Interferometric Observations of Cyanopolyynes toward the G28.28–0.36 High-mass Star-forming Region

Abstract

We have carried out interferometric observations of cyanopolyynes, HC 3 N, HC 5 N, and HC 7 N, in the 36 GHz band toward the G28.28−0.36 high-mass star-forming region using the Ka-band receiver of the Karl G. Jansky Very Large Array. The spatial distributions of HC 3 N and HC 5 N are obtained. HC 5 N emission is coincident with a 450 μ m dust continuum emission, and this clump with a diameter of ∼0.2 pc is located at a position ∼0.15 pc east of the 6.7 GHz methanol maser. HC 7 N is tentatively detected toward the clump. The HC 3 N:HC 5 N:HC 7 N column density ratios are estimated to be 1.0:∼0.3:∼0.2 at an HC 7 N peak position. We discuss possible natures of the 450 μ m continuum clump associated with the cyanopolyynes. This clump seems to contain deeply embedded low- or intermediate-mass protostellar cores, and the most likely formation mechanism of the cyanopolyynes is the mechanism of warm carbon-chain chemistry. In addition, HC 3 N and compact HC 5 N emission is detected at the edge of the 4.5 μ m emission, which possibly implies that such emission has a shock origin.