{
  "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.",
  "abstract_shown": true,
  "affiliations": [
    "Cardiff Hub for Astrophysics Research and Technology (CHART), School of Physical, Chemical and Environmental Sciences , Cardiff University, Cardiff CF24 3AA ,",
    "School of Physics and Astronomy, University of Leeds , Leeds LS2 9JT ,",
    "School Of Natural Science, The University of Manchester Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, , Manchester M13 9PL ,",
    "UK ALMA Regional Centre Node , Manchester M13 9PL ,",
    "SKA Observatory, Jodrell Bank, Lower Withington , Macclesfield SK11 9FT ,",
    "I. Physikalisches Institut, University of Cologne , Zülpicher Str 77, D-50937 Köln ,",
    "Steward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ, 85721",
    "IAPS-INAF, Via Fosso del Cavaliere , 100, I-00133, Rome ,",
    "Aberystwyth University Department of Physics, , Ceredigion SY23 3BZ ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 10,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Michael Anderson",
      "orcid": "0000-0001-7237-3488"
    },
    {
      "affs": [
        0
      ],
      "name": "Nicolas Peretto"
    },
    {
      "affs": [
        0
      ],
      "name": "Sarah E Ragan",
      "orcid": "0000-0003-4164-5588"
    },
    {
      "affs": [
        1
      ],
      "name": "Andrew J Rigby",
      "orcid": "0000-0002-3351-2200"
    },
    {
      "affs": [
        2,
        3,
        4
      ],
      "name": "Adam Avison",
      "orcid": "0000-0002-2562-8609"
    },
    {
      "affs": [
        0
      ],
      "name": "Ana Duarte-Cabral",
      "orcid": "0000-0002-5259-4774"
    },
    {
      "affs": [
        2,
        3,
        5
      ],
      "name": "Gary A Fuller",
      "orcid": "0000-0001-8509-1818"
    },
    {
      "affs": [
        6
      ],
      "name": "Yancy L Shirley"
    },
    {
      "affs": [
        7
      ],
      "name": "Alessio Traficante",
      "orcid": "0000-0003-1665-6402"
    },
    {
      "affs": [
        1,
        8
      ],
      "name": "Gwenllian M Williams",
      "orcid": "0000-0001-5933-2147"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dkwwc395x5kdp.bib",
  "cited_by": 0,
  "doi": "10.1093/mnras/stag1985",
  "fulltext_url": null,
  "id": "dkwwc395x5kdp",
  "issns": [
    "0035-8711",
    "1365-2966"
  ],
  "landing_url": "https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag1985/8943802",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Astrophysics and Star Formation Studies"
    ]
  ],
  "openalex": "W7201879787",
  "pdf_url": "https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag1985/72116896/stag1985.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-19",
  "publisher": "Oxford University Press (OUP)",
  "ris": "https://research.draconitic.com/paper/dkwwc395x5kdp.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:17Z",
      "native_id": "10.1093/mnras/stag1985",
      "source": "crossref",
      "url": "https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag1985/8943802"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Astrophysics and Star Formation Studies",
      "subfield": "stellar"
    }
  ],
  "title": "An ALMA study of hub-filament systemsII. Quiescent filaments converging towards highly dynamic hubs",
  "title_text": "An ALMA study of hub-filament systemsII. Quiescent filaments converging towards highly dynamic hubs",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:17Z",
  "url": "https://research.draconitic.com/paper/dkwwc395x5kdp",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": []
}