Radiation transfer in stellar atmospheres

The most common observable of cosmic objects is electromagnetic radiation emitted from stellar surfaces. The latter are usually referred to as stellar atmospheres. The astrophysical interpretation of starlight is a very complex theoretical problem that involves atomic, nuclear, and molecular physics, hydrodynamics, statistical mechanics, and radiative transfer. 

Our expertise is non-equilibrium radiation transfer in stellar atmospheres. We develop Non-LTE models of atoms and molecules and use them in statistical equilibrium calculations with novel 3-dimensional (3D) radiation-hydrodynamic simulations of stellar convection. The results are accessible via our public database http://nlte.mpia.de

3D Non-LTE models are essential to derive accurate fundamental parameters of stars: masses, ages, and their detailed chemical compositions. Our models are used in the GALAH and Gaia-ESO surveys and will be employed for the analysis of 4MOST and PLATO targets.

Solar oxygen abundance
Bergemann, Hoppe, Semenova et al., MNRAS, 508, 2, 2021

Observational constraints on the origin of the elements II. 3D non-LTE formation of Ba II lines in the solar atmosphere
Gallagher, Bergemann et al. A&A, 634, A55, 2019

Observational constraints on the origin of the elements I. 3D NLTE formation of Mn lines in late-type stars
Bergemann, Gallagher et al. A&A, 631, A80, 2019

NLTE modelling of integrated light spectra. Abundances of barium, magnesium, and manganese in a metal-poor globular cluster
Eitner, Bergemann, & Larsen A&A, 627, A40

Investigation of a sample of carbon-enhanced metal-poor stars observed with FORS and GMOS
Caffau, Gallagher et al. A&A, 614, A68, 2018

Non-local Thermodynamic Equilibrium Stellar Spectroscopy with 1D and <3D> Models. I. Methods and Application to Magnesium Abundances in Standard Stars
Bergemann et al. incl. Kovalev, ApJ, 847, id.15, 2017

Red Supergiant Stars as Cosmic Abundance Probes. III. NLTE effects in J-band Magnesium Lines
Bergemann et al. ApJ, 804, id. 113, 2015

Unveiling systematic biases in the 1D LTE excitation-ionization balance of Fe for FGK stars: a novel approach to determination of stellar parameters
Ruchti, Bergemann et al. MNRAS, 429, 136, 2013

© Maria Bergemann 2023