The G dwarf Metallicity Distribution and the Problem of Stellar Lifetimes Lower than the Disk Age

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We examine the possibility of the inclusion of objects having lifetimes 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 disk age are identified by means of a relation between (b-y), or mass, and [Fe/H], from evolutionary models of stars at the zero-age main sequence. 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 of 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 metallicity dependence of the stellar lifetimes.