Brown dwarf

摘要

Sometimes called a failed star, a brown dwarf forms when a cloud of gas collapses but is not massive enough to ignite the fusion reactions that fuel fully formed stars. Brown dwarfs can be 13 to 75 times the mass of Jupiter. Less massive bodies are rogue planets; more massive ones can sustain fusion and are thus stars. Some brown dwarfs have their own planets. Example: 2M1207.