Kinematics and chemistry of the hot core in G20.08–0.14N

Abstract

We present Submillimeter Array (SMA) observations of the the massive star-forming region G20.08–0.14N at 335 and 345 GHz. With the SMA data, 41 molecular transitions were detected related to 11 molecular species and their isotopologues, including SO2, SO, C34S, NS, C17O, SiO, CH3OH, HC3N, H13CO+, HCOOCH3 and NH2CHO. In G20.08–0.14N, 10 transition lines out of the 41 detected belong to SO2, which dominates the appearance of the submillimetre-wave spectrum. To obtain the spatial kinematic distribution of molecules in G20.08–0.14N, we chose the strongest and unblended lines for the channel maps. The channel maps of C34S and SiO, together with their position–velocity diagrams, show that there are two accretion flows in G20.08–0.14N. Additionally, SiO emission shows a collimated outflow in the north-east–south-west direction. The direction of the outflow is revealed for the first time. The rotational temperature and column density of CH3OH are 105 K and 3.1 × 1017 cm−2, respectively. Our results confirm that a hot core is associated with G20.08–0.14N. The hot core is heated by a protostar radiation at its centre, not by external excitation from shocks. Images of the spatial distribution of different species have shown that the different molecules are located at different positions of the hot core. By comparing the spatial distributions and abundances of molecules, we discuss possible chemical processes for producing the complex sulphur-bearing, nitrogen-bearing and oxygen-bearing molecules in G20.08–0.14N.