Modelling the spectrum of Mg in cool stars

22nd International Conference on Spectral Line Shapes

Barklem, P.S.^1 ; Osorio, Y.^1

Theoretical Astrophysics, Department of Physics and Astronomy, Uppsala University, Box, 516, Uppsala

SE 751 20, Sweden^1

关键词: Collisional;    Cool stars;    Electron impact;    Hydrogen atoms;    Late-type stars;    R-matrix method;    Spectral feature;    Stellar atmospheres;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/548/1/012001/pdf
DOI  :  10.1088/1742-6596/548/1/012001

来源: IOP

【 摘 要 】

The astrophysical importance of Mg, together with its unique range of spectral features in late-type stars, plus its relative simplicity from an atomic physics point of view, makes it a prime target and test bed for detailed ab initio non-local thermodynamic equilibrium (NLTE) modelling in stellar atmospheres. In this paper, we present example first results for calculations of NLTE Mg line based on a new model atom with significant improvements in the collision data for neutral Mg. We perform calculations for excitation of the lower-lying levels due to electron impacts using the R-matrix method. Recent data for excitation and charge transfer due to hydrogen atom impacts involving low-lying levels are now employed. Further, we have made efforts to use physically-motivated methods for calculating radiative and collisional data involving Rydberg states. The results are compared with observed spectra and the impact of the new calculations briefly explored.