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Cloud Atlas: Rotational Spectral Modulations and Potential Sulfide Clouds in the Planetary-mass, Late T-type Companion Ross 458C

Manjavacas, Elena and Apai, Dániel and Lew, Ben W. P. and Zhou, Yifan and Schneider, Glenn and Burgasser, Adam J. and Karalidi, Theodora and Miles-Páez, Paulo A. and Lowrance, Patrick J. and Cowan, Nicolas and Bedin, Luigi R. and Marley, Mark S. and Metchev, Stan and Radigan, Jacqueline (2019) Cloud Atlas: Rotational Spectral Modulations and Potential Sulfide Clouds in the Planetary-mass, Late T-type Companion Ross 458C. Astrophysical Journal Letters, 875 (2). Art. No. L15. ISSN 2041-8213. doi:10.3847/2041-8213/ab13b9.

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Measurements of photometric variability at different wavelengths provide insights into the vertical cloud structure of brown dwarfs and planetary-mass objects. In seven Hubble Space Telescope consecutive orbits, spanning ~10 hr of observing time, we obtained time-resolved spectroscopy of the planetary-mass T8 dwarf Ross 458 C using the near-infrared Wide Field Camera 3. We found spectrophotometric variability with a peak-to-peak signal of 2.62 ± 0.02% (in the 1.10–1.60 μm white light curve). Using three different methods, we estimated a rotational period of 6.75 ± 1.58 hr for the white light curve, and similar periods for narrow J- and H-band light curves. Sine wave fits to the narrow J- and H-band light curves suggest a tentative phase shift between the light curves with wavelength when we allow different periods between both light curves. If confirmed, this phase shift may be similar to the phase shift detected earlier for the T6.5 spectral type 2MASS J22282889–310262. We find that, in contrast with 2M2228, the variability of Ross 458C shows evidence for a color trend within the narrow J-band, but gray variations in the narrow H-band. The spectral time-resolved variability of Ross 458C might be potentially due to heterogeneous sulfide clouds in the atmosphere of the object. Our discovery extends the study of spectral modulations of condensate clouds to the coolest T-dwarf, planetary-mass companions.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Manjavacas, Elena0000-0003-0192-6887
Apai, Dániel0000-0003-3714-5855
Lew, Ben W. P.0000-0003-1487-6452
Zhou, Yifan0000-0003-2969-6040
Schneider, Glenn0000-0002-4511-5966
Burgasser, Adam J.0000-0002-6523-9536
Karalidi, Theodora0000-0001-7356-6652
Miles-Páez, Paulo A.0000-0003-2446-8882
Lowrance, Patrick J.0000-0001-8014-0270
Cowan, Nicolas0000-0001-6129-5699
Bedin, Luigi R.0000-0003-4080-6466
Marley, Mark S.0000-0002-5251-2943
Metchev, Stan0000-0003-3050-8203
Radigan, Jacqueline0000-0002-6732-3651
Additional Information:© 2019 The American Astronomical Society. Received 2019 January 29; revised 2019 March 25; accepted 2019 March 25; published 2019 April 16. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555, under GO-14241. 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
NASANAS 5-26555
Subject Keywords:brown dwarfs – stars: atmospheres
Issue or Number:2
Record Number:CaltechAUTHORS:20190418-105239660
Persistent URL:
Official Citation:Elena Manjavacas et al 2019 ApJL 875 L15
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94786
Deposited By: Tony Diaz
Deposited On:18 Apr 2019 18:09
Last Modified:16 Nov 2021 17:07

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