Astrochemical study along M83 circumnuclear ring

We used the Atacama Large Millimeter/submillimeter Array (ALMA) to image molecular species indicative of shocks (SiO and CH_3_OH), dense cores (N_2_H^+^), and photodissociation regions (CN and CCH), as well as a radio recombination line (H41{alpha}) tracing active star-forming regions.

M83 has a circumnuclear gas ring that is joined at two intersections by gas streams from the leading- edge gas lanes on the bar. We found elevated abundances of the shock and dense-core tracers in one of the orbit-intersecting areas, and found peaks of CN and H41{alpha} downstream. In the other orbit-intersection area, we found a similar enhancement of the shock tracers, but less variation of other tracers, and no sign of active star formation in the stream.