How do various elements form in stars?

When hydrogen runs out, the star fuses helium followed by increasingly larger elements. This is known as the red giant phase. Elements heavier than iron are formed when a massive star dies in a supernova and very large atoms fuse together, forming elements with up to 92 protons (Uranium). Helium is created during the main sequence stage of a star's life.

Nuclear fusion reactions produce a variety of elements in stars. In a star's core, protons fuse to form helium nuclei, releasing a great deal of energy in the process. As the star develops and goes through various stages of fusion, heavier elements, like carbon, oxygen, and iron, are formed through fusion reactions involving lighter elements that take place under the intense heat and pressure that stars experience. Elements heavier than iron are formed through processes such as supernova explosions or neutron star mergers.