On the origin of white dwarfs with carbon-dominated atmospheres: the case of H1504+65

Abstract

We explore different evolutionary scenarios to explain the helium deficiency observed in H1504+65, the most massive known PG1159 star. We concentrate mainly on the possibility that this star could be the result of mass loss shortly after the born-again and during the subsequent evolution through the [WCL] stage. This possibility is sustained by recent observational evidence of extensive mass-loss events in Sakurai's object and is in line with the recent finding that such mass losses give rise to PG1159 models with thin helium-rich envelopes and large rates of period change, as demanded by the pulsating star PG1159-035. We compute the post born again evolution of massive sequences by taking into account different mass-loss rate histories. Our results show that stationary winds during the post-born-again evolution fail to remove completely the helium-rich envelope so as to explain the helium deficiency observed in H1504+65. Stationary winds during the Sakurai and [WCL] stages only remove at most half of the envelope surviving the violent hydrogen burning during the born-again phase. In view of our results, the recently suggested evolutionary connection born-again stars --> H1504+65 --> white dwarfs with carbon-rich atmospheres is difficult to sustain unless the whole helium-rich envelope could be ejected by non-stationary mass-loss episodes during the Sakurai stage.

arXiv comment5 pages, 2 figures. To be published in Astronomy & Astrophysics

References in corpus (11)

• The Element Abundances in Bare Planetary Nebula Central Stars and the Shell Burning in AGB Stars
• The formation and evolution of hydrogen-deficient post-AGB white dwarfs: the emerging chemical profile and the expectations for the PG1159-DB-DQ evolutionary connection
• Rare White dwarf stars with carbon atmospheres
• Evolution on the AGB and beyond: On the formation of H-deficient post-AGB stars
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• Hot DQ White Dwarfs: Something Different
• Chandra and FUSE spectroscopy of the hot bare stellar core H1504+65
• The onset of photoionization in Sakurai's Object (V4334 Sgr)
• The temporal changes of the pulsational periods of the pre-white dwarf PG 1159-035
• Evidence of thin helium envelopes in PG1159 stars
• High-gravity central stars

Cited by in corpus (4)

• Evolutionary and pulsational properties of white dwarf stars
• New cooling sequences for old white dwarfs
• New evolutionary sequences for hot H-deficient white dwarfs on the basis of a full account of progenitor evolution
• Variability in Hot Carbon-Dominated Atmosphere (hot DQ) White Dwarfs: Rapid Rotation?