Spiral structure and massive star formation in the hub-filament-system G326.27-0.49

Abstract

ABSTRACT Hub-filament systems (HFSs) are potential sites of formation of star clusters and high mass stars. To understand the HFSs and to provide observational constraints on current theories that attempt to explain star formation globally, we report a study of the region associated with G326.27-0.49 using infrared data of dust continuum and newly obtained observations on molecular tracers using the APEX (Atacama Pathfinder EXperiment) telescope. We use the spectroscopic observations to identify velocity-coherent structures (filaments and clumps) and study their properties at a resolution of 0.4 pc. The region contains two main velocity components: first component shows four filaments between −63 and −55 km s−1 forming a spiral structure converging in a hub, the second filamentary component at ∼−72 km s−1 harbours a massive young stellar object (YSO) and possibly interacts with the hub. The clumps harbouring the three main YSOs in the region are massive (187–535 M⊙), have luminosities consistent with B-type stars, have central densities of ∼106 cm−3, and drive large outflows. Majority of the velocity-coherent clumps in the region shows virial parameters between 2 and 7, which considering the detection of protostars implies collapse to be gradual. We conclude that the region consists of a network of filaments through which mass accretes (∼10−4 M⊙ yr−1) onto the hub. The hub and some of the ends of filaments appear to be undergoing collapse to form new stars. This study identifies a target region for future high-resolution studies that would probe the link between the core and filament evolution.