Brown dwarfs started out the same as ordinary stars, collapsing from giant nebulas of dust and gas. Most brown dwarfs are not quite massive enough to sustain a nuclear fusion reaction at their cores. Brown dwarfs, therefore, are transitional objects, standing between stars and giant gas planets. The mass of a brown dwarf can range from 13 to 90 times the mass of the planet Jupiter, or up to about a tenth the mass of the sun.
(Image: © by Karl Tate, Infographics Artist)