1. Charles Hakes Fort Lewis College1

2. Charles Hakes Fort Lewis College2 Solar Interior/ Nuclear Fusion

3. Charles Hakes Fort Lewis College3 Outline Solar interior Fusion Solar evolution Stars

4. Charles Hakes Fort Lewis College4 Review Sunspots… are darker because they are actually cooler than the rest of the Sun the result of a “kink” in the magnetic field size of Earth; usually come in pairs magnetic field switches every 11 year; cycle is 22 years Maunder minimum corresponded to mini ice age

5. Charles Hakes Fort Lewis College5 Review and… The solar equator rotates faster than the poles the Zeeman effect is a splitting of spectral lines from magnetic fields sunspots magnetic field is about 1000x greater than the surrounding area solar wind is the sun evaporating

6. Charles Hakes Fort Lewis College6 As the Sun rotates, an individual sunspot can be tracked across its face. From Eastern to Western limb, this takes about: A) 12 hours B) A week C) Two weeks D) A month E) 5.5 years

7. Charles Hakes Fort Lewis College7 As the Sun rotates, an individual sunspot can be tracked across its face. From Eastern to Western limb, this takes about: A) 12 hours B) A week C) Two weeks D) A month E) 5.5 years

8. Charles Hakes Fort Lewis College8 Compared to the Earth, the Sun’s average density is: A) lower B) about the same C) much greater

9. Charles Hakes Fort Lewis College9 Compared to the Earth, the Sun’s average density is: A) lower B) about the same C) much greater

10. Charles Hakes Fort Lewis College10 From inside out, which is the correct order? A) core, convective zone, radiative zone B) photosphere, radiative zone, corona C) radiative zone, convective zone, chromosphere D) core, chromosphere, photosphere E) convective zone, radiative zone, granulation

11. Charles Hakes Fort Lewis College11 What about the internal structure?

12. Charles Hakes Fort Lewis College12 Solar Composition Element Number Percent Mass Percent H91.271 He8.727.1 O0.0780.97 C0.0430.4 N0.00880.096

13. Charles Hakes Fort Lewis College13 Figure 9.2 Solar Structure

14. Charles Hakes Fort Lewis College14 What about the internal structure? Core - temperatures hot enough for nuclear reactions Radiation Zone - Temperatures cooler, so no nuclear reactions. Hot enough so everything is ionized. Atoms can’t absorb photons. Convection Zone - Temperature cooler. Atoms form and can absorb radiation.

15. Charles Hakes Fort Lewis College15 Figure 9.6 Solar Interior

16. Charles Hakes Fort Lewis College16 How do we know what is inside the Sun?

17. Charles Hakes Fort Lewis College17 How do we know what is inside the Sun? l Standard model

18. Charles Hakes Fort Lewis College18 Figure 9.4 Stellar Balance

19. Charles Hakes Fort Lewis College19 Figure 9.5 Solar Oscillations

20. Charles Hakes Fort Lewis College20 Figure 9.7 Solar Convection

21. Charles Hakes Fort Lewis College21 Figure 9.8 Solar Granulation

22. Charles Hakes Fort Lewis College22 Figure 9.11 Solar Spicules dynamic jets 5-10 minute life possibly related to seismic activity

23. Charles Hakes Fort Lewis College23 Typically, a granule in the photosphere of the sun is about the size of? A) A city, ~20-30 kilometers across. B) Texas, ~1000 km across. C) The Earth, ~12,000 km across. D) Jupiter, ~100,000 km across.

24. Charles Hakes Fort Lewis College24 Typically, a granule in the photosphere of the sun is about the size of? A) A city, ~20-30 kilometers across. B) Texas, ~1000 km across. C) The Earth, ~12,000 km across. D) Jupiter, ~100,000 km across.

25. Charles Hakes Fort Lewis College25 From inside out, which is the correct order? A) core, convective zone, radiative zone B) photosphere, radiative zone, corona C) radiative zone, convective zone, chromosphere D) core, chromosphere, photosphere E) convective zone, radiative zone, granulation

26. Charles Hakes Fort Lewis College26 From inside out, which is the correct order? A) core, convective zone, radiative zone B) photosphere, radiative zone, corona C) radiative zone, convective zone, chromosphere D) core, chromosphere, photosphere E) convective zone, radiative zone, granulation

27. Charles Hakes Fort Lewis College27 Misc notes Problem 9.1 - note that Mercury’s orbit is very eccentric, so you can’t simply use the semi-major axis for it’s distance at perihelion.

28. Charles Hakes Fort Lewis College28

29. Charles Hakes Fort Lewis College29 Nuclear Fusion

30. Charles Hakes Fort Lewis College30 Forces in Nature Gravity - long range; relatively weak. Electromagnetic - long range; responsible for atomic interactions (chemistry) Weak Nuclear Force - short range; responsible for some radioactive decay Strong Force - short range; holds nuclei together

31. Charles Hakes Fort Lewis College31 Nuclear Fusion Combining light nuclei into heavy ones. nucleus 1 + nucleus 2 = nucleus 3 + energy Law of conservation of mass and energy E = mc 2

32. Charles Hakes Fort Lewis College32 Figure 9.25 Proton Interactions Like charges (two protons) repel by electromagnetic force. With enough energy (temperature) and pressure, can overcome EM force

33. Charles Hakes Fort Lewis College33 Proton-Proton chain Most common reaction in the Sun. 4 protons >->->-> helium-4 + 2 neutrinos + energy Many other reactions are possible, but 90% are the proton-proton chain. Calculate energy produced from mass differences. (use E=mc 2 ), get 4.3x10 -12 J (Joules) when 4 protons fuse to Helium. From Sun’s luminosity, can calculate that 600 million tons of Hydrogen per second are fused into Helium.

34. Charles Hakes Fort Lewis College34 Figure 9.26 Solar Fusion

35. Charles Hakes Fort Lewis College35 Proton-Proton chain Neutrinos - “little neutral one” are almost mass-less, and react with almost nothing.

36. Charles Hakes Fort Lewis College36 Figure 9.27 Neutrino Telescope - Super Kamiokande Need large amounts of matter to detect neutrinos Solar Neutrino Problem - until recently could not explain observed low numbers.

37. Charles Hakes Fort Lewis College37 Proton-Proton chain Neutrinos “oscillations” explain the observation discrepancy. Neutrinos take eight minutes to get to the Earth from the Sun. In that time they can mutate (oscillate) into other forms.

38. Charles Hakes Fort Lewis College38 Three Minute Paper Write 1-3 sentences. What was the most important thing you learned today? What questions do you still have about today’s topics?