With next-generation astronomical facilities like WEAVE, 4MOST, and SDSS-V large datasets of high-quality stellar spectra will become available soon. The need for cutting edge 3D non-LTE radiative transfer codes is clear, but the demand for easy-to-use spectrum synthesis tools is even greater. We aim to provide both by supplying a non-LTE RT module based on the Multi3D code to the recently...
Predictions made by radiation-MHD simulations of the solar atmosphere can be tested by comparing the emergent spectrum to observations. Comparison with observations of the intensity in spectral lines that form in the chromosphere require that non-LTE, non-equilibrium, 3D effects, and partially coherent scattering play important roles. If comparison with the full Stokes vector is required, then...
One of the biggest assumptions in modelling stellar emission has been an assumption of local thermodynamical equilibrium, also known as LTE. While still widely spread, it has been shown to significantly bias results of stellar modelling, for example derived abundances.
In this talk I will focus on what is known as Non-LTE modelling - modelling stellar radiation without assuming LTE.
I will...
Late-type ultra metal-poor stars are thought to be formed from interstellar gas enriched by only one to few supernovae. As such, their elemental abundances and total metal content are important in understanding the limits of star formation in the early universe and the chemical evolution of the Milky Way. In this talk, I will present an updated chemical abundance analysis of the most...
Recent 3D simulations of cool giants and supergiants, specifically the asymptotic giant branch (AGB) and red supergiant (RSG) stars, with the CO5BOLD radiation-hydrodynamics code cover a wider range of stellar parameters and with greater temporal and spatial resolution than before. In these simulations, the hydrodynamical steps were handled straightforwardly with the Roe solver with 1D...
Radiation is the dominant energy transport mechanism in the solar atmosphere, and it is therefore important to have a good description of radiative transfer when modelling the solar atmosphere. For modelling purposes, it is only important to capture the radiative cooling/heating and not the details of the spectrum. For diagnostic purposes, we need the detailed spectrum and 3D radiative...
