uv coverage dispersed in wavelength of the observations acquired during the programs 080.D-0231 (grey-scale), and 084.D-0361 (red-scale). The colour code ranges from 8–12.5 μm, with light colours indicating shorter wavelengths. The sample is restricted to the observations used for this work (marked with (b) and (d) in Table 1).

Normalised intensity distribution at 10 μm in the sky plane of the geometric model that best fits the R For MIDI data of 2009. The position of the asymmetric structure is indicated with a circle. The axis orientation is chosen according to the standard with north up and east left.