Colour–magnitude diagram for the Hercules dSph galaxy (Adén et al. 2009a). • are RGB stars selected for this study. ° indicate RGB stars too faint for this study and open triangles are horizontal-branch stars. The solid line indicates the isochrone by VandenBerg et al. (2006) with colour transformations by Clem et al. (2004). log g values for different magnitudes as indicated. Note that there are two stars at V₀ ~ 18.5 superimposed on each other.