Effective temperature (panels a and b), luminosity from hydrogen and helium burning (panels c and d), surface mass fraction of hydrogen and helium (panels e and f) and total mass of hydrogen (panels g and h) for our Z = 0.0166 (left column) and Z = 0.0002 (right column) models from slightly before Roche-lobe overflow and for the rest of the evolution. In the panels with effective temperature plus signs indicate the times at which the central helium mass fraction has reached 0.9, 0.5 and 0.05. In the luminosity panels we show the total stellar luminosity with a black, dotted line.