Clouds, weather, and the L- to T-dwarf transition
Mark Marley & Andrew Ackerman
Institute:
NASA Ames Research Center
Contact Email: mmarley@mail.arc.nasa.gov
Abstract:
We will discuss the results of the application a new eddy sedimentation
model for cloud formation in substellar atmospheres to the problem of
the L- to T-dwarf transition. We find that a sinking cloud layer, as
described by the new model, accounts for the variation in J-K color
between the red L-dwarfs and the blue T-dwarfs. The rapidity of the
color change may be explained by the appearance of clearings in the
silicate cloud deck as it forms ever more deeply in the convective
atmosphere with lower effective temperature. Like Jupiter's five-micron
hot spots, relatively small holes in the cloud deck can substantially
contribute to the disk-averaged flux. Such clearings are likely
responsible for the variability observed in some late L-dwarfs. We will
also discuss the spectral signatures of clouds, chemistry, and the brown
dwarf effective temperature scale.
No manuscript was submitted to these Proceedings.
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"The Future of Cool-Star Astrophysics', 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.