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HD 196664


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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:Microscopio
Ascensione retta:20h40m13.49s
Declinazione:-37°34'55.9"
Magnitudine apparente:8.07
Distanza:2857.143 parsec
Moto proprio RA:-3.9
Moto proprio Dec:-10.1
B-T magnitude:9.219
V-T magnitude:8.165

Cataloghi e designazioni:
Nomi esatti   (Edit)
HD 1989HD 196664
TYCHO-2 2000TYC 7963-13-1
USNO-A2.0USNO-A2 0450-39096896
HIPHIP 102003

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