The Gaia-ESO Survey: Metallicity of the Chamaeleon I star-forming region^⋆,⋆⋆

¹ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
e-mail: lspina@arcetri.astro.it
² INAF – Osservatorio Astrofisico di Catania, via S. Sofia, 78, 95123 Catania, Italy
³ Instituto de Astrofísica de Andalucía-CSIC, Apdo. 3004, 18080 Granada, Spain
⁴ Centro de Astrofisica, Universidade do Porto, rua das Estrelas, 4150-762 Porto, Portugal
⁵ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, rua do Campo Alegre, 4169-007 Porto, Portugal
⁶ Instituto de Astrofisica de Canarias (IAC), 38205, La Laguna, Tenerife, Spain
⁷ Depto. Astrofisica, Universidad de La Laguna (ULL), 38206, La Laguna, Tenerife, Spain
⁸ Departamento de Astrofisica, Universidad Complutense de Madrid (UCM), Spain
⁹ Institute of Theoretical Physics and Astronomy, Vilnius University, Gostauto 12, LT-01108 Vilnius, Lithuania
¹⁰ INAF − Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
¹¹ Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Università di Catania, via S. Sofia 78, 95123 Catania, Italy
¹² Institute of Astronomy, University of Cambridge , Madingley Road, Cambridge CB3 0HA, UK
¹³ Astrophysics Group, Research Institute for the Environment, Physical Sciences and Applied Mathematics, Keele University, Keele, Staffordshire ST5 5BG, UK
¹⁴ INAF − Padova Observatory, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
¹⁵ Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, 221 00 Lund, Sweden
¹⁶ INAF − Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
¹⁷ Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
¹⁸ ASI Science Data Center, via del Politecnico SNC, 00133 Roma, Italy
¹⁹ Laboratoire Lagrange (UMR7293), Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, CS 34229, 06304 Nice Cedex 4, France
²⁰ Department for Astrophysics, Nicolaus Copernicus Astronomical Center, ul. Rabiańska 8, 87-100 Toruń, Poland

Received: 5 May 2014
Accepted: 8 June 2014

Abstract

Context. Recent metallicity determinations in young open clusters and star-forming regions suggest that the latter may be characterized by a slightly lower metallicity than the Sun and older clusters in the solar vicinity. However, these results are based on small statistics and inhomogeneous analyses. The Gaia-ESO Survey is observing and homogeneously analyzing large samples of stars in several young clusters and star-forming regions, hence allowing us to further investigate this issue.

Aims. We present a new metallicity determination of the Chamaeleon I star-forming region, based on the products distributed in the first internal release of the Gaia-ESO Survey.

Methods. The 48 candidate members of Chamaeleon I have been observed with the high-resolution, spectrograph UVES. We use the surface gravity, lithium line equivalent width, and position in the Hertzsprung-Russell diagram to confirm the cluster members, and we use the iron abundance to derive the mean metallicity of the region.

Results. Out of the 48 targets, we confirm 15 high probability members. Considering the metallicity measurements for nine of them, we find that the iron abundance of Chamaeleon I is slightly subsolar with a mean value [Fe/H] = −0.08 ± 0.04 dex. This result agrees with the metallicity determination of other nearby star-forming regions and suggests that the chemical pattern of the youngest stars in the solar neighborhood is indeed more metal-poor than the Sun. We argue that this evidence may be related to the chemical distribution of the Gould Belt that contains most of the nearby star-forming regions and young clusters.