The Kinematics and Origin of smr Stars

Abstract

Ages and kinematics are revised for SMR stars ([M/H] >+0.30) common to NLTT and HIPPARCOS catalogues. The origin of MR to SMR stars appears heterogeneous: part of them, of intermediate age, were formed few kpc inside the solar orbit, from slowly enriched gas, whereas the oldest SMRs were born early, closer to the galactic center where the metal-enrichment had been fast. Perturbations by the galactic bar explain the peculiar motions of local SMRs as well as their outwards migration.