HB evolutionary tracks in the theoretical plane – luminosity, log(L/L_⊙), vs. effective temperature, log T_eff – for Z = 0.00001, Y = 0.245, and [α/Fe] = 0.00. The top, middle, and bottom left panels show the set of evolutionary tracks corresponding to progenitor masses of M_MS = 0.700 M_⊙, 0.800 M_⊙, and 0.900 M_⊙, respectively. The right panels are a zoom-in around the cooler part of the HB. Each panel also shows the minimum mass, M_min, reached for each set (green lines), corresponding to the hottest track. Blue, red, and gray lines correspond to evolutionary tracks in steps of ΔM = 0.100 M_⊙, ΔM = 0.010 M_⊙ (for masses lower than 0.700 M_⊙), and ΔM = 0.005 M_⊙ (for masses lower than 0.550 M_⊙), respectively. Cyan lines correspond to evolutionary tracks computed with masses greater than 0.700 M_⊙ and lower than 0.800 M_⊙, in steps of ΔM = 0.010 M_⊙. Yellow lines correspond to evolutionary tracks for masses greater than 0.800 M_⊙ and lower than 0.900 M_⊙, in steps of ΔM = 0.010 M_⊙.