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Enviar un nuevo artículo| UBV polarimetry of 361 A- and F-type stars in selected areas We present simultaneous UBV linear polarization measurements for 361 A-and F-type stars with accurate colour excess and distance determination.These stars are distributed in 35 Kapteyn's Selected Areas, covering thethird and fourth quadrants of the galactic plane (|b| <= 30degr ).The obtained polarization and the known colour excess are compared. Ananalysis of the polarization distribution as a function of the stellardistance is also performed. Based on observations collected at theEuropean Southern Observatory (ESO), La Silla, Chile.
 
 
 |  | 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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| Constelación: | Altar |  | Ascensión Recta: | 17h01m54.21s |  | Declinación: | -62°08'26.2" |  | Magnitud Aparente: | 7.618 |  | Distancia: | 91.659 parsecs |  | Movimiento Propio en Ascensión Recta: | -25.4 |  | Movimiento Propio en Declinación: | -65.9 |  | B-T magnitude: | 7.968 |  | V-T magnitude: | 7.647 |  Catálogos y designaciones:
 
 
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