Dipartimento di Astronomia, Università di Firenze, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: email@example.com
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
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