1. Life Cycle of Stars Nebula hundreds of light years in size contract under gravity http://en.wikipedia.org/wiki/Image:Horsehead-Hubble.jpg

2. Life Cycle of Stars Protostar radiate heat from gravitational contraction http://en.wikipedia.org/wiki/Image:Herbig-Haro_object_HH32.jpg

3. Life Cycle of Stars Main Sequence Stars fuse hydrogen into helium (releases energy) hydrostatic equilibrium most of star’s life spent on main sequence http://www.oswego.edu/~kanbur/a100/images/hydrostaticequilibrium.jpg

4. Life Cycle of Stars hydrogen depleted in core core composed of helium core contracts and heats, outer layers expand and cool star leaves main sequence http://personal.tcu.edu/~pmarcum/courses/P2083/handouts/starevol1_lect.html

5. Life Cycle of Stars low mass stars turn into Red Giant Stars helium fuses into carbon very low mass stars (< 1 / 4 solar mass) do not fuse helium http://fas.org/irp/imint/docs/rst/Sect20/Arcturus.jpg

6. Life Cycle of Stars helium depleted in core core contracts and heats, outer layers expand and cool temperatures not hot enough to fuse carbon star leaves red giant region unstable http://personal.tcu.edu/~pmarcum/courses/P2083/handouts/starevol1_lect.html

7. Life Cycle of Stars Planetary Nebula outer layers expelled into space small, dense, hot core exposed http://en.wikipedia.org/wiki/Image:Eskimo_nebula_%28cropped%29.jpg

8. Life Cycle of Stars White Dwarf electron degeneracy pressure cool over time http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit3/Images/WhiteDwarf.gif

9. Life Cycle of Stars high mass stars evolve quickly turn into Supergiant Stars http://abyss.uoregon.edu/~js/images/Aldebaran.jpg

10. Life Cycle of Stars Supergiant Stars are massive enough to produce temperatures and pressure high enough to fuse heavier elements in successive stages iron core is built up http://en.wikipedia.org/wiki/Image:Evolved_star_fusion_shells.svg

11. Life Cycle of Stars iron cannot fuse into heavier elements iron core collapses star explodes known as a Supernova http://en.wikipedia.org/wiki/Image:Crab_Nebula.jpg

12. Life Cycle of Stars Neutron Stars remnant after supernova is less than 3 solar masses neutron degeneracy pressure fast rotating radiate beams of energy known as Pulsars http://upload.wikimedia.org/wikipedia/commons/1/1d/Vela_Pulsar_jet.jpg

13. Life Cycle of Stars Black Hole remnant after supernova is greater than 3 solar masses neutron degeneracy pressure is overwhelmed light cannot escape http://en.wikipedia.org/wiki/Image:BH_LMC.png