Kinematics of halo and high–velocity disk stars

Abstract

uvby – β photometry for 1149 high–velocity and metal–poor stars has been obtained and is being used to derive metallicities, distances, and ages for these stars. The distances have been combined with proper motions and radial velocities from the literature to calculate the stars' galactic space velocities. Our ultimate aim is to reach a better understanding of the early dynamical and chemical evolution of our Galaxy by studying the possible existence of correlations between metallicity, age, and kinematics for these stars. In particular, the V(rot), [Fe/H], Toomre energy, and W′,[Fe/H] diagrams are being used to analyze the kinematic characteristics of this sample. Two distinct, separate populations are very clearly seen, and there is also some evidence for additional stellar components. Our kinematic and metallicity data argue quite strongly for mostly uncoupled evolutions for the disk and halo populations of the Galaxy.