Project title: Accurate Compositions of Sun-like Stars
Main applicant: Anish Amarsi, Division of Astronomy and Space Physics
Grant amount: 3 800 000 SEK for the period 2021-2024
Enormous sets of observational data are being gathered through a number of planned or active large stellar surveys including 4MOST, APOGEE, GALAH, Gaia-ESO, PLATO, and WEAVE. These data will enable us to study the physics of planets, stars, and galaxies with unprecedented precision. However, theoretical models of stellar spectra are needed to convert observations into fundamental parameters and compositions. Inaccuracies in classical models used today limit the full potential of these exquisite observational data.
I shall develop an accurate modelling paradigm that is based on three-dimensional stellar atmospheres and non-equilibrium radiative transfer. Extensive grids of accurate model spectra will be constructed using SNIC resources to carefully study the line formation physics of some of the most important elements in astronomy: magnesium, silicon, and iron. The grids will be used to reanalyse high-quality observational data from the literature, to determine the fundamental parameters and compositions of Sun-like stars with unprecedented precision and accuracy. These accurate data will be used to hunt for subtle signatures of planet formation that may be hidden in the compositions of exoplanet host stars, and to trace the chemical evolution of our Galaxy. These accurate model spectra will be made public, to maximise the impact of large stellar surveys, and get the most value out of the next generation of extremely large telescopes and high resolution spectrographs.
