Discovery and validation of Kepler-452b: A 1.6 R⊕ super earth exoplanet in the habitable zone of a G2 star

Abstract

We report on the discovery and validation of Kepler-452b, a transiting planet identified by a search through the 4 years of data collected by NASA's Kepler Mission. This possibly rocky planet orbits its G2 host star every days, the longest orbital period for a small ( ) transiting exoplanet to date. The likelihood that this planet has a rocky composition lies between 49% and 62%. The star has an effective temperature of 5757 ± 85 K and a of 4.32 ± 0.09. At a mean orbital separation of AU, this small planet is well within the optimistic habitable zone of its star (recent Venus/early Mars), experiencing only 10% more flux than Earth receives from the Sun today, and slightly outside the conservative habitable zone (runaway greenhouse/maximum greenhouse). The star is slightly larger and older than the Sun, with a present radius of and an estimated age of ∼6 Gyr. Thus, Kepler-452b has likely always been in the habitable zone and should remain there for another ∼3 Gyr.