Channel maps of the ¹³CO (J = 2–1) and C¹⁸O (J = 2–1) lines, showing a ¹³CO (J = 2–1) integrated intensity map (start from 6σ) with C¹⁸O (J = 2–1) integrated intensity overlaid as contours. The contours start from 6σ to the peak value with steps of 8σ. The σ of the integrated intensity for both CO isotopologues in the interval velocity range of 0.5 is 0.018 K km s⁻¹. This value is calculated as ﹩{T}_{\mathrm{rms}}\times \sqrt{{N}_{\mathrm{channels}}}\times \delta V﹩, where T _rms = 0.08 K represents the typical rms value of the molecular line observations, N _channels = 5 denotes the total number of line channels, and δ V = 0.1 km s⁻¹ stands for the velocity resolution. The main and branched skeletons are shown as white and black curves, respectively.