Similar to Fig. 1, but displaying ratios of parameters, instead of the absolute ones, for different combinations of L_bol, s/L_bol, p, R_s/R_p, g_s/g_p, and T_eff, s/T_eff, p. The nominal masses and other empirical parameters of V69’s components are the same as listed in Table 1; since the absolute mass values are fixed, tracks for different Y values have different TO ages, as also happens in the case of Fig. 2. The first and third columns show the same evolutionary stages as those covered by the relative tracks presented in Fig. 2. The second and fourth columns are zoomed-in plots corresponding to the first and third columns, respectively. In each panel, solid, dotted, and dashed blue lines correspond to VR tracks for Y = 0.25, 0.29, and 0.33, respectively (Table 2), whereas red tracks in the zoomed-in plots correspond to BaSTI tracks with Y = 0.255, Z = 0.006. In this case, we only show VR tracks (for easier viewing), but the PGPUC models show the same behavior. The points with error bars correspond to the empirical parameters derived for V69 from the empirical data (Table 1), with the error bars propagated from the absolute values.