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arXiv · 1310.5144

Weather on the Nearest Brown Dwarfs: Resolved Simultaneous Multi-Wavelength Variability Monitoring of WISE J104915.57-531906.1AB

Beth A. Biller·Ian J. M. Crossfield·Luigi Mancini·Simona Ciceri·John Southworth·Taisiya G. Kopytova·Mickaël Bonnefoy·Niall R. Deacon·Joshua E. Schlieder·Esther Buenzli·Wolfgang Brandner·France Allard·Derek Homeier·Bernd Freytag·Coryn A. L. Bailer-Jones·Jochen Greiner·Thomas Henning·Bertrand Goldman
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Abstract

We present two epochs of MPG/ESO 2.2m GROND simultaneous 6-band ($r'i'z'JHK$) photometric monitoring of the closest known L/T transition brown dwarf binary WISE J104915.57-531906.1AB. We report here the first resolved variability monitoring of both the T0.5 and L7.5 components. We obtained 4 hours of focused observations on the night of UT 2013-04-22, as well as 4 hours of defocused (unresolved) observations on the night of UT 2013-04-16. We note a number of robust trends in our light curves. The $r'$ and $i'$ light curves appear to be anticorrelated with $z'$ and $H$ for the T0.5 component and in the unresolved lightcurve. In the defocused dataset, $J$ appears correlated with $z'$ and $H$ and anticorrelated with $r'$ and $i'$, while in the focused dataset we measure no variability for $J$ at the level of our photometric precision, likely due to evolving weather phenomena. In our focused T0.5 component lightcurve, the $K$ band lightcurve displays a significant phase offset relative to both $H$ and $z'$. We argue that the measured phase offsets are correlated with atmospheric pressure probed at each band, as estimated from 1D atmospheric models. We also report low-amplitude variability in $i'$ and $z'$ intrinsic to the L7.5 component.

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Beth A. Biller, Ian J. M. Crossfield, Luigi Mancini, Simona Ciceri, John Southworth, Taisiya G. Kopytova, Mickaël Bonnefoy, Niall R. Deacon, Joshua E. Schlieder, Esther Buenzli, Wolfgang Brandner, France Allard, Derek Homeier, Bernd Freytag, Coryn A. L. Bailer-Jones, Jochen Greiner, Thomas Henning, Bertrand Goldman. 2013-10-18. Weather on the Nearest Brown Dwarfs: Resolved Simultaneous Multi-Wavelength Variability Monitoring of WISE J104915.57-531906.1AB. https://doi.org/10.1088/2041-8205%2F778%2F1%2Fl10

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