The Cygnus Allscale Survey of Chemistry and Dynamical Environments: CASCADE

V. Filamentary accretion flows in Cygnus X DR20

¹ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
² Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria
³ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁴ IRAM, 300 rue de la Piscine, Domaine Universitaire de Grenoble, 38406 St.-Martin-d’Hères, France
⁵ I. Physik. Institut, University of Cologne, Cologne, Germany
⁶ Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
⁷ Max Planck Institute for Extraterrestrial Physics, Gießenbachstraße 1, 85749 Garching bei München, Germany

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

Received: 19 February 2024
Accepted: 12 November 2025

Abstract

Context. Filamentary gas flows are an important process for funneling gas from cloud scales onto star-forming cores.

Aims. We investigate the role of filaments in high-mass star formation, whether gas flows from large to small scales along them, and what their properties might reveal about the region they are found in.

Methods. The Max Planck IRAM Observatory Program (MIOP), the Cygnus Allscale Survey of Chemistry and Dynamical Environments (CASCADE), includes high spatial resolution (~3″) data of HCO⁺(1–0) and H¹³CO⁺(1–0) emission in the star-forming region DR20 in the Cygnus X complex. In this data we identify filaments with the structure identification algorithm DisPerSE. We further analyze these filaments using Gaussian fits to the spectra to determine the line peak velocity and full width half maximum along them. The Python package FilChaP was used to determine filament widths.

Results. We find projected velocity gradients inside several filaments between 0.4 and 2.4 km s⁻¹ over projected length-scales of 0.1 pc toward star-forming cores. This can be interpreted as a sign of gas flowing along the filaments toward the cores. The filament width distributions exhibit median values between 0.06 and 0.14 pc depending on the core, the tracer, and the method. Standard deviations are approximately 0.02 to 0.06 pc. These values are roughly in agreement with the filament width of 0.1 pc typically found in nearby low-mass star-forming regions.

Conclusions. This first analysis of filamentary properties within the Cygnus X CASCADE program reveals potential signatures of gas flows along filaments onto star-forming cores. Furthermore, the characteristics of the filaments in this high-mass star-forming region can be compared to those of filaments in low-mass star-forming regions typically studied before. Extending such studies to the entire CASCADE survey will enhance our knowledge of high-mass filament properties on solid statistical grounds.