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 $\hat{I}¼$m show a central region (having M${}_{\mathrm{clump}}$ $\sim$225 M${}_{\odot }$) surrounded by five parsec-scale filaments, revealing a hub-filament system (HFS). In the {\it Herschel} column density ($N({\mathrm{H}}_2)$) map, filaments are identified with higher aspect ratios (length/diameter) and lower $N({\mathrm{H}}_2)$ values ($\sim$0.1--2.4 $\times$10${}^{21}$ cm${}^{-2}$), while the central hub is found with a lower aspect ratio and higher $N({\mathrm{H}}_2)$ 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 {\it 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 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 ${}^{13}$CO 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.

15 pages, 8 figures; Accepted for publication in Journal of Astrophysics and Astronomy (JOAA)