Doktorarbeiten (in Arbeit):
Markus Scheucher: The Effect of Cosmic rays upon Atmospheric Biosignatures in Earth-like Atmospheres
Elyar Sedaghati: Exploring Alien Skies: Detection and Characterisation of Exoplanetary Atmospheres with Ground-based Transmission Spectroscopy
This thesis studies the atmospheres of a few exoplanets in the hot-Jupiter regime, using an instrument at one of telescopes of Europe's Paranal Observatory in Chile. A method known as Transmission Spectroscopy is used to measure the radii of the observed transiting planet at various wavelengths, which leads to inference of its atmospheric composition. This technique is one of the channels through which signs of life on possibly habitable planets can be, in the near future, detected.
"A central objective of this work is to assess of the occurrence rate of extrasolar planets in the Milky Way. Based on this assessment, a correlation between the frequency of planets and their properties (radius, orbital period) as well as stellar characteristics (effective temperature, metallicity) will be evaluated. The motivation for this lies in the understanding of planet formation and evolution models, which themselves rely upon an exhaustive as possible knowledge of the frequency and diversity of planetary systems. The aim of these models is to explain the enormous variety of planetary systems.
The population analysis attempted within this work is based upon the data from the K2 mission."
"In the course of this work a model for the calculation of transmission spectra for hot gas planets was developed in order to address the science question as to
the effect of key parameters upon the spectral appearance. Three independent models were coupled together to achieve this goal. After the validation of the
so-called GCEGT model it was then used for a parameter variation study on the famous HJ HD209458b. The parameters were the internal temperature,
the ratio between mean visible and mean thermal opacity, the mean thermal opacity and the metallicity. The GCEGT model was then validated and a suitable parameter space was determined. This led to 32 different scenarios with maximum and minimum values of each parameter."
"This work focuses on the spectral classification of variable stars. These stars were observed with BEST II from March to September 2010 and were followed up by spectroscopy done with AAOmega in February 2012. The spectral classification is done by comparing the observed spectra with a grid of synthetic spectra created with SME (Spectroscopy Made Easy) using cross-correlation and a chi square fit. The goal is to gain a better understanding of binary star evolution."
"Die Wechselwirkungen zwischen Klimavariablen und der biogenen Aktivität von Mikroorganismen unter Anwendung eines eindimensionalen gekoppelten Klima-Photochemiemodells, welches wiederum an einen biogeochemischen Kreislauf koppelt, sollen untersucht werden. Es werden sowohl Szenarien für erdähnliche extrasolare Planeten, die in der habitablen Zone um M-Zwergsterne kreisen, als auch - im Vergleich - die frühe Erde modelliert."
"Twelve lightcurves of transiting objects from the CoRoT mission were analysed by the application of a model that searches for beaming, ellipsoidal and reflection effects in photometric time-series. The lightcurves of CoRoT-3 and of four other stars with known brown dwarfs as orbiting companions from the Kepler mission helped to evaluate the model. Six lightcurves showed high stellar activity from the host star that is interfering with the beaming variation. From the other six, two substellar and five very low mass stellar candidates could be found via the beaming effect."
Weitere abgeschlossene Arbeiten: