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CCD astrometry and components instrumental magnitude difference of 432 Hipparcos wide visual double stars
Context: We measured the angular separations, position angles, ΔV, Δ y and Δ I of wide visual double stars during the period2003-2005. At least one component of the double stars in our sample hasan entry in the Hipparcos catalogue. Aims: Our measurements are acontribution to the study of the nature of these double stars. Methods: The northern double stars of the project were observed with the1.2 m telescope of the Kryonerion observatory and the southern with the1.0 m SAAO. We performed multiple-exposure CCD imaging of our targetsand used the standard procedure of data reduction and astrometric CCDcalibrations. Results: We present measurements of 213 northern and 219southern wide binaries.Based on observations made at Kryonerion Observatory of the NationalObservatory of Athens, Greece, and the South African AstronomicalObservatory. Full Table 1 and Tables 2, 3 are only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/472/1055
| Interstellar reddening in the Southern Hemisphere. I - The UVBY beta observations
The uvby-beta photometric data obtained from a Southern Hemisphereobservational project is presented. A uvby-beta photometric network ofnearly 3900 A and early F stars has been established with the intentthat the stars serve as 'space probes' for measurements of interstellarreddening.
| A second list of wide visual binaries
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| A second list of wide visual binaries
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| The chemical evolution of the solar neighborhood. I - A bias-free reduction technique and data sample
The possible ways of measuring the age-metallicity relation for thegalactic disk in the neighborhood of the sun are discussed. It is shownthat the use of a field star sample chosen on the basis of effectivetemperature introduces a bias which results in a monotonic increase inthe metal abundance of the disk with time. However, if theage-metallicity relation for the disk can be shown to satisfy certaincriteria, the bias introduced in such a sample can be neglected: thegalactic disk apparently satisfies the criteria. It is concluded that asample analyzed through the use of uvby and H(beta) photometry inconjunction with a self-consistent set of theoretical isochronesprovides the least biased, most accurate estimate of the age-metallicityrelation for the disk.
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