The effect of diffusion on prenova evolution - CNO-enriched envelopes

Abstract

The authors have investigated the effect of diffusion at the core-envelope boundary of a 1.25 M_sun; C-O white dwarf with a 10<SUP>-5</SUP>M_sun; H-rich envelope (with Z = 0.03), a typical nova progenitor. The diffusion equations, which include concentration, pressure, and thermal terms, were solved along with the evolution equations for a mixture of three gases: H, He, and a third component, representative of all CNO elements present. Several models with different initial luminosities were evolved until a thermonuclear runaway developed. The relevance of the results to models of fast novae is discussed.