ASTRON 1144 Study Guide - Midterm Guide: Angular Diameter, Blast Wave, Radial Velocity
3 May 2017
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Photons leave core; hit an atom or electron within ~1 cm & get scattered; slowly staggers to surface ( random walk ); breaks into many low-energy photons. Takes ~1 million years to reach surface photons slowly diffuse out of core. Convection carried by bulk motions of fluid. In the sun, energy is transported by radiative diffusion and convection. Test: solar neutrinos how we know fusion is happening in the core of our sun look for neutrinos created by fusion. Travel (very near) at the speed of light. Interact with matter via the weak nuclear force. Can pass through lead 1 parsec thick. Neutrinos created by nuclear fusion in the sun"s core would stream out of the sun. They are very hard to detect because they interact very weakly. Work deep underground to shield out other radiation. Answer: we detect neutrinos from nuclear fusion in the sun, with the expected energies, in all of the experiments performed to date.
