A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion
- Creators
- Sing, David K.
- Fortney, Jonathan J.
- Nikolov, Nikolay
- Wakeford, Hannah R.
- Kataria, Tiffany
- Evans, Thomas M.
- Aigrain, Suzanne
- Ballester, Gilda E.
- Burrows, Adam S.
- Deming, Drake
- Désert, Jean-Michel
- Gibson, Neale P.
- Henry, Gregory W.
- Huitson, Catherine M.
- Knutson, Heather A.
- Lecavelier des Etangs, Alain
- Pont, Frederic
- Showman, Adam P.
- Vidal-Madjar, Alfred
- Williamson, Michael H.
- Wilson, Paul A.
Abstract
Thousands of transiting exoplanets have been discovered, but spectral analysis of their atmospheres has so far been dominated by a small number of exoplanets and data spanning relatively narrow wavelength ranges (such as 1.1–1.7 micrometres). Recent studies show that some hot-Jupiter exoplanets have much weaker water absorption features in their near-infrared spectra than predicted. The low amplitude of water signatures could be explained by very low water abundances, which may be a sign that water was depleted in the protoplanetary disk at the planet's formation location, but it is unclear whether this level of depletion can actually occur. Alternatively, these weak signals could be the result of obscuration by clouds or hazes, as found in some optical spectra. Here we report results from a comparative study of ten hot Jupiters covering the wavelength range 0.3–5 micrometres, which allows us to resolve both the optical scattering and infrared molecular absorption spectroscopically. Our results reveal a diverse group of hot Jupiters that exhibit a continuum from clear to cloudy atmospheres. We find that the difference between the planetary radius measured at optical and infrared wavelengths is an effective metric for distinguishing different atmosphere types. The difference correlates with the spectral strength of water, so that strong water absorption lines are seen in clear-atmosphere planets and the weakest features are associated with clouds and hazes. This result strongly suggests that primordial water depletion during formation is unlikely and that clouds and hazes are the cause of weaker spectral signatures.
Additional Information
© 2015 Macmillan Publishers Limited. Received 19 June; accepted 1 October 2015. Published online 14 December 2015. This work is based on observations with the NASA/ESA HST, obtained at the Space Telescope Science Institute (STScI) operated by AURA, Inc. This work is also based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement number 336792. D.K.S., F.P. and N.N. acknowledge support from STFC consolidated grant ST/J0016/1. Support for this work was provided by NASA through grants under the HST-GO-12473 programme from the STScI. A.L.E., P.A.W. and A.V.M. acknowledge support from CNES and the French Agence Nationale de la Recherche (ANR), under programme ANR-12-BS05-0012 'Exo-Atmos'. P.A.W. and H.W. acknowledge support from the UK Science and Technology Facilities Council (STFC). G.W.H. and M.H.W. acknowledge support from NASA, NSF, Tennessee State University and the State of Tennessee through its Centers of Excellence programme. Author Contributions: D.K.S. led the data analysis for this project, with contributions from D.D., T.M.E., N.P.G., C.M.H., H.A.K., N.N., H.R.W., S.A., G.E.B. and P.A.W. J.J.F., A.S.B., A.P.S., A.L.E. and T.K. provided atmospheric models. G.W.H. and M.H.W. provided photometric stellar activity monitoring data and J.M.D. provided Spitzer data. D.K.S. wrote the manuscript along with J.J.F., H.R.W, T.K., N.N. and T.M.E. All authors discussed the results and commented on the draft. The authors declare no competing financial interests.Attached Files
Submitted - 1512.04341.pdf
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Additional details
- Eprint ID
- 63103
- DOI
- 10.1038/nature16068
- Resolver ID
- CaltechAUTHORS:20151221-095009065
- NASA/JPL/Caltech
- 336792
- European Research Council (ERC)
- ST/J0016/1
- Science and Technology Facilities Council (STFC)
- HST-GO-12473
- NASA
- Centre National d'Études Spatiales (CNES)
- ANR-12-BS05-0012
- Agence Nationale de la Recherche (ANR)
- NSF
- Tennessee State University
- State of Tennessee Centers of Excellence Program
- Created
-
2015-12-22Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences