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nikkkom
#3
Jan2-12, 08:54 AM
P: 624
Quote Quote by nhmllr View Post
Okay, so so you got two forces acting on a star. Gravity trying to compress it, and the internal pressure, caused by fusion, pushing it out. For the star's life they are at equilibrium, but the star dies when it runs out of nuclear fuel.

Then why do some stars explode? Shouldn't they all collapse?
During collapse (and during slow shrinkage too) temperatures and pressures inside the star rise. If at some point temperature and pressure enable a previously impossible nuclear reaction which releases a lot of energy and has a large dependence on temperature, then this may trigger a runaway burn. This is especially likely if matter is degenerate - because degenerate matter does not noticeably expand when heated. (Expansion may quench the reaction).