Discovery of a Compact Hub-Filament System in G286.21+0.17 with JWST and ALMA: Insights into Protocluster Formation and Competitive Accretion

Abstract

We present a multi-wavelength study of the massive protocluster G286.21+0.17 (G286) using \emph{JWST} near-infrared (NIR) imaging and ALMA H${}^{13}$CO${}^{+}$(1--0) observations. The \emph{JWST} images uncover a compact ($\sim$0.5 pc) hub-filament system (HFS), comprising a dense central hub connected by at least four converging filaments seen in absorption, along with multiple H${}_2$ protostellar jets/outflows. The hub hosts the dense core G286c1. H${}^{13}$CO${}^{+}$ emission confirms this HFS over [$-$19.2, $-$16.4]~km~s${}^{-1}$, while the \emph{JWST} images also trace prominent photodissociation regions surrounding H\,{\sc ii}~region~A, powered by a B-type star. The identified H${}^{13}$CO${}^{+}$ skeletons closely trace the major \emph{JWST} absorption structures and show steep velocity gradients indicative of inflow. The radial distribution of ALMA 1.3 mm continuum cores (ALMAGAL and Cheng et al. 2020) exhibits power-law trends toward the hub center. The core number density, surface density, and core mass follow $Y\propto r^{\alpha }$ with ${\alpha }_{\rho }$ $\sim$$-$2.8 to $-$1.1, ${\alpha }_{\Sigma }$ $\sim$$-$0.4 to $-$0.6, and ${\alpha }_M$ $\sim$$-$0.7, whereas the core diameter remains nearly constant. Together with filament mass accretion rates of 7.6--11$\times 10^{-5}$ M${}_{\odot }$ yr${}^{-1}$, these results are consistent with competitive accretion, highlighting preferential core growth toward the hub. Increasing filament linewidths toward the hub imply gravity-driven inflow, but misaligned local velocity gradient and gravitational force directions along filaments point to a dynamically evolved system. The HFS likely formed through large-scale gas-layer interactions aided by compression from the adjacent H\,{\sc ii} region. Overall, star formation in G286 appears to be regulated by filamentary accretion, competitive core growth in the hub, and stellar feedback.

Accepted for publication in MNRAS, the manuscript consists of 19 pages, 14 figures, and 1 table