Statistics on Planetary Candidates by Kepler and TESS

To date, more than 4000 exoplanets have been successfully identified and confirmed, almost half of them by Kepler mission. Now TESS mission has confirmed more than 130 exoplanets and yet another 4000 planetary candidates waiting to be confirmed. The distribution of planetary candidates in the parameters space may give us some clues to the planetary formation process. From the statistics of exoplanets candidates released by TESS, we find that most of exoplanet candidates are observed in the one-planet system and only about two hundred planets are in multiple planetary systems up to now. The largest planetary system, hosting six planets, is TOI-178. As for the planetary radius, the Kepler planets’ radii are mainly concentrated in 1-3 Earth radius, however, the radii distribution TESS planets shows two peaks, one at 1-3 Earth radius and a higher one at 10-20 Earth radius, respectively. Additionally, most planets discovered by the TESS mission have orbital periods within 100 days and pile up at about 3 days, implying that TESS mission will find more hot-Neptune than Kepler mission. The density of planets in multiple planetary systems tends to be higher than that in one-planet systems, which is consistent with the Kepler results. By analyzing the period ratio and relative space between two adjacent planets, we find that many planet pairs are in the configuration of near mean motion resonances and most two nearby planets distances further than 10 Hill Radius, which makes the planets pair stable in more than 10⁸ years. The analyses on the statistical results of the planetary candidates observed by TESS mission, which is ongoing, will surely reveal more information on the formation of planetary systems.