Model atmospheres and spectra: The role of dust

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.

Guillot, T (författare)
Ludwig, Hans-GünterLund University,Lunds universitet,Astronomi - Genomgår omorganisation,Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation,Naturvetenskapliga fakulteten,Lund Observatory - Undergoing reorganization,Department of Astronomy and Theoretical Physics - Undergoing reorganization,Faculty of Science(Swepub:lu)astr-hl0 (författare)
Hauschildt, P H (författare)
Schweitzer, A (författare)
Alexander, DR (författare)
Ferguson, JW (författare)
Martín, Eduardo L. (redaktör/utgivare)
Astronomi - Genomgår omorganisationInstitutionen för astronomi och teoretisk fysik - Genomgår omorganisation (creator_code:org_t)

Ingår i:Proceedings of the International Astronomical Union (Brown Dwarfs)211, s. 325-3320074-1809158381132X

Av författaren/redakt...: Allard, F; Guillot, T; Ludwig, Hans-Gün ...; Hauschildt, P H; Schweitzer, A; Alexander, DR; visa fler...; Ferguson, JW; Martín, Eduardo ...; visa färre...

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