Snapshots of model density structures and Hα intensity distributions for 3 hydrodynamical sequences: 0.605 M_⊙ “hydro”, (left), 0.595 M_⊙ “α = 3”, (middle), and 0.625 M_⊙ “α = 2” (right) at selected times (right ordinate). Left part of the panels: normalised total ion (solid) and electron densities (dotted) over radius r at the indicated times, for comparisons. Right part of the panels: evolution of R_out (solid) and R₁₀ (dotted) with time t. At a number of times, defined by the cut of the intensity line with the right ordinate, the (normalised) Hα intensity profiles are plotted over the impact parameter p. Note that the extremely sharp density peaks seen in the right panel at times of 4000 and 7000 years have no correspondence in the intensity profiles because the gas is not ionised.