uvby(-$\beta$) photometry of high-velocity and metal-poor stars X. Stars of very low metal abundance: observations, reddenings, metallicities, classifications, distances, and relative ages

Abstract

uvby(--$\beta$) photometry has been obtained for an additional 411 very metal-poor stars selected from the HK survey, and used to derive basic parameters such as interstellar reddenings, metallicities, photometric classifications, distances, and relative ages... These very metal-poor stars are compared to M92 in the c_0,(b-y)_0 diagram, and evidence is seen for field stars 1-3 Gyrs younger than this globular cluster. The significance of these younger very metal-poor stars is discussed in the context of Galactic evolution, mentioning such possibilities as hierarchical star-formation/mass-infall of very metal-poor material and/or accretion events whereby this material has been acquired from other (dwarf) galaxies with different formation and chemical-enrichment histories

20 pages, 11 figures, and 9 tables

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• Two distinct halo populations in the solar neighborhood. III. Evidence from stellar ages and orbital parameters
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• A photometric and spectroscopic study of the new dwarf spheroidal galaxy in Hercules
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• HAT-P-15b: A 10.9-day Extrasolar Planet Transiting a Solar-type Star
• The ability of intermediate-band Stromgren photometry to correctly identify dwarf, subgiant, and giant stars and provide stellar metallicities and surface gravities
• The usage of Stromgren photometry in studies of Local Group Dwarf Spheroidal Galaxies - Application to Draco: a new catalogue of Draco members and a study of the metallicity distribution function and radial gradients
• The stellar content of the Hamburg/ESO survey VI. The metallicity distribution of main-sequence turnoff stars in the Galactic halo
• 6Li/7Li estimates for metal-poor stars
• uvby-$\beta$ photometry of solar twins: the solar colors, model atmospheres, and the Teff and metallicity scales
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• Kinematics, ages and metallicities for F and G type stars in the solar neighbourhood
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• The Age-Metallicity Relation in the Thin Disk of the Galaxy
• CCD $UBV(RI{)}_C$ Photometry of Twenty Open Clusters
• Strömgren uvby photometry of the peculiar globular cluster NGC 2419
• UBV(RI)_C photometry of the open clusters Be 15, Be 80, and NGC 2192
• New intrinsic-colour calibration for $uvby$--$\beta$ photometry
• New Lithium Measurements in Metal-Poor Stars
• Hot Subdwarf Stars Among the Objects Rejected from the PG Catalog: a First Assessment Using GALEX Photometry