CaltechAUTHORS
Published January 7, 2016 | Version Submitted + Supplemental Material
Journal Article Open

A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion

Creators

  • 1. ROR icon University of Exeter
  • 2. ROR icon University of California, Santa Cruz
  • 3. ROR icon University of Oxford
  • 4. ROR icon University of Arizona
  • 5. ROR icon Princeton University
  • 6. ROR icon University of Maryland, College Park
  • 7. ROR icon University of Colorado Boulder
  • 8. ROR icon European Southern Observatory
  • 9. ROR icon Tennessee State University
  • 10. ROR icon California Institute of Technology
  • 11. ROR icon Institut d'Astrophysique de Paris

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.

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Submitted - 1512.04341.pdf

Supplemental Material - nature16068-sf1.jpg

Supplemental Material - nature16068-sf2.jpg

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Additional details

Identifiers

Eprint ID
63103
DOI
10.1038/nature16068
Resolver ID
CaltechAUTHORS:20151221-095009065

Related works

Describes
http://arxiv.org/abs/1512.04341 (URL)

Funding

NASA/JPL/Caltech
European Research Council (ERC)
336792
Science and Technology Facilities Council (STFC)
ST/J0016/1
NASA
HST-GO-12473
Centre National d'Études Spatiales (CNES)
Agence Nationale de la Recherche (ANR)
ANR-12-BS05-0012
NSF
Tennessee State University
State of Tennessee Centers of Excellence Program

Dates

Created
2015-12-22
Created from EPrint's datestamp field
Updated
2021-11-10
Created from EPrint's last_modified field

Caltech Custom Metadata

Caltech groups
Division of Geological and Planetary Sciences (GPS)