Composition influence upon the core mass-luminosity relation and possible implications for the extinction timescales of classical novae

A revised core mass-luminosity relation for shell hydrogen burning on degenerate cores is derived, which takes into account the dependencies on the composition of the nuclear burning shell. Our calculations reveal that, for a specified core mass, the hydrogen burning luminosity will increase with both increasing metallicity (Z) and increasing helium concentration (Y). The derived core mass-luminosity relation is then applied to the case of classical novae, for which shell hydrogen burning is well known to occur in extremely metal-enriched material (e.g., Z ∼ 0.25). For the specific cases of the recent novae GQ Muscae 1983 and V1974 Cygni 1992, it is shown that the envelope masses required to initiate the thermonuclear runaways that define the outbursts exceed the envelope masses below which stable models exist. For this condition, it follows that the remnant envelope masses in the postoutburst stage can be significantly reduced by dynamical instability.