http://www.nature.com/news/astronomer-locates-previously-unseen-neighbor-to-the-sun-1.12592
March 11, 2013 - Nature.com
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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