Bibcode
Villanova, S.; Carraro, G.; Scarpa, R.; Marconi, G.
Bibliographical reference
New Astronomy, Volume 15, Issue 6, p. 520-529.
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8
2010
Journal
Citations
8
Refereed citations
8
Description
The globular cluster ω Centauri (NGC 5139) is a puzzling stellar
system harboring several distinct stellar populations whose origin still
represents a unique astrophysical challenge. Current scenarios range
from primordial chemical inhomogeneities in the mother cloud to merging
of different sub-units and/or subsequent generations of enriched stars
- with a variety of different pollution sources - within the
same potential well. In this paper we study the chemical abundance
pattern in the outskirts of ω Centauri, half-way to the tidal
radius (covering the range of 20-30 arcmin from the cluster
center), and compare it with chemical trends in the inner cluster
regions, in an attempt to explore whether the same population mix and
chemical compositions trends routinely found in the more central regions
is also present in the cluster periphery. We extract abundances of many
elements from FLAMES/UVES spectra of 48 RGB stars using the equivalent
width method and then analyze the metallicity distribution function and
abundance ratios of the observed stars. We find, within the
uncertainties of small number statistics and slightly different
evolutionary phases, that the population mix in the outer regions cannot
be distinguished from the more central regions, although it is clear
that more data are necessary to obtain a firmer description of the
situation. From the abundance analysis, we did not find obvious radial
gradients in any of the measured elements.