Density and velocity distributions (Σ and v_los, respectively) in model B 1 at three points in time (top row) and the corresponding background-normalised Ca II lines (bottom row). The discs are viewed from below. The sublimation radius is marked by a black dashed line, and the orbital direction of the planet is shown with a black arrow. In the Panels showing the Ca II lines, vertical dashed lines indicate the centre of the line. The retrograde precession of the disc causes a periodic shift in the intensity maximum.