Radial distribution of clumps that can potentially exist below and beyond the dust sublimation zone, i.e., 0.4 R_d–R_d (dashed lines). The distance limits from Sect. 5.3 are marked with colored arrows. For all estimates we use the average measured parameters of WA₂ plus the average ionizing luminosity. The red upper limit from Sect. 5.3.1 uses the definition of the ionization parameter, while the blue upper limit from Sect. 5.3.2 is determined from geometrical constraints on a spherical homogeneous cloud in photoionization balance. The Keplerian orbital motion of this hypothetical cloud passing the line of sight is additionally included to form the lower limit in green (Sect. 5.3.3) while the second, larger lower limit in green is determined for an orbiting cloud neglecting the information on its ionization or column density.