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.