Gaia FGK Benchmark Stars - Metallicity

TL;DR

This paper provides a homogeneous set of metallicity measurements for 34 Gaia FGK benchmark stars, essential for calibrating stellar parameter pipelines, including a new metallicity value for psi Phe.

Contribution

It offers a detailed, homogeneous metallicity determination for 34 benchmark stars using multiple methods, enhancing calibration accuracy for Gaia data analysis.

Findings

Homogeneous metallicity values for 34 stars.

First metallicity measurement for psi Phe.

Quantified uncertainties for each measurement.

Abstract

To calibrate automatic pipelines that determine atmospheric parameters of stars, one needs a sample of stars -- ``benchmark stars'' -- with well defined parameters to be used as a reference We provide a detailed documentation of the determination of the iron abundance of the 34 FGK-type benchmark stars selected to be the pillars for calibration of the one billion Gaia stars. They cover a wide range of temperatures, surface gravities and metallicities. Up to seven different methods were used to analyze an observed spectral library of high resolution and high signal-to-noise ratio. The metallicity was determined assuming a value of effective temperature and surface gravity obtained from fundamental relations, i.e. these parameters were known a priori independently from the spectra. We present a set of metallicity values obtained in a homogeneous way for our sample of Benchmark Stars. In addition to this value, we provide a detailed documentation of the associated uncertainties. Finally, we report for the first time a value of the metallicity of the cool giant psi Phe.