A Mystery of Space: S T A R S- [How Does a Star Work?]

A star is like a huge nuclear reactor. Scientists do not know for sure, but hypothesize that the inside of a star is the place that enormous thermonuclear reactions happen. A thermonuclear reaction is the fusion of atomic nuclei (the "brain" of atoms, the smallest particles in the world, that make up everything, even you!) at a very high temperature. The nuclear reactions that take place in a star can last for billions of years.
A star is formed in a huge cocoon of dust grains, gas, and molecules. The gas starts to contract (get smaller), and the temperature starts to rise.

A star birth cloud

When the temperature reaches about 1,800,000° F (1,000,000° C), a thermonuclear reaction begins, between the nuclei of hydrogen atoms and heavy hydrogen deuterons (nuclei of heavy hydrogen atoms). The star then stops contraction after energy from the nuclei of the hydrogen nucleus and deuteron and. After that, the star goes through several sequences of halting and contracting, using up all of the light materials (like lithium), then, the hydrogen begins to be converted into helium and it finally swells to the size of a red giant. After this point it has finished expanding and it will take different paths to its death.

click here for the life of a star animation

click on image above for the life of a star animation