Publication Abstracts

Tremblin et al. 2016

Tremblin, P., D.S. Amundsen, 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

  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},
  journal={Astrophys. J. Lett.},

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RIS Citation

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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