Discovery of the closest hot subdwarf binary with white dwarf companion
  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 $\simeq0.04987 {\rm d}$ 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 $50 {\rm Myr}$. 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 ($>0.74\,M_{\rm \odot}$) making this binary a possible progenitor candidate for a supernova type Ia event. 
S. Geier, T. R. Marsh, B. H. Dunlap, B. N. Barlow, V. Schaffenroth, E.   Ziegerer, U. Heber, T. Kupfer, P. F. L. Maxted, B. ...
astro-ph.SR