a) MWISP ¹²CO intensity map of the inner rim. The blue and pink contours show the emission integrated between [−66, −60] and [−58, −55] km s^-1, respectively. The blue contours start at 5σ and increase in steps of 3σ (1σ ~ 0.6 K km s^-1), while the pink contours start at 3σ and increase in steps of 2σ (1σ ~ 0.47 K km s^-1). The red circle shows the position and size of the shell-like structure (8′ in diameter). The yellow dashed arrow lines show the cuts toward the southeast and northeast clouds (see Figs. 4 and 5). b)–c) Position-velocity diagrams along the two cuts marked in panel a) (white dashed arrow lines). The contours in the two diagrams start at 0.5 K and increase in steps of 0.5 K (1σ ~ 0.14 K). The blue ellipse in panel c) shows a fitting toward the diagram with a velocity radius of ~3.8 km s^-1.