CLOSE AND COLD NEIGHBOUR OF OUR SUN DISCOVERED

This artist's conception shows the object named WISE J085510.83-071442.5, the coldest known brown dwarf. This cool star-like body is as frosty as the North Pole. It is also the fourth closest system to our sun, at 7.2 light-years from Earth. Image Credit: Penn State University/NASA/JPL-Caltech.

ByANDY FLEMING

NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope have discovered what appears to be the coldest "brown dwarf" known - a dim, star-like body that, surprisingly, is as frosty as Earth's North Pole.

 Images from the space telescopes also pinpointed the object's distance to 7.2 light-years away, earning it the title for fourth closest system to our sun. The closest system, a trio of stars, is Alpha Centauri, at about 4 light-years away.

"It's very exciting to discover a new neighbour of our solar system that is so close," said Kevin Luhman, an astronomer at Pennsylvania State University's Centre for Exoplanets and Habitable Worlds, University Park.

 "And given its extreme temperature, it 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 is named WISE J085510.83-071442.5. It has a chilly temperature between minus 48 to minus 13 degrees Celsius. Previous record holders for coldest brown dwarfs, also found by WISE and Spitzer, were about room temperature.