CO J = 4− 3 Velocity-resolved surface brightness distribution of a Keplerian disk seen edge-on (see Sect. 3.1.1 for details). (a) No features. (b) Cavity at r_in = 60 au. The inclined black dashed line indicates the lack of flux inside the cavity. (c) Gap between r_in = 40 and 60 au. The inclined black dashed lines indicate the lack of flux inside the gap. (d) Sin-wave density profile. Black lines indicate the flux maxima (minima) corresponding to the location of maxima (minima) of the density distribution.