An infrared study of the high-mass, multi-stage star-forming region IRAS 12272-6240

IRAS 12272-6240 is a complex star forming region with a compact massive dense clump and several associated masers, located at a well-determined distance of d=9.3 kpc from the Sun. For this study, we obtained sub-arcsec broad- and narrow-band near-IR imaging and low-resolution spectroscopy with the Baade/Magellan telescope and its camera PANIC. Mosaics of size 2 × 2 square arcmin in the JHK_s bands and with narrow-band filters centred in the 2.12 μm H_2 and 2.17 μm Brγ lines were analysed in combination with HI-GAL/Herschel and archive IRAC/Spitzer and WISE observations. We found that the compact dense clump houses two Class I YSOs that probably form a 21 kAU-wide binary system. Its combined 1 to 1200 μm SED is consistent with an O9V central star with a 10^-2 M_⊙ disc and a 1.3 × 10^4 M_⊙ dust envelope. Its total luminosity is 8.5 × 10^4 L_⊙. A series of shocked H_2 emission knots are found in its close vicinity, confirming the presence of outflows. IRAS 12272-6240 is at the centre of an embedded cluster with a mean age of 1 Myr and 2.6 pc in size that contains more than 150 stars. At its nucleus, we found a more compact and considerably younger sub-cluster containing the YSOs. We also identified and classified the O-type central stars of two dusty radio/IR HII regions flanking the protostars. Our results confirm that these elements form a single giant young complex where massive star formation processes started some 1 million years ago and is still active.