Cluster formation induced by a cloud–cloud collision in [DBS2003]179

Abstract

Abstract [DBS2003]179 is a super star cluster in the Galaxy discovered in deep near-infrared observations. We carried out CO J = 1–0 and J = 3–2 observations of the region of [DBS2003]179 with NANTEN2, ASTE, and the Mopra 22 m telescope. We identified and mapped two molecular clouds that are likely to be associated with the cluster. This association is supported by the spatial correlation with the corresponding 8$\, \mu$m Spitzer image and by a high ratio of the two transitions of $^{12}$CO(J = 3–2 and J = 1–0). The two clouds show complementary distributions in space, and bridging features connect them in velocity. We hypothesize that the two clouds collided with each other 1–2 Myr ago and that the collision compressed the interfacial layer, triggering the formation of the cluster. This offers an additional piece of evidence for a super star cluster formed by a cloud–cloud collision, alongside the four super star clusters Westerlund$\:2$, NGC 3603, RCW 38, and R 136. These findings indicate that the known super star clusters with closely associated dust emission were formed by cloud–cloud collisions, lending support to the important role of cloud–cloud collisions in high-mass star formation.