I. Saviane

Publications (179) View all

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  Available from: I. Saviane

  Article: Homogeneous Metallicities and Radial Velocities for Galactic Globular Clusters

  Ivo Saviane, Gary S. Da Costa, Enrico V. Held, Veronica Sommariva, Marco Gullieuszik, Beatriz Barbuy, Sergio Ortolani
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  ABSTRACT: Well determined radial velocities and abundances are essential for analyzing the properties of the Globular Cluster system of the Milky Way. However more than 50% of these clusters have no spectroscopic measure of their metallicity. In this context, this work provides new radial velocities and abundances for twenty Milky Way globular clusters which lack or have poorly known values for these quantities. The radial velocities and abundances are derived from spectra obtained at the Ca II triplet using the FORS2 imager and spectrograph at the VLT, calibrated with spectra of red giants in a number of clusters with well determined abundances. For about half of the clusters in our sample we present significant revisions of the existing velocities or abundances, or both. We also confirm the existence of a sizable abundance spread in the globular cluster M54, which lies at the center of the Sagittarius dwarf galaxy. In addition evidence is provided for the existence of a small intrinsic internal abundance spread (sigma [Fe/H](int) ~ 0.11-0.14 dex, similar to that of M54) in the luminous distant globular cluster NGC 5824. This cluster thus joins the small number of Galactic globular clusters known to possess internal metallicity ([Fe/H]) spreads.
  02/2012;
• Article: A Fossil Bulge Globular Cluster Revealed by very Large Telescope Multi-conjugate Adaptive Optics

  Sergio Ortolani, Beatriz Barbuy, Yazan Momany, Ivo Saviane, Eduardo Bica, Lucie Jilkova, Gustavo M. Salerno, and Bruno Jungwiert
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  ABSTRACT: The globular cluster HP 1 is projected on the bulge, very close to the Galactic center. The Multi-Conjugate Adaptive Optics Demonstrator on the Very Large Telescope allowed us to acquire high-resolution deep images that, combined with first epoch New Technology Telescope data, enabled us to derive accurate proper motions. The cluster and bulge fields' stellar contents were disentangled through this process and produced an unprecedented definition in color-magnitude diagrams of this cluster. The metallicity of [Fe/H] –1.0 from previous spectroscopic analysis is confirmed, which together with an extended blue horizontal branch imply an age older than the halo average. Orbit reconstruction results suggest that HP 1 is spatially confined within the bulge.
  The Astrophysical Journal 07/2011; 737(1):31. · 6.02 Impact Factor
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  Available from: I. Saviane

  Article: A Fossil Bulge Globular Cluster revealed by VLT Multi-Conjugate Adaptive Optics

  Sergio Ortolani, Beatriz Barbuy, Yazan Momany, Ivo Saviane, Eduardo Bica, Lucie Jilkova, Gustavo Malta Salerno, Bruno Jungwiert
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  ABSTRACT: The globular cluster HP1 is projected on the bulge, very close to the Galactic center. The Multi-Conjugate Adaptive Optics (MCAO) Demonstrator (MAD) at the Very Large Telescope (VLT) allowed to acquire high resolution deep images that, combined with first epoch New Technology Telescope (NTT) data, enabled to derive accurate proper motions. The cluster and bulge field stellar contents were disentangled by means of this process, and produced unprecedented definition in the color-magnitude diagrams for this cluster. The metallicity of [Fe/H] ~ -1.0 from previous spectroscopic analysis is confirmed, which together with an extended blue horizontal branch, imply an age older than the halo average. Orbit reconstruction results suggest that HP1 is spatially confined within the bulge.
  06/2011;
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  Available from: I. Saviane

  Article: Is Palomar 1 really associated with the Canis Major overdensity?

  Ivo Saviane, Lorenzo Monaco, Matteo Correnti, Piercarlo Bonifacio, Doug Geisler
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  ABSTRACT: It has recently been suggested that the peculiar cluster Pal 1 is associated to the Canis Major dwarf galaxy, which existence is still at the center of a debate. Our first measurement of the cluster's chemical abundance ratios allows us to examine this association and to advance further in the clarification of Pal 1 possible origin. Comment: Poster contribution to conference "A Universe of Dwarf Galaxies" (Lyon, June 14-18, 2010)
  11/2010;
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  Article: Morphological transformation of NGC 205?

  Ivo Saviane, Lorenzo Monaco, Tony Hallas
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  ABSTRACT: NGC 205 is a dwarf elliptical galaxy which shows many features that are more typical of disk galaxies, and our recent study of the central stellar population has added another peculiarity. In the central regions, star formation has been on-going continuously for a few hundred Myr, until ca. 20 Myr ago, perhaps fed by gas funneled to the center in the course of morphological transformation. In this contribution we use a deep, wide-field image obtained at a scale of 2"/px to show that subtle structures can be detected in and near the body of the dwarf galaxy. The southern tidal tail can be mapped out to unprecedented distances from the center, and we suggest that the northern tail is partially hidden behind a very extended dust lane, or ring, belonging to M31. A spiral pattern emerges across the body of the galaxy, but it might be explained by another M31 dust filament. Comment: 2 pages, 1 figure, poster contributed to IAU Symposium 262, Stellar Populations -- Planning for the Next Decade, G. Bruzual & S. Charlot, eds
  10/2009;