Searching the Entirety of Kepler Data. II. Occurrence Rate Estimates for FGK Stars

Abstract

We present exoplanet occurrence rates estimated with approximate Bayesian computation for planets with radii between 0.5 and 16 $R_{⨁}$ and orbital periods between 0.78 and 400 days, orbiting FGK dwarf stars. We base our results on an independent planet catalogue compiled from our search of all ~200,000 stars observed over the Kepler mission, with precise planetary radii supplemented by Gaia DR2-incorporated stellar radii. We take into account detection and vetting efficiency, planet radius uncertainty, and reliability against transit-like noise signals in the data. By analyzing our FGK occurrence rates as well as those computed after separating F-, G-, and K-type stars, we explore dependencies on stellar effective temperature, planet radius, and orbital period. We reveal new characteristics of the photoevaporation-driven "radius gap" between ~1.5 and 2 $R_{⨁}$, indicating that the bimodal distribution previously revealed for $P$ < 100 days exists only over a much narrower range of orbital periods, above which sub-Neptunes dominate and below which super-Earths dominate. Finally, we provide several estimates of the "eta-Earth" value -- the frequency of potentially habitable, rocky planets orbiting Sun-like stars. For planets with sizes 0.75 - 1.5 $R_{⨁}$ orbiting in a conservatively defined habitable zone (0.99 - 1.70 AU) around G-type stars, we place an upper limit (84.1th percentile) of <0.18 planets per star.

31 pages, 14 figures, accepted for publication in The Astronomical Journal

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Cited by in corpus (6)

• The Occurrence of Rocky Habitable Zone Planets Around Solar-Like Stars from Kepler Data
• Departure from the Exact Location of Mean Motion Resonances Induced by the Gas Disk in the Systems Observed by Kepler
• A Distinct Population of Small Planets: Sub-Earths
• Comparing Approximate Bayesian Computation with the Poisson-Likelihood Method for Exoplanet Occurrence Rates
• Combining Transit and RV: A Synthesized Population Model
• Relative occurrence rates of terrestrial planets orbiting FGK stars