Position of 31 Comae and OU And (circle and square, respectively) on the Hertzsprung-Russell diagram (HRD) diagram. Solar metallicity tracks of evolution models with different masses (indicated on the plot, in solar mass) are shown. The dashed black line delimits the beginning of the first dredge-up phase and corresponds with the evolution points when the mass of the convective envelope of the models encompasses 2.5% of the total stellar mass. The loops on the evolutionary tracks in the right part of the HRD (effective temperature below ~5000 K) correspond to the central helium-burning phase.