An S-shaped Filament Formed Due to Cloud–Cloud Collision in Molecular Cloud G178.28-00.61

Abstract

We present compelling observational evidence supporting G178.28-00.61 as an early-stage candidate for cloud–cloud collision (CCC), with indications of the formation of an S-shaped filament, evenly separated dense cores, and young star clusters. The observations of CO molecular line emission demonstrate the existence of two interacting molecular clouds with systemic velocities of 0.8 km s−1 and −1.2 km s−1, respectively. The convergence zone of these two clouds reveals an S-shaped filament in the James Clerk Maxwell Telescope 850 μm continuum image, suggesting cloud interaction. In line with expectations from CCC simulations, broad bridging features are discernible in the position–velocity diagrams. An elevated concentration of identified Class I and II young stellar objects along the filament at the intersection area further supports the hypothesis of a collision-induced origin. This observation could be explained by a recent MHD model of CCC, which predicts a similar morphology, scale, density, and unbound status, as well as the orientation of the polarization.