Scientist believe that stars are "born" in clusters. They are probably formed from gas and dust. A star the size of the sun will burn about 10 million years. (Larger stars may burn shorter amounts of time.) Then it will become either a red giant or a supernova. If it becomes a red giant, it will eventually lose much of its mass and leave a core, called a white dwarf. If it becomes a supernova, it will explode. Then its material may eventually form new stars. The core will either collapse into a pulsar (also known as a neutron star) or will collapse into a black hole.