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A&A 458, 121-134 (2006)
DOI: 10.1051/0004-6361:20065175
Old open clusters as key tracers of Galactic chemical evolution
I. Fe abundances in NGC 2660, NGC 3960, and Berkeley 32
P. Sestito1, 2, 3, A. Bragaglia3, S. Randich2, E. Carretta3, L. Prisinzano1 and M. Tosi31 INAF - Osservatorio Astronomico "G.S. Vaiana" di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
e-mail: sestito@arcetri.astro.it
2 INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
3 INAF - Osservatorio Astronomico di Bologna, via C. Ranzani 1, 40127 Bologna, Italy
(Received 9 March 2006 / Accepted 14 June 2006 )
Abstract
Aims.We obtained high-resolution UVES/FLAMES observations of
a sample of nine
old open clusters spanning a wide range
of ages and Galactocentric radii. The goal of
the project is to
investigate the radial metallicity
gradient in the disk, as well as the abundance
of key elements (
and Fe-peak elements).
In this paper we present the
results for the metallicity of three clusters: NGC 2660
(age ~1 Gyr, Galactocentric distance of 8.68 kpc),
NGC 3960 (~1 Gyr, 7.80 kpc), and Be 32 (~6-7 Gyr, 11.30 kpc).
For Be 32 and NGC 2660, our study provides the first metallicity determination
based on high-resolution spectra.
Methods.We performed equivalent width analysis with the spectral code MOOG,
which
allows us to define a metallicity scale and build a homogeneous sample.
Results.We find that NGC 3960 and NGC 2660 have a metallicity
that is very close to solar
([Fe/H] = +0.02
and +0.04, respectively), while the older Be 32 turns out to have
[Fe/H] = -0.29.
Key words: stars: abundances -- stars: evolution -- Galaxy: disk -- open clusters and associations: individual: NGC 2660 -- open clusters and associations: individual: NGC 3960 -- open clusters and associations: individual: Berkeley 32
© ESO 2006