Brown Dwarf Star Not Hot Enough to Boil Water

In a new discovery that blurs the lines between stars and planets, astronomers at the University of Hawaii have found the coldest brown dwarf star yet, 75 light years from Earth. Surface temperatures of the star are only around 206 degrees F (or 97 degrees C). Brown dwarfs are sometimes called "failed stars" because they have the chemical properties of stars, but not enough mass to ignite nuclear fusion at their cores. The star, named CFBDSIR 1458 10b (and shown below in an artist's interpretation), is part of a binary system in close orbit with another brown dwarf star.

The star has an estimated mass of only about 6 to 15 times that of Jupiter, and is the smaller and dimmer of the pair of binary stars. The star is so cold that it may even have a watery atmosphere with clouds. Though Jupiter is very cold, with surface temperatures around -236 degrees F, there have been "hot Jupiters" found that have surface temperatures up to 1000 degrees F. But the size of CFBDSIR 1458 10b is what classifies it as a star.

Study leader Michael Liu, astronomer at the University of Hawaii said, "Over the years there has been steady but slow progress in pushing the boundaries of finding the coldest stars. But with this latest discovery we have made a big leap forward—besting the previous record holder by at least 150 Kelvin [270 degrees F, or 150 degrees C]."

The faint infrared signature of the star was seen from the W.M Keck Observatory and the Canada-France-Hawaii Telescope, which are both located on the summit of Mauna Kea in Hawaii. But the star may not keep the title of "coldest" for very long. Astronomers with NASA's Spitzer Space Telescope are now trying to confirm another cold brown dwarf that has surface temperatures as low as 86 degrees F.

[via National Geographic]