The Way To a Double Degenerate: $\sim15-20$ per cent of $1M_{\odot} \le   M \le 8M_{\odot}$ Stars have a $M>1M_{\odot}$ Companion
  We find that $\sim 15-20$ per cent of A-type stars or red giants are bound with a massive companion ($M_{\rm secondary} > 1M_{\odot}$) in an intermediate wide orbit ($0.5<P<5000\mbox{ yr}$). These massive binaries are expected to form wide-orbit, double-degenerate systems (WODDs) within $\lesssim10\mbox{ Gyr}$ implying that $\sim10$ per cent of white dwarfs (WDs) are expected to be part of a WODD with a lighter WD companion. These findings are based on an analysis of previous adaptive optics observations of A-type stars and radial velocity measurements of red giants and shed light on the claimed discrepancy between the seemingly high multiplicity function of stars and the rather low number of detected double degenerates. We expect that GAIA will find $\sim 10$ new WODDs within $20\mbox{ pc}$ from the sun. These results put a stringent constraint on the collision model of type Ia supernovae in which triple stellar systems that include a WODD as the inner binary are required to be abundant. 
Ygal Klein and Boaz Katz
astro-ph.SR