Color map of [C II] emission in velocity interval v_LSR = 0−5 km s⁻¹, with contours of the channel emission in v_LSR = 0−1 km s⁻¹, v_LSR = 2−3 km s⁻¹, and v_LSR = 4−5 km s⁻¹ (blue, green, and red, respectively). From the displacement of the structure of brightest emission in these channels with respect to each other, points marked by the white crosses, we can estimate the expansion velocity to be v_exp ≃ 4.25 km s⁻¹. The projected distance between the crosses is 0.2 pc, and the projected distance from the Trapezium stars of the outermost filament, traced by blue contours, is 1.75 pc.