The Gaia FGK Benchmark Stars

Library of high resolution and high signal to noise ratio stellar spectra.

The Gaia FGK Benchmark Stars are a common set of calibration stars, covering different regions of the HR diagram and spanning a wide range in metallicity. We have created a homogeneous library in the visual range (480-680 nm) of high resolution and signal to noise ratio (S/N) spectra corresponding to the 202 Benchmark Stars as of 2025 (evolved from the archived 2014 version). The library provides a powerful tool to assess spectral analysis methods and cross-calibrate spectroscopic surveys. The latest version of the spectra can be downloaded from this site. We thank you to cite Blanco-Cuaresma et al. (2014) and Casamiquela et al. (2025) whenever this library is used.

The star selection and the reference parameters improve and evolve with time. Here you can find the list of articles on Gaia FGK benchmark stars:

I. Gaia FGK benchmark stars: Effective temperatures and surface gravities. Heiter et al. 2015, A&A 582, A49.

II. The Gaia FGK benchmark stars. High resolution spectral library. Blanco-Cuaresma et al. 2014, A&A 566, A98.

III. Gaia FGK benchmark stars: Metallicity. Jofré et al. 2014, A&A 564, A133.

IV. Gaia FGK benchmark stars: abundances of alpha and iron-peak elements. Jofré et al. 2015, A&A 582, A81

V. Gaia FGK benchmark stars: new candidates at low metallicities. Hawkins et al. 2016, A&A 592, A70.

VI. Gaia FGK benchmark stars: Opening the black box of stellar element abundance determination. Jofré et al. 2017, A&A, 601, A38. | GBS v2.1 at CDS

VII. Gaia FGK benchmark stars: Fundamental Teff and log g of the third version . Soubiran et al. 2024, A&A, 682, A145.

VIII. Gaia FGK benchmark stars: spectral library, metallicities and abundances of α and Fe-peak elements of the third version. Casamiquela et al. 2025, A&A, in press

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