On Study of the Occurrence of Earth-Size Planets in Kepler Mission Using Spatial Poisson Model

Abstract

The problem of determining the occurrence rate for Earth-size planets orbiting Sun-like stars is emerging in the universe. We propose a methodology based on a spatial Poisson regression model with model parameters being inferred by the Bayesian framework to investigate this occurrence rate. We analyzed an exoplanet sample and its corresponding survey completeness data. Our results suggest that 46% of Sun-like stars have an Earth-size (i.e., 1–2 times Earth radii) planet with an orbital period of 5–100 days. Furthermore, we are also interested in the occurrence rate of Earth analogs hosted by GK dwarf stars (i.e., orbital period of 200–400 days and size 1–2 times Earth radii). After completeness correction, we obtained an occurrence rate of 0.18% based on the proposed methodology.