Left panels: maps of σ_V, in km s⁻¹ units. Central panels: Maps of the molecular column density of o-H₂D⁺, in unit of log₁₀(cm⁻²). Right panels: maps of V_lsr, in km s⁻¹ units. Each row shows a different core, labelled at the top of the central panel. The beam size of the H₂D⁺ observations is shown in the bottom right corners. The coordinates are shown in the ICRS system. The dashed contours show the continuum emission at levels [1, 5, 10, 15, 20] mJy beam⁻¹.