Photoelectric Vilnius photometry of Hipparcos turn-off region stars

Seven-color photometry in the Vilnius system and photometric classification in terms of spectral type, absolute magnitude and metallicity are presented for 145 Hipparcos stars of the turn-off region, most of which have parallaxes determined to an accuracy of at least 15 percent. The stars selected for the observing program included those identified kinematically as intermediate between the thin disk and halo, plus a number of weak-lined stars discovered previously from objective prism surveys. The metallicity distribution we find for a kinematically defined sample of possible members of the thick disk has a mean abundance = -0.3 dex and a dispersion of 0.3 dex. Our data seem to suggest a large age for this intermediate population. (Author)