1. Life Cycle of Stars

2. The Start
Stars have very long life periods, however, nothing lasts forever!
Nebula – the cloud of gas and dust that stars form inside of.
Gravity pulls mass together in some regions. As this happens, a hot dense sphere forms; this is the star!

3. Low Mass Stars
Main Sequence – The stage in which stars produce energy through fusion of hydrogen into helium.
Low mass stars remain in this sequence for billions of years.
When the star runs out of hydrogen, it expands into a giant star. Cools off, turns red, and expands.

4. High Mass Star Stars more than eight times the mass of our sun.
Less time as main sequence stars.
When they run out, they become red supergiant stars. They cool off and expand
Once the supergiant runs out of elements to use for fusion, the star becomes a supernova.

5. Neutron Stars and Black Holes
Neutron Star – the collapsed core of a supergiant star.
Only 20 kilometers in diameter, more mass than the sun!
Black Hole – the core of a supernova with more mass than three times the Sun.
Gravity in here is so strong that no radiation can escape.