Positions of the sample stars on giant branches of 12 Gyr isochrones (Dotter et al. 2008, solid lines) with [Fe/H] from −2.5 (violet) to −1.5 (red) with a step of 0.25 dex. For comparison, we show the 12 Gyr Dotter (2016) isochrone with [Fe/H] = −1.75, which includes advanced evolutionary stages (dashed orange line). Larger symbols represent stars at more advanced evolutionary stages. The symbols have the same metallicity colour coding as the lines.