Position-velocity diagram of the ¹²CO emission clouds along the white straight lines in Fig. 2. The position corresponding to offset 0 is at RA(J2000) = 19^h52^m177, Dec(J2000) = +26°22′058. The position angle of clump BC is positive, and that of clump AD is negative. The contour levels rang from 0.97 to 8.72 by 0.97 K for the left panel, while from 1.23 to 11.07 by 1.23 K for the right panel. The color bar of the grayscale for the ¹²CO emission is above the diagram. The letters A, B, C, and D correspond to the positions of the same letters as in Fig. 2.