NASA space telescope data has revealed the third-closest star system yet spotted, astronomers report, a pair of dim "brown dwarf" stars.

Discovered in a sky map made by the space agency's Wide-field Infrared Survey Explorer (WISE) satellite, the system has been dubbed "WISE J104915.57-531906," the closest stars discovered near Earth since 1916. The two dim, small stars orbit each other some 6.5 light years (roughly 38.4 trillion miles) away from Earth.

"So close that Earth's television transmissions from 2006 are now arriving there," said discoverer Kevin Luhman of Penn State, in a statement. "It was a lot of detective work."

The newly-discovered stars are just a bit farther away than the 2nd-closest star to Earth, Barnard's Star, some 6 light-years distant. The closest star system is Alpha Centauri, three stars only about 4.1 light years away. Brown dwarfs are large, roughly 13 to 80 times heavier than Jupiter, but not massive enough for their gravity to spark the fusion of hydrogen atoms that powers larger stars such as our sun. Instead the two brown dwarfs most likely resemble Jupiter in their appearance, Luhman concludes, rather than our sun.

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This diagram illustrates the locations of the star systems that are closest to the sun.(Photo: Janella Williams, Penn State)

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A report on the discovery will be published in the journal Astrophysical Journal Letters. Luhman speculates that future space explorers will visit the brown dwarfs because of the closeness, in astronomical terms, and that telescopes such as NASA's upcoming James Webb Space Telescope will eyeball the system, looking for possible planets accompanying the brown dwarfs.

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Quelle: USA Today

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