TY  - GEN
ID  - heidok30357
KW  - exoplanets
KW  -  instrumentation
KW  -  radial velocity method
KW  -  RV method
KW  -  data processing
KW  -  giant stars
AV  - public
CY  - Heidelberg
TI  - Testing Planet Candidates around Giant Stars: Computation and Analysis of High Precision Radial Velocities
Y1  - 2021///
N2  - The radial velocity (RV), or Doppler, technique is one of the most successful methods in the search for exoplanets; with more than two decades of RV measurements acquired for some stars, and thanks to a precision around 1 m s ? 1 and better reached by modern spectrographs, it allows to explore an ever greater variety of planetary systems. In this PhD dissertation, I present my contributions to the RV survey of G- and K-giant stars, which is conducted by the Exoplanet Group at the Landessternwarte (LSW) Heidelberg. The aim is to track planet candidates in the sample, and thus strengthen our understanding of planet occurrence rates around these types of stars and discern between planetary signatures and false positives caused by intrinsic stellar variations.
My work can be split into two parts: First, I was involved in the Waltz telescope project, which will act as a successor to the CAT telescope at Lick observatory and allow to continue the RV survey of giant stars with an LSW-owned telescope. I describe my work on opto-mechanical components which enabled to reach first light on-sky, and I present results from early observations. My main task in the project was the build-up of the Waltz DRS (data reduction software), which will be used to reduce acquired spectra and extract RVs. I detail the structure of the software and implementation of mathematical methods, and discuss first test results on early
Waltz and archived Lick spectra.
The second part of my work concerns the analysis of the highly eccentric stellar binary Epsilon Cygni, which is part of the K-giant sample. RV data obtained at Lick, with the SONG telescope on Tenerife, and from the literature show short-period variations in addition to the long signal caused by the stellar companion, which might hint at a planetary companion on a S-type orbit around the primary. I present Keplerian and dynamical models and constrain the orbit of the stellar companion; however, in combination with a stability analysis of the system, the models deem the planet hypothesis to be highly unlikely. I examine possible alternative explanations for the short-period RV variations and find tidally induced stellar oscillations as a plausible cause.
A1  - Heeren, Paul Phillip
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/30357/
ER  -