Comparison of a Keplerian disc and model B1. The upper panel displays the line-of-sight velocity distribution in a Keplerian disc as well as that of model B1 from the hydrodynamic simulations (t = 132.3 days). The sublimation radius is indicated by black dashed lines. The lower panel shows the calculated Ca II line profiles with dashed and solid lines in the two cases. The line centres are marked by vertical grey lines.