Top panel: temporal evolution of the surface CZ base for the following final stellar masses: M_final = 1.5, 1.2, 1, 0.8 and 0.5 M_⊙ from top to bottom. In all cases, accretion stops at 10⁷ years, and ξ = 0.1, X_D = 28 ppm and a uniform heat distribution are assumed. Bottom panel: mass fraction of the CZ as a function of stellar mass. The lines from top to bottom denote the temporal evolution from 10⁷ to 10⁹ yr.