Cis Lagae (Stockholm University): The metal-poor universe in 3D non-LTE

Wednesday 11 Sept 2024, 15:30 → 16:30 Europe/Stockholm

Title: The metal-poor universe in 3D non-LTE
Speaker: Cis Lagae
Affiliation: Stockholm University
Time: Wednesday 11th September 2024, 15:30 to 16:30
Location: 101136A Å

Abstract: I will present an overview of the research carried out during my PhD which focused on metal-poor, low-mass Milky Way stars, aiming to understand the nature of the first stars and galactic chemical evolution. To reach this goal, we require knowledge of the chemical composition of (metal-poor) stars, which are conventionally determined from a simple 1D LTE abundance analysis. To reduce large systematic errors in abundance measurements and prevent erroneous conclusions, it is necessary to compute synthetic spectra in non-LTE and with 3D stellar atmospheres, simultaneously. For this purpose, I have updated the STAGGER-grid of 3D model atmospheres in the subgiant region (logg<3.5) and prepared the STAGGER-grid for public release. In addition, I am working on a grid of 3D non-LTE spectra of the Ca II triplet lines, which are commonly used for abundance analysis and radial velocity determination in metal-poor stars.