TPD12 models recalculated to include the effects of the stellar magnetic field. Left: effect of an internal magnetic field, simulated by using a value of α = 0.6. The isomasses of the solar value α = 1.74 are also plotted for comparison. Right: effect of stellar spots, computed for an effective spot coverage of β = 0.3 (Somers & Pinsonneault 2015). The isomasses for β = 0 (standard models with no spots) are also plotted for comparison. In both cases, the isochrones (dashed lines) of the altered models are also shown and are to be compared with the isochrones of the TPD12 models in Fig. 7. See text.