Dane Spaeth
Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V.
In order to fully explore the diversity of exoplanets it is crucial to investigate planetary systems around all types of hosts including evolved stars. The relatively few systems known around these giant stars show several distinct peculiarities. In contrast to main-sequence stars only a handful of planets are known around giants with periods shorter than several weeks. Radial velocity follow-up of evolved TESS Objects of Interest allow occurrence rate studies in order to investigate the cause of the lack of these planets. On the opposite side of the period range, there is also just one planet known to orbit an evolved star with a period longer than ten years. The newly built Waltz spectrograph will soon start to continue an RV monitoring program of a large sample of giants carried out at Lick observatory between 1999 and 2011. The combined baseline of more than 20 years will allow to investigate the long period population of planets orbiting evolved stars. Radial Velocity monitoring of giant stars is however complicated by the fact that non-radial oscillations caused by e.g. oscillatory convective modes might mimick RV periodicity caused by planets. Using CARMENES data for a sample of 20 evolved stars with ambiguous RV periodicity along with simulations of the effect of non-radial oscillations on stellar spectra, we aim to derive metrics apt to distinguish between planets and oscillations.