Scissor handle like push effect of the expanding HII region. From left to right: accretion disk and protostellar outflow at t = 20, 30, and 40 kyr of evolution. The disk density is color-coded as in Fig. 1. The outflow velocity is color-coded as in Fig. 3. The images cover ≈5000 au in width. The outermost velocity iso-contour at each time resembles the extent of the HII region in the polar direction.