Total velocity gradients of the N₂D⁺(2–1) (red), N₂H⁺(1–0) (blue), DCO⁺(2–1) (orange), H¹³CO⁺(1–0) (green), and C¹⁸O(1–0) (black) lines across the cores. The colour scale shows the integrated intensities of N₂D⁺(2–1) across the cores except core 3, where the integrated intensity of N₂H⁺(1–0) is shown. The ellipses show the 2D Gaussian FWHM fitted to the N₂D⁺(2–1) integrated intensity maps (N₂H⁺(1–0) for core 3). 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.