Flux density of the model CPDs for a range of viscous parameters α and mass accretion rates ﹩\dot{M}﹩. The horizontal axis shows the mass accretion rate in units of Neptune masses per year. The upper horizontal axis indicates the planet formation timescale, which is calculated by ﹩{M}_{\mathrm{pl}}/\dot{M}﹩ assuming a constant mass accretion rate. Different solid lines are for calculations with different viscous parameters.