An S-shaped filament formed due to Cloud-Cloud Collision in molecular cloud G178.28-00.61

TL;DR

This paper provides observational evidence that a molecular cloud filament with an S-shape was formed due to a cloud-cloud collision, leading to star formation and specific filament morphology.

Contribution

It presents the first detailed observational confirmation of an S-shaped filament formed by cloud-cloud collision in G178.28-00.61, supporting recent MHD simulation predictions.

Findings

Identification of two interacting molecular clouds with distinct velocities.

Detection of an S-shaped filament at the collision zone.

Enhanced young star cluster formation at the filament intersection.

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 and -1.2 km/s, respectively. The convergence zone of these two clouds reveals an S-shaped filament in the JCMT 850 micron 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 (Kong et al. 2024), which predicts a similar morphology, scale, density, and unbound status, as well as the orientation of the polarization.