What is the heaviest element that the sun can fuse?
Also, what is the heaviest element any star can fuse? What happens to a star after that?
The heaviest element that our Sun produces is probably silicon; the core temperature and pressure would need to be MUCH higher to produce heavier elements. The heaviest element that can be produced in ANY star is iron.
The reason for this is something called the "packing fraction curve". As light elements are fused into heavier elements, they release energy; this is how the Sun and other stars work, by fusing hydrogen into helium. Toward the end of a star’s life, the temperature and pressure increase enough to fuse helium into carbon, and then carbon into heavier elements, but each stage releases less and less energy. Finally, when elements fuse into iron, you can get no more energy out. To fuse iron into heavier things, or anything into elements heavier than iron, you must put energy IN. When a star begins fusing iron into heavy elements, it suddenly stops producing energy to support the star against the tremendous gravity, but instead starts sucking energy OUT of the core of the star to power fusion!
This loss of energy from the core of the star causes a sudden and catastrophic implosion as the core of the star collapses the core into a black hole or neutron star, and the outer layers of the star are compressed and expelled in a shock wave that creates gigatons of heavy elements and throws the remainder of the star’s mass into space; a supernova explosion.
So, nothing heavier than iron can be produced in a normal star; heavier elements are only created in supernovas.
January 20th, 2010 at 1:07 am
The heaviest element that our Sun produces is probably silicon; the core temperature and pressure would need to be MUCH higher to produce heavier elements. The heaviest element that can be produced in ANY star is iron.
The reason for this is something called the "packing fraction curve". As light elements are fused into heavier elements, they release energy; this is how the Sun and other stars work, by fusing hydrogen into helium. Toward the end of a star’s life, the temperature and pressure increase enough to fuse helium into carbon, and then carbon into heavier elements, but each stage releases less and less energy. Finally, when elements fuse into iron, you can get no more energy out. To fuse iron into heavier things, or anything into elements heavier than iron, you must put energy IN. When a star begins fusing iron into heavy elements, it suddenly stops producing energy to support the star against the tremendous gravity, but instead starts sucking energy OUT of the core of the star to power fusion!
This loss of energy from the core of the star causes a sudden and catastrophic implosion as the core of the star collapses the core into a black hole or neutron star, and the outer layers of the star are compressed and expelled in a shock wave that creates gigatons of heavy elements and throws the remainder of the star’s mass into space; a supernova explosion.
So, nothing heavier than iron can be produced in a normal star; heavier elements are only created in supernovas.
References :
January 20th, 2010 at 1:55 am
I don’t know the answer to the first part of your question, but I do know that the final product is iron. Stars make iron but can’t fuse it. What happens to a star when it has used up all its fuel depends on the star’s mass. If it is up to about twice the mass of the sun, the core heats up and blows away the outer layers, leaving a white dwarf. If it’s more that about twice the mass of the sun but less than three times, it explodes and the core collapses into a neutron star only about 10 kilometers in diameter. If it is more massive than three times, it explodes and collapses into a black hole with an event horizon about 10 kilometers in diameter. These explosions create elements heavier than iron and as heavy as uranium.
References :