Chandrasekhar's (1939) white dwarf radius by a factor of 60. Xuclear reactions, neutrino losses, and relativistic degeneracy of the electrons are included. Xine hundred ninety-five models have been computed by using an adaptation of the Henyey method. During the first 190 000 yr the star contracts. The temperature rises throughout the star except in the core where, after log Tc has risen to 8.64, cooling results due to neutrino losses. The continuing temperature rise in the outer layers produces a temperature inversion (cf. Vila, S. C. Astrophys. J. 146, 437, 1966) and ignites the carbon (i.e., En> Ep) in an e-degenerate shell at Mr/M* =0.64 and log T=8.76, log p=6.O3. The subsequent evolution is dominated by the nuclear reactions. It occurs on a time scale short relative to the diffusion time (about 1000 yr), but long relative to the free fall time (about 10 sec). Within 130 yr of ignition, the nuclear shell-burning reverses the contraction and 29.4 yr later the total rate of nuclear energy release reaches its maximum, equaling 3 X 108 L o. A convective zone develops that extends to Mr/M* =0.96. As the e degeneracy in the shell-burning region is removed, the star expands (maximum expansion velocity =34cm/sec), cools, and reduces the burning rate and convection. Four hundred years after ignition, the energy loss by p emission again dominates the energy balance throughout the star. The core contracts, but the radius still grows until it is 3.4 times larger than at the point of minimum contraction. Within about 106 yr of the starting model, il~e star reaches a white dwarf configuration. The addition of a H-He envelope to this `2C model and the possibility that these light elements are carried inward by convection may lead to an explosive situation producing mass-ejection. Publication: The Astronomical Journal Pub Date: September 1967 DOI: 10.1086/110327 Bibcode: 1967AJ.....72..811K full text sources ADS |