As Fig. 3 but only for the BLH objects. The blue and red edge of the fundamental mode IS of BLH (between log L ~ 1.81–2.1, for a mass of 0.65 M_⊙) are indicated by the solid line (Di Criscienzo et al. 2007). The dashed lines indicate the location of the first overtone blue edge and fundamental mode red edge of RR Lyrae (see text). PARSEC horizontal branch models (Bressan et al. 2012) are plotted in light blue (Z = 0.001), magenta (Z = 0.004), and yellow (Z = 0.008) for, respectively, 0.515, 0.56, 0.62 M_⊙ (decreasing in luminosity), 0.505, 0.53, 0.57 M_⊙, and 0.50, 0.52, 0.57 M_⊙ (see text). A point is plotted for every 1 Myr of evolution.