Contributed Talk - Splinter Exoplanets

Thursday, 16 September 2021, 14:30   (virtual Exo)

The stellar pulsation timing method to detect sub-stellar companions

F. Mackebrandt, S. Schuh
Max Planck Institute for Solar System Research

We use the change in arrival times of coherent stellar pulsations to conclude on the presence sub-stellar companions. Contrary to other exoplanet detection methods, this timing method is particularly sensitive to planets at large distances and thus extends the parameter space of potential exoplanet host stars that can be probed with long term ground-based programs and space mission like Kepler, TESS and PLATO. We apply this method to two data sets. First, we investigate a possible formation scenario of apparently single subdwarf B stars (sdB). During the RGB, the progenitor star lost its envelope and leaves a He-burning core with a thin layer of hydrogen. The formation of a common envelope with a giant planet could be responsible for the loss of the envelope. In order to detect those possible companions, we analyse the extensive set of ground-based observations the four large amplitude p-mode pulsators DW Lyn, V1636 Ori, QQ Vir and V541 Hya from the EXOTIME project and can derive upper limits on sub-stellar companion masses from the observations. Second, we probe pulsating evolved main-sequence A stars as exoplanet host stars. Planet occurrence rates predict a maximum for host stars with masses close to the mass of those delta Scuti stars. However, actual planet detections are affected by observational selection effects, because exoplanets are expected to orbit delta Scuti stars in wide orbits with small transit probabilities. We analyse Kepler data using the timing method and confirm previously detected exoplanets orbiting delta Scuti stars.