Searching for Earth Analogs Around the Nearest Stars: The Disk Age‐Metallicity Relation and the Age Distribution in the Solar Neighborhood

Abstract

The chemical composition of Earth's atmosphere has undergone substantial evolution over the course of its history. It is possible, even likely, that terrestrial planets in other planetary systems have undergone similar changes; consequently, the age distribution of nearby stars is an important consideration in designing surveys for Earth-analogues. provide age and metallicity estimates for 1039 FGK dwarfs in the Solar Neighbourhood. Using the Hipparcos catalogue as a reference to calibrate potential biases, we have extracted volumelimited samples of nearby stars from the Valenti-Fischer dataset. Unlike other recent investigations, our analysis shows clear evidence for an age-metallicity relation in the local disk, albeit with substantial dispersion at any epoch. The mean metallicity increases from ∼-0.3 dex at a lookback time of ∼10 Gyrs to ∼+0.15 dex at the present day. Supplementing the Valenti-Fischer measurements with literature metallicity data to give a complete volume-limited sample, the age distribution of nearby FGK dwarfs is broadly consistent with a uniform starformation rate over the history of the Galactic disk. In striking contrast, most

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