Contributed Talk - Splinter Computation

Friday, 25 September 2020, 11:43   (virtual room B)

Exoplanetary atmospheres: Three-dimensional continuum radiative transfer of polarized radiation

M. Lietzow, S. Wolf, R. Brunngräber
Institute of Theoretical Physics and Astrophysics, Kiel University

We developed a radiative transfer tool that contains all relevant continuum polarization mechanisms for the comprehensive analysis of the polarized flux resulting from the scattering in the atmosphere, on the surface, and in the local planetary environment (e.g., planetary rings, exomoons) of extra-solar planets. In this approach common simplifications are avoided such as locally plane-parallel planetary atmospheres, the missing "cross-talk" between different latitudinal and longitudinal regions, and the assumption of either a point-like star or planet-parallel illumination. Spatially extended radiation sources and their possibly inhomogeneous brightness distribution (e.g., due to limb darkening) can be taken into account. As a platform for the newly developed numerical algorithms, we applied the publicly available 3D-Monte-Carlo radiative transfer code POLARIS (Reissl et al. 2016). This simulation software will provide the basis for investigations of the impact of various parameters characterizing the atmosphere and surface of exoplanets on the resulting polarization signal. Rayleigh scattering by small particles (e.g., gas molecules), Mie-scattering by larger particles (e.g., water clouds, dust clouds), as well as surface reflections (e.g., by water oceans, landmasses with our without biomass) can be considered. In addition, the influence of horizontally and vertically inhomogeneous atmospheres as well as the contribution of the local planetary environment on the net polarization signal can be analyzed.