Comparison of modified blackbody spectra for the three different dust models displayed in Fig. 2 for a dust temperature of T_d = 20 K and upper values of a_max of 0.02 μm (D1 ), 2 μm (D3 ), and 200 μm (D5 ), respectively.These spectra are more narrowly peaked and skewed toward smaller wavelengths than the corresponding Planck function B_λ(T_d), because the emission is weighted by the absorption cross section, C_abs,λ, which drops significantly at sub-mm and mm wavelengths.