NASA discovers 6 brown dwarf stars 9 to 40 light-years from our Sun

The Extinction Protocol

August 24, 2011 – SPACE – Scientists using data from NASA’s Wide-field Infrared Survey Explorer (WISE) have discovered six “Y dwarfs”– star-like bodies with temperatures as cool as the human body. This artist’s conception illustrates what a “Y dwarf” might look like. Y dwarfs are the coldest star-like bodies known, with temperatures that can be even cooler than the human body. Astronomers hunted these dark orbs for more than a decade without success. When viewed with a visible-light telescope, they are nearly impossible to see. WISE’s infrared vision allowed the telescope to finally spot the faint glow of a half dozen Y dwarfs relatively close to our sun, within a distance of about 40 light-years. “WISE scanned the entire sky for these and other objects, and was able to spot their feeble light with its highly sensitive infrared vision,” says Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. The Y’s are the coldest members of the brown dwarf family. Brown dwarfs are sometimes referred to as “failed” stars. They are too low in mass to fuse atoms at their cores and thus don’t burn with the fires that keep stars like our sun shining steadily for billions of years. Instead, these objects cool and fade with time, until what little light they do emit is at infrared wavelengths. The atmospheres of brown dwarfs are similar to those of gas giant planets like Jupiter, but they are easier to observe because they are alone in space, away from the blinding light of a parent star. So far, WISE data have revealed 100 new brown dwarfs. Of these, six are classified as cool Y’s. One of the Y dwarfs, called WISE 1828+2650, is the record holder for the coldest brown dwarf with an estimated atmospheric temperature cooler than room temperature, or less than 80 degrees Fahrenheit (25 degrees Celsius). The Y dwarfs are in our sun’s neighborhood, from approximately nine to 40 light-years away. The Y dwarf approximately nine light-years away, WISE 1541-2250, may become the seventh closest star system, bumping Ross 154 back to eighth. By comparison, the star closest to our solar system, Proxima Centauri, is about four light-years away. “Finding brown dwarfs near our Sun is like discovering there’s a hidden house on your block that you didn’t know about,” says Michael Cushing, a WISE team member at JPL. “It’s thrilling to me to know we’ve got neighbors out there yet to be discovered. With WISE, we may even find a brown dwarf closer to us than our closest known star.” –NASA