Space telescope picks out 'green dot' in a field of stars - a tiny star whose surface is cooler than human blood




A £200 million Nasa space telescope has picked out a star with a surface cooler than a human body - at just 25 degrees celsius, it's around room temperature.



It's the coldest 'brown dwarf' ever detected outside the solar system.



Like other brown dwarfs, it began life like a star - before it collapsed under its own weight into a dense ball of gas. But unlike a star, it didn't 'ignite'.

The green dot shines out against the background because the star is so cold - its surface is room temperature, colder than a human bloodstream. It's located in the constellation Lyra. The blue dots are a mix of stars and galaxies

But, unlike a star, it didn't have enough mass to fuse atoms at its core, and shine steadily with starlight.

Instead, it has continued to cool and fade since its birth, and now gives off only a feeble amount of infrared light.

Ever since brown dwarfs first were discovered in 1995, astronomers have been trying to find new record holders for the coldest brown dwarfs - the objects are seen as valuable laboratories to help us understand the atmospheres of extrasolar planets with Earth-like temperatures.

The mission mapped the entire sky in 2010 with vastly better sensitivity than its predecessors - capturing 560 million stars, galaxies and asteroids. It collected more than 2.7 million images taken in infrared wavelengths

ISE's highly sensitive infrared detectors were able to catch the glow of this object during its two year sky-scan - stitching together an incredible 'sky Atlas' from 2.7 million telescope images which capture the whole sky around us, and pick out details from cold, dusty galaxies, to tiny, distant stars.



Half a billion stars are visible in the 'Atlas', which shows every part of the sky visible from Earth, captured by hi-tech infrared instruments which can pick out dusty and distant objects invisible to many other telescopes.

‘Today, the Wide-field Infrared Survey Explorer, or WISE delivers the fruit of 14 years of effort to the astronomical community,’ said Edward Wright, WISE principal investigator at UCLA, who first began working on the mission with other team members in 1998.

The WISE mission captures a supernova tearing through a distant galaxy in the constellation of Cassiopeia: The central bright cloud of dust is the blast wave moving through interstellar space heating up dust as it goes. The blast wave travels fast -- at an average speed of about 11,000 miles per second. By the time WISE took this image, the blast wave has expanded out to about a distance of 21 light-years from the original explosion

Since it launched in 2009 the £200million infrared telescope, WISE, has been scanning the cosmos with some of the most sophisticated cameras ever deployed in space.

The final image stitches together 18,000 WISE images.



WISE mapped the entire sky in 2010 with vastly better sensitivity than its predecessors. It collected more than 2.7 million images taken at four infrared wavelengths of light, capturing everything from nearby asteroids to distant galaxies.



Since then, the team has been processing more than 15 trillion bytes of returned data. A preliminary release of WISE data, covering the first half of the sky surveyed, was made last April.



‘With the release of the all-sky catalog and atlas, WISE joins the pantheon of great sky surveys that have led to many remarkable discoveries about the universe,’ said Roc Cutri, who leads the WISE data processing and archiving effort at the Infrared and Processing Analysis Center at the California Institute of Technology in Pasadena.