Analogy to Fig. 7 for the case with the bow-shock. Top left: the evolution of an initially spherical Gaussian envelope in the presence of a star for chosen epochs since the start of the simulation. Bottom left: representation of the evolution from the top-left panel is shown in the velocity-distance plane. The angular distance is expressed in miliarcseconds. Top right: as in the top-left panel, but for a star-disc system. Bottom right: the track in the velocity-position plane corresponds to the trajectory from the top-right panel.