Gaia FGK benchmark stars: Fundamental T_eff and log g of the third version^★

¹ Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
e-mail: caroline.soubiran@u-bordeaux.fr
² Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Bd de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
³ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
⁴ Millenium Nucleous ERIS, Santiago, Chile
⁵ GEPI, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Paris Cité, 5 place Jules Janssen, 92190 Meudon, France
⁶ Institut de Ciències del Cosmos (ICCUB), Departament de Física Quàntica i Astrofísica, Universitat de Barcelona (UB), Martí i Franquès, 1, 08028 Barcelona, Spain
⁷ Observational Astrophysics, Division of Astronomy and Space Physics, Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
⁸ Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
⁹ School of Physical and Chemical Sciences – Te Kura Matū, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
¹⁰ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK

Received: 9 June 2023
Accepted: 17 October 2023

Abstract

Context. Large spectroscopic surveys devoted to the study of the Milky Way, including Gaia, use automated pipelines to determine the atmospheric parameters of millions of stars. The Gaia FGK benchmark stars are reference stars with T_eff and log 𝑔 derived through fundamental relations, independently of spectroscopy, to be used as anchors for the parameter scale. The first and second versions of the sample have been extensively used for that purpose, and more generally to help constrain stellar models.

Aims. We provide the third version of the Gaia FGK benchmark stars, an extended set intended to improve the calibration of spectroscopic surveys, and their interconnection.

Methods. We have compiled about 200 candidates that have precise measurements of angular diameters and parallaxes. We determined their bolometric fluxes by fitting their spectral energy distribution. Masses were determined using two sets of stellar evolution models. In a companion paper, we describe the determination of metallicities and detailed abundances.

Results. We provide a new set of 192 Gaia FGK benchmark stars with their fundamental T_eff and log 𝑔, and with uncertainties lower than 2% for most stars. Compared to the previous versions, the homogeneity and accuracy of the fundamental parameters are significantly improved thanks to the high quality of the Gaia photometric and astrometric data.