Photospheric dust grains formation in brown dwarfs

We have constructed a grid of brown dwarf model atmospheres with T-eff less than or equal to 3000 K that includes (i) the formation of over 600 gas phase species, and 1000 liquids and crystals, and (ii) the opacities of corundum (Al2O3), iron, enstatite (MgSiO3) and forsterite (Mg2SiO4), as well as amorphous carbon and SIG. We confirm earlier findings of Tsuji, Ohnaka & Aoki (1996) that grains are abundant in the outer photospheric layers of red and brown dwarfs with spectral type later than M8. We identify hot temperature condensates including perovskite (CaTiO3) that depletes the photospheres of important absorbers including TiO, and we confirm the disappearance of TiO bands in the observed spectra of cool dwarfs.