All stars (except stars that have died like white dwarves and neutron stars etc) have fusion going on somewhere inside of them. As a star burns up its hydrogen over time, it builds up a core of helium. The hydrogen fusion occurs in a shell outside this inert (but very hot) core. If it's massive enough, the core can build up enough heat from compression to begin helium fusion building up a core of carbon and oxygen, which may eventually fuse into things like silicon etc etc.
Main sequence stars fuse Hydrogen in their cores. Stars that have gone off the main sequence may have inert cores with some kind of fusion going on in shells around it.
2007-03-07 15:59:47
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answer #1
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answered by Arkalius 5
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When stars exit the main sequence, depending on size, several things can happen. In a star like the Sun, the core will be composed of helium and fusion will continue in a shell around the core. Smaller stars will not be able to do this, and red dwarfs will just fade. Larger stars start fusing helium to heavier elements and become red supergiants that will eventually go supernova, scattering these heavy elements into the galaxy.
2007-03-07 16:06:52
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answer #2
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answered by novangelis 7
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The mass of the star determines what happens after the main sequence phase. A star is a ball of gas held together by its own gravity. The force of gravity is continually trying to cause the star to collapse. During most of the lifetime of a star, the interior heat and radiation is provided by nuclear (hydrogen burning up) reactions near the center; this phase of the star's life is called the main sequence. Before the main sequence the star is contracting, and is not yet hot nor dense enough in the interior for the nuclear reactions to begin.
After the main sequence, most of the nuclear fuel (hydrogen) in the center has been used up. At this stage Helium in the center of star starts burning up and Hydrogen in the outer layer continues to burn up. In this phase the star size grows large and cooler. This star is called Red Giant. While Helium burns up carbon gets left over. Eventually, in the more massive stars, the carbon may burn to even heavier elements, but eventually the energy generation will fizzle out (no fusion stage, as you were mentioning) and the star will collapse to a white dwarf. Astronomers think that white dwarfs ultimately cool to become black dwarfs. These are non-radiating stars. No energy is radiated from these stars. They would be so small and dark that we may not see them with naked eye.
The story of more and more massive stars is different. They end up or die in a different way.
2007-03-14 11:01:10
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answer #3
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answered by Wiser 2
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A star is a massive, luminous ball of plasma.
A star shines because nuclear fusion in its core releases energy which traverses the star's interior and then radiates into outer space. Without stars, life on Earth and most atomic elements would not exist.
A star begins as a collapsing cloud of material that is composed primarily of hydrogen along with some helium and heavier trace elements. Once the stellar core is sufficiently dense, some of the hydrogen is steadily converted into helium through the process of nuclear fusion. The remainder of the star's interior carries energy away from the core through a combination of radiation and convective processes. These processes keep the star from collapsing upon itself and the energy generates a stellar wind at the surface and radiation into outer space.
2007-03-07 16:18:58
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answer #4
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answered by neumor 2
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1. Fusion is the only source of energy in all active stars
2. Dead stars (white dwarf, browndwarf (neutron star)), they still have remaining energy from when they were active, the energy doesn't just disappear. So they are acutally using what's left in them after the collapse.
2007-03-07 18:14:44
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answer #5
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answered by kairvette 1
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There are neutrons stars, in which it is supposed that nothing much is going on. There are black holes, and I think everyone knows that generally accepted theories about these. There are brown dwarfs, and they are nearing the end of their life and any type of thermonuclear action. And then there are just dead stars that are just floating around and occupying space.
2007-03-07 16:54:42
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answer #6
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answered by Scarp 3
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Arkalius is exactly right.
As for the white dwarfs that are no longer fusing. They are no longer producing energy, but rather cooling off over time, like a gigantic coal.
2007-03-07 16:01:36
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answer #7
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answered by mobaxus 2
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All stars...repeat, ALL stars...produce their energy by nuclear fusion. You may have misunderstood a little whatever it was you read.
2007-03-07 16:44:10
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answer #8
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answered by Chug-a-Lug 7
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In the beginning God created the (heaven,s) and earth.Guess he didn't fell it was important to tell us any detail,s about there "energy" being we are never going to tap one for energy."Kinda" think he put them up there for us to look at (pretty ain,t they?) enjoy them. h a n d
2007-03-15 12:32:55
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answer #9
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answered by Anonymous
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...Hydrogen gas
2007-03-13 16:06:48
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answer #10
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answered by Anonymous
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