Frequency-dependent gas and dust opacities in relation to the irradiating blackbody spectrum of the central star. The black lines indicate the Planck function of the irradiation, where the dash-dotted line represents the star during the quiescent phase (with negligible contribution from the accretion luminosity), whereas the dashed line shows the irradiating spectrum that includes the effect of the maximum accretion luminosity occurring in our models. The separation of the frequency space into the 50 bins is indicated by the thin vertical lines, where each bin is coloured according to its relative spectral weight. The orange crosses mark the dust opacities in their respective bins, multiplied by the maximum dust-to-gas mass ratio f₀. The gas opacities in each bin were evaluated for a density of 10⁻¹⁰ g cm⁻³ and are shown for two representative temperatures: 1000 K (blue crosses) and 3000 K (magenta crosses).