Large Eccentricity, Low Mutual Inclination: The Three-dimensional Architecture of a Hierarchical System of Giant Planets

Creators: Dawson, Rebekah I.; Johnson, John Asher; Fabrycky, Daniel C.; Foreman-Mackey, Daniel; Murray-Clay, Ruth A.; Buchhave, Lars A.; Cargile, Phillip A.; Clubb, Kelsey I.; Fulton, Benjamin J.; Hebb, Leslie; Howard, Andrew W.; Huber, Daniel; Shporer, Avi; Valenti, Jeff A.

Abstract

We establish the three-dimensional architecture of the Kepler-419 (previously KOI-1474) system to be eccentric yet with a low mutual inclination. Kepler-419b is a warm Jupiter at semi-major axis ɑ = 0.370^(+0.007)_(-0.006) AU with a large eccentricity (e = 0.85^(+0.08)_(-0.07)) measured via the "photoeccentric effect." It exhibits transit timing variations (TTVs) induced by the non-transiting Kepler-419c, which we uniquely constrain to be a moderately eccentric (e = 0.184 ± 0.002), hierarchically separated (a = 1.68 ± 0.03 AU) giant planet (7.3 ± 0.4 M J_(up)). We combine 16 quarters of Kepler photometry, radial-velocity (RV) measurements from the HIgh Resolution Echelle Spectrometer on Keck, and improved stellar parameters that we derive from spectroscopy and asteroseismology. From the RVs, we measure the mass of the inner planet to be 2.5 ± 0.3 M J_(up) and confirm its photometrically measured eccentricity, refining the value to e = 0.83 ± 0.01. The RV acceleration is consistent with the properties of the outer planet derived from TTVs. We find that despite their sizable eccentricities, the planets are coplanar to within 9^(+8)_(-6) degrees, and therefore the inner planet's large eccentricity and close-in orbit are unlikely to be the result of Kozai migration. Moreover, even over many secular cycles, the inner planet's periapse is most likely never small enough for tidal circularization. Finally, we present and measure a transit time and impact parameter from four simultaneous ground-based light curves from 1 m class telescopes, demonstrating the feasibility of ground-based follow-up of Kepler giant planets exhibiting large TTVs.

Additional Information

© 2014 American Astronomical Society. Received 2014 March 13; accepted 2014 June 12; published 2014 July 31. We are grateful to the referee for a helpful report. We thank David Hogg, Gongjie Li, Katherine Deck, Joshua Carter, Guillaume Hébrard, Boas Katz, Yoram Lithwick, Smadar Naoz, Eugene Chiang, Scott Tremaine, Ellen Price, Leslie Rogers, Eric Ford, Cristobal Petrovich, and Doug Lin for helpful discussions. R.I.D. gratefully acknowledges the Miller Institute for Basic Research in Science, University of California Berkeley. J.A.J. is grateful for the generous grant support provided by the Alfred P. Sloan and David and Lucile Packard foundations. D.F.M. is supported by NASA under grant NNX12AI50G and the National Science Foundation under grant IIS-1124794. D.H. acknowledges support by an appointment to the NASA Postdoctoral Program at Ames Research Center administered by Oak Ridge Associated Universities, and NASA Grant NNX14AB92G issued through the Kepler Participating Scientist Program. This work benefited from the Summer Program on Modern Statistical and Computational Methods for Analysis of Kepler Data, held at SAMSI, Research Triangle Park, NC in 2013 June. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate.We are grateful to the Kepler Team for their extensive efforts in producing such high-quality data. Some of the data presented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute (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. We are very grateful to Geoff Marcy and Howard Isaacson for contributing to the radial-velocity observations of Kepler- 419. J.A.J. is grateful for Keck/HIRES time allocated through the Caltech Time Allocation Committee for some of the spectra used herein. The spectroscopic and radial-velocity measurements presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. We gratefully acknowledge the efforts and dedication of the Keck Observatory staff, especially Scott Dahm, Greg Doppman, Hien Tran, and Grant Hill for support of HIRES and Greg Wirth for support of remote observing. We extend special thanks to those of Hawai'ian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests.Without their generous hospitality, the Keck observations presented herein would not have been possible. This paper uses observations obtained with facilities of the Las Cumbres Observatory Global Telescope. The Byrne Observatory at Sedgwick (BOS) is operated by the Las Cumbres Observatory Global Telescope Network and is located at the Sedgwick Reserve, a part of the University of California Natural Reserve System.

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