doi.eso.org

• Christlieb, Norbert [Zentrum für Astronomie der Universität Heidelberg/Landessternwarte, Germany]
• Battistini, Chiara [Zentrum für Astronomie der Universität Heidelberg/Landessternwarte, Germany]
• Bonifacio, Piercarlo [GEPI, Observatoire de Paris, Université PSL, CNRS, France]
• Caffau, Elisabetta [GEPI, Observatoire de Paris, Université PSL, CNRS, France]
• Ludwig, Hans-Günter [Zentrum für Astronomie der Universität Heidelberg/Landessternwarte, Germany]
• Asplund, Martin [Research School of Astronomy & Astrophysics, Australian National University, Canberra, Australia]
• Barklem, Paul [Department of Physics and Astronomy, Uppsala universitet, Sweden]
• Bergemann, Maria [Max-Planck-Institut für Astronomie, Heidelberg, Germany]
• Church, Ross [Lund Observatory, Lund University, Sweden]
• Ford, Dominic [Lund Observatory, Lund University, Sweden]
• Grebel, Eva K. [Zentrum für Astronomie der Universität Heidelberg/Astronomisches Rechen-Institut, Germany]
• Hansen, Camilla Juul [Max-Planck-Institut für Astronomie, Heidelberg, Germany]
• Helmi, Amina [Kapteyn Instituut, Rijksunversiteit Groningen, The Netherlands]
• Kordopatis, Georges [Observatoire de la Côte d’Azur, Nice, France]
• Kovalev, Mikhail [Max-Planck-Institut für Astronomie, Heidelberg, Germany]
• Korn, Andreas [Department of Physics and Astronomy, Uppsala universitet, Sweden]
• Lind, Karin [Max-Planck-Institut für Astronomie, Heidelberg, Germany]
• Quirrenbach, Andreas [Zentrum für Astronomie der Universität Heidelberg/Landessternwarte, Germany]
• Rybizki, Jan [Max-Planck-Institut für Astronomie, Heidelberg, Germany]
• Skúladóttir, Ása [Max-Planck-Institut für Astronomie, Heidelberg, Germany]
• Starkenburg, Else [Leibniz-Institut für Astrophysik Potsdam (AIP), Germany]

We will study the formation history of the Milky Way, and the earliest phases of its chemical enrichment, with a sample of more than 1.5 million stars at high galactic latitude. Elemental abundances of up to 20 elements with a precision of better than 0.2 dex will be derived for these stars. The sample will include members of kinematically coherent substructures, which we will associate with their possible birthplaces by means of their abundance signatures and kinematics, allowing us to test models of galaxy formation. Our target catalogue is also expected to contain 30 000 stars at a metallicity of less than one hundredth that of the Sun. This sample will therefore be almost a factor of 100 larger than currently existing samples of metal-poor stars for which precise elemental abundances are available (determined from high-resolution spectroscopy), enabling us to study the early chemical evolution of the Milky Way in unprecedented detail.