1 Massachusetts Institute of Technology, Kavli Institute of Astrophysics & Space Research, Cambridge, MA, USA
2 Department of Astronomy, Indiana University, Bloomington, IN, USA
3 Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands
4 INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Florence, Italy
5 INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
6 INAF–Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy
7 Dipartimento di Fisica e Astronomia, via Ranzani 1, 40127 Bologna, Italy
8 Dipartimento di Fisica e Astronomia, Universita di Padova, vicolo Osservatorio 3, 35122 Padova, Italy
9 Department for Astrophysics, Nicolaus Copernicus Astronomical Center, ul. Rabiańska 8, 87-100 Toruń, Poland
10 European Southern Observatory, Alonso de Cordova 3107 Vitacura, Santiago de Chile, Chile
11 Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, 01108 Vilnius, Lithuania
12 Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza San Juan 1, 44001 Teruel, Spain
13 Departamento de Astronomía, Casilla 160-C, Universidad de Concepción, Concepción, Chile
14 Centro de Astrobiología (INTA-CSIC), Dpto. de Astrofísica, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
15 Suffolk University, Madrid Campus, C/ Valle de la Viña 3, 28003 Madrid, Spain
16 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
17 Instituto de Astrofísica de Andalucía-CSIC, Apdo. 3004, 18080 Granada, Spain
18 Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, 221 00 Lund, Sweden
19 INAF–Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
20 Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
21 ASI Science Data Center, via delPolitecnico SNC, 00133 Roma, Italy
22 Laboratoire Lagrange (UMR7293), Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, CS 34229, 06304 Nice Cedex 4, France
23 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
24 Departamento de Ciencias Fisicas, Universidad Andres Bello, Republica 220, Santiago, Chile
25 Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
26 Moscow MV Lomonosov State University, Sternberg Astronomical Institute, 119992 Moscow, Russia
Received: 27 October 2015
Accepted: 4 May 2016
Context. The nature of the metallicity gradient inside the solar circle (RGC < 8 kpc) is poorly understood, but studies of Cepheids and a small sample of open clusters suggest that it steepens in the inner disk.
Aims. We investigate the metallicity gradient of the inner disk using a sample of inner disk open clusters that is three times larger than has previously been studied in the literature to better characterize the gradient in this part of the disk.
Methods. We used the Gaia-ESO Survey (GES) [Fe/H] values and stellar parameters for stars in 12 open clusters in the inner disk from GES-UVES data. Cluster mean [Fe/H] values were determined based on a membership analysis for each cluster. Where necessary, distances and ages to clusters were determined via comparison to theoretical isochrones.
Results. The GES open clusters exhibit a radial metallicity gradient of −0.10 ± 0.02 dex kpc-1, consistent with the gradient measured by other literature studies of field red giant stars and open clusters in the range RGC ~ 6−12 kpc. We also measure a trend of increasing [Fe/H] with increasing cluster age, as has also been found in the literature.
Conclusions. We find no evidence for a steepening of the inner disk metallicity gradient inside the solar circle as earlier studies indicated. The age-metallicity relation shown by the clusters is consistent with that predicted by chemical evolution models that include the effects of radial migration, but a more detailed comparison between cluster observations and models would be premature.
Key words: Galaxy: formation / Galaxy: disk / Galaxy: abundances / stars: abundances
Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002 and 193.B-0936. These data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di Arcetri. These data have been obtained from the Gaia-ESO Survey Data Archive, prepared and hosted by the Wide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, which is funded by the UK Science and Technology Facilities Council.
Full Table 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A37
© ESO, 2016