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Radial velocities in three fields along the southern galactic equator
A list of radial velocities for 764 stars is given for three fields inthe Vela-Carina region of the galaxy. They were obtained from GPO-platestaken at La Silla and reduced following Fehrenbach's method.Slit-spectra were collected with the 152 cm-spectrographic telescope atLa Silla, to derive an accurate radial velocity for a sufficient numberof calibration stars: out of the 29 stars, 26 had no formerly publishedvalue. The global motions of 10 to 14 km/s can be considered as normalon the basis of galactic rotation. Some stars, however, show highvelocities, and are therefore marked with one or two asterisks in thetable.
| 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: | Yelken |
| Sað Açýklýk: | 09h41m51.55s |
| Yükselim: | -54°13'00.9" |
| Görünürdeki Parlaklýk: | 7.817 |
| Uzaklýk: | 250 parsek |
| özdevim Sað Açýklýk: | -31.1 |
| özdevim Yükselim: | 15.2 |
| B-T magnitude: | 8.15 |
| V-T magnitude: | 7.845 |
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