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		| Paper: | 
		M31N 2008-12a — The Remarkable Recurrent Nova in M31 | 
	 
	
		| Volume: | 
		509, 20th European Workshop on White Dwarfs (EuroWD16) | 
	 
	
		| Page: | 
		515 | 
	 
	
		| Authors: | 
		Darnley, M. J. | 
	 
	
	
		| Abstract: | 
		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 M☉) and high mass accretion rate (∼1.6×10–7 M☉ yr–1).  Such a high accretion rate appears to be provided by the stellar wind of a red giant companion.  Deep Hα 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. | 
	 
	
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