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 ?m show a central region (having Mclump ?225 M?) surrounded by five parsec-scale filaments, revealing a hub-filament system (HFS). In the {\it 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 {\it 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 the 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 toward the HFS appear to be observed, suggesting the gas flow in the RAFGL 5085 HFS and the applicability of the clump-fed scenario.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 ?m show a central region (having Mclump ?225 M?) surrounded by five parsec-scale filaments, revealing a hub-filament system (HFS). In the {\it 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 {\it 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 the 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 toward the HFS appear to be observed, suggesting the gas flow in the RAFGL 5085 HFS and the applicability of the clump-fed scenario.