Moment maps of CO (2-1) for DK Cha. Only data within the velocity interval of 0–5 km s^–1 were utilized to calculate the moment maps (Sect. 3.2.1). Velocity channels with intensities exceeding 3σ are included in the moment map calculation. In each panel, data outside the dashed white circle have been masked out. White curves represent the streamers identified from the SO emission (Fig. 8). The black contours denote the ALMA continuum, as shown in panel a of Fig. 8. The two ALMA observations were conducted in 2015 and 2023, respectively (Sect. 2). Position shifts due to proper motion and/or possible phase calibration uncertainties have been corrected by cross-matching their continuum peaks, determined via 2D Gaussian fitting. In panel a, the synthesis beams of the CO and SO data are represented by the black and cyan ellipses at the lower left corner, respectively.