Simultaneously modeling the orbital architecture and size distribution of the small exoplanets revealed by the KEPLER mission

Pin-Gao Gu^1*, Yuji Matsumoto^1,2, Eiichiro Kokubo², Kenji Kurosaki³

¹Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
²National Astronomical Observatory of Japan, Tokyo, Japan
³Department of Physics, Nagoya University, Nagoya, Japan

* Presenter:Pin-Gao Gu, email:gu@asiaa.sinica.edu.tw

The KEPLER transit survey with follow-up spectroscopic observations has discovered numerous super-Earth sized planets and revealed intriguing features of their sizes, orbital periods, and their relations between adjacent planets. The planet size distribution exhibits a bimodal distribution separated by a "radius gap" at around 1.8 Earth radii. Besides, super-Earths within multiplanet systems show that adjacent planets are similar in size and their period ratios of adjacent planet pairs are similar as well, a phenomenon often referred to as “peas-in-a-pod” in the exoplanet community. While the "radius gap" has been predicted and theorized for years, whether it can be relevant to the orbital architecture "pears-in-a-pod" is physically unknown. For the first time, we attempt to model both features together through planet formation and evolution processes involving giant impacts and photoevaporation. I shall show that our model is generally consistent with the KEPLER results, with slight differences from detailed observational results such as the radius gap. This research was supported by the MoST grant 109-2112-M-001-052.

Keywords: exoplanet, KEPLER space telescope, planet atmosphere, planet formation and evolution, N-body simulation