1. Stellar Evolution From Nebula to Neutron Star

2. Basic Structure The more massive the star the hotter it is, the hotter it is the brighter it burns Mass is the most important Determines brightness, temperature & diameter (volume)

3. Pressure Balance Force of gravity pulling in = Pressure from fusion pushing out Otherwise it would expand & contract

4. Sun’s Energy Remember how the sun produces energy? !!FUSION!!

5. Sun’s Energy Cont’d Not all stars fuse H into He Helium can be fused to Carbon, Carbon to nitrogen and more… All to produce enough energy to fight gravity

6. Stellar Evolution Stars change throughout their life Changes in what they fuse as they run out of fuel causes them to adjust to differing pressure

7. The Beginnings All stars start out the same Begin as nebulas: diffuse cloud of dust and gas

8. Fusion Begins When enough pressure builds and enough heat is produced H is fused to helium Has enough force pushing out to balance gravity pulling in (balance) Remains this way for up to ten billion years

9. Average Size Stars When a star begins fusing Hydrogen into Helium it enters the Main Sequence The amount of H is limited so it runs out (~10bil yrs) Outer regions of the core push out the surface Becomes a Red Giant

10. Average Size Stars During Red giant stage 1.Fuses He into Carbon 2.Outer layers expand 3.He fusion last a fraction as long as H fusion stage Star then shrinks back to normal Becomes stable for a while

11. Average Size Star Outer layers are given off and star becomes a planetary nebula

12. Average Size Stars White Dwarf Star shrinks to that of Earth’s size Becomes stable No fusion is going on

13. Massive Stars Begin their life in the same as medium sized stars Go through life cycle much quicker Think of them as a huge SUV’s, very low gas mileage

14. Massive Stars Produce enough heat to fuse heavier elements From many layers w/fusion of different elements

15. Death of Massive Stars May also become white dwarfs After Iron, no more fuel to fuse Collapses violently & 2 things can happen 1.Electrons & protons form solid ball of neutrons (Neutron Star) 2.Outer gases rebound off a neutron star shooting outward as a Supernovae

16. Neutron Star

17. Supernovae

18. Black Holes Happens to stars that begin 20x the mass of the Sun Core of neutrons not strong enough to fight gravity Continues to collapse until it’s so massive that gravity won’t even let light escape

19. Black Holes