Left column: density distributions (grey scale) and location of forsterite (green) for the different models described in Sect. 4.1. The white arrow shows the inclination of the system. Second and third columns: strength of the 11.3 μm band and the other mid-infrared bands and fourth column: flux in the 69 μm band of forsterite, all as described in Sect. 4.3. The different colours of the curves in the second, third and fourth column are for the observations (grey) and models with forsterite grains with different grain sizes: black (0.1 μm), blue (1.0 μm), red (2.0 μm), orange (4.0 μm), yellow (6.0 μm), purple (8.0 μm). The forsterite abundances are listed in Table 2.