It is quite common to find periodic signals in time series of precise radial velocities that cannot unambiguously be attributed either to a planetary companion or to intrinsic variability of the star. In such cases, plausibility criteria (e.g., fit quality, expected “typical” RV jitter, dynamical stability) and different types of additional information (e.g., stability of line profiles or line...
The nearby mid-M dwarf K2-18 hosts a known transiting super-Earth. The so-called K2-18b orbits close to the inner edge of the habitable zone making it an interesting target for future atmospheric characterization of an M dwarf planet receiving Earth-like insolation. In 2017, the HARPS follow-up campaign to characterize the mass of K2-18b revealed a strong periodic signal at $\sim 9$ days that...
We've been developping a new technique - FourIEr $\textit{phase}$ SpecTrum Analysis ($\mathit{\Phi}$ESTA or FIESTA) - that studies the spectral line profile variability in the Fourier space. It enables us to distinguish a line deformation from a line shift and provides the possibility to correct jitter. I will briefly lay out the theories and demonstrate its application in two example stars:...
