Fusion and Stellar Evolution

In the first reaction a positively charged electron is formed. This particle is called a positron. In addition to the fusion of hydrogen nuclei, the helium created can also enter into fusion reactions  

Fusion reactions signify the formation of a true star. The fusion reactions balance the gravitational contraction and an equilibrium 

Once a star has expended its supply of energy, it will contract to a glowing white ember called a white dwarf. The elements produced in the interior of a star depend on the size of the star. Small stars do not have sufficient mass to produce the temperatures required to create the heaviest elements. The most massive stars, though, may go through a series of rapid contractions in their final stages. These massive stars have the ability to generate the temperatures and pressures necessary to produce the heaviest elements such as thorium and uranium. The final fate of these massive stars is a cataclysmic explosion called a supernova. It is in this manner that scientists believe all the naturally occurring elements in the universe 

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