Age-metallicity relation for Selene disc stars, colour-coded according to their current radial positions (see text, Table 2, and Fig. 4 for more information). Blue crosses represent stars currently located in region 1. Green asterisks represent stars currently in region 2. Red dots represent stars currently in region 3. Black triangles represent stars currently in region 4. The two histograms on top of the AMR and on the right represent the age and metallicity distribution function, respectively (colour-coded in the same way). The parameter t_jump is denoted by the dashed cyan vertical line. Solid lines correspond to the linear fits performed to the AMR of the stars in the four radial regions for epoch 2 (from t_jump until 10 Gyr ago) and epoch 3 (from the present day until t_jump).