a1 Lund Observatory, Box 43, SE 22100 Lund, Sweden
a2 Niels Bohr Institute for Astronomy, Physics & Geophysics, DK 2100 Copenhagen, Denmark
a3 Astronomical Observatory, DK 2100 Copenhagen, Denmark
a4 Nordic Optical Telescope Scientific Association, Apartado 474, ES 38700 Santa Cruz de La Palma, Spain
a5 Observatoire de Genève, CH 1290 Sauverny, Switzerland
We report on a new survey of metallicities, ages, and Galactic orbits for a complete, magnitude-limited, and kinematically unbiased all-sky sample of 16 682 nearby F- and G-dwarfs. Our ∼ 63 000 new, accurate radial velocities for nearly 13 500 of the stars, combined with Hipparcos parallaxes and Tycho-2 proper motions, complete the kinematic data for 14 139 stars and allow us to identify most of the binary stars in the sample. Isochrone ages have been determined whenever reliable results are possible, with particular attention to realistic error estimates.
Among the basic properties of the Galactic disk that can be reinvestigated from our data are the metallicity distribution of G-dwarfs and the age–metallicity and age–velocity relations of the solar neighbourhood. We confirm the lack of metal-poor G-dwarfs relative to classical model predictions (the 'G-dwarf problem'), the near-constancy of the mean metallicity since the formation of the thin disk, and the appearance of the kinematic signature of the thick disk ∼ 10 Gyr ago.
(Received November 21 2003)
(Accepted February 06 2004)