Integrated intensities of the N₂D⁺(2–1), N₂H⁺(1–0), DCO⁺(2–1), and H¹³CO⁺(1–0) lines across the cores. The contours show 60% of the intensity peak; filled circles show the emission peaks. Stars show the positions of YSOs from Rebull et al. (2010): black stars are young, flat, and Class I objects; white stars are more evolved, Class II and III objects. The 27.8′′ beam size of N₂H⁺(1–0) is shown in the bottom left of each panel.