Chandra data (above, graph) from observations of RX J0806.3+1527 (or J0806), show that
its X-ray intensity varies with a period of 321.5 seconds. This implies that J0806 is
a binary star system where two white dwarf stars are orbiting each other (above, illustration)
approximately every 5 minutes.

The short orbital period implies that the stars are only about 50,000 miles apart, a fifth of the
distance from the Earth to the Moon, and are moving in excess of a million miles per hour.
According to Einstein's General Theory of Relativity, such a system should produce
gravitational waves - ripples in space-time - that carry energy away from the system
at the speed of light.

Energy loss by gravitational waves will cause the stars to move closer together. X-ray
and optical observations indicate that the orbital period of this system is decreasing by
1.2 milliseconds every year, which means that the stars are moving closer together at a
rate of about 2 feet per day.