WASHINGTON, DC.- White dwarfs are the burned-out cores of stars like our Sun. Astronomers have discovered a pair of white dwarfs spiraling into one another at breakneck speeds. Today, these white dwarfs are so near they make a complete orbit in just 13 minutes, but they are gradually slipping closer together. About 900,000 years from now – a blink of an eye in astronomical time – they will merge and possibly explode as a supernova. By watching the stars converge, scientists will test both Einstein’s general theory of relativity and the origin of some peculiar supernovae. The two white dwarfs are circling at a bracing speed of 370 miles per second (600 km/s), or 180 times faster than the fastest jet on Earth. “I nearly fell out of my chair at the telescope when I saw one star change its speed by a staggering