The Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars^⋆,⋆⋆

¹ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
e-mail: rsmiljanic@ncac.torun.pl
² Department for Astrophysics, Nicolaus Copernicus Astronomical Center, ul. Rabiańska 8, 87-100 Toruń, Poland
³ Department of Physics and Astronomy, Division of Astronomy and Space Physics, Uppsala University, Box 516, 75120 Uppsala, Sweden
e-mail: andreas.korn@physics.uu.se
⁴ Max Planck Institute for Astrophysics, Karl-Schwarzschild Str. 1, 85741 Garching, Germany
⁵ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
⁶ INAF − Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
⁷ INAF − Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Florence, Italy
⁸ Université Libre de Bruxelles, Campus Plaine, CP 226, Boulevard du Triomphe, 1050 Bruxelles, Belgium
⁹ INAF − Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
¹⁰ ASI Science Data Center, via del Politecnico SNC, 00133, Roma, Italy
¹¹ Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, 221 00 Lund, Sweden
¹² Departamento de Astronomía, Universidad de Concepción, Casilla 160 Concepción, Chile
¹³ Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Königstuhl 12, 69117 Heidelberg, Germany
¹⁴ Millennium Institute of Astrophysics, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
¹⁵ Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
¹⁶ Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹⁷ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
¹⁸ Dept. Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁹ Institute of Theoretical Physics and Astronomy, Vilnius University, Goštauto 12, 01108 Vilnius, Lithuania
²⁰ Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
²¹ Laboratoire Lagrange (UMR 7293), Université deNice-Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, BP 4229, 06304 Nice Cedex 4, France
²² Instituto de Astrofísica de Canarias, C via Lactea s/n, 38200, La Laguna, Tenerife, Spain
²³ Dept. Astrofísica, Universidad de La Laguna (ULL), 38206, La Laguna, Tenerife, Spain
²⁴ LAB UMR 5804, Univ. Bordeaux et CNRS, 33270 Floirac, France
²⁵ GEPI, Observatoire de Paris, CNRS, Univ. Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
²⁶ INAF − Osservatorio Astronomico di Padova, Vicolo Osservatorio 2, 35122 Padova, Italy
²⁷ Dipartimento di Fisica e Astronomia “G. Galilei” Università degli Studi di Padova. via Marzolo 8, 35131 Padova, Italy
²⁸ Dipartimento di Fisica & Astronomia, Universita’ di Bologna, Viale Berti/Pichat 6/2, 40127 Bologna, Italy
²⁹ Department of Astronomy, Indiana University, Bloomington, IN 47405, USA
³⁰ Kavli Institute for Astrophysics & Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
³¹ Astrophysics Section, Department of Physics and Astronomy, University of Catania, via S. Sofia 78, 95123 Catania, Italy
³² Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août, Bât. B5c, 4000 Liège, Belgium
³³ Institute of Space Sciences (IEEC-CSIC), Campus UAB, Fac. Ciències, Torre C5 parell 2, 08193 Bellaterra, Spain
³⁴ Dipartimento di Fisica e Astronomia, Università di Firenze, via Sansone, 1, 50019 Sesto Fiorentino ( FI), Italy
³⁵ Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611, Australia
³⁶ Rudolf Peierls Centre for Theoretical Physics, Keble Road, Oxford OX1 3NP, UK
³⁷ Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield, AL10 9AB, UK
³⁸ Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
³⁹ Astrophysics Group, Research Institute for the Environment, Physical Sciences and Applied Mathematics, Keele University, Keele, Staffordshire ST5 5BG, UK
⁴⁰ INAF − Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
⁴¹ Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain
⁴² ESA, ESTEC, Keplerlaan 1, PO Box 299, 2200 AG Noordwijk, The Netherlands
⁴³ Max Planck Institute für Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁴⁴ Instituto de Astrofísica de Andalucía-CSIC, Apdo. 3004, 18080 Granada, Spain
⁴⁵ Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium
⁴⁶ Instituto de Física y Astronomía, Universidad de Valparaíso, 2340000 Valparaíso, Chile
⁴⁷ European Southern Observatory, Alonso de Cordova, 3107 Vitacura, Santiago de Chile, Chile

Received: 3 April 2014
Accepted: 1 September 2014

Abstract

Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using FLAMES at the VLT to obtain high-quality medium-resolution Giraffe spectra for about 10⁵ stars and high-resolution UVES spectra for about 5000 stars. With UVES, the Survey has already observed 1447 FGK-type stars.

Aims. These UVES spectra are analyzed in parallel by several state-of-the-art methodologies. Our aim is to present how these analyses were implemented, to discuss their results, and to describe how a final recommended parameter scale is defined. We also discuss the precision (method-to-method dispersion) and accuracy (biases with respect to the reference values) of the final parameters. These results are part of the Gaia-ESO second internal release and will be part of its first public release of advanced data products.

Methods. The final parameter scale is tied to the scale defined by the Gaia benchmark stars, a set of stars with fundamental atmospheric parameters. In addition, a set of open and globular clusters is used to evaluate the physical soundness of the results. Each of the implemented methodologies is judged against the benchmark stars to define weights in three different regions of the parameter space. The final recommended results are the weighted medians of those from the individual methods.

Results. The recommended results successfully reproduce the atmospheric parameters of the benchmark stars and the expected T_eff-log  g relation of the calibrating clusters. Atmospheric parameters and abundances have been determined for 1301 FGK-type stars observed with UVES. The median of the method-to-method dispersion of the atmospheric parameters is 55 K for T_eff, 0.13 dex for log  g and 0.07 dex for [Fe/H]. Systematic biases are estimated to be between 50−100 K for T_eff, 0.10−0.25 dex for log  g and 0.05−0.10 dex for [Fe/H]. Abundances for 24 elements were derived: C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ba, Nd, and Eu. The typical method-to-method dispersion of the abundances varies between 0.10 and 0.20 dex.

Conclusions. The Gaia-ESO sample of high-resolution spectra of FGK-type stars will be among the largest of its kind analyzed in a homogeneous way. The extensive list of elemental abundances derived in these stars will enable significant advances in the areas of stellar evolution and Milky Way formation and evolution.