Fast-evolving weather for the coolest of our two new substellar neighbours

Author： Gillon M. Triaud A. H. M. J. Jehin E. Delrez L. Opitom C. Magain P. Lendl M. Queloz D.

E-ISSN： 1432-0746|555|issue|L5-L5

ISSN： 0004-6361

Source： Astronomy & Astrophysics, Vol.555, Iss.issue, 2013-07, pp. : L5-L5

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Abstract

We present the results of intense photometric monitoring in the near-infrared (~0.9 μm) with the TRAPPIST robotic telescope of the newly discovered binary brown dwarf WISE J104915.57-531906.1, the third closest system to the Sun at a distance of only 2 pc. Our twelve nights of time-series photometry reveal a quasi-periodic (P = 4.87 ± 0.01h) variability with a maximum peak-peak amplitude of ~11% and strong night-to-night evolution. We attribute this variability to the rotational modulation of fast-evolving weather patterns in the atmosphere of the coolest component (~T1-type) of the binary. No periodic signal is detected for the hottest component (~L8-type). For both brown dwarfs, our data allow us to firmly discard any unique transit during our observations for planets ≥2 R_⊕. For orbital periods smaller than ~9.5 h, transiting planets are excluded down to an Earth-size.