Evidence of high-mass star formation through multi-scale mass accretion in hub-filament-system clouds

TL;DR

This study uses high-resolution ALMA data to analyze 17 hub-filament-system clouds, revealing a sequence of mass growth and star formation activity that supports a multi-scale accretion process for high-mass star formation.

Contribution

It provides the first statistical evidence linking multi-scale mass accretion in hub-filament systems to high-mass star formation, across different evolutionary stages.

Findings

Mass and surface density increase from IR-dark to IR-bright stages.

Massive YSOs are concentrated in hubs, with low-mass YSOs spread out.

Outflows escape through cavities, minimally disrupting star-forming regions.

Abstract

We present a statistical study of a sample of 17 hub-filament-system (HFS) clouds of high-mass star formation using high-angular resolution ($\sim$1-2 arcsecond) ALMA 1.3mm and 3mm continuum data. The sample includes 8 infrared (IR)-dark and 9 IR-bright types, which correspond to an evolutionary sequence from the IR-dark to IR-bright stage. The central massive clumps and their associated most massive cores are observed to follow a trend of increasing mass ($M$) and mass surface density ($\Sigma$) with evolution from IR-dark to IR-bright stage. In addition, a mass-segregated cluster of young stellar objects (YSOs) are revealed in both IR-dark and IR-bright HFSs with massive YSOs located in the hub and the population of low-mass YSOs distributed over larger areas. Moreover, outflow feedback in all HFSs are found to escape preferentially through the inter-filamentary diffuse cavities, suggesting that outflows would render a limited effect on the disruption of the HFSs and ongoing high-mass star formation therein. From the above observations, we suggest that high-mass star formation in the HFSs can be described by a multi-scale mass accretion/transfer scenario, from hub-composing filaments through clumps down to cores, that can naturally lead to a mass-segregated cluster of stars.