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Vertical distribution of Galactic disk stars. I. Kinematics and metallicity
Nearly 400 Tycho-2 stars have been observed in a 720 square degree fieldin the direction of the North Galactic Pole with the high resolutionechelle spectrograph ELODIE. Absolute magnitudes, effectivetemperatures, gravities and metallicities have been estimated, as wellas distances and 3D velocities. Most of these stars are clump giants andspan typical distances from 200 pc to 800 pc to the galactic mid-plane.This new sample, free of any kinematical and metallicity bias, is usedto investigate the vertical distribution of disk stars. The old thindisk and thick disk populations are deconvolved from thevelocity-metallicity distribution of the sample and their parameters aredetermined. The thick disk is found to have a moderate rotational lag of-51 +/- 5 km s-1 with respect to the Sun with velocityellipsoid (sigmaU , sigmaV , sigmaW )=(63+/- 6, 39+/- 4, 39+/- 4) km s-1, mean metallicity of[Fe/H] = -0.48 +/- 0.05 and a high local normalization of 15 +/- 7%.Combining this NGP sample with a local sample of giant stars from theHipparcos catalogue, the orientation of the velocity ellipsoid isinvestigated as a function of distance to the plane and metallicity. Wefind no vertex deviation for old stars, consistent with an axisymmetricGalaxy. Paper II is devoted to the dynamical analysis of the sample,puting new constraints on the vertical force perpendicular to thegalactic plane and on the total mass density in the galactic plane.Based on observations made at the Observatoire de Haute Provence(France). Data are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/398/141
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
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