Theoretical decay rates of cataclysmic variable eruptions

The relation between outburst decay time and binary period in dwarf novae is examined with time-dependent α-disc evolution models. Outbursts caused by variations in the mass transfer rate into the disc exhibit the same dependence on period as is observed, provided the mass transfer profile decays on a faster time-scale than the viscous evolution time-scale of the disc, and that α is approximately equal to 1. The relation is a consequence of the increase in the time taken for matter to diffuse through larger discs in longer period systems. (author)