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double star

'Explosive' double-star systems seen

Cambridge, Mass. -- U.S. astronomers say they've discovered a number of previously unobserved double-star systems, some of them heading toward a spectacularly explosive fate.

The newly identified binary star systems all consist of two white dwarf stars that are on a collision course with each other, reported Wednesday.

A white dwarf is the hot, incredibly dense dead core that remains after a sun-like star blows off its outer layers as it dies.

"These are weird systems -- objects the size of the Earth orbiting each other at a distance less than the radius of the sun," says astronomer Warren Brown of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.