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dc.contributor.authorZhou, Yifan
dc.contributor.authorBowler, Brendan P.
dc.contributor.authorMorley, Caroline V.
dc.contributor.authorApai, Dániel
dc.contributor.authorKataria, Tiffany
dc.contributor.authorBryan, Marta L.
dc.contributor.authorBenneke, Björn
dc.date.accessioned2021-02-09T23:30:44Z
dc.date.available2021-02-09T23:30:44Z
dc.date.issued2020-07-23
dc.identifier.citationZhou, Y., Bowler, B. P., Morley, C. V., Apai, D., Kataria, T., Bryan, M. L., & Benneke, B. (2020). Spectral Variability of VHS J1256–1257b from 1 to 5 μm. The Astronomical Journal, 160(2), 77.en_US
dc.identifier.issn0004-6256
dc.identifier.doi10.3847/1538-3881/ab9e04
dc.identifier.urihttp://hdl.handle.net/10150/652231
dc.description.abstractMultiwavelength time-resolved observations of rotationally modulated variability from brown dwarfs and giant exoplanets are the most effective method for constraining their heterogeneous atmospheric structures. In a companion paper, we reported the discovery of strong near-infrared variability in HST/WFC3/G141 light curves of the very red L-dwarf companion VHS J1256-1257b. In this paper, we present a follow-up 36 hr Spitzer/IRAC Channel 2 light curve together with an in-depth analysis of the Hubble space telescope (HST) and the Spitzer data. The combined data set provides time-resolved light curves of VHS1256b sampling 1.1 to 4.5 mu m. The Spitzer light curve is best fit with a single sine wave with a period of 22.04 +/- 0.05 hr and a peak-to-peak amplitude of 5.76 +/- 0.04%. Combining the period with a previously measured projected rotational velocity (v sin i), we find that VHS1256b is most consistent with equatorial viewing geometry. The HST/G141+Spitzer spectral energy distribution favors a model with a T-eff of 1000 K and low surface gravity with disequilibrium chemistry. The spectral variability of VHS1256b is consistent with predictions from partly cloudy models, suggesting that heterogeneous clouds are the dominant source of the observed modulations. We find evidence at the 3.3 sigma level for amplitude variations within the 1.67 mu m CH4 band, which is the first such detection for a variable L-dwarf. We compare the HST/G141 time-resolved spectra of three red L-dwarfs with high-amplitude near-infrared rotational modulations and find that although their time-averaged spectra are similar, their spectroscopic variabilities exhibit notable differences. This diversity reinforces the advantage of time-resolved spectroscopic observations for understanding the atmospheres of brown dwarfs and directly imaged exoplanets.en_US
dc.description.sponsorshipSpace Telescope Science Instituteen_US
dc.language.isoenen_US
dc.publisherIOP PUBLISHING LTDen_US
dc.rights© 2020. The American Astronomical Society. All rights reserved.en_US
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en_US
dc.titleSpectral Variability of VHS J1256–1257b from 1 to 5 μmen_US
dc.typeArticleen_US
dc.identifier.eissn1538-3881
dc.contributor.departmentUniv Arizona, Steward Observ, Dept Astronen_US
dc.contributor.departmentUniv Arizona, Dept Planetary Sci, Lunar & Planetary Laben_US
dc.identifier.journalASTRONOMICAL 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.journaltitleThe Astronomical Journal
dc.source.volume160
dc.source.issue2
dc.source.beginpage77
refterms.dateFOA2021-02-09T23:30:54Z


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