dc.contributor.author | Tremblin, Pascal | |
dc.contributor.author | Amundsen, David S. | |
dc.contributor.author | Chabrier, G. | |
dc.contributor.author | Baraffe, I. | |
dc.contributor.author | Drummond, B. | |
dc.contributor.author | Hinkley, Sasha | |
dc.contributor.author | Mourier, P. | |
dc.contributor.author | Venot, O. | |
dc.date.accessioned | 2016-02-22T15:17:17Z | |
dc.date.issued | 2016-01-28 | |
dc.description.abstract | 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. | en_GB |
dc.description.sponsorship | European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013) | en_GB |
dc.description.sponsorship | Royal Society award | en_GB |
dc.description.sponsorship | KU Leuven IDO project | en_GB |
dc.description.sponsorship | FWO Postdoctoral Fellowship programme. | en_GB |
dc.identifier.citation | Astrophysical Journal Letters, 2016, Volume 817, Number 2 | en_GB |
dc.identifier.doi | 10.3847/2041-8205/817/2/L19 | |
dc.identifier.grantnumber | 247060 | en_GB |
dc.identifier.grantnumber | 247060-PEPS | en_GB |
dc.identifier.grantnumber | 320478-TOFU | en_GB |
dc.identifier.grantnumber | WM090065 | en_GB |
dc.identifier.grantnumber | IDO/10/2013 | en_GB |
dc.identifier.uri | http://hdl.handle.net/10871/20047 | |
dc.language.iso | en | en_GB |
dc.publisher | American Astronomical Society | en_GB |
dc.relation.url | http://dx.doi.org/10.3847/2041-8205/817/2/L19 | en_GB |
dc.relation.url | http://arxiv.org/abs/1601.03652v1 | en_GB |
dc.rights | © 2016. The American Astronomical Society. All rights reserved. | en_GB |
dc.subject | astro-ph.EP | en_GB |
dc.subject | astro-ph.EP | en_GB |
dc.subject | astro-ph.SR | en_GB |
dc.title | Cloudless atmospheres for L/T dwarfs and extra-solar giant planets | en_GB |
dc.type | Article | en_GB |
dc.date.available | 2016-02-22T15:17:17Z | |
dc.identifier.issn | 2041-8205 | |
dc.description | Accepted in ApJL, comments welcome | en_GB |
dc.identifier.journal | Astrophysical Journal Letters | en_GB |