ABSTRACT
Nova explosions – the observed nuclear incineration of accreted (mostly hydrogen) matter on the surface of white dwarf stars, and subsequent ejection of much of the “ashes” resulting from this explosion – have posed a number of long-standing puzzles regarding both the energetics governing these stellar transients and the composition of the ejecta. The puzzling aspect of the ejecta composition is related to the fact that the observed ejecta abundances are substantially enriched by CNO nuclei (cf., Truran, 1985; Gehrz et al., 1998 and references therein). This is difficult to understand because these nuclei cannot be the result of nuclear burning in the accreted hydrogen envelope prior to ejection – theoretical calculations of nuclear processing during nova outbursts carried out as early as the late 1970s and early 1980s (e.g., Starrfield et al., 1978; Fujimoto, 1982) clearly showed that nuclear processing during the hydrogen burning leading to the nova flash could not account for the observed CNO abundances, which can reach 30% by mass.
