Location of stellar evolution tracks computed with the PARSEC and COLIBRI codes (Bressan et al. 2012; Marigo et al. 2013) for a few selected values of the initial mass (as indicated). The initial metallicity is Z = 0.006 for the tracks with M_i = 1.3, 1.6, 2.6, and 4.4 M_⊙, and Z = 0.008 for the massive ones with M_i = 12 M_⊙ (solid line) and 20 M_⊙ (dashed line). The TP-AGB phase is color-coded according to the surface C/O ratio, while the previous evolution is shown with a black line. In the right-bottom panel the visible sections of the massive star tracks include part of the H-shell burning phase, the core-helium burning phase in blue (a blue loop is visible for the 20 M_⊙ models), and the stages immediately preceding the ignition of carbon in the core. The circles mark the beginning of the core-helium-burning phases in the two massive stars.