Geometrical and kinematic scenarios as explained in Sect. 4 (originally suggested by Meier & Turner 2005, and slightly modified in this work). The red and blue lobe structures indicate the bi-conic expanding H II gas mentioned in the text. Blue gas is moving toward the observer, red gas is moving away. The mini-spiral (green) and ring (yellow) are surrounding the central nuclear star cluster (white stars), which gives rise to the expanding H II regions as well as to the intense PDR emission from the gas in the ring/spiral facing the cluster. The black arrows indicate a potential direction of motion consistent with the velocity structure observed in ¹²CO (1−0). a) Standard geometry as proposed by Meier & Turner (2005) with arms in a trailing configuration. b) Proposed new geometry, spiral/arm plane flipped by 90° and a leading arm pattern. (The observer is located directly above the plane of paper.)