Central temperature as a function of the central density along the evolution of the 0.8 M_⊙ models computed with various initial helium mass fractions from 0.248 to 0.8 (colors correspond to evolutionary phases as in Fig. 2); the bend at the end of the RGB is characteristic of the helium flash. The straight dotted line corresponds to the limit where the pressure given by the non-relativistic perfect gas law is equal to the pressure given by the completely degenerate non-relativistic gas, and where the mean molecular weight is of the core of a RGB star, i.e., log(T_c) = 4.7 + 2/3 log(ρ_c).