- a cold, dark star that is too small to initiate the nuclear reactions that generate heat and light.
* * *Sometimes described as failed stars, brown dwarfs are believed to form in the same way as stars, from fragments of an interstellar cloud that contract into gravitationally bound objects. However, they do not have enough mass to produce the internal heat that in stars ignites hydrogen and establishes nuclear fusion. Though they generate some heat and light, they also cool rapidly and shrink; they may differ from high-mass planets only in how they form.
* * *astronomical object that is intermediate between a planet and a star. Brown dwarfs have a mass less than 0.08 solar mass, and their surface temperatures are below 2,500 K (the lower limit of the temperature of red dwarfs). They are not brown in colour but red. Brown dwarfs were first hypothesized in 1963 by American astronomer Shiv Kumar, who called these objects “black” dwarfs. American astronomer Jill Tarter proposed the name “brown dwarf” in 1975. Searches for brown dwarfs in the 1980s and 1990s found several candidates; however, none could be definitively identified as a brown dwarf. In 1995 astronomers at Palomar Observatory and Johns Hopkins University found Gliese 229 B. Its extremely low luminosity showed it had a mass less than 0.05 solar mass, and the detection of methane in its spectrum showed that it had a surface temperature less than 1,200 K. Hence, Gliese 229 B was the first object that was definitively identified as a brown dwarf.Sometimes described as failed stars, brown dwarfs are believed to form in the same way that stars form; fragments of an interstellar cloud contract into smaller, denser clouds. Unlike stars, however, brown dwarfs do not have mass enough to generate the internal heat that in stars ignites hydrogen and establishes thermonuclear fusion reactions, which are the source of stellar energies. Though they generate some heat and some light, brown dwarfs also cool rapidly and shrink. Similar in appearance to high-mass planets, brown dwarfs may be distinguishable from planets only in their formation mechanism.
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Brown dwarf — Brown dwarfs are sub stellar objects which are too low in mass to sustain hydrogen 1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no… … Wikipedia
brown dwarf — brown′ dwarf′ n. astron. a cold, dark star that is too small to initiate the nuclear reactions that generate heat and light … From formal English to slang
brown dwarf — n. a hypothetical celestial object consisting of a body of gas that gives off a small amount of radiation but lacks sufficient mass to initiate the nuclear fusion that characterizes true stars … English World dictionary
brown dwarf — /braʊn ˈdwɔf/ (say brown dwawf) noun an astronomical body which is not of sufficient mass and temperature to produce hydrogen fusion and become a star: *Astronomers found weather similar to that on Jupiter in the atmospheres of brown dwarfs –… … Australian English dictionary
brown dwarf — noun Date: 1978 a celestial object that is much smaller than a normal star and has insufficient mass to sustain nuclear fusion but that is hot enough to radiate energy especially at infrared wavelengths … New Collegiate Dictionary
brown dwarf — noun A star that is typically about the volume of the planet Jupiter, which has mass approaching that of a star, but insufficient to ignite its elements and cause it to burn as a true star, except that of deuterium … Wiktionary
brown dwarf — noun Astronomy a celestial object which is intermediate in size between a giant planet and a small star, believed to emit mainly infrared radiation … English new terms dictionary
Brown Dwarf — Bodies that are much larger than planets, but are too small to carry out continuous nuclear fusion in their cores, so they can t become stars … The writer's dictionary of science fiction, fantasy, horror and mythology
brown dwarf — noun : a celestial object that is much smaller than a normal star and has insufficient mass for nuclear fusion to begin but that is hot enough to radiate energy especially at infrared wavelengths … Useful english dictionary
Brown-dwarf desert — A brown dwarf desert is an orbital distance around a star at which brown dwarfs cannot exist as binary stars. [cite book | title = Planet Formation: Theory, Observations, and Experiments | author = Hubert Klahr and Wolfgang Brandner | publisher … Wikipedia