recurrent nova

A recurrent nova is a nova that repeats. They qualify as cataclysmic variable stars. They have been observed, generally repeating at rough intervals from about 1 to 100 years, the intervals of each such novae showing a variation of generally 10% or less. About ten recurrent novae are known in the Milky Way. Others are known in Local Group galaxies such as Andromeda and Triangulum Galaxy, and also in Messier 81. Observed recurrent novae have been somewhat less bright than typical for non-recurrent (aka, classical novae). Some prominent Milky-Way examples:

In a general way, the mechanism of a recurrent nova is presumed to be similar to that of a nova or Type Ia supernova: a white dwarf accreting material from a binary companion, likely a giant star, those being stars much of whose volume is very tenuous and easily drawn away by a companion's gravity. An explosion occurs after a certain amount of such accretion. The triggering mechanisms and conditions that produce each of these three types of events are of research interest. I've seen it said that a higher accretion rate leads to small explosions that recur. To the degree that recurrent novae are like these similar events, they offer the big advantage that they can be predicted, allowing added observation leading up to the event.

I have also seen it asserted that classical novae are essentially recurrent novae with periods so long that we don't observe the recurrences. Possibly this means that recurrency periods form a continuum with no actual maximum, a nova that never repeats being merely at tail end of that continuum.

I've also seen the notion that recurrent novae are, or can be Type Ia supernova progenitors.