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Hyades and Sirius supercluster members brighter than magnitude(V) 7.1. I - The first six hours of right ascension
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| Preliminary UVBY calibrations for G and K type dwarf stars
Four-color uvby photometry for several hundred late-type dwarf stars oftypes G, K and M is discussed. Mean values of photometric indices aregiven for MK spectral types between F8/G0V and M2V. Preliminary standardrelations between the four-color indices are derived. Based onparallaxes and results from high-dispersion spectroscopic analyses,calibrations of the observed indices in terms of Mv, log Te and Fe/Hhave been derived. The means errors are 0.29 mag, 0.009 dex, and 0.17dex, respectively. The calibrations are valid for class-V stars of allpopulations between G0 and M2. If extreme population-II dwarfs areexcluded, the mean error of the abundance calibration decreases to 0.13dex. Calibrations in terms of log g have been attempted,, but the lowaccuracy of the spectroscopic g determinations does not inspireconfidence in the results. The possible contribution of a'fourth-parameter' variation to the mean errors of the calibrations isbriefly discussed. This fourth parameter could be the intrinsic heliumabundance of the stars.
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Osservazione e dati astrometrici
| Costellazione: | Eridano |
| Ascensione retta: | 04h15m11.58s |
| Declinazione: | -38°17'41.7" |
| Magnitudine apparente: | 7.061 |
| Distanza: | 112.994 parsec |
| Moto proprio RA: | -22.7 |
| Moto proprio Dec: | 69.8 |
| B-T magnitude: | 8.227 |
| V-T magnitude: | 7.158 |
Cataloghi e designazioni:
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