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The signature of orbital motion from the dayside of the planet τ Boötis b

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Abstract

The giant planet orbiting τ Boötis (named τ Boötis b) was amongst the first extrasolar planets to be discovered1. It is one of the brightest exoplanets and one of the nearest to us, with an orbital period of just a few days. Over the course of more than a decade, measurements of its orbital inclination have been announced2 and refuted3, and have hitherto remained elusive4,5,6,7,8. Here we report the detection of carbon monoxide absorption in the thermal dayside spectrum of τ Boötis b. At a spectral resolution of ∼100,000, we trace the change in the radial velocity of the planet over a large range in phase, determining an orbital inclination of 44.5° ± 1.5° and a mass 5.95 ± 0.28 times that of Jupiter, demonstrating that atmospheric characterization is possible for non-transiting planets. The strong absorption signal points to an atmosphere with a temperature that is decreasing towards higher altitudes, in contrast to the temperature inversion inferred for other highly irradiated planets9,10. This supports the hypothesis that the absorbing compounds believed to cause such atmospheric inversions are destroyed in τ Boötis b by the ultraviolet emission from the active host star11.

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Figure 1: CO signal in the dayside spectrum of the extrasolar planet τ Boötis b.
Figure 2: Comparison of in-trail and out-of-trail cross-correlation values.
Figure 3: The orbital trail of CO absorption.

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References

  1. Butler, R. P., Marcy, G. W., Williams, E., Hauser, H. & Shirts, P. Three new “51-Pegasi-type” planets. Astrophys. J. 474, L115–L118 (1997)

    Article  ADS  Google Scholar 

  2. Collier Cameron, A., Horne, K., Penny, A. & James, D. Probable detection of starlight reflected from the giant planet orbiting τ Boötis. Nature 402, 751–755 (1999)

    Article  ADS  Google Scholar 

  3. Collier Cameron, A., Horne, K., James, D., Penny, A. & Semel, M. in Proceedings of IAU Symposium 202: Planetary Systems in the Universe (eds Penny, A. J., Artymowicz, P., Lagrange, A.-M. & Russell, S. ) 75–77 (Astronomical Society of the Pacific, 2004)

    Google Scholar 

  4. Leigh, C., Collier Cameron, A., Horne, K., Penny, A. & James, D. A new upper limit on the reflected starlight from τ Bootis b. Mon. Not. R. Astron. Soc. 344, 1271–1282 (2003)

    Article  ADS  Google Scholar 

  5. Charbonneau, D., Noyes, R. W., Korzennik, S. G., Nienson, P. & Jha, S. An upper limit on the reflected light from the planet orbiting the star τ Bootis. Astrophys. J. 522, L145–L148 (1999)

    Article  ADS  CAS  Google Scholar 

  6. Wiedemann, G., Deming, D. & Bjoraker, G. A sensitive search for methane in the infrared spectrum of τ Bootis. Astrophys. J. 546, 1068–1074 (2001)

    Article  ADS  CAS  Google Scholar 

  7. Lucas, P. W. et al. Planetpol polarimetry of the exoplanet systems 55 Cnc and τ Boo. Mon. Not. R. Astron. Soc. 393, 229–244 (2009)

    Article  ADS  Google Scholar 

  8. Rodler, F., Kürster, M. & Henning, T. τ Boötis b: hunting for reflected starlight. Astron. Astrophys. 514, A23 (2010)

    Article  ADS  Google Scholar 

  9. Burrows, A., Budaj, J. & Hubeny, I. Theoretical spectra and light curves of close-in extrasolar giant planets and comparison with data. Astrophys. J. 678, 1436–1457 (2008)

    Article  ADS  CAS  Google Scholar 

  10. Fortney, J. J., Lodders, K., Marley, M. S. & Freedman, R. S. A unified theory for the atmospheres of the hot and very hot Jupiters: two classes of irradiated atmospheres. Astrophys. J. 678, 1419–1435 (2008)

    Article  ADS  CAS  Google Scholar 

  11. Knutson, H. A., Howard, A. W. & Isaacson, H. A correlation between stellar activity and hot-Jupiter emission spectra. Astrophys. J. 720, 1569–1576 (2010)

    Article  ADS  CAS  Google Scholar 

  12. Kaeufl, H. U. et al. CRIRES: a high resolution infrared spectrograph for ESO’s VLT. Proc. SPIE 5492, 1218–1227 (2004)

    Article  ADS  Google Scholar 

  13. Snellen, I. A., de Kok, R. J., de Mooij, E. J. W. & Albrecht, S. The orbital motion, absolute mass and high-altitude winds of exoplanet HD 209458b. Nature 465, 1049–1051 (2010)

    Article  ADS  CAS  Google Scholar 

  14. Donati, J.-F. et al. Magnetic cycles of the planet-hosting star τ Bootis. Mon. Not. R. Astron. Soc. 385, 1179–1185 (2008)

    Article  ADS  Google Scholar 

  15. Takeda, G. et al. Structure and evolution of nearby stars with planets. II. Physical properties of ∼1000 cool stars from the SPOCS catalog. Astrophys. J. Suppl. Ser. 168, 297–318 (2007)

    Article  ADS  CAS  Google Scholar 

  16. Butler, R. P. et al. Catalog of nearby exoplanets. Astrophys. J. 646, 505–522 (2006)

    Article  ADS  CAS  Google Scholar 

  17. Catala, C., Donati, J.-F., Shkolnik, E., Bohlender, D. & Alecian, E. The magnetic field of the planet-hosting star τ Bootis. Mon. Not. R. Astron. Soc. 374, L42–L46 (2007)

    Article  ADS  Google Scholar 

  18. Winn, J. N., Fabrycky, D., Albrecht, S. & Johnson, J. A. Hot stars with hot Jupiters have high obliquities. Astrophys. J. 718, L145–L149 (2010)

    Article  ADS  Google Scholar 

  19. Johnson, J. A. et al. HAT-P-30b: a transiting hot Jupiter on a highly oblique orbit. Astrophys. J. 735, 24–31 (2011)

    Article  ADS  Google Scholar 

  20. Hébrard, G. et al. Observation of the full 12-hour-long transit of the exoplanet HD 80606b. Warm-Spitzer photometry and SOPHIE spectroscopy. Astron. Astrophys. 516, A95 (2010)

    Article  Google Scholar 

  21. Schneider, J., Dedieu, C., Le Sinader, P., Savalle, R. & Zolotukhin, I. Defining and cataloguing exoplanets: the exoplanet.eu database. Astron. Astrophys. 532, A79 (2011)

    Article  ADS  Google Scholar 

  22. Knutson, H. A., Charbonneau, D., Burrows, A., O'Donovan, F. T. & Mandushev, G. Detection of a temperature inversion in the broadband infrared emission spectrum of TrES-4. Astrophys. J. 691, 866–874 (2009)

    Article  ADS  Google Scholar 

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Acknowledgements

We thank the ESO support staff of the Paranal Observatory for their help during the observations. This work is based on observations collected at the European Southern Observatory (186.C-0289). S.A. acknowledges support by a Rubicon fellowship from the Netherlands Organisation for Scientific Research (NWO), and by NSF grant no. 1108595.

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Authors and Affiliations

  1. Leiden Observatory, Leiden University, Postbus 9513, 2300RA Leiden, The Netherlands ,

    Matteo Brogi, Ignas A. G. Snellen, Jayne Birkby & Ernst J. W. de Mooij

  2. SRON, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands ,

    Remco J. de Kok

  3. Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, 02139, Massachusetts, USA

    Simon Albrecht

  4. Department of Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, Ontario M5S 3H4, Canada,

    Ernst J. W. de Mooij

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  1. Matteo Brogi
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  2. Ignas A. G. Snellen
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  3. Remco J. de Kok
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  4. Simon Albrecht
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  5. Jayne Birkby
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  6. Ernst J. W. de Mooij
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Contributions

M.B. led the observations and data analysis, and co-wrote the manuscript. I.A.G.S. conceived the project, contributed to the analysis and co-wrote the manuscript. R.J.d.K. constructed the planet atmosphere models. S.A. conducted the MCMC orbital analysis. J.B., E.J.W.d.M., R.J.d.K. and S.A. discussed the analyses, results and commented on the manuscript.

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Correspondence to Matteo Brogi.

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The authors declare no competing financial interests.

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Brogi, M., Snellen, I., de Kok, R. et al. The signature of orbital motion from the dayside of the planet τ Boötis b. Nature 486, 502–504 (2012). https://doi.org/10.1038/nature11161

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