brown dwarf


noun Astronomy.

a cold, dark star that is too small to initiate the nuclear reactions that generate heat and light.

British Dictionary definitions for brown dwarf

brown dwarf

noun

a type of celestial body midway in mass between a large planet and a small star

Scientific definitions for brown dwarf

brown dwarf

A celestial body with insufficient mass to sustain the nuclear fusion that produces radiant energy in normal stars. It is believed that a brown dwarf is formed with enough mass to start nuclear fusion in its core, but without enough for the fusion to become self-sustaining. Theory suggests that a body with about one percent of the mass of the Sun-or ten times the mass of Jupiter-can generate this initial fusion, but that it needs at least eight percent of the Sun's mass to sustain the fusion. After the fusion ends, the dwarf still glows for a period from radiating heat, with a surface temperature of about 2,500°K (4,532°F) or less. See Note at dwarf star.