Asked in AstronomyPhysicsChemistryNuclear Energy
How is energy released in stars and how does this effect the composition of elements in the universe?
April 25, 2011 2:00PM
Energy is released by fusion of elements to heavier elements, i.e. fusion of hydrogen to helium in the sun's core.
I'm not sure what you mean by the 'composition of elements', but the hydrogen that our sun, like billions of other main sequence stars, is fusing right now is the leftover hydrogen from the Big Bang which, in billions of years' time, will eventually run out, and stars will have to fuse heavier elements, going up to iron (which means the universe will, eventually, die).
Bigger stars than the sun do fuse heavier elements, in 'layers', with the heaviest (Fe) in the middle, and the lightest (H) at the surface (look up onion structure star).