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C. Johnas

Research: Non-analytical line profiles in stellar atmospheres : for planetary host star systems

In my work, non-analytical line profiles for both cool and hot, dense atmospheres are added to the opacity calculations of the multi-purpose stellar atmosphere code PHOENIX. In this work, various non-analytical alkali line profiles, including far line wing and near line wing profiles, for Na I D, Li I, KI, and Rb I are included in order to describe the strong alkali absorption features which are characteristic for late-type dwarfs. The various alkali line profiles are compared among each other and their influence in synthetic spectra. Towards improved descriptions of extreme exo-planets synthetic spectra, I have studied the coupling between the dust treatment and the effects of line profiles with Teff = 2000 K and log(g) = 5.0 in a static model atmosphere. The emphasis lies on the new dust treatment. It is a non-equilibrium treatment of the chemically heterogeneous dust clouds (DRIFT). My improved synthetic spectra are important for the determination of parameters of planet host stars, e.g. when using the lithium test. My results can also be applied to exo-planets.

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