Evidence for cloud disruption in the l/t dwarf transition
May, 200212 pages
Published in:
- Astrophys.J.Lett. 571 (2002) L151-L154
e-Print:
- astro-ph/0205051 [astro-ph]
DOI:
View in:
Citations per year
Abstract: (arXiv)
Clouds of metal-bearing condensates play a critical role in shaping the emergent spectral energy distributions of the coolest classes of low-mass stars and brown dwarfs, L and T dwarfs. Because condensate clouds in planetary atmospheres show distinct horizontal structure, we have explored a model for partly cloudy atmospheres in brown dwarfs. Our model successfully reproduces the colors and magnitudes of both L and T dwarfs for the first time, including the unexpected brightning of the early- and mid-type T dwarfs at J-band, provided that clouds are rapidly removed from the photosphere at T_eff ~ 1200 K. The clearing of cloud layers also explains the surprising persistence and strengthening of gaseous FeH bands in early- and mid-type T dwarfs. The breakup of cloud layers is likely driven by convection in the troposphere, analogous to phenomena observed on Jupiter. Our results demonstrate that planetary-like atmospheric dynamics must be considered when examining the evolution of free-floating brown dwarfs.References(27)
Figures(0)