THE G-DWARF METALLICITY DISTRIBUTION AND THE PROBLEM OF STELLAR LIFETIMES LOWER THAN THE DISK AGE

We examine the possibility of the inclusion of objects having lifetime s lower than the disk age in the database of recent determinations of the G dwarf metallicity distribution for the solar neighbourhood. As a preliminary step, stars with lifetimes potentially lower than the dis k age are identified by means of a relation between (b-y), or mass, an d [Fe/H], from evolutionary models of stars at the zero-age main seque nce. We apply these results to the G dwarf samples of Rocha-Pinto and Maciel (1996) and Wyse and Gilmore (1995). We show that the majority o f G dwarfs in these samples can be regarded as long-lived objects for chemical evolution purposes, provided the disk age is greater than 12 Gyr. We also find that the G dwarf problem is not an effect of the met allicity dependence of the stellar lifetimes.