Gaia FGK benchmark stars: abundances of α and iron-peak elements^⋆,⋆⋆

¹ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
e-mail: pjofre@ast.cam.ac.uk
² Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
³ Univ. Bordeaux, CNRS, Laboratoire d’Astrophysique de Bordeaux (UMR 5804), 33270 Floirac, France
⁴ Observatoire de Genève, Université de Genève, 1290 Versoix, Switzerland
⁵ Institut d’Astronomie et d’Astrophysique, U. Libre de Bruxelles, CP 226, Boulevard du Triomphe, 1050 Bruxelles, Belgium
⁶ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, rua das Estrelas, 4150-762 Porto, Portugal
⁷ Max-Planck Institute for Astronomy, 69117 Heidelberg, Germany
⁸ INAF, Osservatorio di Padova, Università di Padova, Vicolo Osservatorio 5, Padova 35122, Italy
⁹ Laboratoire Lagrange (UMR 7293), Univ. Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, 06304 Nice, France
¹⁰ Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
¹¹ INAF/Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
¹² Institute of Theoretical Physics and Astronomy, Vilnius University, A. Goštauto 12, 01108 Vilnius, Lithuania
¹³ INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
¹⁴ ASI Science Data Center, via del Politecnico s/n, 00133 Roma, Italy
¹⁵ Dpto. Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁶ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain

Received: 26 May 2015
Accepted: 29 June 2015

Abstract

Context. In the current era of large spectroscopic surveys of the Milky Way, reference stars for calibrating astrophysical parameters and chemical abundances are of paramount importance.

Aims. We determine elemental abundances of Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni for our predefined set of Gaia FGK benchmark stars.

Methods. By analysing high-resolution spectra with a high signal-to-noise ratio taken from several archive datasets, we combined results of eight different methods to determine abundances on a line-by-line basis. We performed a detailed homogeneous analysis of the systematic uncertainties, such as differential versus absolute abundance analysis. We also assessed errors that are due to non-local thermal equilibrium and the stellar parameters in our final abundances.

Results. Our results are provided by listing final abundances and the different sources of uncertainties, as well as line-by-line and method-by-method abundances.

Conclusions. The atmospheric parameters of the Gaia FGK benchmark stars are already being widely used for calibration of several pipelines that are applied to different surveys. With the added reference abundances of ten elements, this set is very suitable for calibrating the chemical abundances obtained by these pipelines.