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To Expand Upon The Above
Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To Posted by Joe Antognini on April 7, 2002 00:14:52 UTC |
He is correct, and I too will add some points of my own. The reason main sequence stars (stable stars more or less) retain a constant size is because of a delicate balance between the force of gravity, causing the star to collapse inward, and the force of the radiation the star produces, forcing it outward. Eventually, the star runs out of hydrogen to fuse to helium (the energy produced by this reaction is what produces the radiation) so there is no force keeping the gravity from imploding the star. But it isn't over yet. As it collapses, the core gets hotter and hotter. (Temperature is simply a measure of the speed of particles) This means that the temperature will be great enough for helium to start fusing. This produces more energy than the hydrogen reactions did, so the star gets larger than ever. It is now a red giant. It quickly runs out of helium and collapses again. It might be large enough to start fusing over again. Some stars have enough mass to fuse into lead eventually. Anyway, when the star cannot produce any more radiation, gravity starts the implosion of the star. Although the entire star does implode, as the core is closest to the center and much denser, it implodes faster than the rest of the star, thus leaving a gap between the core and the rest of the star. The core now has a large amount of gravity which pulls in the rest of the star. However (if I am correct, which I admit I may not be) the core is spinning faster than the rest of the star because it is so much denser, and so it blows away the outer part of the star in what is called a supernova. This is exactly the same as a nova, except a star continues to live after a nova, fusing a heavier element, but a supernova is the end of the line. If the core is large enough it will start to collapse beyond the point of most stars (a white dwarf) and will literally 'squish' the atoms together, forcing the electrons and protons upon each other, creating neutrons. The core has become a neutron star. If it is still dense enough, the core can overcome the strong force (It may be the weak force, or some other force, I can't remember) and will start to squish the neutrons together indefinitly, leading to the infinitly dense singularity of a black hole. Remember the star implodes because there is no outward force keeping the star from collapsing (excepting the strong force, or whatever force it is, which is overcome by the immense gravity anyway). We do not create a black hole because we cannot, as it would take such an incredible amount of matter to force the overcoming of strong force, that one couldn't find it all in our solar system. Anyway, we would actually be creating a big star, and would have to wait billions of years for it to die. Plus, we probably couldn't do much with a black hole at our current technological level. Of course in a few billion years that shall probably change... |
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