Detection limits for each observed field. The star symbol denotes the Δmag of the faintest source detected in the NACO image (if any) while the dot symbol refers to the Δmag of the faintest detected artificial source, injected into the image. The minimum angular separation at which companions are found is about 2.7″ which translates to ∼5000 au at a typical distance of 2 kpc. However, the faintest companion of each field is found at a typical separation of 8.7″ (∼17 000 au).