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Stellar Spin-Orbit Misalignment in a Multiplanet System

Abstract

Stars hosting hot Jupiters are often observed to have high obliquities, whereas stars with multiple coplanar planets have been seen to have low obliquities. This has been interpreted as evidence that hot-Jupiter formation is linked to dynamical disruption, as opposed to planet migration through a protoplanetary disk. We used asteroseismology to measure a large obliquity for Kepler-56, a red giant star hosting two transiting coplanar planets. These observations show that spin-orbit misalignments are not confined to hot-Jupiter systems. Misalignments in a broader class of systems had been predicted as a consequence of torques from wide-orbiting companions, and indeed radial velocity measurements revealed a third companion in a wide orbit in the Kepler-56 system.United States. National Aeronautics and Space Administration (Science Mission Directorate)United States. National Aeronautics and Space Administration (NASA Postdoctoral Program at Ames Research Center)National Science Foundation (U.S.) (NSF Graduate Research Fellowship)National Science Foundation (U.S.) (NSF Graduate Research Fellowship, grant DGE1144469)Netherlands Organization for Scientific ResearchBelgian Federal Science Policy Office (BELSPO, contract PRODEX COROT)United States. National Aeronautics and Space Administration (NASA Kepler Participating Scientist program)National Science Foundation (U.S.) (NSF grant AST-1105930)David & Lucile Packard FoundationAlfred P. Sloan FoundationHarvard-Smithsonian Center for Astrophysics (Hubble Fellow

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