title: A Critical Appraisal of Planets Orbiting Giant Stars
creator: Späth, Dane Marvin
subject: ddc-520
subject: 520 Astronomy and allied sciences
description: Giant stars provide a unique opportunity to study planets around intermediate-mass stars  through radial velocity surveys and examine the impact of stellar evolution on planetary  systems. Despite their growing numbers, few planets have been found with very short  or long orbital periods. Furthermore, detections around luminous giants are debated as  intrinsic mechanisms can mimic planetary signals. In this thesis, I rule out two transiting  planet candidates from TESS via spectroscopic follow-up. To address the planet controversy  surrounding luminous giants, I develop the simulation tool pyoscillot, showing that the  radial velocities and activity indicators of the false-positive planet host NGC 4349 No. 127  can be reproduced by a non-radial oscillation model. I further combine data from the Lick,  SONG, and CARMENES spectrographs to analyze ten planet candidates with intermediate  orbital periods. I find that testing an extensive baseline of radial velocities for consistency  with Keplerian orbits is crucial to rule out or confirm planets around luminous giants. While  the signals of seven stars are intrinsically induced, I identify a long-period planet candidate  orbiting HIP 64823. Finally, I present first results of the new échelle spectrograph mounted  at the Waltz telescope at Landessternwarte, Heidelberg, demonstrating its potential for  detecting planets around giants.
date: 2025
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserver/36740/1/dissertation_spaeth.pdf
identifier: DOI:10.11588/heidok.00036740
identifier: urn:nbn:de:bsz:16-heidok-367404
identifier:   Späth, Dane Marvin  (2025) A Critical Appraisal of Planets Orbiting Giant Stars.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/36740/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng