Article Posted on : - Nov 10, 2010

The green dot in the middle of this image is the first ultra-cool brown dwarf discovered by WISE. Photo: NASA/JPL-Caltech/UCLA

PASADENA (BNS): NASA's Wide-field Infrared Survey Explorer (WISE) has captured images of its first ultra-cool brown dwarf, which was floating all alone in space.

The tiny, ultra-cold star appears green in colour due to the presence of methane in the atmosphere.

The explorer is on a mission to scan whole sky in infrared light. Till now, millions of images has been sent to Earth, in which infrared light of different wavelengths is color-coded in the images.

"The brown dwarfs jump out at you like big, fat, green emeralds," Amy Mainzer, the deputy project scientist of WISE at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a press release.

Brown dwarfs are usually made up of gas filled with methane, hydrogen sulfide, and ammonia.

"If you could bottle up a gallon of this object's atmosphere and bring it back to Earth, smelling it wouldn't kill you, but it would stink pretty badly -- like rotten eggs with a hint of ammonia," Mainzer added.

Brown dwarfs have masses somewhere between those of a star and a planet. They start out like stars as collapsing balls of gas, but they lack the mass to fuse atoms together at their core and shine with starlight. As time goes on, these lightweights cool off, until they can only be seen in infrared light.

According to the astronomers, many such objects may be lurking in the neighborhood of our sun, but only few have been discovered so far. WISE is expected to find hundreds, including the coolest and closest of all.

WISE's new brown dwarf is named WISEPC J045853.90+643451.9 for its location in the sky. It is estimated to be 18 to 30 light-years away and is one of the coolest brown dwarfs known, with a temperature of about 600 Kelvin, or 620 degrees Fahrenheit.

The fact that this brown dwarf jumped out of the data so easily and so quickly -- it was spotted 57 days into the survey mission -- indicates that WISE will discover many more star soon.