Published online by Cambridge University Press: 14 August 2015
Before discussing observational inputs and actual model calculations, I want to give a very elementary review of the relevant parts of stellar evolution theory. We shall only be dealing with stellar masses M below the Chandrasekhar limiting mass Mch(~1·2–1·45 M⊙, depending on chemical composition). The inequality M<Mch implies that relativistic effects are not of overriding importance and I will not mention them further (however, all quantitative model calculations which I will mention later include all the relativistic corrections to the equation of state, including radiation pressure which is also not very important). Let us try to estimate how the central temperature Tc and (total bolometric) luminosity L varies with central density ρc or radius R(ρc~MR−3) for a star of fixed mass.