Accrete, Accrete, Accrete... Bang! (and repeat): The Remarkable Recurrent Novae

Abstract

All novae recur, but only a handful have been observed in eruption more than once. These systems, the recurrent novae (RNe), are among the most extreme examples of novae. RNe have long been thought of as potential type Ia supernova progenitors, and their claim to this 'accolade' has recently been strengthened. In this short review RNe will be presented within the framework of the maximum magnitude-rate of decline (MMRD) phase-space. Recent work integrating He-flashes into nova models, and the subsequent growth of the white dwarf, will be explored. This review also presents an overview of the Galactic and extragalactic populations of RNe, including the newly identified 'rapid recurrent nova' subset - those with recurrence periods of ten years, or less. The most exciting nova system yet discovered - M31N 2008-12a, with its annual eruptions and vast nova super-remnant, is introduced. Throughout, open questions regarding RNe, and some of the expected challenges and opportunities that the near future will bring are addressed.