Molecular gas and a new young stellar cluster in the far outer Galaxy
  We investigate the star-formation ocurring in the region towards
IRAS07527-3446 in the molecular cloud [MAB97]250.63-3.63, in the far outer
Galaxy. We report the discovery of a new young stellar cluster, and describe
its properties and those of its parent molecular cloud. Near-infrared JHKS
images were obtained with VLT/ISAAC, and millimetre line CO spectra were
obtained with the SEST telescope. VLA archive date were also used. The cloud
and cluster are located at a distance of 10.3 kpc and a Galactocentric distance
of 15.4 kpc, in the far outer Galaxy. Morphologically, IRAS 07527-3446 appears
as a young embedded cluster of a few hundred stars seen towards the position of
the IRAS source, extending for about 2-4 pc and exhibiting sub-clustering. The
cluster contains low and intermediate-mass young reddened stars, a large
fraction having cleared the inner regions of their circumstellar discs
responsible for (H-Ks) colour excess. The observations are compatible with a <
5 Myr cluster with variable spatial extinction of between Av = 5 and Av = 11.
Decomposition of CO emission in clumps, reveals a clump clearly associated with
the cluster position, of mass 3.3 x 10^3 M(solar). Estimates of the slopes of
the Ks-band luminosity function and of the star-formation efficiency yield
values similar to those seen in nearby star-formation sites. These findings
reinforce previous results that the distant outer Galaxy continues to be active
in the production of new and rich stellar clusters, with the physical
conditions required for the formation of rich clusters continuing to be met in
the very distant environment of the outer Galactic disc.
