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 μm show a central region (having Mclump ∼ 225 M ) surrounded by five parsec-scale filaments, revealing a hub-filament system (HFS). In the Herschel column density (N(H2)) map, filaments are identified with higher aspect ratios (length/diameter) and lower N(H2) values (∼0.1–2.4 × 1021 cm−2), while the central hub is found with a lower aspect ratio and higher N(H2) values (∼3.5–7.0 × 1021 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 13CO(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 13CO 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.