Contributed Talk - Splinter Exoplanets

Friday, 17 September 2021, 16:45   (virtual Exo)

On stellar chemical abundances for studies of exoplanets - preparing for PLATO science using CoRoT examples

Matthias Ammler-von Eiff
Max Planck Institute for Solar System Research

Studies of the formation and structure of planets highly benefit from a knowledge of the chemical composition of their host stars. However, the knowledge of stellar chemical abundances is often insufficient if one is interested in accuracies at a level of 0.10dex or better, even for Sun-like stars and commonly studied species, such as iron and magnesium. Many studies claim precisions at this level but frequently, the underlying stellar parameters, such as effective temperature and surface gravity, are validated only statistically, and not per star. Then, the true error bars can be larger than the given ones but would not be propagated to the final result. Also, there are useful and available spectroscopic constraints on stellar parameters that are rarely used. This work combines the use of additional constraints with a validation for single objects. This way, it aims at a better visibility of the full error budget but also at its reduction. I will present two showcase examples of distant Sun-like planet host stars measured with CoRoT and show how Gaia parallaxes can help to improve the determination of their stellar fundamental parameters. Finally, I will illustrate the impact on the measurement of stellar magnesium and iron abundance. This study is particularly interesting regarding the characterisation of planets in the PLATO P5 sample.