1994A&A...287..191P

We discuss Li abundances in a well defined sample of nearby (G0-G5) solar-like stars. High resolution (R=100,000), high S/N (≥ 150) data have been analysed using state-of-the-art techniques and up-to-date atmospheric models. We have investigated whether the abundance of Li in solar-type stars can be described in terms of stellar physical parameters like T_eff, age and metallicity. We confirm the presence of a group of stars with high Li content, but apparently old age, finding that this group is rather conspicuous and not restricted to a few exceptional cases. The analysis of our data, together with published observations of G dwarfs in open clusters, strongly suggests that for stars older than ∼1Gyr another parameter in addition to the overmentioned ones plays a relevant role in Li depletion. When this additional mechanism is effective, it depletes Li by a factor 10-100, but in some stars it may not act at all during a large part of their main sequence lifetimes. We make some suggestions as to the nature of this additional parameter but none of them can be definitely proven. When compared to the other stars in our sample, the Sun appears to be representative of the low-Li stars, which comprise about one half of the G dwarfs having stellar parameters and ages similar to the Sun. We confirm that Li is not a good tracer of age for solar-type stars, but we show that a high Li content coupled to high chromospheric activity can be used to identify stars significantly younger than the Hyades.