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Spatially resolved solar spectroscopy as benchmark for exoplanet observations

Presentation #102.130 in the session Poster Session.

Published onJun 20, 2022
Spatially resolved solar spectroscopy as benchmark for exoplanet observations

The detection of exoplanets is nowadays highly limited by stellar activity itself. High spectral resolution observations of the Sun at different centre-to-limb angles are crucial to get a better understanding how stellar activity affects radial-velocity measurements and perturb the detection of Earth-like planets as well as to improve further 3D MHD simulations.

We want to give an overview about spatially resolved solar observations taken at the Institute for Astrophysics and Geophysics in Göttingen. We observe the solar surface (32 arcsec) using a high resolution Fourier Transform Spectrograph (FTS) with a resolution of R ~ 700,000 at a wavelength of ~600nm for the entire visible band-pass (~ 450 to 950 nm). Our relative spectral accuracy varies between 15 and 30 m/s from the disc-centre to the limb. We created a quiet Sun atlas covering 14 different observation angles on the solar surface with a total number of 173 observations.

Our observations of the resolved Sun provide an insight into the variable spectral behaviour across different limb angles, which can provide crucial information about limb darkening, convective velocities, and line profile variabilities relevant for radial velocity (RV) work. We show first results of different lines and bisectors at different limb angles, which can be used to put models of transit observations as well as also solar and stellar RV variability on a firm footing.

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