Cloud Atlas: Variability in and out of the Water Band in the Planetary-mass HD 203030B Points to Cloud Sedimentation in Low-gravity L Dwarfs
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Final Published Version
Author
Miles-Páez, Paulo A.
Metchev, Stanimir
Apai, Dániel

Zhou, Yifan

Manjavacas, Elena
Karalidi, Theodora

Lew, Ben W. P.

Burgasser, Adam J.

Bedin, Luigi R.
Cowan, Nicolas
Lowrance, Patrick J.

Marley, Mark S.

Radigan, Jacqueline
Schneider, Glenn

Affiliation
Univ Arizona, Dept Astron, Steward ObservUniv Arizona, Lunar & Planetary Lab, Dept Planetary Sci
Issue Date
2019-10-03
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IOP PUBLISHING LTDCitation
Paulo A. Miles-Páez et al 2019 ApJ 883 181Journal
ASTROPHYSICAL JOURNALRights
Copyright © 2019. 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 the Wide Field Camera 3 on the Hubble Space Telescope to spectrophotometrically monitor the young L7.5 companion HD 203030B. Our time series reveal photometric variability at 1.27 and 1.39 mu m on timescales compatible with rotation. We find a rotation period of 7.5(0.5)(+0.6) hr: comparable to those observed in other brown dwarfs and planetary-mass companions younger than 300 Myr. We measure variability amplitudes of 1.1% +/- 0.3% (1.27 mu m) and 1.7% +/- 0.4% (1.39 mu m), and a phase lag of 56 degrees +/- 28 degrees between the two light curves. We attribute the difference in photometric amplitudes and phases to a patchy cloud layer that is sinking below the level where water vapor becomes opaque. HD 203030B and the few other known variable young late-L dwarfs are unlike warmer (earlier-type and/or older) L dwarfs, for which variability is much less wavelength-dependent across the 1.1-1.7 mu m region. We further suggest that a sinking of the top-most cloud deck below the level where water or carbon monoxide gas become opaque may also explain the often enhanced variability amplitudes of even earlier-type low-gravity L dwarfs. Because these condensate and gas opacity levels are already well-differentiated in T dwarfs, we do not expect the same variability amplitude enhancement in young versus old T dwarfs.ISSN
0004-637XVersion
Final published versionSponsors
NASANational Aeronautics & Space Administration (NASA) [NAS 5-26555, GO 14241]; Natural Sciences and Engineering Research Council of CanadaNatural Sciences and Engineering Research Council of Canada [RGPIN-04396-2014]; Canada Research Chairs ProgramCanada Research Chairsae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/ab3d25