ASTRONOMERS have spotted a star that is no hotter than a pizza oven.
The brown dwarf, called 2MASS 0415-0935, was discovered in 2001, but researchers have only now taken its temperature. Frederick Vrba of the US Naval Observatory鈥檚 Flagstaff Station in Arizona and his team first measured the star鈥檚 distance by observing how much it appears to move against the background of more distant stars as the Earth goes around the Sun. Knowing that it鈥檚 19 light years from Earth, as well as its infrared brightness and diameter (all brown dwarfs are about the same size), enabled the researchers to work out how hot the surface must be.
They reported the answer at the American Astronomical Society meeting in Seattle last week. While our Sun has a surface temperature of about 6000 K, this dingy dwarf is only around 680 K, making it the coldest star ever found. At such a low temperature, it would look not brown, but black.
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