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Media type:
E-Article
Title:
Searching the Entirety of Kepler Data. II. Occurrence Rate Estimates for FGK Stars
Contributor:
Kunimoto, Michelle;
Matthews, Jaymie M.
imprint:
American Astronomical Society, 2020
Published in:The Astronomical Journal
Language:
Not determined
DOI:
10.3847/1538-3881/ab88b0
ISSN:
0004-6256;
1538-3881
Origination:
Footnote:
Description:
<jats:title>Abstract</jats:title>
<jats:p>We present exoplanet occurrence rates estimated with approximate Bayesian computation for planets with radii between 0.5 and 16 <jats:italic>R</jats:italic>
<jats:sub>⊕</jats:sub> and orbital periods between 0.78 and 400 days orbiting FGK dwarf stars. We base our results on an independent planet catalog 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 <jats:italic>R</jats:italic>
<jats:sub>⊕</jats:sub>, indicating that the bimodal distribution previously revealed for <jats:italic>P</jats:italic> < 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 <jats:italic>R</jats:italic>
<jats:sub>⊕</jats:sub> 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.</jats:p>