2020ApJ...895..137S

We present maps in several molecular emission lines of a 1 square degree region covering the W40 and Serpens South molecular clouds belonging to the Aquila Rift complex. The observations were made with the 45 m telescope at the Nobeyama Radio Observatory. We found that the ¹²CO and ¹³CO emission lines consist of several velocity components with different spatial distributions. The component that forms the main cloud of W40 and Serpens South, which we call the "main component," has a velocity of V_LSR ≃ 7 km s^–1. There is another significant component at V_LSR ≃ 40 km s^–1, which we call the "40 km s^–1 component." The latter component is mainly distributed around two young clusters: W40 and Serpens South. Moreover, the two components look spatially anticorrelated. Such spatial configuration suggests that the star formation in W40 and Serpens South was induced by the collision of the two components. We also discuss a possibility that the 40 km s^–1 component consists of gas swept up by superbubbles created by SNRs and stellar winds from the Scorpius-Centaurus association.