Stellar Contamination in Exoplanet Transmission Spectra

The purpose of the project is to constrain the contamination of exoplanet transmission spectra from stellar inhomogeneities (i.e., spots and faculae) in order that exoplanet atmospheric retrievals can be performed with greater accuracy. To begin, forward modelling of stellar atmospheres with magneto-hydrodynamic simulations will be done with a varying mean magnetic field and for different spectral types. The covering fraction and contrasts of the spots and faculae for each simulation will enable the contamination level to be known. The simulations will also explore the effect of having different active latitudes for spot and faculae emergence on the degree of contamination. Atmospheric retrievals will then be done to simulated transit data for a standard exoplanet transiting each of the stellar simulations. This will allow the effect of the known contamination on each of the derived transmission spectra to be constrained for varying magnetic field strength and stellar spectral type. The findings from this investigation will then be applied to real transit data.