Planetary Science Seminar fall-2018

The Kepler and K2 missions blessed the community with a plethora of planet transit detections which enabled studies of exoplanet size demographics. Much of the recent progress in this field is driven by improved characterization of the stellar hosts. Our group recently used precise radius measurements from the California-Kepler Survey (CKS) to detect a gap in the distribution of planet radii. The paucity of planets with sizes between 1.5 and 2.0 Earth radii supports the emerging picture that close-in planets smaller than Neptune are composed of small, rocky cores enveloped by varying amounts of low-density gas that determine their total sizes. This result demonstrated the value of precise and homogeneous stellar parameters. Fortunately, Gaia DR2 has all but solved this problem for exoplanet host stars. With the combination of CKS and Gaia we updated the planet radius distribution again and found that 1) details of the distribution depend on the properties of the host stars and, 2) the region between 1.5-2.0 Earth radii is not completely devoid of planets. I will discuss implications of the radius distribution and the future prospects of exoplanets enabled by the exquisite stellar characterization from Gaia and next-generation extremely precise radial velocity instruments.