Aerosol Properties of the Atmospheres of Extrasolar Giant Planets
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Lavvas_2017_ApJ_847_32.pdf
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Univ Arizona, Lunar & Planetary LabIssue Date
2017-09-20Keywords
meteorites, meteors, meteoroidsplanets and satellites: atmospheres
planets and satellites: composition
planets and satellites: gaseous planets
planets and satellites: individual (HD 209458 b, HD 189733 b)
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IOP PUBLISHING LTDCitation
Aerosol Properties of the Atmospheres of Extrasolar Giant Planets 2017, 847 (1):32 The Astrophysical JournalJournal
The Astrophysical JournalRights
© 2017. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We use a model of aerosol microphysics to investigate the impact of high-altitude photochemical aerosols on the transmission spectra and atmospheric properties of close-in exoplanets, such as HD 209458 b and HD 189733 b. The results depend strongly on the temperature profiles in the middle and upper atmospheres, which are poorly understood. Nevertheless, our model of HD 189733 b, based on the most recently inferred temperature profiles, produces an aerosol distribution that matches the observed transmission spectrum. We argue that the hotter temperature of HD 209458 b inhibits the production of high-altitude aerosols and leads to the appearance of a clearer atmosphere than on HD 189733 b. The aerosol distribution also depends on the particle composition, photochemical production, and atmospheric mixing. Due to degeneracies among these inputs, current data cannot constrain the aerosol properties in detail. Instead, our work highlights the role of different factors in controlling the aerosol distribution that will prove useful in understanding different observations, including those from future missions. For the atmospheric mixing efficiency suggested by general circulation models, we find that the aerosol particles are small (similar to nm) and probably spherical. We further conclude that a composition based on complex hydrocarbons (soots) is the most likely candidate to survive the high temperatures in hot-Jupiter atmospheres. Such particles would have a significant impact on the energy balance of HD 189733 b's atmosphere and should be incorporated in future studies of atmospheric structure. We also evaluate the contribution of external sources to photochemical aerosol formation and find that their spectral signature is not consistent with observations.ISSN
1538-4357Version
Final published versionSponsors
Programme National de Planetologie (PNP-INSU) under project AMG; Projet International de Cooperation Scientifique (PICS/CNRS) under project TACAdditional Links
http://stacks.iop.org/0004-637X/847/i=1/a=32?key=crossref.2589ce51ea299b63a866617047304d82Scopus Count
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