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Full evolution of low-mass white dwarfs with helium and oxygen cores.

Authors :
Panei, J. A.
Althaus, L. G.
Chen, X.
Han, Z.
Source :
Monthly Notices of the Royal Astronomical Society. 12/1/2007, Vol. 382 Issue 2, p779-792. 14p. 7 Charts, 17 Graphs.
Publication Year :
2007

Abstract

We study the full evolution of low-mass white dwarfs with helium and oxygen cores. We revisit the age dichotomy observed in many white dwarf companions to millisecond pulsar on the basis of white dwarf configurations derived from binary evolution computations. We evolve 11 dwarf sequences for helium cores with final masses of 0.1604, 0.1869, 0.2026, 0.2495, 0.3056, 0.3333, 0.3515, 0.3844, 0.3986, 0.4160 and . In addition, we compute the evolution of five sequences for oxygen cores with final masses of 0.3515, 0.3844, 0.3986, 0.4160 and . A metallicity of is assumed. Gravitational settling, chemical and thermal diffusion are accounted for during the white dwarf regime. Our study reinforces the result that diffusion processes are a key ingredient in explaining the observed age and envelope dichotomy in low-mass helium-core white dwarfs, a conclusion we arrived at earlier on the basis of a simplified treatment for the binary evolution of progenitor stars. We determine the mass threshold where the age dichotomy occurs. For the oxygen white dwarf sequences, we report the occurrence of diffusion-induced, hydrogen-shell flashes, which, as in the case of their helium counterparts, strongly influence the late stages of white dwarf cooling. Finally, we present our results as a set of white dwarf mass–radius relations for helium and oxygen cores. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00358711
Volume :
382
Issue :
2
Database :
Academic Search Index
Journal :
Monthly Notices of the Royal Astronomical Society
Publication Type :
Academic Journal
Accession number :
27550580
Full Text :
https://doi.org/10.1111/j.1365-2966.2007.12400.x