Accurate spectroscopic parameters of WASP planet host stars★

We have made a detailed spectral analysis of 11 Wide Angle Search for Planets (WASP) planet host stars using high signal-to-noise ratio (S/N) HARPS spectra. Our line list was carefully selected from the spectra of the Sun and Procyon, and we made a critical evaluation of the atomic data. The spectral lines were measured using equivalent widths. The procedures were tested on the Sun and Procyon prior to be being used on the WASP stars. The effective temperature (Teff), surface gravity (log g), microturbulent velocity (vmic) and metallicity were determined for all the stars. We show that abundances derived from high S/N spectra are likely to be higher than those obtained from low S/N spectra, as noise can cause the equivalent width to be underestimated. We also show that there is a limit to the accuracy of stellar parameters that can be achieved, despite using high S/N spectra, and the average uncertainty in Teff, log g, vmic and metallicity is 83 K, 0.11 dex, 0.11 km s−1 and 0.10 dex, respectively.