To see an enlargement of this picture, choose either picture at the top and click on the picture. Then select JPEG 200KB at the top of the page and click. Most stars are hot and bright and appear white or blue. They stay like this for millions of years. When a star's supply of gas begins to run out, it starts to die.
Different stars die in different ways.
They are called red giants during this phase. Then the star shrinks, becomes hotter, and turns white. It is now called a white dwarf. It can stay like this for a long time - up to billions of years. During this stage it is known as a black dwarf.