brown dwarf

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for brown dwarf

brown dwarf

noun
  1. a type of celestial body midway in mass between a large planet and a small star
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

brown dwarf in Science

brown dwarf

  1. 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.