DECam Community Science Workshop 2018: Science Highlights, Coming Opportunities, LSST Synergies
May 21-22, 2018 • Tucson, Arizona
I will present multi-band photometry based on a catalog of ~2 million cluster members for a field of view of ~5x5 degrees across Omega Cen. Data were collected with DECam and
combined with Hubble Space Telescope catalogs of the central
regions of the cluster. The unprecedented photometric accuracy, depth and field coverage allowed us for the first time to investigate the spatial distribution of Omega Cen multiple populations from the core to the tidal radius and beyond, confirming its very complex structure. The color-magnitude diagrams show preliminary evidence for the presence of extra-tidal stars and differences in the spatial distribution of the stellar populations. We found that the frequency of blue main-sequence stars is increasing compared to red main-sequence stars in the outskirts of the cluster. Stars belonging to the reddest red-giant branch also show a more extended spatial distribution in the outskirts of Omega Cen, a region never explored before. Both these stellar sub-populations, according to spectroscopic measurements, are more metal-rich compared to the cluster main stellar population. These findings, once confirmed, make Omega Cen the only stellar system currently known where metal-rich stars have a more extended spatial distribution compared to metal-poor stars.
Authors: Annalisa Calamida, G. Strampelli, A. Rest, G. Bono, I. Ferraro, A. Saha, G, Iannicola, D. Scolnic, D. James, C. Smith, A. Zenteno