1. Charles Hakes
Fort Lewis College 1

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

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

4. Tutoring Wednesday 4:30-6:00 Berndt 640 USE IT OR LOSE IT
Charles Hakes
Fort Lewis College 4

5. 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
Charles Hakes
Fort Lewis College 5

6. 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
Charles Hakes
Fort Lewis College 6

7. 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
Charles Hakes
Fort Lewis College 7

8. 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
Charles Hakes
Fort Lewis College 8

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

10. Compared to the Earth, the Sun’s average density is:
A) lower
B) about the same
C) much greater
Charles Hakes
Fort Lewis College 10

11. 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
Charles Hakes
Fort Lewis College 11

12. Solar Atmosphere Photosphere - Chromosphere - Transition zone/Corona -
What we see. (~5780 K)
Chromosphere -
pinkish color (from Ha line); can see during eclipse.
cooler temperature (~4500 K)
Transition zone/Corona -
Shift from absorption spectrum to emission spectrum
Corona very hot (~3 million K)
Solar Wind -
The Sun is evaporating!
Charles Hakes
Fort Lewis College 12

13. Figure 9.10 Solar Chromosphere
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Fort Lewis College 13

14. Figure 9.12 Solar Corona
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Fort Lewis College 14

15. Figure 9.24 Active Corona
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Fort Lewis College 15

16. Figure 9.13 Solar Atmospheric Temperature
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Fort Lewis College 16

17. What about the internal structure?
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Fort Lewis College 17

18. Solar Composition Element Number Percent Mass Percent H 91.2 71 He 8.7
27.1 O
0.078
0.97 C
0.043
0.4 N
0.0088
0.096
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Fort Lewis College 18

19. Figure 9.2 Solar Structure
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Fort Lewis College 19

20. Internal Structure Core - Radiation Zone - Convection Zone -
temperatures hot enough for nuclear reactions (~15 million K)
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.
Charles Hakes
Fort Lewis College 20

21. Figure 9.6 Solar Interior
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Fort Lewis College 21

22. How do we know what is inside the Sun?
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Fort Lewis College 22

23. How do we know what is inside the Sun?
Standard model
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Fort Lewis College 23

24. Figure 9.4 Stellar Balance
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Fort Lewis College 24

25. Figure 9.5 Solar Oscillations
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Fort Lewis College 25

26. Figure 9.7 Solar Convection
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Fort Lewis College 26

27. Figure 9.8 Solar Granulation
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Fort Lewis College 27

28. possibly related to seismic activity
Figure 9.11 Solar Spicules
dynamic jets
5-10 minute life
possibly related to seismic activity
Charles Hakes
Fort Lewis College 28

29. 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.
Charles Hakes
Fort Lewis College 29

30. 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.
Charles Hakes
Fort Lewis College 30

31. 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
Charles Hakes
Fort Lewis College 31

32. 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
Charles Hakes
Fort Lewis College 32

33. Misc notes Problem 9.1 Should say “Section 9.1” and NOT 16.1.
And note that Mercury’s orbit is very eccentric, so you can’t simply use the semi-major axis for it’s distance at perihelion.
Charles Hakes
Fort Lewis College 33

34. Charles Hakes
Fort Lewis College 34

35. Nuclear Fusion
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Fort Lewis College 35

36. 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
Charles Hakes
Fort Lewis College 36

37. nucleus 1 + nucleus 2 = nucleus 3 + energy
Nuclear Fusion
Combining light nuclei into heavy ones.
nucleus 1 + nucleus 2 = nucleus 3 + energy
Law of conservation of mass and energy
E = mc2
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Fort Lewis College 37

38. Figure 9.25 Proton Interactions
Like charges (two protons) repel by electromagnetic force.
With enough energy (temperature) and pressure, can overcome EM force
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Fort Lewis College 38

39. 4 protons ==>> helium-4 + 2 neutrinos + energy
Proton-Proton chain
Most common reaction in the Sun.
4 protons ==>> helium neutrinos + energy
Many other reactions are possible, but 90% are the proton-proton chain.
Calculate energy produced from mass differences. (use E=mc2), 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.
Charles Hakes
Fort Lewis College 39

40. Figure 9.26 Solar Fusion
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Fort Lewis College 40

41. Proton-Proton chain
Neutrinos - “little neutral one” are almost mass-less, and react with almost nothing.
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Fort Lewis College 41

42. 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.
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Fort Lewis College 42

43. 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.
Charles Hakes
Fort Lewis College 43

44. 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?
Charles Hakes
Fort Lewis College 44