Indications of water clouds in the coldest known brown dwarf

Jacqueline K. Faherty, C. G. Tinney, Andrew Skemer, Andrew J. Monson

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30 Scopus citations


We present a deep near-infrared image of the newly discovered brown dwarfWISE J085510.83-071442.5 (W0855) using the FourStar imager at Las Campanas Observatory. Our detection of J 3 = 24.8+0.53-0.35 (JMKO = 25.0+0.53-0.35) at 2.6σ- or equivalently an upper limit of J 3 > 23.8 (JMKO > 24.0) at 5σ makes W0855 the reddest brown dwarf ever categorized (JMKO - W2 = 10.984+0.53-0.35 at 2.6σ- or equivalently an upper limit of JMKO - W2 > 9.984 at 5σ) and refines its position on color-magnitude diagrams. Comparing the new photometry with chemical equilibrium model atmosphere predictions, we demonstrate that W0855 is 2.7σ from models using a cloudless atmosphere and well reproduced by partly cloudy models (50%) containing sulfide and water ice clouds. Non-equilibrium chemistry or non-solar metallicity may change predictions, however using currently available model approaches, this is the first candidate outside our own solar system to have direct evidence for water clouds.

Original languageEnglish (US)
Article numberL16
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Sep 20 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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