Temporal evolution of (a) the equivalence radius (see text for the definition), (b) the average atomic hydrogen number density, (c) the average temperature (T/µ), (d) the average absolute vorticity, (e) the ²⁶Al mass, (f) the ⁵³Mn mass, (g) the ⁶⁰Fe mass, and (h) the ²⁴⁴Pu mass of the LB (turquoise curve) and the LHB (orange curve) gas in our fiducial simulation. The averages given for the LB (LHB) gas are weighted by mass (volume). The vertical dashed lines mark the explosion times of the individual SNe. Thus, the part of the profiles to the right of the rightmost dashed line reflects the conditions during the wind-driven phase, whereas almost all the rest of the profiles corresponds to the SN-driven phase. Only the part covering the last few 0.1 Myr before present belongs to the final phase of evolution. In panel a, the self-similar wind solution of Weaver et al. (1977) appropriate for the SN-driven phase is shown for comparison (black curve).