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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
| Photoelectric photometry of bright stars in the vicinity of the North Galactic Pole
Not Available
| U, V, W velocity components for the old disk using radial velocities of 1295 stars in the three cardinal Galactic directions
New radial velocities are presented for 1295 stars chosen at random nearthe three cardinal Galactic directions of l = 180 deg, b = 0; l = 90deg, b = 0 deg; and b = 90 deg, giving the distribution in U, V, and W,respectively, from the radial velocities alone. The measurements weremade with the coude spectrograph of the Mount Wilson 100 in. Hookerreflector. The purpose of the program is to set limits on the densitynormalization in the solar neighborhood of the old thin disk, the oldthick disk, and the halo. Many more high-velocity stars are present inthe unbiased sample than expected from previous estimates of thenormalization. The data suggest the density ratios in the solarneighborhood to be about 90 percent, 10 percent, and about 0.5 percentfor the thin disk, thick disk, and halo populations, respectively.
| A kinematic and abundance survey at the galactic poles
The DDO intermediate band system is used to obtain detailed informationabout abundance gradients and velocity dispersions in the galaxy, withan emphasis on the properties of halo stars in the range of from 1 to 5kpc. The DDO abundance index is calibrated agianst (Fe/H) for metal-poorstars, with a resulting gradient of about -0.2 per kpc. However, whenthe sample is divided into two subsamples with (Fe/H) less than -0.5 andequal to or greater than -0.5, the gradients are -0.14 and 0.00,respectively. DDO observations of about 1000 stars, mostly G5-K5 giants,show that the velocity dispersion increases both with decrease inmetallicity and increase in z distance. The abundances found for high-zstars are similar to the A-star results of Rodgers (1971) in that abouthalf the K giants above 1 kpc appear to have solar abundances.
| Radial velocities of faint north galactic pole stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976PASP...88..949Y&db_key=AST
| Spectral types and UBV photometry of G-K giants at the north galactic pole
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973AJ.....78...37S&db_key=AST
| The density distribution, color excess and metallicity of K giants atthe north galactic pole.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76...31M&db_key=AST
| Photoelectric Magnitudes and Colors of Stars Near the North Galactic Pole.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1964ApJ...140..151H&db_key=AST
| The space distribution of late type stars in a North galactic pole region.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1962AJ.....67...37U&db_key=AST
| Photographic photometry at the North galactic Pole.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956AJ.....61...80S&db_key=AST
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| Takýmyýldýz: | Berenisin Saci |
| Sað Açýklýk: | 12h44m20.51s |
| Yükselim: | +27°58'55.2" |
| Görünürdeki Parlaklýk: | 8.027 |
| Uzaklýk: | 235.849 parsek |
| özdevim Sað Açýklýk: | -38.7 |
| özdevim Yükselim: | 14.9 |
| B-T magnitude: | 9.272 |
| V-T magnitude: | 8.13 |
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