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

Beth Biller, Ian Crossfield, Luigi Mancini, Simona Ciceri, John Southworth, Taisiya Kopytova, Mickaël Bonnefoy, Niall Deacon, Joshua Schlieder, Esther Buenzli, Wolfgang Brandner, France Allard, Derek Homeier, Bernd Freytag, Coryn Bailer-Jones, Jochen Greiner, Thomas Henning

Research output: Contribution to journalArticlepeer-review

Abstract

We present two epochs of MPG/ESO 2.2 m GROND simultaneous six-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 hr of focused observations on the night of 2013 April 22 (UT), as well as 4 hr of defocused (unresolved) observations on the night of 2013 April 16 (UT). We note a number of robust trends in our light curves. The r' and i' light curves appear to be anti-correlated with z' and H for the T0.5 component and in the unresolved light curve. In the defocused dataset, J appears correlated with z' and H and anti-correlated 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 light curve, the K band light curve 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 one-dimensional atmospheric models. We also report low-amplitude variability in i' and z' intrinsic to the L7.5 component.
Original languageEnglish
Pages (from-to)10
Number of pages6
JournalAstrophysical Journal Letters
Volume778
Issue number1
Publication statusPublished - Nov 2013

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