An ALMA study of hub-filament systemsII. Quiescent filaments converging towards highly dynamic hubs

Anderson, Michael ORCID: https://orcid.org/0000-0001-7237-3488, Peretto, Nicolas ORCID: https://orcid.org/0000-0002-6893-602X, Ragan, Sarah E. ORCID: https://orcid.org/0000-0003-4164-5588, Rigby, Andrew J., Avison, Adam, Duarte-Cabral, Ana ORCID: https://orcid.org/0000-0002-5259-4774, Fuller, Gary A., Shirley, Yancy L., Traficante, Alessio and Williams, Gwenllian M. ORCID: https://orcid.org/0000-0001-5933-2147 2026. An ALMA study of hub-filament systemsII. Quiescent filaments converging towards highly dynamic hubs. Monthly Notices of the Royal Astronomical Society , stag1985. 10.1093/mnras/stag1985

PDF - Accepted Post-Print Version Available under License Creative Commons Attribution. Download (15MB)

Abstract

Hub-filament systems are networks of converging interstellar filaments, often with active star formation at their centres, that may play an important role in high-mass star formation. In the first paper of this series, we found that the mass fraction that ends up in a clump’s most massive core is significantly higher in IR-dark hubs than IR-bright clumps, suggesting that the most-massive cores form early on. Such early massive core formation requires large inflow rates and dynamically active IR-dark clumps. We now present N2H+(J=1–0) observations of six IR-dark hub-filament systems mapped with ALMA 12m, 7m, and total power at ∼3″ resolution, to trace the kinematics of the dense gas. The data show intricate emission structures and complex spectra. To characterise their kinematics, we have developed mwydyn, a fully-automated, multiple velocity component, hyperfine line-fitting code. Our results reveal that the emission invariably consists of quiescent individual filaments in the outskirts that converge towards the hub centres where a systematic increase in velocity dispersion and number of components is observed. We also find that the distribution of centroid velocities is remarkably similar between clumps, despite spanning more than one order of magnitude in mass. We propose that our results are best explained by the mixing of gravitationally-driven multi-directional inflows, resulting in highly complex and dynamic hub centres. We also discuss the implications of the observed differentiated filament and hub gas kinematics in the context of the 3D morphology of hub-filament systems.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Physical, Chemical & Environmental Sciences Schools > Physics and Astronomy
Publisher:	Oxford University Press
ISSN:	0035-8711
Date of First Compliant Deposit:	30 October 2026
Last Modified:	30 Oct 2026 11:00
URI:	https://orca.cardiff.ac.uk/id/eprint/190544

Actions (repository staff only)

Edit Item