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A ground-based near-infrared emission spectrum of the exoplanet HD 189733b

Nature volume 463, pages 637–639 (2010)Cite this article

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Abstract

Detection of molecules using infrared spectroscopy probes the conditions and compositions of exoplanet atmospheres. Water (H2O), methane (CH4), carbon dioxide (CO2), and carbon monoxide (CO) have been detected1,2,3,4,5 in two hot Jupiters. These previous results relied on space-based telescopes that do not provide spectroscopic capability in the 2.4–5.2 μm spectral region. Here we report ground-based observations of the dayside emission spectrum for HD 189733b between 2.0–2.4 μm and 3.1–4.1 μm, where we find a bright emission feature. Where overlap with space-based instruments exists, our results are in excellent agreement with previous measurements2,6. A feature at ∼3.25 μm is unexpected and difficult to explain with models that assume local thermodynamic equilibrium (LTE) conditions at the 1 bar to 1 × 10-6 bar pressures typically sampled by infrared measurements. The most likely explanation for this feature is that it arises from non-LTE emission from CH4, similar to what is seen in the atmospheres of planets in our own Solar System7,8,9. These results suggest that non-LTE effects may need to be considered when interpreting measurements of strongly irradiated exoplanets.

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Figure 1: Dayside spectra and secondary eclipse light curves.
Figure 2: Unexpectedly strong 3.25-μm emission present in the dayside spectrum.

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References

  1. Tinetti, G. et al. Water vapour in the atmosphere of a transiting extrasolar planet. Nature 448, 169–171 (2007)

    Article  ADS  CAS  Google Scholar 

  2. Swain, M. R., Vasisht, G. & Tinetti, G. The presence of methane in the atmosphere of an extrasolar planet. Nature 452, 329–331 (2008)

    Article  ADS  CAS  Google Scholar 

  3. Grillmair, C. J. et al. Strong water absorption in the dayside emission spectrum of the planet HD 189733b. Nature 456, 767–768 (2008)

    Article  ADS  CAS  Google Scholar 

  4. Swain, M. R. et al. Molecular signatures in the near-infrared dayside spectrum of HD 189733b. Astrophys. J. 690, L114–L117 (2009)

    Article  ADS  CAS  Google Scholar 

  5. Swain, M. R. et al. Water, methane, and carbon dioxide present in the dayside spectrum of the exoplanet HD 209458b. Astrophys. J. 704, 1616–1221 (2009)

    Article  ADS  CAS  Google Scholar 

  6. Charbonneau, D. et al. The broadband infrared emission spectrum of the exoplanet HD 189733b. Astrophys. J. 686, 1341–1348 (2008)

    Article  ADS  CAS  Google Scholar 

  7. Drossart, P. et al. Fluorescence in the 3 microns bands of methane on Jupiter and Saturn from ISO/SWS observations. ESA SP 427, 169–172 (1999)

    ADS  Google Scholar 

  8. Brown, R. H. et al. Observations with the Visual and Infrared Mapping Spectrometer (VIMS) during Cassini’s flyby of Jupiter. Icarus 164, 461–470 (2003)

    Article  ADS  CAS  Google Scholar 

  9. Kim, S. J., Geballe, T. R. & Noll, K. S. Three-micrometer CH4 line emission from Titan’s high-altitude atmosphere. Icarus 147, 588–591 (2000)

    Article  ADS  CAS  Google Scholar 

  10. Rauscher, E. & Menou, K. Atmospheric circulation in hot Jupiters: a shallow three-dimensional model. Astrophys. J. 700, 887–897 (2009)

    Article  ADS  Google Scholar 

  11. Showman, A. P., Cooper, C. S., Fortney, J. J. & Marley, M. S. Atmospheric circulation of hot Jupiters: three-dimensional circulation models of HD 209458b and HD 189733b with simplified forcing. Astrophys. J. 682, 559–576 (2008)

    Article  ADS  CAS  Google Scholar 

  12. Rayner, J. T. et al. SpeX: a medium-resolution 0.8–5.5 micron spectrograph and imager for the NASA infrared telescope. Publ. Astron. Soc. Pacif. 115, 362–382 (2003)

    Article  ADS  Google Scholar 

  13. Pagiatakis, S. D., Yin, H. & Abd El-Gelil, M. Least-squares self-coherency analysis of superconducting gravimeter records in search for the Slichter triplet. Phys. Earth Planet. Inter. 160, 108–123 (2007)

    Article  ADS  Google Scholar 

  14. Barman, T. B. On the presence of water and global circulation in the transiting planet HD 189733b. Astrophys. J. 676, L61–L64 (2008)

    Article  ADS  CAS  Google Scholar 

  15. Redfield, S., Endl, M., Cochran, W. D. & Koesterke, L. Sodium absorption from the exoplanetary atmosphere of HD 189733b detected in the optical transmission spectrum. Astrophys. J. 673, L87–L90 (2008)

    Article  ADS  CAS  Google Scholar 

  16. Snellen, I. A. G., Albrecht, S., de Mooij, E. J. W. & Lee Poole, R. S. Ground-based detection of sodium in the transmission spectrum of exoplanet HD 209458b. Astron. Astrophys. 487, 357–362 (2008)

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

We thank S. Bus at the IRTF for several discussions regarding the operation of the SpeX instrument and for support during our observing runs. We thank the observing staff at the IRTF for their assistance and advice during observing runs. We thank L. Brown for making recommendations on molecular line lists and G. Orton for extensive discussions about the interpretation of these results. G. Tinetti was supported by the UK Sciences and Technology Facilities Council and the European Space Agency. The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Author Contributions M.R.S. wrote the paper, participated in developing the calibration methods, and wrote the telescope proposals. P.D. worked on developing and testing the calibration method. C.A.G. and G.T. worked on the interpretation of the results. A.T. worked on the calibration method. G.V. and P.C. worked on calibration validation. J.B. worked on the calibration of the Spitzer data. I.J.C. worked on an early version of the calibration method. D.A. contributed to the atmospheric calibration approach. C.A. and T.H. were co-authors on the original telescope proposal and provided comments on the paper text.

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Authors and Affiliations

  1. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099, USA ,

    Mark R. Swain, Pieter Deroo, Gautam Vasisht & Pin Chen

  2. University of Arizona, Lunar and Planetary Laboratory, Space Science Building Room 525, 1629 East University Boulevard, Tucson, Arizona 85721, USA ,

    Caitlin A. Griffith

  3. Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, London, UK,

    Giovanna Tinetti

  4. Astronomy Department UCLA, 475 Portola Plaza, Los Angeles, California 90034, USA,

    Ian J. Crossfield

  5. Woodruff School of Mechanical Engineering, MRDC Building, Room 4111, Georgia Institute of Technology, Atlanta, Georgia 30332-0405, USA ,

    Azam Thatte

  6. Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117, Heidelberg, Germany ,

    Jeroen Bouwman, Cristina Afonso & Thomas Henning

  7. German SOFIA Institute, Institute for Space Systems, Pfaffenwaldring 3170569, Stuttgart, Germany ,

    Daniel Angerhausen

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  1. Mark R. Swain
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Correspondence to Mark R. Swain.

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Swain, M., Deroo, P., Griffith, C. et al. A ground-based near-infrared emission spectrum of the exoplanet HD 189733b. Nature 463, 637–639 (2010). https://doi.org/10.1038/nature08775

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