The solar neighborhood age-metallicity relation - Does it exist?

We test the hypothesis that the spread in the age-metallicity plot of the solar neighborhood is due to a mixture of stars belonging to kinematically different sub-populations of the Galactic disk, i.e., the thin and the thick disk. We use a kinematic subsample of similar to 600 stars from a sample of similar to 6000 dwarf and subgiant stars from the Hipparcos catalog. All of these stars have a full set of stellar parameters determined, including good ages. We find that a significant spread in [Me/H] is present in both kinematic populations, especially at large stellar ages. This implies that a simple one-to-one relation between ages and metallicities is not possible. In fact, there are stars that are-truly old and at the same time have [Me/H] > 0.2 dex.