A Model for the Outbursts of the Recurrent Nova RS Ophiuchi

A model is presented for the outbursts of the recurrent nova RS Ophiuchi. The known observational constraints are reviewed, and difficulties with possible alternative models for these outbursts are discussed. It is demonstrated, specifically, that the high accretion rate demanded to reconstitute a sufficient envelope to trigger a thermonuclear runaway on the short recurrence time scale for RS Oph implies a luminosity and effective temperature which are incompatible with observations of the system at quiescence. The model proposed here involves an episodic accretion event and the direct impact of the accretion stream with the secondary, which is assumed to be an expanded main-sequence star. The model is shown to be consistent both with all existing observations and with the similarities and differences of RS Oph and T CrB both in and out of outburst.