Opacity laws used in the modeling of the multiwavelength observations. Left panels: absorption opacity (top), albedo (middle), and total extinction (bottom) at 1.3 mm as a function of maximum grain size (a_max), for three values of the power-law index of the particle size distribution (p). The nine panels on the right show the spectral index of the absorption opacity (β_κ ; top), the scattering opacity (β_σ; middle), andthe total extinction (β_χ; bottom) between the different wavelengths of our data, as a function of a_max, and for p = 4.0 (left column), p = 3.5 (middle column), and p = 3.0 (right column). The vertical dashed line in all the panels indicates a_max = 200 μm, the limit we set to separate between the two families of solutions in our analysis.