Merging White Dwarfs
Smithsonian scientists and colleagues are discovering extremely low mass white dwarfs in extremely close pairs. In the system called J0651, for example, a pair of Earth-sized white dwarfs, separated by a third of the Earth-Moon distance, go around each other every 12.75 minutes. This system is a gravitational wave source 10,000 times stronger than the Hulse-Taylor pulsar; the white dwarfs will merge and possibly explode as a supernova in about 1 million years.
Warren Brown, Mukremin Kilic, Scott Kenyon