Related papers: Omega Centauri as a Disrupted Dwarf Galaxy: Eviden…
We present wide-field and high-precision BV and Ca & Stromgren by photometry of omega Centauri, which represents one of the most extensive photometric surveys to date for this cluster. The member stars of omega Cen are well discriminated…
The discovery of the Sagittarius dwarf galaxy, which is being tidally disrupted by and merging with the Milky Way, supports the view that the halo of the Galaxy has been built up at least partially by the accretion of similar dwarf systems.…
We present wide-field and high-precision BV and Ca & Stromgren by photometry of omega Centauri and its RR Lyrae stars, which represents one of the most extensive photometric surveys to date for this cluster. The member stars of omega Cen…
CCD vby Stroemgren photometry of a statistically complete sample of red giants and stars in the main sequence turn-off region in omega Centauri has been used to analyse the apparently complex star formation history of this cluster. From the…
We present multi-wavelength observations of the northern population of Omega Cen from the main-sequence turn-off to high on the red giant branch. We show that the best information about the metallicity and age of the stars can be gained…
We report on the complex structure of the red giant branch (RGB) of omega Cen, based on a new wide field and wide color baseline B and I photometry. Our color magnitude diagram (CMD) shows the presence of multiple populations along this…
In this contribution, results from CCD vby Stroemgren photometry of a statistically complete sample of red giants and stars in the main sequence turn-off region in omega Centauri are presented. From the location of stars in the (b-y),m_1…
We report the results of an extensive VLT high-resolution imaging campaign of the central region of the giant globular cluster omega Centauri. More than 100,000 stars have been measured in the inner 9'x 9' region of the cluster. On the…
In this contribution I am going to present some preliminary results of a high-resolution spectroscopic campaign focussed on the most metal rich red giant stars in Omega Cen. This study is part of a long term project we started a few years…
There is a growing body of evidence for the presence of multiple stellar populations in some globular clusters, including NGC 1851. For most of these peculiar globular clusters, however, the evidence for the multiple red giant-branches…
Omega Cen is composed of several stellar populations. Their history might allow us to reconstruct the evolution of this complex object. We performed a statistical cluster analysis on the large data set provided by Johnson and Pilachowski…
We have constructed synthetic color-magnitude diagrams (CMDs) for omega Cen and other massive globular clusters with apparently peculiar CMD morphology. Our population models, which adopt the most up-to-date input physics and parameters,…
The most massive globular cluster in the Milky Way, omega Centauri, is thought to be the remaining core of a disrupted dwarf galaxy, as expected within the model of hierarchical merging. It contains several stellar populations having…
Using current observational data and simple dynamical modeling, we demonstrate that Omega Cen is not special among the Galactic globular clusters in its ability to produce and retain the heavy elements dispersed in the AGB phase of stellar…
A new formation scenario for omega-Cen is presented, in which omega-Cen has formed from a star cluster complex (= super-cluster). The star-burst which has led to the formation of this cluster of star clusters was triggered by the infall and…
We present the first result of the Ital-FLAMES survey of red giant branch (RGB) stars in omega Cen. Radial velocities with a precision of ~0.5 km/s are presented for 650 members of omega Cen observed with FLAMES-Giraffe at the Very Large…
We focus on two aspects of Omega Cen that are rather uncharacteristic of globular clusters: its metallicity distribution and its orbit. We use (1) a Washington (M-T_2,M)_o color-magnitude diagram containing 130,000 stars, (2) DDO51…
Recent wide-field photometric surveys (Lee et al.; Pancino et al.) have shown the existence of a previously unknown metal-rich ([Fe/H] -0.6) stellar population in the galactic globular cluster omega Centauri. The discovery of this new…
We present HST observations that show a bifurcation of colors in the middle main sequence of the globular cluster Omega Centauri. We see this in three different fields, observed with different cameras and filters. We also present high…
We have observed (with vby filters) a field north of the core of the most massive globular cluster in our galaxy, Omega Centauri. We have found a correlation of age and metallicity in a region which avoids the dense core and the…