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Clouds and Clearings in the Atmospheres of the L and T Dwarfs

Published online by Cambridge University Press:  26 May 2016

M. S. Marley ,
A. S. Ackerman ,
A. J. Burgasser ,
D. Saumon ,
K. Lodders  and
R. Freedman
M. S. Marley
Affiliation:
Space Sciences Division, Mail Stop 245–3, NASA Ames Research Center, Moffett Field, CA 94035
A. S. Ackerman
Affiliation:
Earth Sciences Division, Mail Stop 245–4, NASA Ames Research Center, Moffett Field, CA 94035
A. J. Burgasser
Affiliation:
Hubble Fellow, Department of Astronomy & Astrophysics, UCLA, Los Angeles, CA 90095–1562
D. Saumon
Affiliation:
Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235
K. Lodders
Affiliation:
Dept. of Earth & Planetary Science, Washington University, St. Louis, MO 63130
R. Freedman
Affiliation:
SETI Institute, NASA Ames Research Center, Moffett Field, CA 94035

Abstract

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A sophisticated approach to condensate opacity is required to properly model the atmospheres of L and T dwarfs. Here we review different models for the treatment of condensates in brown dwarf atmospheres. We conclude that models which include both particle sedimentation and upwards transport of condensate (both gas and particles) provide the best fit for the L dwarf colors. While a globally uniform cloud model fits the L dwarf data, it turns to the blue in J - K too slowly to fit the T dwarfs. Models which include local clearings in the global cloud deck, similar to Jupiter's prominent five-micron hot spots, better reproduce the available photometric data and also account for the observed resurgence of FeH absorption in early type T dwarfs.

Type
Part 7. Atmospheres and Internal Structure
Information
Symposium - International Astronomical Union , Volume 211: Brown Dwarfs , 2003 , pp. 333 - 344
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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