Y² stellar isochrones from Demarque et al. (2004) for solar metallicity ( [Fe/H] = 0.05,  [α/Fe] = 0) and ages of 0.2,0.4,0.6,0.8, and 1 Gyr, from top-left to bottom-right. Left: M_V(T_eff) isochrones. Right: M(T_eff) isochrones. Our estimations for C0121-A, C0121-Ba, and C0121-Bb are marked by a red diamond, a green square, and a blue circle, respectively. The absolute magnitude and mass of C0121-Bb were taken as the average value of the isochrones for a 6500 K star, assuming no error.