Star-forming site RAFGL 5085: Is a perfect candidate of hub-filament system?

Abstract

To investigate the star-formation process, we present a multi-wavelength study of a massive star-forming site RAFGL 5085, which has been associated with the molecular outflow, Hii region and near-infrared cluster. The continuum images at 12, 250, 350 and 500 \(\mu \)m show a central region (having \(M_\textrm{clump}\sim 225\) \(M_{\odot }\)) surrounded by five parsec-scale filaments, revealing a hub-filament system (HFS). In the Herschel column density (\(N(\textrm{H}_{2})\)) map, filaments are identified with higher aspect ratios (length/diameter) and lower \(N(\textrm{H}_{2})\) values (\(\sim \)0.1–\(2.4 \times 10^{21}\) cm\(^{-2}\)), while the central hub is found with a lower aspect ratio and higher \(N(\textrm{H}_{2})\) values (\(\sim \)3.5–\(7.0 \times 10^{21}\) cm\(^{-2}\)). The central hub displays a temperature range of [19, 22.5] K in the Herschel temperature map, and is observed with signatures of star formation (including radio continuum emission). The JCMT \(^{13}\)CO(J \(=\) 3–2) line data confirm the presence of HFS and its hub is traced with supersonic and non-thermal motions having higher Mach number and lower thermal to non-thermal pressure ratio. In the \(^{13}\)CO position–velocity diagrams, velocity gradients along the filaments towards the HFS appear to be observed, suggesting the gas flow in the RAFGL 5085 HFS and the applicability of the clump-fed scenario.