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Observed Variability at 1 and 4 μm in the Y0 Brown Dwarf WISEP J173835.52+273258.9

Leggett, S. K. and Cushing, Michael C. and Hardegree-Ullman, Kevin K. and Trucks, Jesica L. and Marley, M. S. and Morley, Caroline V. and Saumon, D. and Carey, S. J. and Fortney, J. J. and Gelino, C. R. and Gizis, J. E. and Kirkpatrick, J. D. and Mace, G. N. (2016) Observed Variability at 1 and 4 μm in the Y0 Brown Dwarf WISEP J173835.52+273258.9. Astrophysical Journal, 830 (2). Art. No. 141. ISSN 0004-637X.

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We have monitored photometrically the Y0 brown dwarf WISEP J173835.52+273258.9 (W1738) at both near- and mid-infrared wavelengths. This ≾ 1 Gyr old 400 K dwarf is at a distance of 8 pc and has a mass around 5 M Jupiter. We observed W1738 using two near-infrared filters at λ ≈ 1 μm, Y and J, on Gemini Observatory and two mid-infrared filters at λ ≈ 4 μm, [3.6] and [4.5], on the Spitzer observatory. Twenty-four hours were spent on the source by Spitzer on each of 2013 June 30 and October 30 UT. Between these observations, around 5 hr were spent on the source by Gemini on each of 2013 July 17 and August 23 UT. The mid-infrared light curves show significant evolution between the two observations separated by 4 months. We find that a double sinusoid can be fit to the [4.5] data, where one sinusoid has a period of 6.0 ± 0.1 hr and the other a period of 3.0 ± 0.1 hr. The near-infrared observations suggest variability with a ~3.0 hr period, although only at a ≾ 2σ confidence level. We interpret our results as showing that the Y dwarf has a 6.0 ± 0.1 hr rotation period, with one or more large-scale surface features being the source of variability. The peak-to-peak amplitude of the light curve at [4.5] is 3%. The amplitude of the near-infrared variability, if real, may be as high as 5%–30%. Intriguingly, this size of variability and the wavelength dependence can be reproduced by atmospheric models that include patchy KCl and Na_2S clouds and associated small changes in surface temperature. The small number of large features, as well as the timescale for evolution of the features, is very similar to what is seen in the atmospheres of the solar system gas giants.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Cushing, Michael C.0000-0001-7780-3352
Hardegree-Ullman, Kevin K.0000-0003-3702-0382
Marley, M. S.0000-0002-5251-2943
Morley, Caroline V.0000-0002-4404-0456
Carey, S. J.0000-0002-0221-6871
Fortney, J. J.0000-0002-9843-4354
Gizis, J. E.0000-0002-8916-1972
Kirkpatrick, J. D.0000-0003-4269-260X
Mace, G. N.0000-0001-7875-6391
Additional Information:© 2016. The American Astronomical Society. Received 2016 April 5; revised 2016 July 25; accepted 2016 July 26; published 2016 October 18. Based in part on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). Based in part on observations obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. S.L.'s research is supported by Gemini Observatory. D.S.'s work was supported in part by NASA grant NNH12AT89I from Astrophysics Theory. We thank the referee for comments that greatly improved the paper.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
National Research Council of CanadaUNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)UNSPECIFIED
Australian Research CouncilUNSPECIFIED
Ministério da Ciência, Tecnologia e InovaçãoUNSPECIFIED
Ministerio de Ciencia, Tecnología e Innovación ProductivaUNSPECIFIED
Subject Keywords:brown dwarfs; stars: atmospheres; stars: individual (WISEP J173835.52+273258.9)
Issue or Number:2
Record Number:CaltechAUTHORS:20161019-121436698
Persistent URL:
Official Citation:S. K. Leggett et al 2016 ApJ 830 141
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71276
Deposited By: George Porter
Deposited On:19 Oct 2016 19:30
Last Modified:09 Mar 2020 13:19

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