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  • Bellini, G Piotto, +4 authors Momany
  • 2009
Aims. We present a detailed study of the radial distribution of the multiple populations identified in the Galactic globular cluster ω Cen. Methods. We used both space-based images (ACS/WFC and WFPC2) and ground-based images (FORS1@VLT and WFI@2.2m ESO telescopes) to map the cluster from the inner core to the outskirts (∼20 arcmin). These data sets have(More)
We have examined the radial distribution of white dwarfs over a single HST/ACS field in the nearby globular cluster NGC 6397. In relaxed populations , such as in a globular cluster, stellar velocity dispersion, and hence radial distribution, is directly dependent on stellar masses. The progenitors of very young cluster white dwarfs had a mass of ∼ 0.8 M ⊙ ,(More)
From deep color–magnitude arrays made from V and I images taken with Hubble Space Telescope's WFPC2 camera we have determined luminosity functions (LFs) down to a level that corresponds to ∼0.13 M ⊙ , for the low-metal-abundance globular clusters M15, M30, M92, and NGC 6397. Because of the similarity of the metallicities of these clusters, differences in(More)
We present the results of a deep Hubble Space Telescope (HST) exposure of the nearby glob-ular cluster NGC 6397, focussing attention on the cluster's white dwarf cooling sequence. This sequence is shown to extend over 5 magnitudes in depth, with an apparent cutoff at magnitude F 814W ∼ 27.6. We demonstrate, using both artificial star tests and the(More)
We present the complete photometric database and the color-magnitude diagrams for 74 Galactic globular clusters observed with the HST/WFPC2 camera in the F439W and F555W bands. A detailed discussion of the various reduction steps is also presented, and of the procedures to transform instrumental magnitudes into both the HST F439W and F555W flight system and(More)
In the old, populous, and metal-rich open cluster NGC 6791 we have used deep HST/ACS images to track the white dwarf cooling sequence down to m F606W ≃ 28.5. The white dwarf luminosity function shows a well defined peak at m F606W ≃ 27.4, and a bending to the blue in the color–magnitude diagram. If this peak corresponds to the end of the white dwarf cooling(More)
We present metallicity measurements based on GIRAFFE@VLT spectra of 80 subgiant-branch stars of the Galactic globular cluster ω Centauri. The VLT spectroscopic data are complemented by color-magnitude diagrams from high-accuracy photometry on a ∼ 10 × 10 arcmin 2 mosaic of ACS/HST images centered on the cluster center, and on multicolor images of a ∼ 34 ×(More)