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Alignment of the stellar spin with the orbits of a three-planet system

Sanchis-Ojeda, Roberto and Fabrycky, Daniel C. and Winn, Joshua N. and Barclay, Thomas and Clarke, Bruce D. and Ford, Eric B. and Fortney, Jonathan J. and Geary, John C. and Holman, Matthew J. and Howard, Andrew W. and Jenkins, Jon M. and Koch, David and Lissauer, Jack J. and Marcy, Geoffrey W. and Mullally, Fergal and Ragozzine, Darin and Seader, Shawn E. and Still, Martin and Thompson, Susan E. (2012) Alignment of the stellar spin with the orbits of a three-planet system. Nature, 487 (7408). pp. 449-453. ISSN 0028-0836.

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The Sun’s equator and the planets’ orbital planes are nearly aligned, which is presumably a consequence of their formation from a single spinning gaseous disk. For exoplanetary systems this well-aligned configuration is not guaranteed: dynamical interactions may tilt planetary orbits, or stars may be misaligned with the protoplanetary disk through chaotic accretion, magnetic interactions or torques from neighbouring stars. Indeed, isolated ‘hot Jupiters’ are often misaligned and even orbiting retrograde. Here we report an analysis of transits of planets over starspots on the Sun-like star Kepler-30 (ref. 8), and show that the orbits of its three planets are aligned with the stellar equator. Furthermore, the orbits are aligned with one another to within a few degrees. This configuration is similar to that of our Solar System, and contrasts with the isolated hot Jupiters. The orderly alignment seen in the Kepler-30 system suggests that high obliquities are confined to systems that experienced disruptive dynamical interactions. Should this be corroborated by observations of other coplanar multi-planet systems, then star–disk misalignments would be ruled out as the explanation for the high obliquities of hot Jupiters, and dynamical interactions would be implicated as the origin of hot Jupiters.

Item Type:Article
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URLURL TypeDescription ReadCube access Paper
Sanchis-Ojeda, Roberto0000-0002-6193-972X
Fabrycky, Daniel C.0000-0003-3750-0183
Winn, Joshua N.0000-0002-4265-047X
Barclay, Thomas0000-0001-7139-2724
Ford, Eric B.0000-0001-6545-639X
Fortney, Jonathan J.0000-0002-9843-4354
Holman, Matthew J.0000-0002-1139-4880
Howard, Andrew W.0000-0001-8638-0320
Jenkins, Jon M.0000-0002-4715-9460
Lissauer, Jack J.0000-0001-6513-1659
Marcy, Geoffrey W.0000-0002-2909-0113
Thompson, Susan E.0000-0001-7106-4683
Additional Information:© 2012 Macmillan Publishers Limited. Received 25 April 2012; Accepted 08 June 2012; Published online 25 July 2012. Kepler was competitively selected as the tenth Discovery mission. Funding for this mission was provided by NASA’s Science Mission Directorate. The data presented in this Letter were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. S. Albrecht, E. Agol, J. A. Carter, L. Doyle and A. Shporer provided comments on the manuscript. D.C.F. acknowledges NASA support through Hubble Fellowship grant HF-51272.01-A, awarded by STScI. D.R. acknowledges the Harvard Institute for Theory and Computation. E.B.F., M.J.H. and J.N.W. acknowledge NASA support through the Kepler Participating Scientist programme. Author Contributions: R.S.-O. performed the spot analysis and wrote the first draft of the paper. D.C.F. performed the dynamical analysis, contributed to the spot modelling, and helped write the paper. J.N.W. contributed to the modelling and helped write the paper. The remaining authors listed below contributed equally. T.B., B.D.C., F.M., S.E.S., M.S. and S.E.T. worked on the data collection, processing and review that yielded the time-series photometry. E.B.F. and M.J.H. provided feedback on the text and interpretation. J.J.F. and J.J.L. worked on elucidating the structure and radii of the planets. J.C.G. worked on the development of Kepler spacecraft photometer electronics, is a builder of Keplercam for the Kepler Input Catalog and follow-up spectral typing. A.W.H. contributed the Keck-HIRES spectra from which the stellar properties were derived. J.M.J. is the Co-Investigator for Data Analysis and designed and built the pipeline that produced the light curves on which this paper is based. D.K. contributed to the concept, design, development, testing and commissioning of the Kepler Mission. G.W.M. contributed the Keck spectroscopy and helped with the imaging, and with some other parts of the original follow-up observations. D.R. studied the possibility of mutual transits and provided feedback on the technical details of the analysis. All authors discussed the results and commented on the manuscript. The authors declare no competing financial interests.
Funding AgencyGrant Number
NASA Hubble FellowshipHF-51272.01-A
Harvard Institute for Theory and ComputationUNSPECIFIED
Kepler Participating Scientist ProgrammeUNSPECIFIED
Issue or Number:7408
Record Number:CaltechAUTHORS:20170621-132744415
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78421
Deposited By: Tony Diaz
Deposited On:21 Jun 2017 20:38
Last Modified:09 Mar 2020 13:19

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