V_LSR local gradients of the N₂D⁺(2–1), N₂H⁺(1–0), DCO⁺(2–1), and H¹³CO⁺(1–0) lines across the cores (black arrows) and V_LSR local gradients of the C¹⁸O(1–0) line from Hacar et al. (2013; red arrows). The scale of the C¹⁸O(1–0) gradients is 2.5 times larger than the scale indicated in the figures. The colour scale shows integrated intensities of corresponding species across the cores. Stars show the positions of YSOs from Rebull et al. (2010): black stars indicate young, flat and Class I objects, white stars indicate more evolved, Class II and III objects.