http://arxiv.org/abs/1611.01301
M31N 2008-12a is a remarkable recurrent nova within the Andromeda Galaxy. With eleven eruptions now identified, including eight in the past eight years, the system exhibits a recurrence period of one year, and possibly just six months. This short inter eruption period is driven by the combination of a high mass white dwarf ($1.38\,\mathrm{M}_\odot$) and high mass accretion rate ($\sim1.6\times10^{-7}\,\mathrm{M}_\odot\,\mathrm{yr}^{-1}$). Such a high accretion rate appears to be provided by the stellar wind of a red giant companion. Deep H$\alpha$ observations have revealed the presence of a vastly extended nebula around the system, which could be the `super-remnant’ of many thousands of past eruptions. With a prediction of the white dwarf reaching the Chandrasekhar mass in less than a mega-year, M31N 2008-12a has become the leading pre-explosion type Ia supernova candidate. The 2016 eruption – to be the twelfth detected eruption – is expected imminently, and a vast array of follow-up observations are already planned.
M. Darnley
Mon, 7 Nov 16
42/48
Comments: 6 pages, 1 figure, to appear in the proceedings of the 20th European Workshop on White Dwarfs (EuroWD16) held July 25-29th, 2016 at the University of Warwick, United Kingdom