1. Chapter 9
The Main Sequence

2. Four fundamental forces of nature
All four forces have to do with the Sun

3. Hydrostatic equilibrium: negative feedback loop
If core T drops,
fusion rate drops,
core contracts
heats up
If core heats up,
fusion rate rises
core expands
cools down

4. Main sequence stars are modeled as concentric spherical shells in hydrostatic equilibrium
Mass element dm
Constant density 
Inward force = outward force

5. Binding energy holds a nucleus together: BE = total mass of each individual nucleon - mass of nucleus

8. The Coulomb barrier:
1 in 1085 particles has the energy to cross it

9. Wave function
Probability distribution

10. Quantum tunneling

11. energy region where the reaction is more likely to take place
Gamow Peak:
energy region where the reaction is more likely to take place
Can’t tunnel through Coulomb barrier
From
The Gamow peak is the product of the Maxwell-Boltzmann distribution with the tunnelling probability of the nuclei through their Coulomb barrier. This is the energy region where the reaction is more likely to take place: at higher energies, the number of particles becomes insignificant while at lower energies the tunnelling through the Coulomb barrier makes the reaction improbable. The dimension of the Maxwell-Boltzmann distribution and of the Gamow peak is keV-1, while the tunnelling probability is dimensionless.
Few particles

12. Another view of Gamow peak

13. One of 3 branches of proton-proton chain

15. CNO cycle: C, N O atoms act as catalysts

17. T-dependence of pp chain and CNO cycle

18. Solar neutrino problem:
Early searches for solar neutrinos only found ~1/3 the expected number of neutrinos

19. Solar neutrino problem:
Early searches for solar neutrinos only found ~1/3 the expected number of neutrinos
Neutrinos apparently can change form. According to nuclear physics theory, this means they must have mass!
“flavor oscillation”

20. Super-Kamiokande in Japan.
1 km underground (in a mine)
11,000 light-detectors in/around a pool of water
Neutrino can (rarely) interact with a proton
A particle is produced that moves faster than the speed of light in water
Causes an optical “sonic boom”