Distributions of dust colour temperature (left) and H₂ column density (right). The dust emissivity index, β, was fixed at 1.8. The colour-scale bars on the right indicate the units in K and cm^-2, respectively. The plus signs show the target positions of our previous molecular-line observations. The diamond symbol indicates the 24-μm emission peak of I05399. The direction towards NGC 2024 is indicated by an arrow in the left panel. The annuli used to compute the density profile shown in Fig. 6 are shown by the green circles, while the black solid line in the right panel shows the location of the slice used to extract the central column density discussed in Sect. 4.5. The resolution of the images is or about 0.043 pc.