Chemical Composition in the IRAS 16562–3959 High-mass Star-forming Region

Abstract

Abstract We have analyzed the Atacama Large Millimeter/submillimeter Array cycle 2 data of band 6 toward the G345.4938+01.4677 massive young protostellar object (G345.5+1.47 MYSO) in the IRAS 16562–3959 high-mass star-forming region with an angular resolution of ∼0.″3, corresponding to ∼760 au. We spatially resolve the central region, which consists of three prominent molecular emission cores. A hypercompact H ii region (Core A) and two molecule-rich cores (Core B and Core C) are identified using the moment zero images of the H30α line and a CH3OH line, respectively. Various oxygen-bearing complex organic molecules, such as (CH3)2CO and CH3OCHO, have been detected toward the positions of Core B and Core C, while nitrogen-bearing species, CH3CN, HC3N, and its 13C isotopologues, have been detected toward all of the cores. We discuss the formation mechanisms of H2CO by comparing the spatial distribution of C18O with that of H2CO. The 33SO emission, on the other hand, shows a ring-like structure surrounding Core A, and it peaks on the outer edge of the H30α emission region. These results imply that SO is enhanced in a shock produced by the expanding motion of the ionized region.