Expansion properties as derived from the half width at half maximum (HWHM) of the spatially integrated line profiles for the same six α = 3 sequences shown in Fig. 12 vs. the post-AGB age, for Hβ (left) and [O iii] 5007 Å (right). Again, the five black dots along the abscissas refer to the snapshots depicted in Figs. 5−9. The shadowed areas indicate the thermal Doppler broadening, computed by means of the mean electron temperatures (see next section). The lower boundary refers to the models with the highest metallicity, 3   Z_GD, the upper boundary to those with the lowest metallicity, Z_GD/100.