11.1 The Solar Interior Joey Schmissrauter Hydrostatic equilibrium Kelvin-Helmholtz Contraction It was initially proposed by English physicist Lord Kelvin and German scientist Hermann Helmholtz that compression is what heats the gas and makes the Sun shine. Internal Structure of the Sun • There is rising temperature and density as we go from the surface of the Sun towards the center. • The density at the center of the Sun is 150 g/cm3. • The temperature at the center of the Sun is roughly 15 million Kelvin. • P = nkT, the ideal gas law, applies. How Solar Energy is transported • Created in the core by way of thermonuclear fusion. • Energy is passed outward by photons which are emitted and absorbed by atoms (mostly H and He) in what is called the radiative zone. • Just below the photosphere, there is rising and sinking gas caused by a form of energy transfer called convection. This is the convection zone. Thermal equilibrium • Energy leaves the Sun in the form of heat and light. If it stopped creating energy, it would collapse in on itself due to gravity. • Nuclear fusion was found to be the most likely and feasible way that the Sun creates energy. • Nuclear fusion is possible in the Sun’s core, because high temperature allows for the electrical force between protons to be overwhelmed by the strong force. Proton-Proton chain The importance of neutrino research SuperKamiokande neutrino detector in Hida, Japan • • • Neutrino detectors detect neutrinos that are side products of solar fusion. By detecting how many neutrinos, we can infer what the temperature and density are at the core and also get a clear understanding of how the Sun works. Neutrino research is very important in backing up solar theory and our understanding of the Sun’s internal processes. Works Cited • Arny, Thomas, and Stephen E. Schneider. Explorations: an Introduction to Astronomy. New York, NY: McGraw-Hill, 2008. Print. • Carroll, Bradley W., and Dale A. Ostlie. An Introduction to Modern Astrophysics. San Francisco: Pearson Addison-Wesley, 2007. Print. • Fiction Science Reporter. Web. 01 Apr. 2010. <http://fictionsciencereporter.com/?p=223>.