Publication Abstracts
Tremblin et al. 2016
Tremblin, P., , G. Chabrier, I. Baraffe, B. Drummond, S. Hinkley, P. Mourier, and O. Venot, 2016: Cloudless atmospheres for L/T dwarfs and extra-solar giant planets. Astrophys. J. Lett., 817, L19, doi:10.3847/2041-8205/817/2/L19.
The admitted, conventional scenario to explain the complex spectral evolution of brown dwarfs (BD) since their first detections twenty years ago, has always been the key role played by micron-size condensates, called "dust" or "clouds", in their atmosphere. This scenario, however, faces major problems, in particular the J-band brightening and the resurgence of FeH absorption at the L to T transition, and a physical first-principle understanding of this transition is lacking. In this paper, we propose a new, completely different explanation for BD and extrasolar giant planet (EGP) spectral evolution, without the need to invoke clouds. We show that, due to the slowness of the CO/CH4 and N2/NH3 chemical reactions, brown dwarf (L and T, respectively) and EGP atmospheres are subject to a thermo-chemical instability similar in nature to the fingering or chemical convective instability present in Earth oceans and at the Earth core/mantle boundary. The induced small-scale turbulent energy transport reduces the temperature gradient in the atmosphere, explaining the observed increase in near infrared J-H and J-K colors of L dwarfs and hot EGPs, while a warming up of the deep atmosphere along the L to T transition, as the CO/CH4 instability vanishes, naturally solves the two aforementioned puzzles, and provides a physical explanation of the L to T transition. This new picture leads to a drastic revision of our understanding of BD and EGP atmospheres and their evolution.
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BibTeX Citation
@article{tr06200a,
author={Tremblin, P. and Amundsen, D. S. and Chabrier, G. and Baraffe, I. and Drummond, B. and Hinkley, S. and Mourier, P. and Venot, O.},
title={Cloudless atmospheres for L/T dwarfs and extra-solar giant planets},
year={2016},
journal={Astrophys. J. Lett.},
volume={817},
pages={L19},
doi={10.3847/2041-8205/817/2/L19},
}
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RIS Citation
TY - JOUR ID - tr06200a AU - Tremblin, P. AU - Amundsen, D. S. AU - Chabrier, G. AU - Baraffe, I. AU - Drummond, B. AU - Hinkley, S. AU - Mourier, P. AU - Venot, O. PY - 2016 TI - Cloudless atmospheres for L/T dwarfs and extra-solar giant planets JA - Astrophys. J. Lett. VL - 817 SP - L19 DO - 10.3847/2041-8205/817/2/L19 ER -
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