Schematic representation of the 4 scenarii discussed for the origin of the wide-angle rovibrational H₂ emission in DG Tau. The layer of emitting H₂ at 2000 K is drawn in solid red. Wide-angle wind streamlines are shown as dashed (black if atomic, red if molecular) lines. The velocity of the emitting gas perpendicular and parallel to the cavity wall (V_⊥ and V_∥), and the shock speed V_s and preshock density n_H when applicable, are also listed as a function of the expansion proper motion of the cavity V_exp, the velocity of the H₂ 1–0 S(1) emitting layer in the frame of the shock wave, V_n(H₂), and the initial velocity of the ambient gas (V_a) or molecular wind (V_w).