2005MNRAS.359...73C

We have investigated, in the ¹³CO(1-0) line, the region between the stars Cyg OB2 No. 5 and No. 12. The integrated intensity contour map reveals the existence of a condensation at 12 km/s (core C), north-west of Cyg OB2 No. 5, with a core-halo structure. The morphology and the derived physical parameters make it quite similar to core A, previously discovered towards Cyg OB2 No. 12. A second condensation at 7 km/s, near Cyg OB2 No. 12, has been mapped in the same line (1-0) of ¹³CO. A summary of different observations, in all spectral regions, towards Cyg OB2 No. 5 and No. 12 is presented to provide the material for a further comprehensive discussion of this intricate and still intriguing region.