Filamentary accretion flows in high-mass star-forming clouds

¹ Max-Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
² Fakultät für Physik und Astronomie, Universität Heidelberg, Im Neuenheimer Feld 226, D-69120 Heidelberg, Germany
³ Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg, Germany
⁴ Department of Astronomy, Xiamen University (Haiyun Campus), Zengcuo’an West Road, Xiamen, 361995 China
⁵ UK Astronomy Technology Centre, Royal Observatory, Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ UK
⁶ INAF – Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy
⁷ INAF – Osservatorio Astronomico di Cagliari, Via della Scienza 5, I-09047 Selargius (CA), Italy
⁸ Centre for Astrophysics and Planetary Science, University of Kent, Canterbury, CT2 7NH UK
⁹ Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro 8701, Ex-Hda. San José de la Huerta, 58089 Morelia, Michoacán, México
¹⁰ Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 24 June 2025
Accepted: 28 October 2025

Abstract

Context. Filamentary accretion flows as gas-funneling mechanisms are a key aspect in high-mass star formation research. The kinematic properties along these structures are of particular interest.

Aims. This paper focuses on the question of whether gas is transported to dense clumps inside high-mass star-forming regions through filamentary structures, from scales of several parsecs down to the subparsec scale.

Methods. We quantified the gas flows from a scale of up to several parsecs down to the subparsec scale along filamentary structures. For this work the accretion flow mechanisms based on gas kinematic data in the three high-mass star-forming regions G75.78, IRAS21078+5211, and NGC7538 were studied with data obtained from the IRAM 30 m telescope. The analysis was carried out using the surface density derived from 1.2 mm continuum emission and velocity differences estimated from HCO⁺ (1 − 0) and H¹³CO⁺ (1 − 0) molecular line data.

Results. The mass flow behavior of the gas in the vicinity of high-mass star-forming clumps shows characteristic dynamical patterns, for example an increased mass flow rate toward the clumps. We assume that the velocity differences originate from filamentary-gas infall onto the high-mass star-forming clumps; however, the inclination of the filament structures along the line of sight is unknown. Nevertheless, using the velocity differences and mass surface densities, we can estimate the mean flow rates along the filamentary structures with respect to the line of sight and toward the clumps. We quantified the flow rates toward the clumps in a range from about 10⁻³ M_⊙ yr⁻¹ to 10⁻⁵ M_⊙ yr⁻¹, inferred from clump-centered polar plots. Slight variations in the flow rates along the filamentary structures may be caused by overdensities and velocity gradients along the filaments.

Conclusions. While the initial studies presented here already reveal interesting results such as an increasing mass flow rate toward clumps, the properties of filamentary gas flows from large to small spatial scales, as well as potential variations over the evolutionary sequence, are subject to future studies.