Fitted empirical age–H-peak relations. The data points are the same as in Fig. 6. The blue solid line represents the peak-age function fitted from the observed data (blue points). The area shaded in blue is the uncertainty range, and the lower and upper bounds of the uncertainty are indicated by the thin blue dot-dashed lines. The black line is the peak-age function fitted from the PARSEC model points (black bars). The area shaded in gray is the uncertainty range and the lower and upper bounds are given by the thin black dashed lines.