TY  - GEN
TI  - High-Contrast Imaging Characterization of Exoplanets
Y1  - 2019///
AV  - public
CY  - Heidelberg
ID  - heidok26838
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/26838/
A1  - Samland, Matthias Severin
N2  - Direct imaging of exoplanetary systems and the spectral characterization of exoplanetary atmospheres are amongst the most challenging, as well as rapidly developing fields in astronomy, propelled by new technologies and observational strategies. In this thesis, I contributed to the atmospheric analysis of exoplanets, the development of new algorithms to find faint planet signatures in the data, and the improvement of the fidelity of obtained exoplanet spectra. I performed atmospheric analyses of directly imaged planets observed with the planet imaging instrument VLT/SPHERE. For this purpose, I wrote a statistical inference code (BACON, Bayesian Atmospheric CharacterizatiON), which uses self-consistently computed model atmospheres to derive atmospheric parameters. The planets I studied in this thesis are: 51 Eridani b, one the coldest methane-rich directly imaged planets; PDS 70 b, the first young planet discovered inside the gap of its host star?s transition disk; HIP 65426 b, a planet of similar spectral type to PDS 70 b, but hotter and older; and GJ 504 b, a colder
methane-rich companion which, depending on its age, could be a planet or brown dwarf. The new algorithm I developed to detect planets in high-contrast imaging data shifts the focus from an image analysis interpretation of the data, towards a time-domain analysis approach. I show that with this technique (TRAP, Temporal Reference Analysis for Exoplanets), an improvement of up to a factor of six in signal-to-noise can be achieved at very small angular separations between the planet and host star. Furthermore, I adapted the CHARIS instrument pipeline to use with SPHERE-IFS. This pipeline opens new possibilities for improving the quality of spectra obtained for exoplanets using SPHERE. Using this pipeline, I confirm the low flux emitted at around 1 micron previously obtained for 51 Eridani b, consistent with the absorption due to methane and water opacities predicted by models. Lastly, I discuss the future prospects for my work and how these approaches can be combined into a single framework.
ER  -