A New Metallicity Calibration for Dwarfs for the RGU-Photometry

Abstract

We adopted the procedure of Carney to obtain a metallicity calibration for dwarfs for the RGU-photometry. For this purpose we selected 76 dwarfs of different metallicities from Carney, and Strobel et al., and evaluated their δ(U-G) ultra-violet excess relative to Hyades by transforming their UBV magnitudes to RGU via metallicity dependent equations of Ak-Gungor. The δ_{0.6}/\deltaM normalized factors of Sandage transform δ(U-G) excess at any G-R to δ=δ_{1.08}, i.e.: the ultra-violet excess at G-R=1.08 mag, corresponding to B-V = 0.60 mag in the UBV-system. Finally, the (δ, [Fe/H]) couples were fitted by the equation [Fe/H] = 0.11-2.22d-7.95d^2. This calibration covers the metallicity interval (-2.20, +0.20) dex.