Star formation history in terms of mass fraction per age bin, of the stellar disk (Sect. 2.3) in the galaxy Au8. Age bins (of a half-Gyr in width) are color-coded by the average [Fe/H] metallicity in the top panels and by the average [Mg/Fe] abundance in the bottom panels. The leftmost panels show the mass fraction in each age bin for the entire stellar disk. This mass fraction is split into the in situ (middle panels) and the ex situ stars (rightmost panels). The age can be interpreted as the look-back time when the corresponding mass fraction was formed. The corresponding redshift is indicated on the top axes. All star formation histories were normalized to the galaxy mass. The total mass fractions of the in situ and ex situ components are indicated at the top of each panel.