03 February, 1998. Brown dwarfs definitely seem to exist. In addition to the cool body Gliese 229 B (which has a temperature of only 1100 Kelvins and a mass clearly well under the brown dwarf limit of only 0.08 solar masses), several dim candidates have been found in the Pleiades cluster. Planets form from the accumulation of dusty debris within a circumstellar nebula, whereas brown dwarfs form whole from the dusty gas of interstellar space. Another distinction between brown dwarfs and planets is that above 0.13 times the mass of Jupiter, bodies become hot enough to fuse their natural deuterium. Some 10 bodies between this limit and 0.08 solar masses have been found from Doppler studies to be orbiting other stars. However, it is not know if planets can grow to this mass.