FIRESTORM I: Stellar Feedback and Gas Kinematics in the Evolved W40 Hub-Filament System

The FIRESTORM project–Feedback-Induced Regions and Emission from Star-forming Tracers of ObseRvable Molecular Gas–has targeted four star-forming regions to quantify the impact of stellar feedback on star formation. In this paper, we present multiwavelength results for one of the targets, the nearby high-mass star-forming region W40. Using dense-gas tracers C${}^{18}$O(1–0) and H${}^{13}$CO${}^{+}$(1–0), we identified six velocity-coherent filaments: five at \vlsr $\sim$,7.5\kms! and one at \vlsr $\sim$,5\kms. Four of these converge towards an infrared-bright cluster hosting the most massive star of the region (IRS 1A South, O9.5V), forming a hub-filament system (HFS). Key physical parameters, including filament lengths, widths, masses, velocity dispersions, and line masses, are derived. Five dense clumps traced by N${}_2$H${}^{+}$(1–0) exhibit subsonic to transonic turbulence, contrasting with the supersonic motions of their parental filaments, indicating turbulence dissipation. A deficit of emission at \vlsr $\sim$,7\kms! in several molecular lines, along with a blueshifted absorption dip in the HCN(1–0) profile, suggests that emission from OB-heated gas is being absorbed by a cold foreground cloud. A bridge-like feature in position-velocity space connects the \vlsr $\sim$,5 and $\sim$,7.5\kms! filaments, and spatially coinciding with dense condensations and radio continuum peaks. These findings suggest that a past interaction–likely a cloud-cloud collision–triggered the formation of HFS and ultimately the central massive cluster.