The fate of a WD accreting H-rich material at high accretion rates

Irit Idan*, Nir J. Shaviv, Giora Shaviv

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

We study C/O white dwarfs (WDs) with masses of 1.0-1.4M⊙ accreting solar-composition material at very high accretion rates. We address the secular changes in the WDs, and in particular, the question whether accretion and the thermonuclear runaways result is net accretion or erosion. The present calculation is unique in that it follows a large number of cycles, thus revealing the secular evolution of the WD system. We find that counter to previous studies, accretion does not give rise to steady-state burning. Instead, it produces cyclic thermonuclear runaways of two types. During most of the evolution, many small cycles of hydrogen ignition and burning build a helium layer over the surface of theWD. This He layer gradually thickens and progressively becomes more degenerate. Once a sufficient amount of He has accumulated, several very large helium burning flashes take place and expel the accreted envelope, leaving no net mass accumulation. Thus, the multicycle evolution has a notable effect on the overall behaviour of theWD system - under the assumptions considered, such a scenario will not lead to an accretion-induced collapse, nor will it produce a Type Ia supernova, unless a major new physical process is found.

Original languageAmerican English
Pages (from-to)2884-2892
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume433
Issue number4
DOIs
StatePublished - Aug 2013

Keywords

  • Cataclysmic variables - supernovae: general
  • Novae

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