Effect of the dust on the line profile. The adopted ejecta geometry and dust distribution are invariant and only the dust optical depth, τ_d, is varied (values reported on the figure itself). The unabsorbed line profile was produced assuming a biconical ejecta having cone opening half-angle θ = 70° and thickness Δr/R = 0.6, viewed from an inclination, i = 40°. The dust was assumed to be in the inner half of the ejecta.