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Stroemgren photometry of F- and G-type stars brighter than V = 9.6. I. UVBY photometry
Within the framework of a large photometric observing program, designedto investigate the Galaxy's structure and evolution, Hβ photometryis being made for about 9000 stars. As a by-product, supplementary uvbyphotometry has been made. The results are presented in a cataloguecontaining 6924 uvby observations of 6190 stars, all south ofδ=+38deg. The overall internal rms errors of one observation(transformed to the standard system) of a program star in the interval6.5
| 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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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Sunak |
| Sað Açýklýk: | 17h10m04.91s |
| Yükselim: | -56°26'57.4" |
| Görünürdeki Parlaklýk: | 8.212 |
| Uzaklýk: | 65.789 parsek |
| özdevim Sað Açýklýk: | 32.4 |
| özdevim Yükselim: | -123.1 |
| B-T magnitude: | 9.074 |
| V-T magnitude: | 8.284 |
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NEWS@SKY (Science&Space News)
