Dust in Brown Dwarfs I. Dust formation under turbulent conditions on microscopic scales

Abstract

Dust formation in turbulent media is studied adopting the example of brown dwarf atmospheres. By combining asymptotic techniques and time-dependent, multi-dimensional numerical simulations, we show that acoustic waves originating from convective motions provide a mechanism to initiate dust nucleation in otherwise dust-hostile environments. The subsequently growing particles cause a radiative cooling strong enough to re-initiate efficient dust formation resulting in a strongly inhomogeneous distribution of dust in such environments. Recent observations bear indications for such cloudy dust distributions in brown dwarf atmospheres.