Issue |
A&A
Volume 426, Number 3, November II 2004
|
|
---|---|---|
Page(s) | 809 - 817 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20041237 | |
Published online | 18 October 2004 |
Lithium evolution in intermediate age and old open clusters: NGC 752 revisited*
1
Dipartimento di Astronomia, Università di Firenze, Largo E. Fermi 5, 50125 Firenze, 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 Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
Received:
6
May
2004
Accepted:
29
June
2004
We present new high resolution spectroscopic observations
of the intermediate age (~2 Gyr) open cluster NGC 752.
We investigate the Li vs. Teff distribution
and we obtain a new accurate determination of the cluster metallicity.
We compare the results for NGC 752 with other intermediate age and
old clusters spanning the age range from the Hyades (~0.6 Gyr) to NGC 188 (~6–8 Gyr). We find that NGC 752 has a solar
iron content ([ Fe/H), at variance with early
reports of sub-solar metallicity. We find that NGC 752 is only slightly more Li depleted than the younger
Hyades and has a Li pattern almost identical to that observed in
the ~2 Gyr old IC 4651 and NGC 3680.
As for the latter clusters,
we find
that NGC 752 is characterized by a tight Li vs. Teff distribution
for solar-type stars, with no evidence for a Li spread as large as
the one observed in the solar age solar metallicity M 67.
We discuss these results in the framework of mixing mechanisms
and Li depletion on the main sequence (MS). We conclude that the
development of a large scatter in Li abundances in old
open clusters might be
an exception rather than the rule
(additional observations of old clusters are required), and that
metallicity variations of the order of ~±0.2 dex do not
affect Li depletion after the age of the Hyades.
Key words: stars: abundances / stars: evolution / Galaxy: open clusters and associations: individual: NGC 752
© ESO, 2004
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