The transition between stellar populations in the Galaxy

An investigation has been made to determine the relationships between kinematic and chemical properties of stars covering all population types in the Galaxy. For this purpose, a sample has been taken of several hundred high-galactic-latitude F-K stars down to V = 14.0, measured photoelectrically in the Vilnius seven-color system during the progress of several photometric programs. Combining the photometric material with the proper motion and radial velocity data enabled us to compute kinematic parameters of the sample stars and then to make plots of the galactic orbital eccentricities, angular momenta and velocity dispersions versus forbidden Fe/H, with much attention drawn to the region where the transition from disk to halo occurs. It is found that correlations of these types show a significant departure from the continuous trend over most of the forbidden Fe /H range, giving thus evidence in favor of a discrete rather than a continuous entity of stellar populations in the Galaxy. The implications of these results on the kinematic and chemical distinctness of the thick disk component are briefly discussed. (Author)