March 11, 2013 - Scientific American
When NASA launched the WISE satellite in 2009, astronomers hoped it would be able to spot loads of cool, dim objects known as brown dwarfs. Bigger than a planet, a brown dwarf is not quite a star, either—it is too small to sustain the nuclear fusion reactions that turn hydrogen to helium. But it may burn to some degree, using a heavy isotope of hydrogen called deuterium as fusion fuel.
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