Comparisons with High-resolution Sample

The figure below shows comparisons of T_eff (left panels), log g (middle panels), and [Fe/H] (right panels) of the SSPP results with the temperature from the IRFM, and surface gravity and metallicity from analysis of high-resolution spectra . The symbols μ and σ are the mean and standard deviation from a Gaussian fit to the sample. ‘Adop’ is the final adopted value in the SSPP; ‘Hi-res’ refers to the high-resolution analysis. The SSPP gravity estimate still overestimates log g by up to 1.0 dex for very cool giants. Note that there are only 107 stars available for the temperature comparison, because only those stars have J, H, and K photometry available.

Because the typical error of the surface gravities in the high-resolution analysis is ~ 0.2 dex, the uncertainty in log g of the SSPP is < 0.35 dex, from a quadratic subtraction, (0.4²-0.2²)^1/2. For the metallicity, the typical error of 0.1 dex in the high-resolution analysis means the uncertainty of the SSPP-derived [Fe/H] is < 0.22 dex from a quadratic subtraction, (0.24²-0.1²)^1/2. These inferred errors in the SSPP log g and [Fe/H] from the high-resolution calibration stars are mostly for the stars with high S/N (≥30).

Comparison of parameters to measurements in the high-resolution spectra (click to get a larger version)