On the formation of hot DQ white dwarfs

Abstract

We present the first full evolutionary calculations aimed at exploring the origin of hot DQ white dwarfs. These calculations consistently cover the whole evolution from the born-again stage to the white dwarf cooling track. Our calculations provide strong support to the diffusive/convective-mixing picture for the formation of hot DQs. We find that the hot DQ stage is a short-lived stage and that the range of effective temperatures where hot DQ stars are found can be accounted for by different masses of residual helium and/or different initial stellar masses. In the frame of this scenario, a correlation between the effective temperature and the surface carbon abundance in DQs should be expected, with the largest carbon abundances expected in the hottest DQs. From our calculations, we suggest that most of the hot DQs could be the cooler descendants of some PG1159 stars characterized by He-rich envelopes markedly smaller than those predicted by the standard theory of stellar evolution. At least for one hot DQ, the high-gravity white dwarf SDSS J142625.70+575218.4, an evolutionary link between this star and the massive PG1159 star H1504+65 is plausible.

4 pages, 2 figures. To be published in The Astrophysical Journal Letters

References in corpus (9)

• Updated Electron-Conduction Opacities: The Impact on Low-Mass Stellar Models
• Pulsating White Dwarf Stars and Precision Asteroseismology
• Rare White dwarf stars with carbon atmospheres
• Hot DQ White Dwarfs: Something Different
• Asteroseismological measurements on PG 1159-035, the prototype of the GW Vir variable stars
• The temporal changes of the pulsational periods of the pre-white dwarf PG 1159-035
• SDSS J142625.71+575218.3: The First Pulsating White Dwarf with a Large Detectable Magnetic Field
• Evidence of thin helium envelopes in PG1159 stars
• SDSSJ212531.92-010745.9 - the first definite PG1159 close binary system

Cited by in corpus (6)

• Magnetized Moving Mesh Merger of a Carbon-Oxygen White Dwarf Binary
• Buoyant crystals halt the cooling of white dwarf stars
• On the Spectral Evolution of Hot White Dwarf Stars. III. The PG 1159$-$DO$-$DB$-$DQ Evolutionary Channel Revisited
• The spectral evolution of white dwarfs: where do we stand?
• Follow-up Studies of the Pulsating Magnetic White Dwarf SDSS J142625.71+575218.3
• A hot white dwarf merger remnant revealed by an ultraviolet detection of carbon