The fusion of hydrogen nuclei uses up hydrogen to produce helium and energy. Hydrogen is the fuel for the process. As the hydrogen is used up, the core of the star condenses and heats up even more. This promotes the fusion of heavier and heavier elements, ultimately forming all the elements up to iron.
The energy source of stars. The energy released from the collapse of the gas into a protostar causes the center of the protostar to become extremely hot. When the core is hot enough, nuclear fusion commences. Fusion is the process where two hydrogen atoms combine to form a helium atom, releasing energy.
