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Cloud Atlas: Discovery of Patchy Clouds and High-amplitude Rotational Modulations in a Young, Extremely Red L-type Brown Dwarf

Lew, Ben W. P. and Apai, Dániel and Zhou, Yifan and Schneider, Glenn and Burgasser, Adam J. and Karalidi, Theodora and Yang, Hao and Marley, Mark S. and Cowan, Nicolas B. and Bedin, Luigi R. and Metchev, Stanimir A. and Radigan, Jacqueline and Lowrance, Patrick J. (2016) Cloud Atlas: Discovery of Patchy Clouds and High-amplitude Rotational Modulations in a Young, Extremely Red L-type Brown Dwarf. Astrophysical Journal Letters, 829 (2). Art. No. L32. ISSN 2041-8205.

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Condensate clouds fundamentally impact the atmospheric structure and spectra of exoplanets and brown dwarfs, but the connections between surface gravity, cloud structure, dust in the upper atmosphere, and the red colors of some brown dwarfs remain poorly understood. Rotational modulations enable the study of different clouds in the same atmosphere, thereby providing a method to isolate the effects of clouds. Here, we present the discovery of high peak-to-peak amplitude (8%) rotational modulations in a low-gravity, extremely red (J-K_s = 2.55) L6 dwarf WISEP J004701.06+680352.1 (W0047). Using the Hubble Space Telescope (HST) time-resolved grism spectroscopy, we find a best-fit rotational period (13.20 ± 0.14 hr) with a larger amplitude at 1.1 μm than at 1.7 μm. This is the third-largest near-infrared variability amplitude measured in a brown dwarf, demonstrating that large-amplitude variations are not limited to the L/T transition but are present in some extremely red L-type dwarfs. We report a tentative trend between the wavelength dependence of relative amplitude, possibly proxy for small dust grains lofted in the upper atmosphere, and the likelihood of large-amplitude variability. By assuming forsterite as a haze particle, we successfully explain the wavelength-dependent amplitude with submicron-sized haze particle sizes of around 0.4 μm. W0047 links the earlier spectral and later spectral type brown dwarfs in which rotational modulations have been observed; the large amplitude variations in this object make this a benchmark brown dwarf for the study of cloud properties close to the L/T transition.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Lew, Ben W. P.0000-0003-1487-6452
Apai, Dániel0000-0003-3714-5855
Zhou, Yifan0000-0003-2969-6040
Schneider, Glenn0000-0002-4511-5966
Burgasser, Adam J.0000-0002-6523-9536
Karalidi, Theodora0000-0001-7356-6652
Yang, Hao0000-0002-8241-6231
Marley, Mark S.0000-0002-5251-2943
Cowan, Nicolas B.0000-0001-6129-5699
Bedin, Luigi R.0000-0003-4080-6466
Metchev, Stanimir A.0000-0003-3050-8203
Radigan, Jacqueline0000-0002-6732-3651
Lowrance, Patrick J.0000-0001-8014-0270
Additional Information:© 2016. The American Astronomical Society. Received 2016 August 30. Accepted 2016 September 15. Published 2016 September 30. We thank the anonymous referee for useful comments that improved the manuscript. We would like to thank Min Fang, Alex Bixel, Kevin Wagner, Belle Yu-Ya Huang, and Carol Yang for providing useful comments. Ben W.P. Lew is supported in part by the Technology Research Initiative Fund (TRIF) Imaging Fellowship, University of Arizona. Support for Program number 14241 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained in GO program 14241 at the Space Telescope Science Institute. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
University of ArizonaUNSPECIFIED
Subject Keywords:brown dwarfs; stars: atmospheres; stars: individual (WISEP J004701.06+680352.1) ; stars: low-mass
Issue or Number:2
Record Number:CaltechAUTHORS:20160930-162423629
Persistent URL:
Official Citation:Ben W. P. Lew et al 2016 ApJ 829 L32
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70737
Deposited By: George Porter
Deposited On:03 Oct 2016 19:40
Last Modified:09 Mar 2020 13:19

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