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Model atmospheres and spectra: The role of dust

Allard, F; Guillot, T; Ludwig, Hans-Günter LU ; Hauschildt, P H; Schweitzer, A; Alexander, DR and Ferguson, JW (2003) 211th Symposium of the International Astronomical Union In Proceedings of the International Astronomical Union (Brown Dwarfs) 211. p.325-332
Abstract
Brown dwarf atmospheres form molecules, then high temperature condensates (corundum, titanates, silicates, and iron compounds), and then low temperature condensates (ices) as they cool down over time. These produce large opacities which govern entirely their spectral energy distribution. Just as it is important to know molecular opacities (TiO, H2O, CH4, etc.) with accuracy, it is imperative to understand the interplay of processes (e.g. condensation, sedimentation, coagulation, convection) that determines the radial and size distribution of grains. Limiting case models have shown that young, hot brown (L) dwarfs form dust mostly in equilibrium, while at much cooler stages (late T dwarfs) all high temperature condensates have sedimented... (More)
Brown dwarf atmospheres form molecules, then high temperature condensates (corundum, titanates, silicates, and iron compounds), and then low temperature condensates (ices) as they cool down over time. These produce large opacities which govern entirely their spectral energy distribution. Just as it is important to know molecular opacities (TiO, H2O, CH4, etc.) with accuracy, it is imperative to understand the interplay of processes (e.g. condensation, sedimentation, coagulation, convection) that determines the radial and size distribution of grains. Limiting case models have shown that young, hot brown (L) dwarfs form dust mostly in equilibrium, while at much cooler stages (late T dwarfs) all high temperature condensates have sedimented out of their photospheres. But this process is gradual and all intermediate classes of brown dwarfs can partly be understood in terms of partial sedimentation of dust. With new models accounting for these processes, we describe the effects they may have upon brown dwarf spectral properties. (Less)
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author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
in
Proceedings of the International Astronomical Union (Brown Dwarfs)
editor
Martín, Eduardo L. and
volume
211
pages
325 - 332
publisher
Astronomical Society of the Pacific
conference name
211th Symposium of the International Astronomical Union
external identifiers
  • wos:000184043700071
ISSN
0074-1809
ISBN
ISBN:1-58381-132-X
language
English
LU publication?
yes
id
31e6f6e9-a18c-44f8-9ca1-26ca5e748a84 (old id 306853)
date added to LUP
2007-08-22 09:10:39
date last changed
2016-04-16 04:10:04
@inproceedings{31e6f6e9-a18c-44f8-9ca1-26ca5e748a84,
  abstract     = {Brown dwarf atmospheres form molecules, then high temperature condensates (corundum, titanates, silicates, and iron compounds), and then low temperature condensates (ices) as they cool down over time. These produce large opacities which govern entirely their spectral energy distribution. Just as it is important to know molecular opacities (TiO, H2O, CH4, etc.) with accuracy, it is imperative to understand the interplay of processes (e.g. condensation, sedimentation, coagulation, convection) that determines the radial and size distribution of grains. Limiting case models have shown that young, hot brown (L) dwarfs form dust mostly in equilibrium, while at much cooler stages (late T dwarfs) all high temperature condensates have sedimented out of their photospheres. But this process is gradual and all intermediate classes of brown dwarfs can partly be understood in terms of partial sedimentation of dust. With new models accounting for these processes, we describe the effects they may have upon brown dwarf spectral properties.},
  author       = {Allard, F and Guillot, T and Ludwig, Hans-Günter and Hauschildt, P H and Schweitzer, A and Alexander, DR and Ferguson, JW},
  booktitle    = {Proceedings of the International Astronomical Union (Brown Dwarfs)},
  editor       = {Martín, Eduardo L.},
  isbn         = {ISBN:1-58381-132-X},
  issn         = {0074-1809},
  language     = {eng},
  pages        = {325--332},
  publisher    = {Astronomical Society of the Pacific},
  title        = {Model atmospheres and spectra: The role of dust},
  volume       = {211},
  year         = {2003},
}