Poster - Splinter eROSITA   (SFG 0140 / virtual eROSITA)

An exploration of different methods to remove telluric signatures from exoplanet transit observations

J Wokittel, K Poppenhaeger
Leibniz Institute for Astrophysics Potsdam

The atmosphere of our Earth causes absorption and emission features in spectroscopic observations (so-called telluric lines). Physical models of the Earth atmosphere can be used to treat tellurics in observations, but they depend on the completeness of the used telluric line atlas. Other telluric removal approaches rely only on the variability of the observed spectra themselves throughout the observation. In this master thesis I explore multiple approaches to remove telluric features from the transit observations for several exoplanets with the PEPSI high-resolution spectrograph at LBT. For a purely data-based approach, we analyze the behaviour of each individual spectral pixel throughout the observing night and approximate its changes in flux with a low-order smoothing spline. Our preliminary results show that this approach can remove tellurics from the exoplanet transmission spectrum efficiently, while leaving exoplanetary signals mostly intact. We will compare this to the tellurics removal performed by ESO's molecfit tool, which uses a physical model for the Earth atmosphere and the telluric lines. Comparing the performance of different approaches for tellurics removal will remain an important task, because high-resolution spectroscopy for exoplanets will continue to be performed from the ground for the foreseeable future.