The ALMA-QUARKS Survey: Discovery of Dusty Fibrils inside Massive Star-forming Clumps

TL;DR

This study reports the discovery of over 300 superfine dusty fibrils within massive star-forming clumps across the Galaxy, revealing their properties and emphasizing their role in star formation processes.

Contribution

It presents the first large sample of superfine dusty fibrils in massive clumps, with detailed measurements of their widths, densities, and mass-length relations, expanding understanding of filamentary structures in star formation.

Findings

Fibrils are about ten times narrower than nearby cloud filaments.

Fibrils exhibit higher densities than previously observed filaments.

Mass versus length relation follows M ∝ L², consistent with known filament properties.

Abstract

We report the discovery of more than 323 superfine dusty filamentary structures (fibrils) inside 121 massive star forming clumps that are located in widely different Galactic environments (Galactocentric distances of $\sim$0.5-12.7 kpc). These fibrils are identified from the 1.3~mm continuum emission in the ALMA-QUARKS survey, which has a linear resolution of $\sim900$ AU for a source at $\sim$3 kpc, using the \textit{FilFinder} software. Using \textit{RadFil} software, we find that the typical width of these fibrils is $\sim$0.01 pc, which is about ten times narrower than that of dusty filaments in nearby clouds identified by the \textit{Herschel} Space Observatory. The mass ($M$) versus length ($L$) relation for these fibrils follows $M\propto L^{2}$, similar to that of Galactic filaments identified in space (e.g., \textit{Herschel}) and ground-based single-dish (e.g., \textit{APEX}) surveys. However, these fibrils are significantly denser ($\mathrm{N_{H_2} = 10^{23}-10^{24}\ cm^{-2}}$) than the filaments found in previous \textit{Herschel} surveys ($\mathrm{N_{H_2} = 10^{20}-10^{23}\ cm^{-2}}$). This work contributes a large sample of superfine fibrils in massive clumps, following the identification of large 0.1-pc wide filaments and associated internal velocity coherent fibers in nearby molecular clouds, further emphasizing the crucial role played by filamentary structures in star formation at various physical scales.