Fractional residuals of the SED fitting at different wavelengths for β = 1.0,1.2,1.5,1.8,2.0. The fractional residual is calculated as the difference at each wavelength between the measured flux density and best-fit model divided by the best-fit model. The vertical dotted lines correspond to fractional residuals of 0 and ±0.1. The colours correspond to the four wavelengths considered for the SED fitting: 350 μm (red), 250 μm (black), 160 μm (green), 100 μm (blue).