Asteroseismic measurement of the inclination angle: characterizing exoplanetary systems

Information on stellar inclinations are of prime importance to characterize the formation and dynamics of transiting exoplanetary systems, by helping to constrain the angle between the stellar spin axis and the planetary orbit axis, namely the obliquity. As PLATO will observe about 150 000 main-sequence stars potentially hosting exoplanets, it is crucial to have at hand a fast, robust and automated method to measure the stellar inclination angle.
I will present the method I developed and the results I derived for almost 1200 red giant stars that have been observed by the Kepler space mission, which exhibit mixed modes offering the opportunity to obtain accurate measurements of the inclination angle of the stellar rotation axis. I could characterize the biases affecting inclination measurements, in particular for extreme values close to 0 ◦ and 90 ◦ . This study allowed me to provide a way to infer the underlying statistical distribution of inclinations for a given sample of stars, free from observational limitations. This method has the advantage to be able to derive seismic measurements of the inclination angle for any solar-type pulsator with identified oscillation modes.