Upper panel: obtained ζ₂ values are plotted as function of total gas column density towards each core (including the column density integrated along the line of sight). The solid points and error bars are computed using L = 0.1 pc. The upper limits are shown with downward arrows. The transparent points show the range of ζ₂ values obtained when L is computed using the 40% or 60% contours of N(H₂). as described in the main text. Lower panel: ζ₂ values (computed for L = 0.1 pc) are plotted as a function of the core’s dust temperature, as derived from the Herschel maps. The dashed line shows the linear regression computed in the log₁₀(ζ₂)-T_dust plane, and the computed regression coefficients are shown at the top of the panel. In both panels, the data points are colour-coded by parental cloud (red: Corona Australis; green: Ophiuchus; blue: Taurus; orange: isolated sources).