Author(s): , , ,
Institution(s): 1. University of Birmingham
The quantity η-Earth, the number density of planets per star per logarithmic planetary radius per logarithmic orbital period at one Earth radius and one year period, describes the occurrence of Earth-like extrasolar planets. I will present a measurement of η-Earth from a parameterised forward model of the (correlated) period-radius distribution and the observational selection function in the most recent (Q17) data release from the Kepler satellite. I will discuss the novel statistical methodology that permits this measurement. We find η-Earth = 3.9 (+2.2 -1.6)% (90\% CL). We are also able to measure that each Sun-like hosts 3.83 (+0.76 -0.62) planets with P < 3 yr and R > 0.2 REarth. Our empirical model for false-positive contamination is consistent with the dominant source being background eclipsing binary stars. The distribution of planets we infer is consistent with a highly-stochastic planet formation process producing many correlated, fractional changes in planet sizes and orbits.