Massive star formation in the hub–filament system of RCW 117

Abstract

ABSTRACT We present a multiwavelength investigation of the hub–filament system RCW 117 (IRAS 17059-4132), which shows intricate filamentary features in the far-infrared, mapped using Herschel images. We obtain the column density and dust temperature maps for the region using the Herschel images and identify 88 cores and 12 filaments from the column density map of the region (18 arcmin × 18 arcmin). We employ the ThrUMMS 13CO (J = 1–0) data for probing the kinematics in RCW 117, and find velocity gradients (∼0.3–1 km s−1 pc−1) with hints of matter inflow along the filamentary structures. Ionized gas emission from the associated H ii region is examined using the Giant Metrewave Radio Telescope (GMRT) at 610 and 1280 MHz and is found to be of extent 5 × 3 pc2 with intensity being brightest towards the hub. We estimate the peak electron density towards the hub to be ∼750 cm−3. Thirty-four Class 0/I young stellar objects (YSOs) have been identified in the region using the Spitzer GLIMPSE colour–colour diagram, with many lying along the filamentary structures. Based on the (i) presence of filamentary structures, (ii) distribution of cores across the region, with ∼39 per cent found along the filamentary structures, (iii) massive star formation tracers in the hub, and (iv) the kinematics, we believe that global hierarchical collapse can plausibly explain the observed features in RCW 117.