Stellar Evolution

Stellar Evolution - The Birth, Life, and Death of a Star:
The Milky Way Galaxy contains several hundred billion stars of all ages, sizes and masses. A typical star, such as the Sun, radiates small amounts of X-rays continuously and larger bursts of X-rays during a solar flare.

The Sun and other stars shine as a result of nuclear reactions deep in their interiors. These reactions change light elements into heavier ones and release energy in the process. The outflow of energy from the central regions of the star provides the pressure necessary to keep the star from collapsing under its own weight.

A star collapses when the fuel is used up and the energy flow from the core of the star stops. Nuclear reactions outside the core cause the dying star to expand outward in the "red giant" phase before it begins its inevitable collapse.

If the star is about the same mass as the Sun, it will turn into a white dwarf star. If it is somewhat more massive, it may undergo a supernova explosion and leave behind a neutro