Gaia FGK benchmark stars: Metallicity⋆,⋆⋆

P. Jofré1,2, U. Heiter3, C. Soubiran2, S. Blanco-Cuaresma2, C. C. Worley1,4, E. Pancino5,6, T. Cantat-Gaudin7,8, L. Magrini9, M. Bergemann1,10, J. I. González Hernández11, V. Hill4, C. Lardo5, P. de Laverny4, K. Lind1, T. Masseron1,12, D. Montes13, A. Mucciarelli14, T. Nordlander3, A. Recio Blanco4, J. Sobeck15, R. Sordo7, S. G. Sousa16, H. Tabernero13, A. Vallenari7 and S. Van Eck12

A&A 564, A133 (2014)

1 Institute of Astronomy, University of Cambridge, Madingley Rd, Cambridge CB3 0HA, UK

e-mail: pjofre@ast.cam.ac.uk

2 LAB UMR 5804, Univ. Bordeaux – CNRS, 33270 Floirac, France

3 Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden

e-mail: ulrike.heiter@physics.uu.se

4 Laboratoire Lagrange (UMR7293), Univ. Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, 06304 Nice, France

5 INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy

6 ASI Science Data Center, via del Politecnico s/n, 00133 Roma, Italy

7 INAF, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, Padova, 35122 Italy

8 Dipartimento di Fisica e Astronomia, Università di Padova, vicolo Osservatorio 3, 35122 Padova, Italy

9 INAF/Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy

10 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany

11 Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain

12 Institut d’Astronomie et d’Astrophysique, Univ. Libre de Bruxelles, CP 226, Bd du Triomphe, 1050 Bruxelles, Belgium

13 Dpto. Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain

14 Dipartimento di Fisica & Astronomia, Universitá degli Studi di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy

15 Department of Astronomy & Astrophysics, University of Chicago, Chicago IL 60637, USA

16 Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal



Received: 2 August 2013

Accepted: 24 January 2014

Abstract

Context. To calibrate automatic pipelines that determine atmospheric parameters of stars, one needs a sample of stars, or “benchmark stars”, with well-defined parameters to be used as a reference.

Aims. We provide detailed documentation of the iron abundance determination of the 34 FGK-type benchmark stars that are selected to be the pillars for calibration of the one billion Gaia stars. They cover a wide range of temperatures, surface gravities, and metallicities.

Methods. Up to seven different methods were used to analyze an observed spectral library of high resolutions and high signal-to-noise ratios. The metallicity was determined by assuming a value of effective temperature and surface gravity obtained from fundamental relations; that is, these parameters were known a priori and independently from the spectra.

Results. 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 detailed documentation of the associated uncertainties. Finally, we report a value of the metallicity of the cool giant ψ Phe for the first time.

Key words: standards / techniques: spectroscopic / surveys / stars: fundamental parameters