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Cloud Atlas: Rotational Modulations in the L/T Transition Brown Dwarf Companion HN Peg B

Zhou, Yifan and Apai, Dániel and Metchev, Stanimir and Lew, Ben W. P. and Schneider, Glenn and Marley, Mark S. and Karalidi, Theodora and Manjavacas, Elena and Bedin, Luigi R. and Cowan, Nicolas B. and Miles-Páez, Paulo A. and Lowrance, Patrick J. and Radigan, Jacqueline and Burgasser, Adam J. (2018) Cloud Atlas: Rotational Modulations in the L/T Transition Brown Dwarf Companion HN Peg B. Astronomical Journal, 155 (3). Art. No. 132. ISSN 1538-3881. doi:10.3847/1538-3881/aaabbd.

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Time-resolved observations of brown dwarfs' rotational modulations provide powerful insights into the properties of condensate clouds in ultra-cool atmospheres. Multi-wavelength light curves reveal cloud vertical structures, condensate particle sizes, and cloud morphology, which directly constrain condensate cloud and atmospheric circulation models. We report results from Hubble Space Telescope/Wide Field Camera 3 near-infrared G141 taken in six consecutive orbits observations of HN Peg B, an L/T transition brown dwarf companion to a G0V type star. The best-fit sine wave to the 1.1–1.7 μm broadband light curve has an amplitude of 1.206% ± 0.025% and period of 15.4 ± 0.5 hr. The modulation amplitude has no detectable wavelength dependence except in the 1.4 μm water absorption band, indicating that the characteristic condensate particle sizes are large (>1 μm). We detect significantly (4.4σ) lower modulation amplitude in the 1.4 μm water absorption band and find that HN Peg B's spectral modulation resembles those of early T type brown dwarfs. We also describe a new empirical interpolation method to remove spectral contamination from the bright host star. This method may be applied in other high-contrast time-resolved observations with WFC3.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Zhou, Yifan0000-0003-2969-6040
Apai, Dániel0000-0003-3714-5855
Metchev, Stanimir0000-0003-3050-8203
Lew, Ben W. P.0000-0003-1487-6452
Schneider, Glenn0000-0002-4511-5966
Marley, Mark S.0000-0002-5251-2943
Karalidi, Theodora0000-0001-7356-6652
Manjavacas, Elena0000-0003-0192-6887
Bedin, Luigi R.0000-0003-4080-6466
Cowan, Nicolas B.0000-0001-6129-5699
Miles-Páez, Paulo A.0000-0003-2446-8882
Lowrance, Patrick J.0000-0001-8014-0270
Radigan, Jacqueline0000-0002-6732-3651
Burgasser, Adam J.0000-0002-6523-9536
Additional Information:© 2018 American Astronomical Society. Received 2017 November 6. Accepted 2018 January 25. Published 2018 February 28. We acknowledge the anonymous referee for a constructive report that improves the manuscript. We acknowledge Dr. Sandy Leggett for valuable discussion on HN Peg B's spectral fitting and Dr. Peter McCullough for helpful discussion on the cause of the image contamination. Y.Z. acknowledges support in part by the NASA Earth and Space Science Fellowship Program—grant "NNX16AP54H." D.A. acknowledges support by NASA under agreement No. NNX15AD94G for the program Earths in Other Solar Systems. 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.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASA Earth and Space Science FellowshipNNX16AP54H
Subject Keywords:brown dwarfs; methods: observational; stars: atmospheres
Issue or Number:3
Record Number:CaltechAUTHORS:20180228-131454852
Persistent URL:
Official Citation:Yifan Zhou et al 2018 AJ 155 132
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85012
Deposited By: Ruth Sustaita
Deposited On:28 Feb 2018 21:59
Last Modified:15 Nov 2021 20:24

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