ALMA Band 4 continuum-subtracted moment-0 maps of HD1. All maps are based on naturally weighted data. Each panel shows a moment-0 map collapsed over the same same integration width of 200 km s⁻¹, but centred at different frequencies, as indicated at the top of each panel. The central frequencies are indicated in km s⁻¹ with respect to the reference frequency v = 133.2 GHz, the frequency of the expected [C II] line. For all panels, the contours are drawn at −3.5, −2.5, −1.5, 1.5, 2.5, 3.5-σ and have rms values of 8.32, 8.25, 8.44, and 8.88 mJy beam⁻¹ (from left to right). The synthesised beam FWHM is indicated by the ellipse in the lower left and the image scale is shown on the lower right in the left panel. The dashed circle has a radius.