Accurate spectroscopic parameters of WASP planet host stars

TL;DR

This study provides precise spectroscopic parameters for eleven WASP planet host stars using high-quality HARPS spectra, highlighting the impact of spectral noise on abundance measurements and establishing accuracy limits.

Contribution

It presents a detailed spectral analysis methodology with a carefully selected line list, evaluating the effects of spectral noise on stellar parameter determination.

Findings

High S/N spectra yield higher abundance estimates than low S/N spectra.

There is a limit to the accuracy of stellar parameters despite high S/N data.

Average uncertainties are 83 K in temperature, 0.11 dex in gravity, 0.11 km/s in microturbulence, and 0.10 dex in metallicity.

Abstract

We have made a detailed spectral analysis of eleven Wide Angle Search for Planets (WASP) planet host stars using high signal-to-noise (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, surface gravity, microturbulent velocity 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 effective temperature, surface gravity, microturbulent velocity and metallicity is 83 K, 0.11 dex, 0.11 km/s and 0.10 dex respectively.