Synthetic model predictions compared to Anders et al. (2023) stellar ages. Upper panels: in the left panel, APOGEE DR17 stars in the [Mg/Fe] vs. [Fe/H] space selected as in Fig. 1 are colour-coded with the stellar ages computed by Anders et al. (2023, see Section 4.3 for details). Synthetic model predictions also including age errors (see Section 4.3) are reported on the right panel. Lower panels: same as the upper panel, but for the [Fe/Mg] vs. [Mg/H] ratios. Concerning model predictions, point sizes are proportional to the number of stars formed at different evolutionary times and points are colour-coded with the predicted stellar age (only stars with ages <12.5 Gyr are reported).