WD J0651+2844 (often abbreviated J0651)
is an eclipsing binary consisting of two white dwarfs.
which have a 13 minute orbital period,
being less than a thousandth of an AU from each other.
Distance determinations to the pair are rough, but they are generally determined
to be on the order of a kpc, one determination close to 1000 pc.
Potential orbital decay from gravitational waves is of research interest.