NASA's Infrared Explorer Spots a Room-Temperature Brown Dwarf, the Coldest Star Ever Found

Y Dwarf Y dwarfs are the coldest star-like bodies known, with temperatures that can be even cooler than the human body. NASA's Wide-field Infrared Survey Explorer just found them for the first time. NASA/JPL-Caltech

PopSci - Using NASA’s Wide-field Infrared Survey Explorer telescope, astronomers have finally spotted a collection of ultra-cool brown dwarfs they have been hunting for more than a decade. These tepid almost-star orbs are nearly impossible to see with a normal telescope, but WISE’s infrared vision was able to pick them out.

The coldest one ever found is about room temperature, with a reading of less than 80 degrees. That brown dwarf, a Y-class dwarf called WISE 1828+2650, is the green dot in the image below.

Brown dwarfs, sometimes called failed stars, got their name because astronomers didn’t know what color they would have in the visible spectrum. Some classes of brown dwarfs would actually look more reddish than brown, according to NASA. Scientists don’t know what color a Y dwarf would actually be if it was visible — the image above is purple for artistic reasons.

They start out the same way as a normal star, collapsing under their own weight. But they don’t have enough mass to ignite thermonuclear fusion at their cores, so they cool and fade after their birth. Their atmospheres are more like Jupiter’s than a star’s, and this makes them very hard to find in deep space.           More