Gap width normalized to the gap radius R_gap as a function of planet mass. From left to right gap width and radius determined from ¹² CO, ¹³ CO, and C¹⁸ O intensity profiles, respectively. The third power of the gap width is used to emphasize the dependency. As in Fig. 11, circles, squares, and diamonds indicate quantities retrieved from images convolved with a 0.03^′′, 0.08^′′, and 0.15^′′ beam, respectively, for sources located at a distance of 150 pc.