Spectral energy distributions for the spherical radiative transfer for the M15 ice and core composition, with varying dust size distribution, for different visual extinctions (A_V = 15, brown; 30, blue; 60, red; 100, green). Distributions correspond to, from the top left to lower right: silicate core, M15 ice mantle composition and size distribution MRN, and a_max = 0.25 µm (model #4); τ₁, a_max = 1 µm (model #5); τ₃, a_max = 3 µm (model #6); τ₃, a_max = 3 µm (model #6) with ice threshold is set at instead of 3; and τ₅, a_max = 5 µm (model #7). The inserts display close-ups of the CO₂ ice band, with spectra normalised at 4.1 µm.