Images of radio and infrared continuum emission toward the ring G345.50+1.50, overlaid with contours of the ¹³CO(3−2) line integrated between −30 and −2 km s^-1 (levels: 9, 18, 36, 72, and 144 K km s^-1). Panels A) and B): 4.5 and 8.0  μm images from Spitzer. Panel C): 21.34 μm image from MSX. Panel D): 35.6 cm image from MGPS (Murphy et al. 2007). The arrow indicates the position of the 35.6 cm source J165920-400424, and the 2′ white circle shows the area where objects were searched for in the NED database to determine the nature of this source. The ellipse indicates the expanding ring model in the X–Y plane, with its center indicated with an X, see Sect. 3.11.