Probing the atmosphere of HD189733b with the Na I and K I lines
Strassmeier, K. G.; Ilyin, I.; Steffen, M.; Carroll, T. A.; Mallonn, M.; Fossati, L.; Nascimbeni, V.; von Essen, C.; Pino, L.; Kitzmann, D.; Seidel, J. V.; Poppenhäger, K.; Turner, J. D.; Keles, E.; Alexoudi, X.
Germany, Switzerland, Austria, Netherlands, Italy, Denmark, United States
Abstract
High spectral resolution transmission spectroscopy is a powerful tool to characterize exoplanet atmospheres. Especially for hot Jupiters, this technique is highly relevant, due to their high-altitude absorption, e.g. from resonant sodium (Na I) and potassium (K I) lines. We resolve the atmospheric K I absorption on HD189733b with the aim to compare the resolved K I line and previously obtained high-resolution Na I-D line observations with synthetic transmission spectra. The line profiles suggest atmospheric processes leading to a line broadening of the order of ∼10 km/s for the Na I-D lines and only a few km/s for the K I line. The investigation hints that either the atmosphere of HD189733b lacks a significant amount of K I or the alkali lines probe different atmospheric regions with different temperature, which could explain the differences we see in the resolved absorption lines.