CaltechAUTHORS
Published October 1, 2009 | Version Published
Journal Article Open

The Transit Ingress and the Tilted Orbit of the Extraordinarily Eccentric Exoplanet HD 80606b

Creators

  • 1. ROR icon Massachusetts Institute of Technology
  • 2. ROR icon University of California, Berkeley
  • 3. ROR icon University of Hawaii at Manoa
  • 4. ROR icon NIU Observatory
  • 5. ROR icon University of Florida
  • 6. ROR icon The University of Texas at Austin
  • 7. ROR icon San Diego State University
  • 8. ROR icon Princeton University
  • 9. ROR icon University of California, Los Angeles
  • 10. ROR icon Space Telescope Science Institute

Abstract

We present the results of a transcontinental campaign to observe the 2009 June 5 transit of the exoplanet HD 80606b. We report the first detection of the transit ingress, revealing the transit duration to be 11.64 ± 0.25 hr and allowing more robust determinations of the system parameters. Keck spectra obtained at midtransit exhibit an anomalous blueshift, giving definitive evidence that the stellar spin axis and planetary orbital axis are misaligned. The Keck data show that the projected spin-orbit angle λ is between 32° and 87° with 68.3% confidence and between 14° and 142° with 99.73% confidence. Thus, the orbit of this planet is not only highly eccentric (e = 0.93) but is also tilted away from the equatorial plane of its parent star. A large tilt had been predicted, based on the idea that the planet's eccentric orbit was caused by the Kozai mechanism. Independently of the theory, it is worth noting that all three exoplanetary systems with known spin-orbit misalignments have massive planets on eccentric orbits, suggesting that those systems migrate through a different channel than lower mass planets on circular orbits.

Additional Information

© 2009 American Astronomical Society. Received 2009 July 14; accepted 2009 August 19; published 2009 September 16. We thank Carly Chubak for measuring the heliocentric RV, Debra Fischer for help with measuring v sin i★, and Dan Fabrycky for interesting discussions about the Kozai mechanism. We thank Philip Choi, Jason Eastman, Mark Everett, Scott Gaudi, Zev Gurman, Marty Hidas,Matt Holman, and Alexander Rudy, for their willingness to join this campaign even though they were not able to participate due to weather or other factors. Mark Everett, Matt Holman, and Dave Latham also helped to gather the out-of-transit data from FLWO. We thank Bill Cochran and Ed Turner for help recruiting participants. We also thank Steve Fossey, Jonathan Irwin, and David Charbonneau for providing their data in a timely and convenient manner. We are grateful to Greg Laughlin, whose enthusiasm and persistence (and, it is suspected, a deal with the devil) led to the discovery of the eclipses of HD 80606. Some of the data 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, and wasmade possible by the generous financial support of the W.M.Keck Foundation. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. Without their generous hospitality, the Keck and UH 2.2 m observations presented herein would not have been possible. The MONET network is funded by the Alfried Krupp von Bohlen und Halbach-Stiftung. W.F.W. and S.K. acknowledge support from NASA under grant NNX08AR14G issued through the Kepler Discovery Program. K.D.C., E.B.F., F.J.R., and observations from Rosemary Hill Observatory were supported by the University of Florida. Observations at Mt. Laguna Observatory were supported by the HPWREN network, funded by the National Science Foundation Grant Numbers 0087344 and 0426879 to University of California, San Diego. J.A.J. acknowledges support from an NSF Astronomy and Astrophysics Postdoctoral Fellowship (grant No. AST-0702821). Work by J.N.W. was supported by the NASA Origins program through awards NNX09AD36G and NNX09AB33G. J.N.W. also gratefully acknowledges the support of the MIT Class of 1942 Career Development Professorship. Facilities: Keck I (HIRES) FLWO:1.2 m (Keplercam), UH:2.2 m (OPTIC), McD:0.8 m

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Additional details

Identifiers

Eprint ID
36346
Resolver ID
CaltechAUTHORS:20130114-095304108

Funding

W. M. Keck Foundation
Alfried Krupp von Bohlen und Halbach-Stiftung
NASA
NNX08AR14G
University of Florida
HPWREN network
NSF
OAC-0087344
NSF
OAC-0426879
NSF Astronomy and Astrophysics Fellowship
AST-0702821
NASA
NNX09AD36G
NASA
NNX09AB33G
MIT Class of 1942 Career Development Professorship

Dates

Created
2013-01-14
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Updated
2021-11-09
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