Radially resolved, stellar age distribution for Selene, normalised to the total stellar mass. In this plot we study all the particles in the simulation (in Fig. 12 we show only disc particles). The upper panel shows the stellar age distribution of the stars currently located in region 5 (from 4.4h_in to 6.2h_in), while the bottom panel shows stars currently located in region 6 (6.2h_in to 7.9h_in). Lines and colours represent the same as in Fig. 12. A low number of old, in situ stars are responsible for shaping the old outer plateau even in the absence of radial motions if we do not apply our disc criterion.