ASTR 3 Lecture Notes - Lecture 12: Solar Cycle, Radiation Zone, Solar Wind
Document Summary
Solar wind: flow of charged particles (protons and electrons) from the visually opaque. Remember: the sun is a ball of gas throughout. But there is a depth of which it is opaque. Proton-proton chain is how hydrogen fuses into helium in sun. In: 4 protons; out: 4 he nucleus, 2 gamma rays, 2 positrons, 2 neutrons. Decline in core temperature causes fusion rate to drop, so core contracts and heats up. Rise in core temperature causes fusion rate to rise, so core expands and cools down. Energy gradually leaks out of the radiation zone in the form of randomly bouncing photons. It takes well over 100,000 years for a photon to reach the surface. Bright spots on sun"s surface is where hot gas is rising, and darker regions are cooler gas sinking. At the top of the radiation zone the temperature has dropped to ~2 million k. How we learn about the inside of the sun.
