|
|
The Milky Way
Giant clouds of dust and gas in the disk and bulge absorb light from the stars and give the galaxy its patchy appearance. These clouds are the stages on which the long-running drama of stellar evolution is played. Dust and gas collapse to form stars, then nuclear fusion reactions in their interiors build up heavier elements and release energy which is radiated as starlight.
As the stars' nuclear energy supply is exhausted, most stars will expand to become red giants, then shrink to a small dense state called a white dwarf star. Massive stars will explode as supernovas, leaving behind neutron stars or black holes. The explosions disperse heavy elements manufactured by the stars, thereby enriching the galaxy with elements necessary to form planets.
More on Stellar Evolution
 Illustration: CXC/M.Weiss
|
