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 $2 \times 2$
square arcmin in the $JHK_s$ bands and with narrow-band filters centred in the
2.12 $\mu$m H$_2$ and 2.17 $\mu$m Br$\gamma$ lines were analysed in combination
with HI-GAL/{\sl Herschel} and archive IRAC/{\sl Spitzer} and {\sl 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 $\mu$m
SED is consistent with an O9V central star with a $10^{-2} M_\odot$ disc and a
$1.3 \times 10^4 M_\odot$ dust envelope. Its total luminosity is $8.5 \times
10^4 L_\odot$. 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.
