THE UBV(RI)_C colors of the sun

Photometric data in the UBV(RI)_C system have been acquired for 80 solar analog stars for which we have previously derived highly precise atmospheric parameters T _eff, log g, and [Fe/H] using high-resolution, high signal-to-noise ratio spectra. UBV and (RI)_C data for 46 and 76 of these stars, respectively, are published for the first time. Combining our data with those from the literature, colors in the UBV(RI)_C system, with ≃ 0.01mag precision, are now available for 112 solar analogs. Multiple linear regression is used to derive the solar colors from these photometric data and the spectroscopically derived T _eff, log g, and [Fe/H] values. To minimize the impact of systematic errors in the model-dependent atmospheric parameters, we use only the data for the 10 stars that most closely resemble our Sun, i.e., the solar twins, and derive the following solar colors: (B - V) = 0.653 ± 0.005, (U - B) = 0.166 ± 0.022, (V - R) = 0.352 ± 0.007, and (V - I) = 0.702 ± 0.010. These colors are consistent, within the 1σ errors, with those derived using the entire sample of 112 solar analogs. We also derive the solar colors using the relation between spectral-line-depth ratios and observed stellar colors, i.e., with a completely model-independent approach, and without restricting the analysis to solar twins. We find (B - V) = 0.653 ± 0.003, (U - B) = 0.158 ± 0.009, (V - R) = 0.356 ± 0.003, and (V - I) = 0.701 ± 0.003, in excellent agreement with the model-dependent analysis.