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Brown Dwarfs ???
They are not a planet. They are not a star What is the best
definition used to describe them? Is Jupiter a brown dwarf? It does not look brown. Black dwarfs are a white dwarf that has cooled to a point it no longer gives off heat(I think???) Bert |
#3
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Brown Dwarfs ???
Llanzlan Klazmon the 15th wrote:
(G=EMC^2 Glazier) wrote in news:25367-466F0DEB- : They are not a planet. They are not a star What is the best definition used to describe them? Is Jupiter a brown dwarf? It does not look brown. Black dwarfs are a white dwarf that has cooled to a point it no longer gives off heat(I think???) Bert Brown dwarfs have sufficient mass to trigger deuterium burning in their core. Eventually the deuterium runs out and all nuclear reactions stop. A star must have sufficient mass to at least initiate the p-p chain. Jupiter doesn't make the grade of either star or brown dwarf. p-p chain? |
#4
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Brown Dwarfs ???
ah wrote in
: Llanzlan Klazmon the 15th wrote: (G=EMC^2 Glazier) wrote in news:25367-466F0DEB- : They are not a planet. They are not a star What is the best definition used to describe them? Is Jupiter a brown dwarf? It does not look brown. Black dwarfs are a white dwarf that has cooled to a point it no longer gives off heat(I think???) Bert Brown dwarfs have sufficient mass to trigger deuterium burning in their core. Eventually the deuterium runs out and all nuclear reactions stop. A star must have sufficient mass to at least initiate the p-p chain. Jupiter doesn't make the grade of either star or brown dwarf. p-p chain? p + p -- d + e+ + v The weak nuclear reaction that dominates in lower mass main sequence stars. The d produced is fuel for further reactions hence chain. http://en.wikipedia.org/wiki/Proton-...chain_reaction Klazmon. |
#5
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Brown Dwarfs ???
G=EMC^2 Glazier wrote:
They are not a planet. They are not a star What is the best definition used to describe them? Is Jupiter a brown dwarf? It does not look brown. Black dwarfs are a white dwarf that has cooled to a point it no longer gives off heat(I think???) Bert They are simply clumps of matter that failed to sustain nuclear fusion as an energy source. Jupiter does not qualify because it is about 100 times too light to generate the temperatures and densities at its core to initiate, let alone sustain nuclear fusion. |
#6
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Brown Dwarfs ???
Scott Brown is kind of close to the color red.,so can I think of a
brown dwarf evolving in time from a red dwarf? I 'm not confusing them with a "real" red dwarf that can shine for a longer period than the Sun. It is written it would take the mass of 80 Jupiters to create a core that would light the fire of fusion bert |
#7
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Brown Dwarfs ???
G=EMC^2 Glazier wrote:
Scott Brown is kind of close to the color red.,so can I think of a brown dwarf evolving in time from a red dwarf? I 'm not confusing them with a "real" red dwarf that can shine for a longer period than the Sun. It is written it would take the mass of 80 Jupiters to create a core that would light the fire of fusion bert When is a red dwarf not a red dwarf. We are very precise in our language in science, so saying that a brown dwarf evolved from a red dwarf that is not a real red dwarf makes no sense. A red dwarf maintains nuclear fusion in its core, a brown dwarf does not. The transition between one or the other is in the amount of mass each has to create the conditions in the core for fusion to either begin and be sustained, or possibly begin and stop, if begin at all. |
#8
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Brown Dwarfs ???
In article , Scott Miller wrote:
G=EMC^2 Glazier wrote: They are not a planet. They are not a star What is the best definition used to describe them? Is Jupiter a brown dwarf? It does not look brown. Black dwarfs are a white dwarf that has cooled to a point it no longer gives off heat(I think???) Bert They are simply clumps of matter that failed to sustain nuclear fusion as an energy source. Jupiter does not qualify because it is about 100 times too light to generate the temperatures and densities at its core to initiate, let alone sustain nuclear fusion. Jupiter is not a brown dwarf, but what you state is incorrect. You can go as low as 13 Jupiter masses and get deuterium burning (which is fusion), and objects with 60 to 70 Jupiter masses or more burn both deuterium and lithium. |
#9
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Brown Dwarfs ???
Scott It is tricky but I read there are two types of red dwarfs. Maybe
an astronomer would be best to define the two for us? bert |
#10
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Brown Dwarfs ???
Tom I think I should have read your post before answering Scott. What
you posted gives the reason for the type of red dwarf were talking about. Thanks for clearing it up. One has fusion for a short time the other red dwarf evolved from a massive star and will radiate for a long time bert |
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