probably indicates the presence of shocked gas in these last regions. The brightest region in all IRAC bands is G353.2+0.9.

Elephant trunks are present throughout the region. Clear examples are located at 172500, –3414  and at 172450, –341050 (this last one first identified by @bohigas04).

Figure 8 displays a series of images showing the emission distribution within the velocity interval  in steps of 2.5  covering the whole complex. The images show that the bulk of the molecular gas related to the complex has velocities in the range \[–10.0,0.0\] , coincident with previous findings by @massi97. The most outstanding feature is a CO depresion near the centre of the images, encircled by a ring-like structure of strong CO emission easily identified in the range \[$-$7.5,0.0\] (indicated as Shell A in Fig. 8). G353.12+0.86 coincides with the central cavity of Shell A.

In addition to this structure, other molecular clouds are identified in the CO images. These are labelled clouds B to H and appear to be linked to different nebulosities in the complex. They will be analyzed in Sect. 4 to 7.

The large scale CO emission distribution coincides with areas of high extinction and with the massive dense cores identified 