TITLE:
New Candidate Massive Clusters from 2MASS
AUTHORS:
Dirk Froebrich
KEYWORDS:
Open Clusters and Associations; General; Galaxies; Star Clusters; General
JOURNAL NAME:
International Journal of Astronomy and Astrophysics,
Vol.3 No.2,
June
7,
2013
ABSTRACT: Massive stars are important
for the evolution of the interstellar medium. The detailed study of their
properties (such as mass loss, rotation, magnetic fields) is enormously
facilitated by samples of these objects in young massive galactic star
clusters. Using 2MASS we have searched for so far unknown candidates of red
supergiant clusters along the Galactic Plane. Utilising deep high resolution
UKIDSS GPS and VISTA VVV data to study colour-magnitude diagrams, we uncover six new massive cluster candidates
in the inner Galaxy. If spectroscopically confirmed as real clusters, two of
them could be part of the Scutum-Complex. One cluster candidate has a number of
potential red supergiant members comparable to RSGC1 and 3. Our investigation
of UKIDSS data reveals for the first time the main sequence of the massive
cluster RSGC2. The stars of the sequence show an increased projected density at
the same position as the known red supergiants in the cluster and have E(J-K) = 1.6 mag. This either indicates an unusual
extinction law along the line of sight or a much lower near infrared extinction
to the cluster than previously estimated in the literature. We suggest that
psf-photometry in UKIDSS images might be able to uncover the main sequence of
other RSGC clusters.