Chemical evolution of [α/Fe] with age and metallicity for several SFHs. We used the best-fit SFH for silicon (Fig. 7) using meteoric solar abundances from Anders & Grevesse (1989) (“basic”, red line) as well as a sharply initially bursting SFH (“burst”, blue line) and a constant SFR (“constant”, green line). The left-hand column shows the magnesium evolution, the centre column shows the oxygen evolution, and the right-hand column shows the silicon evolution. The additional lines illustrate various modifications to the best-fit SFH. “mod_a” (yellow line) is the track based on the “basic” SFH, where a constant of 0.14 dex has been added to the solar magnesium. “mod_b” (purple line) is the track where a constant of 0.18 dex has been added to the “basic” track, but the late-time (stars older than 8 Gyr) SFR has been reduced by 2. “mod_c” (grey) is the “basic” track where the solar oxygen value is shifted by −0.05 dex.