Radial distribution of surface density (top) and radial velocity (bottom) for model 4. Lines corresponds to 1.8 × 10³ yr (solid line) before protostar formation, 0 yr (dashed line), 1.1 × 10⁴ yr (dotted line) and 4.1 × 10⁴ yr (dot–dashed line) after protostar formation.