Spectral energy distributions for the dust compositions described in Sect. 2.1 and Table 1. The SEDs were obtained considering an optically thin medium with a column density N_H = 10²⁰ H cm⁻² illuminated by the standard ISRF (see Sect. 2.3 for details). The orange lines show the case where the centroid of the log-normal size distribution is a₀ = 0.1 μm, the pink lines where a₀ = 1 μm, the green lines where a₀ = 10 μm, the red lines where a₀ = 100 μm, the black lines where a₀ = 1 mm, and the cyanlines where a₀ = 1 cm. The thick grey curves on the Mix 1:50 plot present the case of power-law size distributions with a_min = 0.01 μm and where the dotted line shows the case of p =−3.5 and a_max = 1 μm, the solid lineof p =−3.5 and a_max = 10 cm, and the dashed line of p = −2 and a_max = 10 cm.