Comparisons with High-resolution Sample – SSPP
The figure below shows comparisons of Teff (left panels), log g (middle panels), and [Fe/H] (right panels) of the DR9-DR12 SSPP with the temperature from the IRFM, and surface gravity and metallicity from the new high-resolution analysis. 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. As was the case for DR8, the DR9-DR12 SSPP gravity estimate still over-estimates log g by up to 1.0 dex for very cool giants. Note that there are only 107 stars available for the temperature comparison, as only those stars have J, H, and K photometry available.
Considering the typical error for measuring the surface gravity in the high-resolution analysis to be around 0.2 dex, the uncertainty in log g of the SSPP is expected to be less than 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 yields less than 0.22 dex in the uncertainty of the SSPP-derived [Fe/H] 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)|