Snapshots of the disk surface density at t = 2 kyr (left), 8 kyr (middle), and 28 kyr (right), for infall rates of ﹩{\dot{M}}_{{\rm{in}}}=1{0}^{-8}\,{M}_{\odot }\,{{\rm{yr}}}^{-1}﹩ (top), 10⁻⁷ M_⊙ yr⁻¹ (middle), and 10⁻⁶ M_⊙ yr⁻¹ (bottom). The short red arc and red dotted lines in the upper-left panel mark the infall zone and the infall trajectories of the fiducial model, respectively.