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

L. Spina, S. Randich, F. Palla, K. Biazzo, G. G. Sacco, E. J. Alfaro, E. Franciosini, L. Magrini, L. Morbidelli, A. Frasca, V. Zh. Adibekyan, E. Delgado Mena, S. G. Sousa, J. I. GonzŠlez HernŠndez, D. Montes, H. Tabernero, G. Tautvai®ienė, R. Bonito, A. C. Lanzafame, G. Gilmore, R. D. Jeffries, A. Vallenari, T. Bensby, A. Bragaglia, E. Flaccomio, A. J. Korn, E. Pancino, A. Recio-Blanco, R. Smiljanic, M. Bergemann, M. T. Costado, C. Damiani, V. Hill, A. Hourihane, P. Jofrť, P. de Laverny, C. Lardo, T. Masseron, L. Prisinzano, C. Worley

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.

Keywords
open clusters and associations: individual: Chamaeleon I, stars: pre-main sequence, stars: abundances, techniques: spectroscopic

Astronomy and Astrophysics
Volume 568, Number of pages A2_1
2014 August

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Instituto de Astrof√≠sica e Ci√™ncias do Espa√ßo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Funda√ß√£o para a Ci√™ncia e a Tecnologia
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