Relations between ${\sigma }_0^{\text{obs}}$ (left panel), EW_Lyα (middle panel), and $f_{\text{esc}}^{\text{Ly}\alpha }$ (bottom panel) with the dust-corrected burst age. Kendall’s τ and the respective p-value are provided in the bottom left of each panel. Different symbols are used for rotating discs (circles), perturbed rotators (squares), and galaxies exhibiting complex kinematics (stars). We colour code the points according to EW_Lyα (left and right panel) or $f_{\text{esc}}^{\text{Ly}\alpha }$ (middle panel). We also highlight points with red outlines that show L_Lyα/L_Hα above the maximum dust screen expectation from Eq. (6). As visual aid for the interpretation we show model calculations for the mechanical luminosity, L_mech, and the intrinsic Lyα equivalent width, EW_Lyα^int, as a function of burst age with grey dotted lines. We note that the ticks on the right side of each panel provide the scale for these model calculations. In particular, we show the L_mech of a Z = 0.008 starburst normalised to 1 M_⊙ in the left panel and we indicate the temporal evolution of EW_Lyα^int for a Z = 0.008 burst and the EW_Lyα^int range for constant star-formation at Z = 0.001 − 0.040 in the middle panel (see text for details).