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Understanding the Main Sequence Stars: Hydrostatic Equilibrium and Fundamental Forces of Nature

Learn about the hydrostatic equilibrium, nuclear fusion, wave functions, quantum tunneling, and the solar neutrino problem in main sequence stars. Explore the interactions and processes that govern these celestial bodies.

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Understanding the Main Sequence Stars: Hydrostatic Equilibrium and Fundamental Forces of Nature

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  1. Chapter 9 The Main Sequence

  2. Four fundamental forces of nature

  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

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

  7. Wave function Probability distribution

  8. Quantum tunneling

  9. Gamow Peak: energy region where the reaction is more likely to take place Can’t tunnel through Coulomb barrier Few particles

  10. Another view of Gamow peak

  11. One of 3 branches of proton-proton chain

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

  13. T-dependence of pp chain and CNO cycle

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

  15. 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”

  16. 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”

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