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Nuclear Reactions Two major reactions: Proton-Proton 5*10^6 < T < 2*10^7 Or if T higher (assuming heavier elements are present) CNO Cycle 2*10^7 < T < 10^8
Note: a star with little CNO cant do this. Above 10^8 Can really be written Must be very dense for three He atoms to coe close enough together all at once Important implications for cosmology --> onely way to make elements heavier than He is to bring these nuclei together -- only in stars/
Stellar Structure Core in thermal/gravitational equilibrium. Above the core structure is quite different. Force of the photons escaping the core adds to the thermakl enerfy density. Lifts a mantle of cooler materical away from the center of the star.
Energy Transport a) Radiation b) Convection c) Conduction
Equations of Structure Hydrostatic Equilibrium
P = nkT + Radiative term Radiative term dominates outside the core Opacity plays big role Imagine no opacity photons escpae -- core sized star Very high opacity gets bigger and bigger longer for energy to escape -- heats and expands If k is known, so is the structure, k is the key
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