Estimation of the Accuracy of Stellar Atmosphere Parameters and Interstellar Extinction from Highly Accurate Broadband Photometry

We analyze the accuracy of estimating the stellar parameters (effective temperature \(T_{\textrm{eff}}\), surface gravity log \(g\), metallicity [Fe/H], angular diameter \(\theta\)) and the color excess \(E(B-V)\) obtained by the \(\chi^{2}\) minimization method from broadband photometry using the Johnson–Cousins, 2MASS photometric systems, and ATLAS9 model stellar atmospheres as an example. The method has been tested for the internal accuracy and with real objects: isolated stars and stars from clusters. A high photometric accuracy (\(\sigma_{m}\leq 0.01\ldots 0.015^{m}\)), at which the errors are \({\sigma}T_{\textrm{eff}}\approx 2{-}5{\%}\), \(\sigma\) log \(g\approx 0.6\), \(\sigma[\textrm{Fe/H}]\approx 1\), \(\sigma\theta\approx 2\%\), and \({\sigma}E(B-V)\approx 0.02{-}0.07^{m}\) for stars with \(T_{\textrm{eff}}\lesssim 8000\) K, is required to obtain acceptable results. For hotter stars \({\sigma}T_{\textrm{eff}}\) reaches \(10\%\), \(\sigma\) log \(g\approx 0.6\) dex, \(\sigma\theta\approx 3\%\), and \({\sigma}E(B-V)\approx 0.02{-}0.07^{m}\), but the determination of the metallicity becomes impossible. We show that the method can be used to estimate the color excess in stellar fields. The limitations of the method are discussed.