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Transiting circumbinary planets Kepler-34 b and Kepler-35 b


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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Figure 1: Observations of Kepler-34.
Figure 2: Observations of Kepler-35.
Figure 3: Orbital configurations.
Figure 4: Variations in insolation received by Kepler-34 b and Kepler-35 b.

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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).

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Authors and Affiliations



W.F.W. led the research effort on these transiting circumbinary planets (CBPs) and wrote much of the Letter. J.A.O. led the ETV (eclipse timing variation) investigation, measured O − Cs, inspected light curves, measured EB (eclipsing binary) properties, measured radial velocities and flux ratios, generated Figs 1 and 2, and assembled the Supplementary Information. J.A.C. created and used the photometric-dynamical code to model the light curve and RVs (radial velocities), measured system parameters, and generated Table 1 and Fig. 3. D.C.F. produced initial dynamical models to interpret the timing of eclipse and transit events leading to the planet interpretation, and developed criteria for non-eclipsing CBP searches. E.B.F. contributed to interpretation and text, checked long-term stability, and did insolation calculations. J.J.L. contributed to interpretation and text, and initiated study of variations in insolation on CBPs. A.P. measured mass, radii and other properties of the EBs, including contamination and flux ratios. S.N.Q. obtained and analysed spectra, and determined stellar parameters and luminosity ratios. D.R. computed the estimated frequency of CBPs. D.R.S. developed the automated ETV code to measure eclipse times and O − C deviations. G.T. contributed to the discussion of the stellar parameters and carried out the comparison with stellar evolution models. J.N.W. contributed to the text, estimated age via gyrochronology, and contributed to topics related to pseudosynchronicity. L.R.D. contributed to the habitable zone discussion and led the initial search for CBPs. T.B. examined pixel level data and contributed basis-vector corrected light curves. N.B. directed EB target selection and identification. S.B. contributed to the text and Supplementary Information. E.B. carried out an independent spectroscopic investigation to measure stellar parameters. L.A.B. gathered spectroscopic observations for the RV and spectroscopic parameter determination. C.C. contributed three nights of spectroscopic observations at the McDonald 2.7 m observatory. D.A.C. contributed to calibration of the Kepler photometer and pipeline necessary for data acquisition. J.L.C. supported the science operations to collect and calibrate the Kepler data. D.R.C. coordinated ground-based follow-up observations. W.D.C. obtained the HET spectra, and processed all McDonald 2.7 m and HET spectra. M.E. contributed HET and McDonald 2.7 m spectra. J.J.F. contributed calculations and discussion regarding the characteristics of the planets’ atmospheres. T.N.G. coordinated the Kepler follow-up observation effort. R.L.G. provided mission support and contributed to the text and discussion of results. M.R.H. led the effort to gather, process and distribute the data necessary for this investigation. J.R.H. contributed to the collection, validation and management of the Kepler data used here. M.J.H. contributed to the discussion of the dynamical stability. A.W.H. made spectroscopic observations using Keck-HIRES. S.B.H. contributed reconnaissance spectroscopy. H.I. obtained spectroscopic observations of targets. J.M.J. developed observation/analysis techniques and calibration software that enables the Kepler photometer to operate successfully. T.C.K. led the design and development of the Science Processing Pipeline Infrastructure needed to process the data used here. D.W.L. contributed spectroscopy and preparation of the Kepler Input Catalog. J.L. contributed to the development of the Data Validation component of the Kepler Science Operations Center pipeline necessary to obtain these data. G.W.M. obtained Keck-HIRES spectra. T.M. analysed the beaming effect in Kepler-35 and participated in the discussion of statistical inference and the spectroscopic light ratio. E.V.Q. developed calibration/validation software necessary for the Kepler data in this paper. P.R. contributed ten nights of spectroscopic observations at the McDonald 2.7m telescope. A.S. contributed ground-based follow-up imaging of the targets. J.H.S. contributed to the text, scope and interpretation. G.W. ran the ETV code, developed tools for analysing O − C variations, and assisted with text. D.G.K. designed major portions of the Kepler photometer that acquired these data. W.J.B. led the design and development of the Kepler mission that acquired these data, and contributed to the text.

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Correspondence to William F. Welsh or Joshua A. Carter.

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The authors declare no competing financial interests.

Additional information

The Kepler light curves used in this work can be downloaded from the MAST (Multimission Archive at Space Telescope Science Institute) at

Supplementary information

Supplementary Information

The file contains Supplementary Text and Data, Supplementary Figures 1-16 with legends, Supplementary Tables 1-7 and additional references. (PDF 0 kb)

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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).

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