Properties of the ‘gem’ in SPT0103−45. Left panel: is the continuum map as described in Sect. 3.2. The white line shows the direction along with the slice for the PV diagram is extracted (Fig. 6). The spectrum shown in the centre panel is extracted at the coordinates of the gem (Sect. 3.3). The frequency range represented by the yellow region is used to compute the integrated intensity of the high-velocity emission, represented in the right panel. The white contours are the 5, 10 and 15σ contours of the continuum emission.