An ALMA study of hub-filament systemsII. Quiescent filaments converging towards highly dynamic hubs
9 affiliations
- 1Cardiff Hub for Astrophysics Research and Technology (CHART), School of Physical, Chemical and Environmental Sciences , Cardiff University, Cardiff CF24 3AA ,
- 2School of Physics and Astronomy, University of Leeds , Leeds LS2 9JT ,
- 3School Of Natural Science, The University of Manchester Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, , Manchester M13 9PL ,
- 4UK ALMA Regional Centre Node , Manchester M13 9PL ,
- 5SKA Observatory, Jodrell Bank, Lower Withington , Macclesfield SK11 9FT ,
- 6I. Physikalisches Institut, University of Cologne , Zülpicher Str 77, D-50937 Köln ,
- 7Steward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ, 85721
- 8IAPS-INAF, Via Fosso del Cavaliere , 100, I-00133, Rome ,
- 9Aberystwyth University Department of Physics, , Ceredigion SY23 3BZ ,
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.
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BibTeX
@article{anderson2026alma,
title = {{An ALMA study of hub-filament systemsII. Quiescent filaments converging towards highly dynamic hubs}},
author = {Michael Anderson and Nicolas Peretto and Sarah E Ragan and Andrew J Rigby and Adam Avison and Ana Duarte-Cabral and Gary A Fuller and Yancy L Shirley and Alessio Traficante and Gwenllian M Williams},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = oct,
doi = {10.1093/mnras/stag1985},
url = {https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag1985/8943802},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - An ALMA study of hub-filament systemsII. Quiescent filaments converging towards highly dynamic hubs
AU - Michael Anderson
AU - Nicolas Peretto
AU - Sarah E Ragan
AU - Andrew J Rigby
AU - Adam Avison
AU - Ana Duarte-Cabral
AU - Gary A Fuller
AU - Yancy L Shirley
AU - Alessio Traficante
AU - Gwenllian M Williams
PY - 2026
DA - 2026/10/19
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag1985
UR - https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag1985/8943802
AB - 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.
SN - 0035-8711
SN - 1365-2966
ER -