HR diagram of selected tracks with 0.75, 0.8, and 0.85 M_⊙ in the left-hand, middle, and right-hand panels, respectively. The tracks are computed with Z = 0.002 and Y = 0.249. The continuous lines show the evolutionary phases we include in the isochrones computation, while dashed lines indicate the pre-MS and the planetary nebula phases (excluded from the computations). Red diamonds and blue circles show the critical points (marked by a number) and the secondary interpolated points, respectively