Elemental Abundances Vs . Kinematics in the Milky Way ’ S Disk

We present the results of our investigation of three samples kinematically representative of the thin and thick disks and the Hercules stream using the catalogue of Soubiran & Girard (2005). We have observed abundance trends and age distribution of each component. Our results show that the two disks are chemically well separated, they overlap greatly in metallicity and both show parallel decreasing trends of alpha elements with increasing metallicity, in the interval-0.80 < [Fe/H] <-0.30. The thick disk is clearly older than the thin disk with a tentative evidence of an AMR over 2-3 Gyr and a hiatus in star formation before the formation of the thin disk. In order to improve the statistics on the disk's abundance trends, we have developed an automatic code, TGMETα, to determine (Teff, logg, [Fe/H], [α/Fe]) for thousands of stellar spectra available in spectroscopic archives. We have assessed the performances of the algorithm for 350 spectra of stars bieng part of the abundance catalogue. 1 Abundances We have compiled a large catalogue of stars from several studies from the literature Ni abundances (Soubi-ran & Girard 2005). Because authors of the different studies do not use the same scales and methods in their spectral analyses, systematics between their results have been investigated (for more details on the construction of the catalogue see Soubiran & Girard 2005). The final catalogue of abundances includes 743 stars. In order to study kinematical groups of the Milky Way's disk we need velocities and orbits of stars from the abundance catalogue. We first cross-correlated the catalogue with Hipparcos (ESA 1997), selecting stars with π >10 mas and σπ π <0.10. Then we have searched for radial velocities in several sources. Distances, proper motions and radial velocities have been combined to compute the 3 components (U, V, W) of the spatial velocities with respect to the Sun and the orbital parameters for 639 stars. In addition the derivation of ages was kindly done by Frédéric Pont making use of the Bayesian method of Pont & Eyer (2004). Good estimations of ages were obtained for 322 stars from the abundance catalogue.