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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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משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | מיקרוסקופ |
| התרוממות ימנית: | 20h40m13.49s |
| סירוב: | -37°34'55.9" |
| גודל גלוי: | 8.07 |
| מרחק: | 2857.143 פארסק |
| תנועה נכונה: | -3.9 |
| תנועה נכונה: | -10.1 |
| B-T magnitude: | 9.219 |
| V-T magnitude: | 8.165 |
קטלוגים וכינוים:
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