Supernovae

When a star becomes a supergiant, it may explode completely, forming what is called a 
supernovae. A supernova completely destroys the star, spewing heavy elements out into 
space. It is believed that the heavier elements in the human body exist because of a 
supernova that exploded before our solar system is formed. After exploding, supernovae 
may form nebulae. An example of this is the Crab Nebula.