The best-fit simulations of the Hα and Hβ lines (thick lines) are overplotted on the corresponding profiles observed on day 11 (thin lines). Unlike the calculations shown in Fig. 5, here we use a simple model with the radial distributions of the Sobolev optical depth and the line emissivity, which are similar for the Hα and Hβ lines, but scaled arbitrarily to fit both profiles. The dotted line represents the Hβ line for the theoretical ratio R_τ = 7.25.