Discovery and Validation of Kepler-452b: A 1.6 R⨁ Super Earth Exoplanet in the Habitable Zone of a G2 Star

Creators: Jenkins, Jon M.; Ciardi, David R.

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 1.63_(-0.20)^(+0.23) R⨁ planet orbits its G2 host star every 384.843_(-0.012)^(+0.007) days, the longest orbital period for a small (R_p < 2 R⨁) 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 log g of 4.32 ± 0.09. At a mean orbital separation of 1.046_(-0.015)^(+0.019) 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 1.11_(-0.09)^(+0.15) R⨁ 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.

Additional Information

© 2015 American Astronomical Society. Received 2015 March 3; accepted 2015 May 23; published 2015 July 23. Kepler was competitively selected as the 10th Discovery mission. Funding for this mission is provided by NASA's Science Mission Directorate. The authors acknowledge the efforts of the Kepler Mission team in obtaining the light curve data and data validation products used in this publication. These data were generated by the Kepler Mission science pipeline through the efforts of the Kepler Science Operations Center and Science Office. The Kepler Mission is led by the project office at NASA Ames Research Center. Ball Aerospace built the Kepler photometer and spacecraft which is operated by the mission operations center at LASP. The Kepler light curves are archived at the Mikulski Archive for Space Telescopes and the Data Validation products are archived at the NASA Exoplanet Science Institute. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership of the California Institute of Technology, the University of California, and NASA. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. M. E. acknowledges support by NASA under grant NNX14AB86G issued through the Kepler Participating Scientist Program. D. W. L. acknowledges partial support from NASA's Kepler Mission under Cooperative Agreements NNX13AB58A with the Smithsonian Astrophysical Observatory. G. T. acknowledges support for this work from NASA under grant NNX14AB83G (Kepler Participating Scientist Program). D. H. acknowledges support by the Australian Research Council's Discovery Projects funding scheme (project number DE140101364) and support by the National Aeronautics and Space Administration under Grant NNX14AB92G issued through the Kepler Participating Scientist Program. A. W.ʼs funding was provided by the National Science Foundation Graduate Research Fellowship under Grant No. 0809125, and by the UC Santa Cruz Graduate Division's Eugene Cota-Robles Fellowship. J. M. J. acknowledges 20 years of unwavering support from Renée M. Schell and excellent editorial suggestions for this paper. We dedicate this discovery to the memory of Kepler's late Deputy PI, Dr. David G. Koch, who represented the epitome of grace, intellect and civility, and who would have been deliriously delighted by the discovery of this planet. Facilities: Kepler.

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