Bibcode
DOI
Freyhammer, L. M.; Monelli, M.; Bono, G.; Cunti, P.; Ferraro, I.; Calamida, A.; Degl'Innocenti, S.; Prada Moroni, P. G.; Del Principe, M.; Piersimoni, A.; Iannicola, G.; Stetson, P. B.; Andersen, M. I.; Buonanno, R.; Corsi, C. E.; Dall'Ora, M.; Petersen, J. O.; Pulone, L.; Sterken, C.; Storm, J.
Bibliographical reference
The Astrophysical Journal, Volume 623, Issue 2, pp. 860-865.
Advertised on:
4
2005
Journal
Citations
14
Refereed citations
11
Description
We present three different optical and near-infrared (NIR) data sets for
evolved stars in the Galactic globular cluster ω Centauri. The
comparison between observations and homogeneous sets of stellar
isochrones and zero-age horizontal branches provides two reasonable
fits. Both of them suggest that the so-called anomalous branch has a
metal-intermediate chemical composition (-1.1<=[Fe/H]<=-0.8) and
is located ~500 pc beyond the bulk of ω Cen stars. These findings
are mainly supported by the shape of the subgiant branch in four
different color-magnitude diagrams (CMDs). The most plausible fit
requires a higher reddening, E(B-V)=0.155 versus 0.12, and suggests that
the anomalous branch is coeval with the bulk of ω Cen stellar
populations to within empirical and theoretical uncertainties. This
result is supported by the identification of a sample of faint
horizontal-branch (HB) stars that might be connected with the anomalous
branch. Circumstantial empirical evidence seems to suggest that the
stars in this branch form a clump of stars located beyond the cluster.
Based on observations made with the ESO Telescopes at the La Silla and
Paranal Observatories, program IDs 63.L-0686, 64.N-0038, and 68.D-0545.