CO (2–1) (blue), ¹³CO (2–1) (green), and C¹⁸O (2–1) (red) channel maps. The color bars indicate the S/N of the observed emission. Dotted white circles in the channel maps denote the maximum bound radius (r_POS,bound), as defined in Section 3. Overlap of emission from different lines is seen as cyan (CO and ¹³CO), yellow (¹³CO and C¹⁸O), and white (all three lines) colors. The horizontal lines in the bottom-left corners, the ellipses in the bottom-right corners, and the gray solid circles represent a length scale of 500 au, the beam size, and the field of view of the data, respectively. The locations of structures A, B, and C are marked on the maps.