Spectral energy distributions as a function of wavelength resulting from the dust temperatures indicated in Fig. 9. The black curve shows the original spectrum for a dynamical model with pure Mg₂SiO₄ grains (M = 1 M_⊙, L = 5000 L_⊙ and T_∗ = 2800 K). Top panel: the spectra produced when setting a minimum grain temperature of 800 K (blue) and 500 K (red) for the pure Mg₂SiO₄ grains, i.e. using the temperature structure in the top panel of Fig. 9. Bottom panel: the spectra produced when using a core of Mg₂SiO₄ and a mantle of MgFeSiO₄. The green, red and blue lines show the spectra for a mantle size of 1%, 5% and 10% of the radius, respectively. The corresponding temperature structures are shown in the lower panels of Fig. 9