On the origin of the dearth of hot exoplanets around fast-rotating stars

In 2013, a dearth of close-in planets around fast-rotating host stars wasfound using statistical tests on Kepler data. The addition of more Kepler andTransiting Exoplanet Survey Satellite (TESS) systems in 2022 seemingly filled this regionof the diagram of stellar rotation period (Prot) versus the planet orbitalperiod (Porb). Here, we revisit the Prot extraction of Kepler planet-host stars, weclassify the stars by their spectral type, and we studied their Prot-Porbrelations.  In order to learn about the physical processes at work, we used the star-planetevolution code ESPEM to compute a realistic, post-disk population synthesis of exoplanet systems andcompared them with observations. We take into account stellar wind braking, and both tidal and magnetic torques applied to the close-in planet which leads to its migration. Because ESPEM works with a single planetorbiting around a single main-sequence star, we limit our study to thispopulation of Kepler observed systems filtering out binaries, evolved stars,and multi-planets.  In this talk, we show that the dearth in close-in planets orbiting around fast-rotating stars is confirmed both in observations and simulations. We unveil adependence of the dearth on the stellar spectral type (F, G, and K), which is a proxy of themass in our sample of stars. There is a change in the edge of the dearth as afunction of the spectral type (and mass). It moves towards shorter Prot astemperature (and mass) increases, making the dearth look smaller. Realisticformation hypotheses included in the model and the proper treatment of post-disk tidaland magnetic migration are all needed to qualitatively explain the dearth of hotplanets around fast-rotating stars and the uncovered trend with spectral type.