HR diagrams with computed stellar evolutionary tracks of stars of different initial masses. Left panel: color-coded convective turnover time τ(H_P/2) (in logarithmic scale) in the stellar convective envelope along the evolution in the Hertzsprung-Russell diagram for solar metallicity with rotation and thermohaline mixing from Charbonnel et al. (2017) as dashed lines (initial masses of 1, 1.25, 1.5, 2, 3, 4, and 6 M_⊙) and our 1.5 M_⊙ model at [Fe/H] = −0.25 dex with thermohaline mixing and without rotation (solid line). The red star marks the location of RZ Ari in the HR diagram (see Table 2). Right panel: same, with the color-coded Rossby number (in linear scale) at half a pressure scale height above the base of the convective envelope for the models from Charbonnel et al. (2017). The track of the dedicated 1.5 M_⊙ nonrotating model at [Fe/H] = −0.25 dex is also shown as the solid black line. A star like this should have the same Rossby number evolution as the colour-coded 1.5 M_⊙ track from Charbonnel et al. (2017) when it rotates, e.g., Ro ≈ 10 at the location of RZ Ari.