Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Uniformly hot nightside temperatures on short-period gas giants

Abstract

Short-period gas giants (hot Jupiters) on circular orbits are expected to be tidally locked into synchronous rotation, with permanent daysides that face their host stars and permanent nightsides that face the darkness of space1. Thermal flux from the nightside of several hot Jupiters has been detected, meaning energy is transported from day to night in some fashion. However, it is not clear exactly what the physical information from these detections reveals about the atmospheric dynamics of hot Jupiters. Here we show that the nightside effective temperatures of a sample of 12 hot Jupiters are clustered around 1,100 K, with a slight upward trend as a function of stellar irradiation. The clustering is not predicted by cloud-free atmospheric circulation models2,3,4. This result can be explained if most hot Jupiters have nightside clouds that are optically thick to outgoing longwave radiation and hence radiate at the cloud-top temperature, and progressively disperse for planets receiving greater incident flux. Phase-curve observations at a greater range of wavelengths are crucial to determining the extent of cloud coverage, as well as the cloud composition on hot Jupiter nightsides5,6.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Dayside and nightside effective temperatures for 12 hot Jupiters, and one brown dwarf (KELT-1b).
Fig. 2: Best-fit models for the nightside temperatures of 12 hot Jupiters.
Fig. 3: Difference in brightness temperatures at Spitzer wavelengths 3.6 μm and 4.5 μm (ch1 and ch2) for the ten planets with both 3.6 μm and 4.5 μm phase curves.

Similar content being viewed by others

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The Gaussian process regression code used is publicly available and can be found at https://github.com/ekpass/gp-teff. The Spitzer Phase Curve Analysis pipeline is publicly available and can be found at https://github.com/lisadang27/SPCA.

References

  1. Showman, A. P. & Guillot, T. Atmospheric circulation and tides of ‘51 Pegasus b-like’ planets. Astron. Astrophys. 385, 166–180 (2002).

    ADS  Google Scholar 

  2. Komacek, T. D., Showman, A. P. & Tan, X. Atmospheric circulation of hot Jupiters: dayside–nightside temperature differences. II. Comparison with observations. Astrophys. J. 835, 198 (2017).

    ADS  Google Scholar 

  3. Komacek, T. D. & Tan, X. Effects of dissociation/recombination on the day–night temperature contrasts of ultra-hot Jupiters. Res. Notes Am. Astron. Soc. 2, 36 (2018).

    ADS  Google Scholar 

  4. Zhang, X. & Showman, A. P. Effects of bulk composition on the atmospheric dynamics on close-in exoplanets. Astrophys. J. 836, 73 (2017).

    ADS  Google Scholar 

  5. Morley, C. V. et al. Forward and inverse modeling of the emission and transmission spectrum of GJ 436b: investigating metal enrichment, tidal heating, and clouds. Astron. J. 153, 86 (2017).

    ADS  Google Scholar 

  6. Tinetti, G. et al. A chemical survey of exoplanets with ariel. Exp. Astron. 46, 135–209 (2018).

    ADS  Google Scholar 

  7. Dang, L. et al. Detection of a westward hotspot offset in the atmosphere of hot gas giant CoRoT-2b. Nat. Astron. 2, 220–227 (2018).

    ADS  Google Scholar 

  8. Wong, I. et al. 3.6 and 4.5 μm Spitzer phase curves of the highly irradiated hot Jupiters WASP-19b and HAT-P-7b. Astrophys. J. 823, 122 (2016).

    ADS  Google Scholar 

  9. Zhang, M. et al. Phase curves of WASP-33b and HD 149026b and a new correlation between phase curve offset and irradiation temperature. Astron. J. 155, 83 (2018).

    ADS  Google Scholar 

  10. Knutson, H. A. et al. 3.6 and 4.5 μm phase curves and evidence for non-equilibrium chemistry in the atmosphere of extrasolar planet HD 189733b. Astrophys. J. 754, 22 (2012).

    ADS  Google Scholar 

  11. Zellem, R. T. et al. The 4.5 μm full-orbit phase curve of the hot Jupiter HD 209458b. Astrophys. J. 790, 53 (2014).

    ADS  Google Scholar 

  12. Cowan, N. B. et al. Thermal phase variations of WASP-12b: defying predictions. Astrophys. J. 747, 82 (2012).

    ADS  Google Scholar 

  13. Wong, I. et al. 3.6 and 4.5 μm phase curves of the highly irradiated eccentric hot Jupiter WASP-14b. Astrophys. J. 811, 122 (2015).

    ADS  Google Scholar 

  14. Maxted, P. F. L. et al. Spitzer 3.6 and 4.5 μm full-orbit light curves of WASP-18. Mon. Not. R. Astron. Soc. 428, 2645–2660 (2013).

    ADS  Google Scholar 

  15. Stevenson, K. B. et al. Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy. Science 346, 838–841 (2014).

    ADS  Google Scholar 

  16. Stevenson, K. B. et al. Spitzer phase curve constraints for WASP-43b at 3.6 and 4.5 μm. Astron. J. 153, 68 (2017).

    ADS  Google Scholar 

  17. Louden, T. & Kreidberg, L. SPIDERMAN: an open-source code to model phase curves and secondary eclipses. Mon. Not. R. Astron. Soc. 477, 2613–2627 (2018).

    ADS  Google Scholar 

  18. Mendonça, J. M., Malik, M., Demory, B.-O. & Heng, K. Revisiting the phase curves of WASP-43b: confronting re-analyzed Spitzer data with cloudy atmospheres. Astron. J. 155, 150 (2018).

    ADS  Google Scholar 

  19. Kreidberg, L. et al. Global climate and atmospheric composition of the ultra-hot Jupiter WASP-103b from HST and Spitzer phase curve observations. Astron. J. 156, 17 (2018).

    ADS  Google Scholar 

  20. Beatty, T. G. et al. Spitzer phase curves of KELT-1b and the signatures of nightside clouds in thermal phase observations. Preprint at https://arxiv.org/abs/1808.09575 (2018).

  21. Komacek, T. D. & Showman, A. P. Atmospheric circulation of hot Jupiters: dayside–nightside temperature differences. Astrophys. J. 821, 16 (2016).

    ADS  Google Scholar 

  22. Bell, T. J. & Cowan, N. B. Increased heat transport in ultra-hot Jupiter atmospheres through H2 dissociation and recombination. Astrophys. J. 857, L20 (2018).

    ADS  Google Scholar 

  23. Cowan, N. B. & Agol, E. A model for thermal phase variations of circular and eccentric exoplanets. Astrophys. J. 726, 82 (2011).

    ADS  Google Scholar 

  24. Yadav, R. K. & Thorngren, D. P. Estimating the magnetic field strength in hot Jupiters. Astrophys. J. 849, L12 (2017).

    ADS  Google Scholar 

  25. Parmentier, V., Fortney, J. J., Showman, A. P., Morley, C. & Marley, M. S. Transitions in the cloud composition of hot Jupiters. Astrophys. J. 828, 22 (2016).

    ADS  Google Scholar 

  26. Powell, D., Zhang, X., Gao, P. & Parmentier, V. Formation of silicate and titanium clouds on hot Jupiters. Astrophys. J. 860, 18 (2018).

    ADS  Google Scholar 

  27. Roman, M. & Rauscher, E. Modeled temperature-dependent clouds with radiative feedback in hot Jupiter atmospheres. Astrophys. J. 872, 1 (2019).

    ADS  Google Scholar 

  28. Kataria, T. et al. The atmospheric circulation of the hot Jupiter WASP-43b: comparing three-dimensional models to spectrophotometric data. Astrophys. J. 801, 86 (2015).

    ADS  Google Scholar 

  29. Arcangeli, J. et al. Climate of an ultra hot Jupiter. spectroscopic phase curve of WASP-18b with HST/WFC3. Astron. Astrophys. 625, A136 (2019).

    Google Scholar 

  30. Bean, J. L. et al. The transiting exoplanet community early release science program for JWST. Publ. Astron. Soc. Pac. 130, 114402 (2018).

    ADS  Google Scholar 

  31. Cowan, N. B. & Agol, E. The statistics of albedo and heat recirculation on hot exoplanets. Astrophys. J. 729, 54 (2011).

    ADS  Google Scholar 

  32. Schwartz, J. C. & Cowan, N. B. Balancing the energy budget of short-period giant planets: evidence for reflective clouds and optical absorbers. Mon. Not. R. Astron. Soc. 449, 4192–4203 (2015).

    ADS  Google Scholar 

  33. Schwartz, J. C., Kashner, Z., Jovmir, D. & Cowan, N. B. Phase offsets and the energy budgets of hot Jupiters. Astrophys. J. 850, 154 (2017).

    ADS  Google Scholar 

  34. Ingalls, J. G. et al. Repeatability and accuracy of exoplanet eclipse depths measured with post-cryogenic Spitzer. Astrophys. J. 152, 44 (2016).

    Google Scholar 

  35. Cowan, N. B. & Agol, E. Inverting phase functions to map exoplanets. Astrophys. J. 678, L129 (2008).

    ADS  Google Scholar 

  36. Lewis, N. K. et al. Atmospheric circulation of eccentric hot Neptune GJ436b. Astrophys. J. 720, 344–356 (2010).

    ADS  Google Scholar 

  37. Cowan, N. B., Fuentes, P. A. & Haggard, H. M. Light curves of stars and exoplanets: estimating inclination, obliquity and albedo. Mon. Not. R. Astron. Soc. 434, 2465–2479 (2013).

    ADS  Google Scholar 

  38. Cowan, N. B., Chayes, V., Bouffard, É., Meynig, M. & Haggard, H. M. Odd harmonics in exoplanet photometry: weather or artifact? Mon. Not. R. Astron. Soc. 467, 747–757 (2017).

    ADS  Google Scholar 

  39. Majeau, C., Agol, E. & Cowan, N. B. A two-dimensional infrared map of the extrasolar planet HD 189733b. Astrophys. J. 747, L20 (2012).

    ADS  Google Scholar 

  40. de Wit, J., Gillon, M., Demory, B.-O. & Seager, S. Towards consistent mapping of distant worlds: secondary-eclipse scanning of the exoplanet HD 189733b. Astron. Astrophys. 548, A128 (2012).

    Google Scholar 

  41. Rauscher, E., Suri, V. & Cowan, N. B. A more informative map: inverting thermal orbital phase and eclipse light curves of exoplanets. Astron. J. 156, 235 (2018).

    ADS  Google Scholar 

  42. Allard, F., Hauschildt, P. H. & Schweitzer, A. Spherically symmetric model atmospheres for low-mass pre-main-sequence stars with effective temperatures between 2000 and 6800 K. Astrophys. J. 539, 366–371 (2000).

    ADS  Google Scholar 

  43. Knutson, H. A. et al. A map of the day–night contrast of the extrasolar planet HD 189733b. Nature 447, 183–186 (2007).

    ADS  Google Scholar 

  44. Knutson, H. A. et al. Multiwavelength constraints on the day–night circulation patterns of HD 189733b. Astrophys. J. 690, 822–836 (2009).

    ADS  Google Scholar 

  45. Demory, B.-O. et al. A map of the large day–night temperature gradient of a super-Earth exoplanet. Nature 532, 207–209 (2016).

    ADS  Google Scholar 

  46. Angelo, I. & Hu, R. A case for an atmosphere on super-Earth 55 Cancri e. Astron. J. 154, 232 (2017).

    ADS  Google Scholar 

  47. Keating, D. & Cowan, N. B. Revisiting the energy budget of WASP-43b: enhanced day–night heat transport. Astrophys. J. 849, L5 (2017).

    ADS  Google Scholar 

  48. Russell, H. N. On the light variations of asteroids and satellites. Astrophys. J. 24, 1–18 (1906).

    ADS  Google Scholar 

  49. Bell, T. et al. Mass loss from the exoplanet WASP-12b inferred from Spitzer phase curves. Preprint at https://arxiv.org/abs/1906.04742 (2019).

Download references

Acknowledgements

The authors thank T. Bell for providing the updated energy balance model code, T. Komacek for providing his analytic day–night temperature difference code and L. Kreidberg for an early look at her WASP-103b phase-curve paper. Thanks to J. Mendonça for providing the phase-curve parameters from his WASP-43b paper. Thanks to E. Pass for an early look at her Gaussian process temperature estimate results. Thanks to J. Bean and V. Parmentier for helpful discussion and comments about the manuscript.

Author information

Authors and Affiliations

Authors

Contributions

D.K. led the data analysis and wrote the manuscript. N.B.C. discussed ideas and contributed to writing the manuscript. L.D. provided the Spitzer data analysis pipeline and helped with reducing Spitzer phase curves.

Corresponding author

Correspondence to Dylan Keating.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information: Nature Astronomy thanks Thaddeus Komacek and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–8 and Tables 1–3.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Keating, D., Cowan, N.B. & Dang, L. Uniformly hot nightside temperatures on short-period gas giants. Nat Astron 3, 1092–1098 (2019). https://doi.org/10.1038/s41550-019-0859-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41550-019-0859-z

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing