Metallicity and absolute magnitude calibrations for F-G type main-sequence stars in the Gaia era

In this study, photometric metallicity and absolute magnitude calibrations were derived using F-G spectral type main-sequence stars in the Solar neighbourhood with precise spectroscopic, photometric and Gaia astrometric data for UBV photometry. The sample consists of 504 main-sequence stars covering the temperature, surface gravity and colour index intervals 5300 < T e f f < 7300 K, log g > 4 (cgs) and 0.3 < ( B − V ) 0 < 0.8 mag, respectively. Stars with relative trigonometric parallax errors σ π / π ≤ 0.01 were preferred from Gaia DR2 data for the estimation of their M V absolute magnitudes. In order to obtain calibrations, ( U − B ) 0 and ( B − V ) 0 colour indices of stars were preferred and a multi-variable second order equation was used. Calibrations are valid for main-sequence stars in the metallicity and absolute magnitude ranges − 2 < [ Fe / H ] < 0.5 dex and 2.5 < M V < 6 mag, respectively. The mean value and standard deviation of the differences between original and estimated values for the metal abundance and absolute magnitude are 〈 Δ [ Fe / H ] 〉 = 0.00 ± 0.11 dex and 〈 Δ M V 〉 = 0.00 ± 0.22 mag, respectively. In this work, it has been shown that more precise iron abundance and absolute magnitude values were obtained with the new calibrations, compared to previous calibrations in the literature.