Chemical analysis of exoplanet host stars
Supervision: Univ.-Prof. Dr. Norbert Przybilla
Work focus: non-LTE & LTE line formation, quantitative analysis
The detection of exoplanets was one of the major achievements in astronomy in the past
two decades. Initally, only indirect methods (e.g. the Doppler and transit methods) were
successful for over a decade. The first bona-fide direct exoplanet detections – via imaging
– were announced in November 2008, around the two stars Fomalhaut and β Pictoris (see
Figure). The two stars are relatively hot, showing spectral morphologies of mid A-type mainsequence stars.
In this work the focus is on the exoplanet host stars. Their chemical composition shall
be determined. For this purpose, high-resolution spectra with high signal-to-noise ratio are
available from the archive of the European Southern Observatory (ESO), taken with FEROS
on the ESO 2.2m-telescope in La Silla/Chile. The fully reduced spectra will be modelled
using state-of-the-art line-formation computations and spectral analysis tools, taking into
account deviations from the standard assumption of local thermodynamic equilibrium (nonLTE) for H, C, N, O, Mg, Si and Fe, and assuming LTE otherwise. This will provide the most
accurate and precise characterisation of the chemical properties of the two stars, surpassing
anything available in the astrophysics literature.
Figure: Two stars, for which exoplanets have been directly imaged: Fomalhaut (left) and β Pictoris
(right panel). In this work, the chemical composition of the exoplanet host stars shall be determined.
Keywords: optical spectroscopy – elemental abundances – stellar atmospheres – non-LTE
& LTE radiative transfer – exoplanet host stars
For further information contact: [email protected]