Cloud properties of Nearest Brown Dwarfs Revealed through Spectral Monitoring Study

starweatherWe’ve just reported the first results from our April 2013  campaign to monitor the nearby brown dwarf binary Luhman 16AB, in a paper published in the Astrophysical Journal.  Our results confirm the earlier “flux reversal” seen in FIRE spectroscopy, and allow us to make the first constraints on the cloud coverage fraction and the temperatures of the “clouds” and “holes” in the atmosphere of Luhman 16B.  We also confirm an apparent correlation between rotation period and variability amplitude, which may emerge if cloud features are related to the Rhine’s scale of brown dwarf atmospheres.

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Observations of Luhman 16AB: A Brown Dwarf Binary at 2 pc

Early in March 2013, Kevin Luhman announced his discovery of a pair of brown dwarfs only 2 pc (6 light-years) from the Sun, the 3rd closest system to us after the α/Proxima Centauri system and Barnard’s Star. This remarkable find was buried in survey data going back 35 years, but elucidated with the mid-infrared sensitivity of the Wide-field Infrared Survey Explorer (WISE) and the object’s very high proper motion (2.8 arcseconds/year, or just under 0.1 degrees/century).  Using optical spectroscopy, Luhman found that the brighter of the two components had a late-L spectral type, suggesting that the system might straddle the transition between L dwarf and T dwarf spectral classes.  Knowing home much we like this really cool transition, we jumped into action.

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