Unraveling Brown Dwarf Origins

Brown dwarfs, which occupy a fuzzy gap in mass between stars and planets, appear to be common both in the solar neighborhood and in star-forming regions. Their origin is a topic of significant current interest and debate. Some astronomers have suggested that brown dwarfs are stellar embryos, ejected from newborn multiple star systems. Others argue that they form in the same manner as stars, through fragmentation and collapse of interstellar clouds. Observations of young brown dwarfs may help distinguish among different scenarios for their formation. The recent discovery that many of them harbor accreting disks of gas and dust points to a similar infancy for brown dwarfs and Sun-like stars. Future infrared and millimeter observations, from telescopes on the ground and in space, could provide more definitive tests.