Upper panel: ejection velocity from the disc versus galacto-centric distance of the ejection point, consistent with the kinematics of DESI-312. We computed the velocities and distances by sampling observational uncertainties over 100000 orbit realizations, integrated backwards over the star’s median lifetime; points are coloured according to the normalized density of orbit crossings in the radius-velocity plane. Lower panel: Fe abundance profiles of the gas 9 Gyr ago (green), 4.56 Gyr ago (yellow), and at present (red), from Prantzos et al. (2023) models.