Left-hand panel: function ψ for core A at selected time steps, indicated in the middle panel of the figure. The green horizontal lines mark the value of ψ that satisfies Eq. (6) at each time step, and the red circles are a guide for the eye to locate the corresponding value of ξ_out (see text). Middle panel: dust (red) and gas (blue) temperature profiles for core A as functions of distance from the core center at different times. Right-hand panel: density profile for core A as a function of distance from the core center at different times. The quoted times are approximate because the time steps considered in the model, save for the first and last, are not exact multiples of ten.