Density structure of the disk at different epochs after the start of the outburst. The horizontal axis is the radial coordinate in au. The vertical axis is π/2 − θ ≃ z/r. Stellar photons move horizontally in this plot. The color scale is logarithmic, normalized to the maximum density of the first image. The white line is the radial τ = 1 line at λ = 0.66 μm with scattering included. The albedo at this wavelength is 0.8. The radiation-hydrodynamics simulations, however, only use the absorption opacity.