Bibcode
Calamida, A.; Bono, G.; Stetson, P. B.; Iannicola, G.; Piersimoni, A. M.; Freyhammer, L. M.; Buonanno, R.; Caputo, F.; Cassisi, S.; Castellani, M.; Corsi, C.; Dall'Ora, M.; Degl'Innocenti, S.; Ferraro, I.; Grundahl, F.; Hilker, M.; Monelli, M.; Nonino, M.; Pietrinferni, A.; Prada Moroni, P. G.; Pulone, L.; Richtler, T.
Bibliographical reference
Memorie della Società Astronomica Italiana Supplement, v.14, p.95 (2010)
Advertised on:
0
2010
Citations
1
Refereed citations
1
Description
We present new intermediate-band Strömgren photometry based on
more than 300 u,v,b,y images of the Galactic globular cluster omega Cen
p, covering a region of more than 20×20 arcmin squared across the
cluster center. By adopting different Strömgren metallicity
indices we estimate the photometric metallicity for ≈ 4,000 Red
Giants, the largest sample ever collected. The metallicity distributions
show multiple peaks ([Fe/H]phot= -1.69±0.08,
-1.28±0.03, -1.07±0.02, -0.88±0.04,
-0.71±0.12 and -0.03±0.08 dex) and a sharp cut-off in the
metal-poor tail ([Fe/H]phot ≲ -2 dex) that agree quite
well with spectroscopic measurements. We identify four distinct
sub-populations, namely metal-poor (MP, [Fe/H] < -1.49),
metal-intermediate (MI, -1.49 < [Fe/H] < -0.93), metal-rich (MR,
-0.95 < [Fe/H] < -0.15) and solar metallicity (SM, [Fe/H] ≈ 0).
The last group includes only a small fraction of stars (˜;
8±5%) and should be confirmed spectroscopically.