Exonephology : transmission spectra from a 3D simulated cloudy atmosphere of HD 209458b
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We present high-resolution transmission spectra, calculated directly from a 3D radiative hydrodynamic simulation that includes kinetic cloud formation, for HD 209458b. We find that the high opacity of our vertically extensive cloud deck, composed of a large number density of sub-μm particles, flattens the transmission spectrum and obscures spectral features identified in the observed data. We use the PANDEXO simulator to explore features of our HD 209458b spectrum which may be detectable with the James Webb Space Telescope. We determine that an 8-12μm absorption feature attributed to the mixed-composition, predominantly silicate cloud particles is a viable marker for the presence of cloud. Further calculations explore, and trends are identified with, variations in cloud opacity, composition heterogeneity, and artificially scaled gravitational settling on the transmission spectrum. Principally, by varying the upper extent of our cloud decks, rainout is identified to be a key process for the dynamical atmospheres of hot Jupiters and shown to dramatically alter the resulting spectrum. Our synthetic transmission spectra, obtained from the most complete, forward atmosphere simulations to date, allow us to explore the model's ability to conform with observations. Such comparisons can provide insight into the physical processes either missing or requiring improvement.
Lines , S , Manners , J , Mayne , N J , Goyal , J , Carter , A L , Boutle , I A , Lee , G K H , Helling , C , Drummond , B , Acreman , D M & Sing , D K 2018 , ' Exonephology : transmission spectra from a 3D simulated cloudy atmosphere of HD 209458b ' , Monthly Notices of the Royal Astronomical Society , vol. 481 , no. 1 , pp. 194-205 . https://doi.org/10.1093/mnras/sty2275
Monthly Notices of the Royal Astronomical Society
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.1093/mnras/sty2275
DescriptionS. Lines and J. Goyal are funded by and thankful to the Leverhulme Trust. N. J. Mayne is part funded by a Leverhulme Trust Research Project Grant. J. Manners and I. A. Boutle acknowledge the support of a Met Office Academic Partnership secondment. B. Drummond acknowledges funding from the European Research Council (ERC) under the European Unions Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement no. 336792. G. K. H. Lee acknowledges support from the Universities of Oxford and Bern through the Bernoulli fellowship program. A. L. Carter is funded by a Science and Technology Facilities Council (STFC) studentship.
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