Examples of single knots progressing over time (2007–2014) and their corresponding P-V array and morpho-kinematic shape. Spatial extent is 12.5 arcsec on each side, and the velocity ranges are 500 km s^-1. On the NOT panels the overlaid slit width and position is shown. The Aristarchos and NOT panels in the bottom row are contaminated by the central star leading to a very strong contrast between knots and star. Here, and in Figs. 3 and 4 the displayed knots are positioned along the observed slit axis highlighted in Fig. 1, where the top row corresponds to a slit position angle of 49° and the bottom row to 173°. The spatial axis distance from the central star is positive towards the top of the slit and negative towards the bottom.