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dc.contributor.authorLeggett, S. K.
dc.contributor.authorDupuy, Trent J.
dc.contributor.authorMorley, Caroline V.
dc.contributor.authorMarley, Mark S.
dc.contributor.authorBest, William M. J.
dc.contributor.authorLiu, Michael C.
dc.contributor.authorApai, D.
dc.contributor.authorCasewell, S. L.
dc.contributor.authorGeballe, T. R.
dc.contributor.authorGizis, John E.
dc.contributor.authorPineda, J. Sebastian
dc.contributor.authorRieke, Marcia
dc.contributor.authorWright, G. S.
dc.date.accessioned2019-10-09T18:59:29Z
dc.date.available2019-10-09T18:59:29Z
dc.date.issued2019-09-09
dc.identifier.citationS. K. Leggett et al 2019 ApJ 882 117en_US
dc.identifier.issn0004-637X
dc.identifier.doi10.3847/1538-4357/ab3393
dc.identifier.urihttp://hdl.handle.net/10150/634706
dc.description.abstractHalf of the energy emitted by late-T- and Y-type brown dwarfs emerges at 3.5 <= lambda mu m <= 5.5. We present new L' (3.43 <= lambda mu m <= 4.11) photometry obtained at the Gemini North telescope for nine late-T and Y dwarfs, and synthesize L' from spectra for an additional two dwarfs. The targets include two binary systems that were imaged at a resolution of 0.'' 25. One of these, WISEP J045853.90+643452.6AB, shows significant motion, and we present an astrometric analysis of the binary using Hubble Space Telescope, Keck Adaptive Optics, and Gemini images. We compare lambda similar to 4 mu m observations to models, and find that the model fluxes are too low for brown dwarfs cooler than similar to 700 K. The discrepancy increases with decreasing temperature, and is a factor of similar to 2 at T-eff = 500 K and similar to 4 at T-eff = 400 K. Warming the upper layers of a model atmosphere generates a spectrum closer to what is observed. The thermal structure of cool brown dwarf atmospheres above the radiative-convective boundary may not be adequately modeled using pure radiative equilibrium; instead heat may be introduced by thermochemical instabilities (previously suggested for the L- to T-type transition) or by breaking gravity waves (previously suggested for the solar system giant planets). One-dimensional models may not capture these atmospheres, which likely have both horizontal and vertical pressure/temperature variations.en_US
dc.description.sponsorshipNational Aeronautics and Space AdministrationNational Aeronautics & Space Administration (NASA); NASANational Aeronautics & Space Administration (NASA) [NAS 5-26555]; W. M. Keck FoundationW.M. Keck Foundation; NSFNational Science Foundation (NSF) [AST-1518339]en_US
dc.language.isoenen_US
dc.publisherIOP PUBLISHING LTDen_US
dc.rightsCopyright © 2019. The American Astronomical Society. All rights reserved.en_US
dc.subjectastrometryen_US
dc.subjectbinaries: generalen_US
dc.subjectbrown dwarfsen_US
dc.subjectinfrared: starsen_US
dc.subjectstars: atmospheresen_US
dc.title3.8 μm Imaging of 400–600 K Brown Dwarfs and Orbital Constraints for WISEP J045853.90+643452.6ABen_US
dc.typeArticleen_US
dc.contributor.departmentUniv Arizona, Dept Astron, Steward Observen_US
dc.contributor.departmentUniv Arizona, Dept Planetary Sci, Lunar & Planetary Laben_US
dc.contributor.departmentUniv Arizona, Steward Observen_US
dc.identifier.journalASTROPHYSICAL JOURNALen_US
dc.description.collectioninformationThis 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.en_US
dc.eprint.versionFinal published versionen_US
dc.source.volume882
dc.source.issue2
dc.source.beginpage117
refterms.dateFOA2019-10-09T18:59:30Z


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