The chemical evolution of the Galactic thick and thin disks

¹ Geneva Observatory, Geneva Univ., Switzerland
e-mail: Cristina.Chiappini@unige.ch
² Osservatorio Astronomico di Trieste, INAF, Italy

Abstract

Many are the proposed scenarios for the formation of the thick disk of the Milky Way, going from the merger with smaller galaxies to fast gas accretion in the early Universe. Crucial information on which was the dominant mechanism for the formation of the thick disk and other Galactic components is encoded in the chemical properties of their stars. By comparing the chemical properties of bulge, thick and thin disk stars one can address the question of which, among the competing processes of dissipation, satellite accretion and radial migration, play the dominant role in the formation of the different Galactic components. The main difficulty at present is that current data samples suffer from selection biases. Gaia shall bring a quantum leap to the solution of this problem, by providing fiducial samples of the different galactic components with both, chemical and full kinematic information. To pave the road for Gaia, theoretical models need to be improved by taking into account both chemistry and dynamical aspects. A work of this kind is underway in Geneva Observatory.