ARDERN-ARENTSEN , Anke

Context. Gaia DR3 has offered the scientific community a remarkable dataset of approximately one million spectra acquired with the radial velocity spectrometer (RVS) in the calcium II triplet region, which is well suited to identify very metal-poor (VMP) stars. However, over 40% of these spectra have no released parameters by Gaia's GSP-Spec...

The most metal-poor stars (e.g., [Fe/H] ≤ -2.5) are the ancient fossils from the early assembly epoch of our Galaxy. They very likely formed before the the thick disk. Recent studies have shown that a non-negligible fraction of them have prograde planar orbits, which means that their origin is a puzzle. It has been suggested that a later-formed...

Context. The emergence of the disc in our Galaxy and the relation between thick and thin disc formation and evolution is still a matter of debate. The chemo-dynamical characterization of disc stars is key to resolving this question, particularly at parameter regimes, where both disc components overlap, such as the region around [Fe/H] ∼ −0.7...

Context. Metal-poor stars hold key information on the early Milky Way. Through the identification and characterisation of substructures, one can understand internal mechanisms (including merger and accretion events), which are indispensable to reconstruct the formation history of the Galaxy. Aims. To allow an investigation of a population of...

The oldest stars in the Milky Way (born in the first few billion years) are expected to have a high density in the inner few kpc, spatially overlapping with the Galactic bulge. We use spectroscopic data from the Pristine Inner Galaxy Survey (PIGS) to study the dynamical properties of ancient, metal-poor inner Galaxy stars. We compute distances...