A new Galactic globular cluster identified by using DOLoRes-TNG data
Observational data taken in June 2008 with DOLoRes-TNG led to the
identification in our Galaxy of a new interesting globular
cluster.
This star system, known as Pfleiderer 2, was discovered in 1977 and
classified as a open cluster projected in a rich star field. Recently,
BVI photometry performed with DOLoRes allowed to draw its
color-magnitude diagrams (CMDs) and to reveal its true nature.
The main CMD features of Pfleiderer 2 are a tilted red giant branch,
and a red horizontal branch. Isochrone fits are compatible with an age
within the range 8-12 Gyr, typical of globular clusters. The
interesting finding is that it exhibits a nearly solar
metallicity. This makes of this star system one of the few metal-rich
globular clusters known in the Milky Way.
Contrary to classical globular clusters, Pfleiderer 2 is a relatively
low-mass system, making part of a recently discovered class of
low-luminosity, obscured, metal-rich globular clusters.
(S. Ortolani et al., "Pfleiderer 2: Identification of A New Globular Cluster in the Galaxy", 2009, Astronomical Journal, vol. 138, pages 889-894)
Figure 1. i'-band image of Pfleiderer 2 taken with DOLoRes-TNG (field 6 by 6 arcmin, North at the top and East to the left).