Question

How were the heavy elements from iron to uranium made?

Answer 1

star releases energy mostly produced by hydrogen fusing into helium. as the star goes older there is less hydrogen gas so it fuses the heavier elements iron to uranium made.

Answer 2

They are released in supernovae, but are made over the life of a star, over many millions and billions of years. The gravitational pressure of a star is so great that it compresses the gasses in its interior to a point that the atoms break down into a plasma state. The atomic nuclei lose their orbiting electrons into a disassociated soup of particles and groups of particles. The nuclei are forced so close together they sometimes fuse into large nuclei, such as Uranium or other heavy atoms. That is atomic fusion. It releases a tremendous amount of energy and it is what powers stars like our sun. Those nuclei which are inherently unstable break down quickly. Those which are stable may survive in the star until it explodes in a nova or supernova and the heavy elements are released into the nebula. Once the elements are in the nebula, they can condense and coalesce into new planets, stars, and other solar system bodies. Our own solar system is probably a third-generation system, with material from the previous generations stars distributed in the planets, asteroids, and icy objects. We are made of the stuff of dead stars; we are stardust.