HR diagram (left) for all calculated models with a mixed mass ~10^-7 M_⊙. Each segment represents the evolution of one model whose mass is color-coded using a simple formula. The metallicity (Z₀) of each series of models is indicated at the left of the sequence. The dotted part represents the first 10 Myr of HB evolution, while the solid line represents the rest of the calculated HB evolution, ususally an additional 27 Myr. In the right panel, g vs. T_eff diagram of a subset of the calculations (those with T_eff > 20   000 K) corresponding to the observations of Geier et al. 2010. This panel contains data (gray and red dots as defined in the text) from their Fig. 2.