Theoretical evolutionary tracks plotted in log g − T_eff diagram (from the main sequence up to the early-AGB) computed with thermohaline instability and rotation-induced mixing at solar metallicity (left panel) and at [Fe/H] = −0.56 (right panel). Different line styles correspond to different stellar masses. Position of the considered set of stars for which ¹²C/¹³C has been measured are represented by a circle for HD 175294, a square for HD 175679, a triangle for HD 181907, and a diamond for α Boo. They are segregated according to their metallicity.