The conductive propagation of nuclear flames. I. Degenerate C + O and O + Ne + Mg white dwarfs

Francis Timmes, S. E. Woosley

Research output: Contribution to journalArticle

218 Citations (Scopus)

Abstract

The physical properties - speed, width, and density structure - of conductive burning fronts in degenerate carbon-oxygen (C + O) and oxygen-neon-magnesium (O + Ne + Mg) compositions are determined for a grid of initial densities and compositions. Assuming a subsonic, isobaric nuclear flame, these properties are computed by four independent methods : a numerical radiation transport code which includes implicit hydrodynamics ; a moving mesh diffusion code ; an eigenvalue method ; and a quasi-analytical, integral expression. The dependence of the physical properties of the flame on the assumed values of nuclear reaction rates, the nuclear reaction network employed, the thermal conductivity, and the choice of coordinate system are all investigated. The new results have implications for the formation of neutron stars by the accretion-induced collapse (AIC) of a white dwarf and for the production of Type Ia supernovae. The occurrence of AIC is critically dependent on the velocity of the nuclear conductive burning front and the growth rate of hydrodynamic instabilities. However, electron capture in nuclear statistical equilibrium behind the flame causes the density to increase (at constant pressure), restoring the density to its initial value some distance behind the front. There consequently exists a maximum length scale for the development of hydrodynamic instabilities. Treating the expanding area of the turbulent burning region as a fractal whose tile size is identical to the minimum unstable Rayleigh-Taylor wavelength, we find, for all reasonable values of the fractal dimension, that for initial C + O or O + Ne + Mg densities above about 9 × 109 g cm-3 the white dwarf should collapse to a neutron star.

Original languageEnglish (US)
Pages (from-to)649-667
Number of pages19
JournalAstrophysical Journal
Volume396
Issue number2
StatePublished - 1992
Externally publishedYes

Fingerprint

flames
propagation
hydrodynamics
nuclear reactions
neutron stars
fractals
physical property
physical properties
accretion
oxygen
radiation transport
neon
tiles
eigenvalue
thermal conductivity
electron capture
reaction rate
supernovae
magnesium
mesh

Keywords

  • Conduction
  • Nuclear reactions, nucleosynthesis, abundances
  • Stars : neutron
  • White dwarfs

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

The conductive propagation of nuclear flames. I. Degenerate C + O and O + Ne + Mg white dwarfs. / Timmes, Francis; Woosley, S. E.

In: Astrophysical Journal, Vol. 396, No. 2, 1992, p. 649-667.

Research output: Contribution to journalArticle

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