Evolution of the relative gas mass: in the disc (blue), accreted onto the star (green), and lost by internal (orange) or external (red) photoevaporation until disc dispersal at 1.38 Myr. This represents a typical disc, with M_⋆ = 0.5 M_⊙, M_G/M_⋆ = 0.1, β = 0.9, R_in = 0.1 au, r₁ = 87.8 au, α = 1 × 10^–3, L_X = 7.02 × 10²⁹ ergs^–1, and F = 10 G₀. The parameters for the solid disc are irrelevant, as this shows only the gas component, except that we used f_D/G = 0.0149 to compute the solid mass needed to set the characteristic radius r₁.