Formation and Evolution of Hydrogen-Deficient post-AGB White Dwarfs

ALTHAUS, L.; PANEI, J.; CÓRSICO, A.; GARCÍA-BERRO, E.; SCÓCCOLA, C.

Kiel, Alemania

Workshop; 14th European Workshop on White Dwarfs; 2004

We explore the formation and evolution of hydrogen-deficient post-AGB white dwarf stars by computing the complete evolution of an initially 2.7MSolar star from the ZAMS through the thermally pulsing and mass-loss phases, the born-again stage to the white dwarf stage. A time-dependent scheme for the simultaneous treatment of abundance changes caused by nuclear reactions, diffusive overshooting, salt fingers and convection is considered. In addition, microscopic element diffusion is taken into account during the white dwarf evolution. Relevant aspects for PG 1159 stars and DB evolution are studied in the frame of these new evolutionary models. The scope of the calculations is extended to the domain of the helium-rich, carbon-contaminated DQ white dwarfs with the aim of exploring the plausibility of the evolutionary connection PG 1159−DB−DQ.