NASA astronomers discover Sun's star-neighbor icy 'as Earth's North Pole'

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NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope have discovered a new neighbour to the Earth - a "brown dwarf," which is as cold as earth's North Pole. Images from the space telescopes also pinpointed the object is just 7.2 light years away, making it the fourth closest system to our Sun.

"It is very exciting to discover a new neighbor of our solar system that is so close," posited Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State, in a statement. "In addition, its extreme temperature should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."

Brown dwarfs start their lives like stars, as collapsing balls of gas, but they lack the mass to burn nuclear fuel and radiate starlight.

The newfound coldest brown dwarf, named WISE J085510.83—071442.5, has a chilly temperature between minus 48 to minus 13 degrees Celsius.

Previous record holders for coldest brown dwarfs were about room temperature.

Although it is very close to our solar system, WISE J085510.83—071442.5 is not an appealing destination for human space travel in the distant future, researchers said.

"Any planets that might orbit it would be much too cold to support life as we know it," Luhman said.

NASA points out that brown dwarf is estimated to be 3 to 10 times the mass of Jupiter. With such a low mass, it could be a gas giant similar to Jupiter that was ejected from its star system. But scientists estimate it is probably a brown dwarf rather than a planet since brown dwarfs are known to be fairly common. In case of that, it is one of the least massive brown dwarfs known.

Astronomers knew the object was close to our Sun because the "[it] appeared to move really fast in the WISE data." According to Luhman, the closer a body, the more it appears to move in photos snapped months apart.

"This object appeared to move really fast in the WISE data. That told us it was something special," said Luhman.

WISE was able to detect the brown star as it observed the entire sky twice in infrared light. Being cool objects, brown dwarfs may be invisible when viewed by visible-light telescopes, but their thermal glow stands out in infrared light.
Read more: http://voiceofrussia.com/news/2014_04_27/NASA-astronomers-discover-Suns-star-neighbor-icy-as-Earths-North-Pole-7322/

List of nearest stars and brown dwarfs - Wikipedia, the free ...

en.wikipedia.org/wiki/List_of_nearest_stars‎

Besides the Sun, only three are first-magnitude stars: Alpha Centauri, Sirius, ...... solar neighborhood IV: discovery of the twentieth nearest star, Todd J. Henry, ...

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