Letter | Published:

A map of the day–night contrast of the extrasolar planet HD 189733b

Nature volume 447, pages 183186 (10 May 2007) | Download Citation

Abstract

‘Hot Jupiter’ extrasolar planets are expected to be tidally locked because they are close (<0.05 astronomical units, where 1 au is the average Sun–Earth distance) to their parent stars, resulting in permanent daysides and nightsides. By observing systems where the planet and star periodically eclipse each other, several groups have been able to estimate the temperatures of the daysides of these planets1,2,3. A key question is whether the atmosphere is able to transport the energy incident upon the dayside to the nightside, which will determine the temperature at different points on the planet’s surface. Here we report observations of HD 189733, the closest of these eclipsing planetary systems4,5,6, over half an orbital period, from which we can construct a ‘map’ of the distribution of temperatures. We detected the increase in brightness as the dayside of the planet rotated into view. We estimate a minimum brightness temperature of 973 ± 33 K and a maximum brightness temperature of 1,212 ± 11 K at a wavelength of 8 μm, indicating that energy from the irradiated dayside is efficiently redistributed throughout the atmosphere, in contrast to a recent claim for another hot Jupiter7. Our data indicate that the peak hemisphere-integrated brightness occurs 16 ± 6° before opposition, corresponding to a hotspot shifted east of the substellar point. The secondary eclipse (when the planet moves behind the star) occurs 120 ± 24 s later than predicted, which may indicate a slightly eccentric orbit.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    , , & Infrared radiation from an extrasolar planet. Nature 434, 740–743 (2005)

  2. 2.

    et al. Detection of thermal emission from an extrasolar planet. Astrophys. J. 626, 523–529 (2005)

  3. 3.

    , , & Strong infrared emission from the extrasolar planet HD 189733b. Astrophys. J. 644, 560–564 (2006)

  4. 4.

    et al. ELODIE metallicity-biased search for transiting hot Jupiters. II. A very hot Jupiter transiting the bright K star HD 189733. Astron. Astrophys. 444, L15–L19 (2005)

  5. 5.

    et al. Refined parameters of the planet orbiting HD 189733. Astrophys. J. 650, 1160–1171 (2006)

  6. 6.

    et al. The Transit Light Curve Project. V. System parameters and stellar rotation period of HD 189733. Astron. J. 133, 1828–1835 (2007)

  7. 7.

    et al. The phase-dependent infrared brightness of the extrasolar planet υ Andromeda b. Science 314, 623–626 (2006)

  8. 8.

    et al. The Infrared Array Camera (IRAC) for the Spitzer Space Telescope. Astrophys. J. Suppl. 154, 10–17 (2004)

  9. 9.

    et al. The Spitzer Space Telescope mission. Astrophys. J. Suppl. 154, 1–9 (2004)

  10. 10.

    , , , & A stellar companion in the HD 189733 system with a known transiting extrasolar planet. Astrophys. J. 641, L57–L60 (2006)

  11. 11.

    A dynamical method for measuring the masses of stars with transiting planets. Astrophys. J. 623, L45–L48 (2005)

  12. 12.

    , , , & Resolving the surfaces of extrasolar planets with secondary eclipse light curves. Astrophys. J. 649, 1020–1027 (2006)

  13. 13.

    et al. Toward eclipse mapping of hot Jupiters. Preprint at 〈〉 (2006)

  14. 14.

    , & On the radii of extrasolar giant planets. Astrophys. J. 592, 555–563 (2003)

  15. 15.

    , , , & Giant planets at small orbital distances. Astrophys. J. 459, L35–L38 (1996)

  16. 16.

    & Atmospheric circulation and tides of “51 Pegasus b-like” planets. Astron. Astrophys. 385, 166–180 (2002)

  17. 17.

    et al. On the dayside thermal emission of hot Jupiters. Astrophys. J. 632, 1122–1131 (2005)

  18. 18.

    , & A time-dependent radiative model of HD 209458b. Astron. Astrophys. 436, 719–727 (2005)

  19. 19.

    , , , & Comparative planetary atmospheres: models of TrES-1 and HD 209458b. Astrophys. J. 627, L69–L72 (2005)

  20. 20.

    , & Phase-dependent properties of extrasolar planet atmospheres. Astrophys. J. 632, 1132–1139 (2005)

  21. 21.

    , & Theory for the secondary eclipse fluxes, spectra, atmospheres, and light curves of transiting extrasolar giant planets. Astrophys. J. 650, 1140–1149 (2006)

  22. 22.

    , , & The changing face of the extrasolar giant planet HD 209458b. Astrophys. J. 587, L117–L120 (2003)

  23. 23.

    , , , & On the surface heating of synchronously spinning short-period Jovian planets. Astrophys. J. 618, 512–523 (2005)

  24. 24.

    & Dynamic meteorology at the photosphere of HD 209458b. Astrophys. J. 629, L45–L48 (2005)

  25. 25.

    & Dynamics and disequilibrium carbon chemistry in hot Jupiter atmospheres, with application to HD 209458b. Astrophys. J. 649, 1048–1063 (2006)

  26. 26.

    & Observational consequences of hydrodynamic flows on hot Jupiters. Astrophys. J. 657, L113–L116 (2007)

  27. 27.

    , , , & Atmosphere, interior, and evolution of the metal-rich transiting planet HD 149026b. Astrophys. J. 642, 495–504 (2006)

  28. 28.

    , , , & The influence of atmospheric dynamics on the infrared spectra and light curves of hot Jupiters. Astrophys. J. 652, 746–757 (2006)

  29. 29.

    & Analytic light curves for planetary transit searches. Astrophys. J. 580, L171–L175 (2002)

  30. 30.

    Solar Abundance Model Atmospheres for 0, 1, 2, 4, and 8 km/s (CD-ROM 19, Smithsonian Astrophysical Observatory, Cambridge, Massachusetts, 1994)

Download references

Acknowledgements

We thank J. Winn for sharing data from a recent paper describing the behaviour of the spots on the star, and D. Sasselov and E. Miller-Ricci for discussions on the properties of these spots. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. We are grateful to the entire Spitzer team for their assistance throughout this process. H.A.K. was supported by a National Science Foundation Graduate Research Fellowship.

Author information

Affiliations

  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA

    • Heather A. Knutson
    • , David Charbonneau
    •  & Lori E. Allen
  2. Space Science and Astrobiology Division, NASA Ames Research Center, MS 245-3, Moffett Field, California 94035, USA

    • Jonathan J. Fortney
  3. SETI Institute, 515 N. Whisman Road, Mountain View, California 94043, USA

    • Jonathan J. Fortney
  4. Department of Astronomy, Box 351580, University of Washington, Seattle, Washington 98195, USA

    • Eric Agol
    •  & Nicolas B. Cowan
  5. Lunar and Planetary Laboratory and Department of Planetary Sciences, University of Arizona, Tucson, Arizona 85721, USA

    • Adam P. Showman
    •  & Curtis S. Cooper
  6. Department of Physics and Astronomy, University of Toledo, 2801 West Bancroft Street, Toledo, Ohio 43606, USA

    • S. Thomas Megeath

Authors

  1. Search for Heather A. Knutson in:

  2. Search for David Charbonneau in:

  3. Search for Lori E. Allen in:

  4. Search for Jonathan J. Fortney in:

  5. Search for Eric Agol in:

  6. Search for Nicolas B. Cowan in:

  7. Search for Adam P. Showman in:

  8. Search for Curtis S. Cooper in:

  9. Search for S. Thomas Megeath in:

Competing interests

Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

Corresponding author

Correspondence to Heather A. Knutson.

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature05782

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.