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		| Paper: | 
		Discovery of the Closest Hot Subdwarf Binary  with White Dwarf Companion | 
	 
	
		| Volume: | 
		469, 18th European White Dwarf Workshop (EUROWD12) | 
	 
	
		| Page: | 
		373 | 
	 
	
		| Authors: | 
		Geier, S.; Marsh, T. R.; Dunlap, B. H.; Barlow, B. N.; Schaffenroth, V.; Ziegerer, E.; Heber, U.; Kupfer, T.; Maxted, P. F. L.; Miszalski, B.; Shporer, A.; Telting, J. H.; Ostensen, R. H.; O'Toole, S. J.; Gänsicke, B. T.; Napiwotzki, R. | 
	 
	
	
		| Abstract: | 
		We report the discovery of an extremely close, eclipsing binary system. A white dwarf is orbited by a core He-burning compact hot subdwarf star with a period as short as ≃ 0.04987 d making this system the most compact hot subdwarf binary discovered so far. The subdwarf will start to transfer helium-rich material on short timescales of less than 50 Myr. The ignition of He-burning at the surface may trigger carbon-burning in the core although the WD is less massive than the Chandrasekhar limit (> 0.74 M☉) making this binary a possible progenitor candidate for a supernova type Ia event. | 
	 
	
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