Most Sun-like stars in the Galaxy reside in gravitationally bound pairs of stars1,2 (binaries). Although long anticipated3,4,5,6,7,8, the existence of a ‘circumbinary planet’ orbiting such a pair of normal stars was not definitively established until the discovery9 of the planet transiting (that is, passing in front of) Kepler-16. Questions remained, however, about the prevalence of circumbinary planets and their range of orbital and physical properties. Here we report two additional transiting circumbinary planets: Kepler-34 (AB)b and Kepler-35 (AB)b, referred to here as Kepler-34 b and Kepler-35 b, respectively. Each is a low-density gas-giant planet on an orbit closely aligned with that of its parent stars. Kepler-34 b orbits two Sun-like stars every 289 days, whereas Kepler-35 b orbits a pair of smaller stars (89% and 81% of the Sun’s mass) every 131 days. The planets experience large multi-periodic variations in incident stellar radiation arising from the orbital motion of the stars. The observed rate of circumbinary planets in our sample implies that more than ∼1% of close binary stars have giant planets in nearly coplanar orbits, yielding a Galactic population of at least several million.
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Kepler was selected as the tenth NASA Discovery mission with funding provided by NASA’s Science Mission Directorate. We thank the many people who made the Kepler mission a reality. W.F.W., J.A.O., E.B.F., A.P., L.R.D., J.J.F., M.J.H., T.M. and J.H.S. were supported by the Kepler Participating Scientist Program. W.F.W., J.A.O., D.R.S. and G.W. were supported by the NSF. D.C.F. and J.A.C. acknowledge NASA support through Hubble Fellowship grants, awarded by STScI, operated by AURA. J.N.W. was supported by the NASA Origins programme. S.B. acknowledges funding from the European Research Council under the European Community's Seventh Framework Programme (PROSPERITY) and from the Research Council of KU Leuven. Some of the reported computations were run on the Odyssey cluster supported by the FAS Science Division Research Computing Group at Harvard University. This Letter is based in part on observations made with the Nordic Optical Telescope (operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias), the W. M. Keck Observatory (operated by the University of California and the California Institute of Technology) and the Hobby-Eberly Telescope (HET; a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximillians-Universitat Munchen, and Georg-August-Universitat Goettingen).
The authors declare no competing financial interests.
The Kepler light curves used in this work can be downloaded from the MAST (Multimission Archive at Space Telescope Science Institute) at http://archive.stsci.edu/kepler/.
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Welsh, W., Orosz, J., Carter, J. et al. Transiting circumbinary planets Kepler-34 b and Kepler-35 b. Nature 481, 475–479 (2012). https://doi.org/10.1038/nature10768
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