Multi-dimensional analysis of the metal-poor Galaxy

ended

The history of the cosmos is written in starlight. The stellar surface contains a fossil fingerprint of the chemical composition of its birth cloud, modulu evolutionary effects. It is therefore possible to extract detailed knowledge about the history of galaxies like the Milky Way by studying stars born at different locations and ages: Galactic archaeology. Deciphering the stellar spectra in terms of stellar properties like temperature and chemical composition, however, requires realistic 3-dimensional models of the stellar atmospheres and non-equilibrium spectral line formation, which is the focus of this ambitious and timely project. Together with unprecedented large stellar spectroscopic surveys of the Milky Way, this project will usher in a new era in stellar astrophysics and Galactic archaeology. We will develop highly realistic 3D hydrodynamical simulations of stellar atmospheres for a very wide range of stellar temperatures, gravities and chemical compositions, which will be used to predict the detailed stellar spectra. I will extend the pioneering work I have done in developing comprehensive 3D non-equilibrium (non-LTE) radiative transfer calculations to a large number of elements of key astrophysical importance, thus removing a major systematic error in current spectroscopic analyses. Our endeavours in this field are unique world-wide and ensure that observations with the new generation of telescopes and instruments will be analysed in an optimal manner. I am spearheading the spectroscopic analyses to determine stellar parameters and chemical compositions for many millions of stars in spectroscopic surveys of the Milky Way, like the 200MEUR 4MOST project. This ERC project will guarantee the success of these major investments by providing the critical manpower for the analysis. I will also exploit these huge surveys to study the very first stars born after the Big Bang and the build-up of the ancient Milky Way halo through accretion of smaller galaxies.