FIRESTORM I: stellar feedback and gas kinematics in the evolved W40 hub-filament system

ABSTRACT 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 $V_{\mathrm{LSR}}$$~\sim$ 7.5$\mathrm{\, km\, s^{-1}}$ and one at $V_{\mathrm{LSR}}$$\sim$ 5$\mathrm{\, km\, s^{-1}}$. 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 $V_{\mathrm{LSR}}$$\sim$ 7 $\mathrm{\, km\, s^{-1}}$ in several molecular lines, along with a blueshifted absorption dip in the HCN(1–0) profile, suggests that emission from OB-heated gas is being absorbed by a cold foreground cloud. A bridge-like feature in position–velocity space connects the $V_{\mathrm{LSR}}$$\sim$ 5 and $\sim$7.5 $\mathrm{\, km\, s^{-1}}$ 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.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-12-13
DOI
https://doi.org/10.1093/mnras/staf2218
Primary Topic
Astrophysics and Star Formation Studies
Type
article
Field-Weighted Citation Impact
0.00

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article

FIRESTORM I: stellar feedback and gas kinematics in the evolved W40 hub-filament system

Saurabh Sharma, Jihye Hwang, L. K. Dewangan, A. M. Jacob et al.
Monthly Notices of the Royal Astronomical Society
Astrophysics and Star Formation Studies
article

FIRESTORM I: stellar feedback and gas kinematics in the evolved W40 hub-filament system

Saurabh Sharma, Jihye Hwang, L. K. Dewangan, A. M. Jacob, L. E. Pirogov, D. K. Ojha, D. Arzoumanian, Mark D. Lim, A. Zavagno, Gain Lee, N. Schneider, Affan Adly Nazri, Ram Kesh Yadav, Jedsada Maklai
article en

Abstract

ABSTRACT 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 $V_{\mathrm{LSR}}$$~\sim$ 7.5$\mathrm{\, km\, s^{-1}}$ and one at $V_{\mathrm{LSR}}$$\sim$ 5$\mathrm{\, km\, s^{-1}}$. 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 $V_{\mathrm{LSR}}$$\sim$ 7 $\mathrm{\, km\, s^{-1}}$ in several molecular lines, along with a blueshifted absorption dip in the HCN(1–0) profile, suggests that emission from OB-heated gas is being absorbed by a cold foreground cloud. A bridge-like feature in position–velocity space connects the $V_{\mathrm{LSR}}$$\sim$ 5 and $\sim$7.5 $\mathrm{\, km\, s^{-1}}$ 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.

Monthly Notices of the Royal Astronomical SocietyVol. 545(4)
Tata Institute of Fundamental Research (IN), Physical Research Laboratory (IN), Centre National de la Recherche Scientifique (FR), Planetary Science Institute (US), Kyushu University (JP), University of Cologne (DE), Institut Universitaire de France (FR), Aix-Marseille Université (FR), Korea Astronomy and Space Science Institute (KR), Aryabhatta Research Institute of Observational Sciences (IN), University of Malaya (MY), Kyushu University Hospital (JP), Institute of Applied Physics (RU), Chiang Mai University (TH), National Astronomical Research Institute of Thailand (TH), Korea University of Science and Technology (KR)
National Astronomical Research Institute of Thailand, Deutsche Forschungsgemeinschaft, Korea Astronomy and Space Science Institute, Institut Universitaire de France, Russian Science Foundation, Thailand Science Research and Innovation
Openalex Percentile: Top 72%
Astrophysics and Star Formation Studies
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