1. Announcements Exam 3 is scheduled for Wednesday April 8. Will be pushed back to Monday April 13 Tentatively will cover the rest of Chapter 4 and all of Chapters 5 & 6. Sample Questions will be posted tomorrow. 1 st Quarter Observing Night Thursday night. Set-up starts at 6:30 if clear, 6:45 if cloudy.

2. Colored Card Questions ClassAction website ISM & Star Formation module Star Formation Masses Emission Nebula Energy Source Stellar Properties II module Stellar Parameters HR Groups

3. Life beyond the Main Sequence What happens when a star runs out of hydrogen fuel in its core?

4. With no more hydrogen fusion occurring in the core, hydrogen fusion continues in a shell around the core

5. Energy imbalance from shell hydrogen fusion creates a Red Giant

6. Helium Fusion starts when core reaches 100,000,000° The higher temperature is needed to overcome the stronger electric repulsion between the nuclei

7. Triple Alpha Helium Fusion

8. Additional Fusion involving He Ash from Helium Fusion: Carbon & Oxygen

9. Helium fusion begins differently for some stars The determining factor is whether or not the core becomes degenerate

10. Normal versus degenerate electron energy levels

11. Degeneracy Electron energy levels crowded together almost continuous All low energy levels are full Pauli Exclusion Principle Only place for additional electrons to go is in high energy levels which means they must be moving at close to the speed of light Adding more mass decreases the volume Temperature is same everywhere

12. Evolution on an H – R Diagram Helium Flash

13. For low mass stars: a second red giant stage The second red giant phase begins when the helium fuel in the core is exhausted and core fusion once again stops

14. Internal Structure of AGB star

15. Convection in final stages dredges up products of earlier fusion and ejects it into space

16. Thermal Pulses cause whole layers of a star to lift off

17. Stars recycle most matter back out into the universe

18. Planetary Nebulae form from low mass stars (<8M sun )

19. In the end, only the cooling core is left: a white dwarf star Canis Major Visible X-ray

20. Colored Card Questions ClassAction website Stellar Evolution module HR Evolutionary Track HR Movement Core Stages 1 Core Stages 2

21. White dwarf stars are planetary size but stellar mass

22. White Dwarf Stars are degenerate matter Chandrasekhar Limit 1.4 M sun

23. The evolutionary path of white dwarf stars are cooling curves

24. A white dwarf in a binary system can be revived to become a cataclysmic variable

25. For stars with mass >8M sun Carbon fusion begins at 600,000,000°

26. Carbon fusion produces Oxygen, Neon and Magnesium

27. Higher fusion requires higher temperatures and takes less time

28. Internal Structure becomes layered like an onion

29. Once iron starts to form energy is no longer produced

30. When the iron core reaches 1.4 solar masses the end comes swiftly

31. The End: Photo-disintegration and Reverse Beta Decay

32. Type IIa Supernova Watch Supernova videos