Two white dwarf stars orbiting each other every five minutes, confirmed

These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.

Yousuf Khan

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SPACE.com -- Fastest Orbiting Stars Circle Each Other in Mere Minutes
"After a decade of mystery, astronomers have now shown that a pair of
white dwarf stars spin around each other in just 5.4 minutes, making
them the fastest-orbiting and tightest binary star system ever found,
the researchers claim.

The record-setting stellar duo, known as HM Cancri or RX J0806.3+1527,
offer challenges in explaining how such a system might form. The
super-quick stars may also present a great future test-bed for detecting
gravitational waves, which are elusive ripples in space-time."
http://www.space.com/scienceastronom...rs-100309.html