Metallicity of low-mass stars in Orion

摘要

Context. Determining the metal content of low-mass members of young associations provides a tool that addresses different issues,such as triggered star formation or the link between the metal-rich nature of planet-host stars and the early phases of planet formation.The Orion complex is a well known example of possible triggered star formation and is known to host a rich variety of proto-planetarydisks around its low-mass stars. Available metallicity measurements yield discrepant results.Aims. We analyzed FLAMES/UVES and Giraffe spectra of low-mass members of three groups/clusters belonging to the Orionassociation. Our goal is the homogeneous determination of the metallicity of the sample stars, which allows us to look for Fe/Hdifferences between the three regions and for the possible presence of metal-rich stars.Methods. Nine members of the ONC and one star each in the λ Ori cluster and OB 1b subgroup were analyzed. After the veilingdetermination, we retrieved the metallicity by means of equivalent widths and/or spectral synthesis using MOOG.Results. We obtain an average metallicity for the ONC Fe/H = –0.01 ± 0.04. No metal-rich stars were detected and the dispersionwithin our sample is consistent with measurement uncertainties. The metallicity of the λ Ori member is also solar, while the OB 1bstar has an Fe/H significantly below the ONC average. if confirmed by additional Fe/H determinations in the OB 1b subgroup, thisresult would support the triggered star formation and the self-enrichment scenario for the Orion complex.