"Early studies of how the spectra of stars are produced had relied on something known as local thermal equilibrium. They had assumed that locally, energy in each region of a star's atmosphere has time to spread out and reach a kind of equilibrium. This would make it possible to assign to each such region a temperature, which leads to a considerable simplification in the calculations.
But as early as the 1950s, astronomers had realized that this picture was oversimplified. Since then, more and more studies incorporated so-called Non-LTE calculations, dropping the assumption of local equilibrium."
The group led by Ekaterina Magg, Maria Bergemann and colleagues leaders in non-LTE calculations resolved a contradiction in solar abundance finding that denser (than helium) materials accounted for 26% more (less than 2% total and each <0.6%) than previous calculations.
But as early as the 1950s, astronomers had realized that this picture was oversimplified. Since then, more and more studies incorporated so-called Non-LTE calculations, dropping the assumption of local equilibrium."
The group led by Ekaterina Magg, Maria Bergemann and colleagues leaders in non-LTE calculations resolved a contradiction in solar abundance finding that denser (than helium) materials accounted for 26% more (less than 2% total and each <0.6%) than previous calculations.