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Title: INDICATIONS OF WATER CLOUDS IN THE COLDEST KNOWN BROWN DWARF

We present a deep near-infrared image of the newly discovered brown dwarf WISE J085510.83-071442.5 (W0855) using the FourStar imager at Las Campanas Observatory. Our detection of J3 = 24.8{sub −0.35}{sup +0.53} (J {sub MKO} = 25.0{sub −0.35}{sup +0.53}) at 2.6σ—or equivalently an upper limit of J3 > 23.8 (J {sub MKO} > 24.0) at 5σ makes W0855 the reddest brown dwarf ever categorized (J {sub MKO} – W2 = 10.984{sub −0.35}{sup +0.53} at 2.6σ—or equivalently an upper limit of J {sub MKO} – 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.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015 (United States)
  2. School of Physics, UNSW Australia, Sydney, NSW 2052 (Australia)
  3. Steward Observatory, Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States)
  4. Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101 (United States)
Publication Date:
OSTI Identifier:
22364981
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 793; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CLOUDS; COLOR; COMPARATIVE EVALUATIONS; DWARF STARS; EQUILIBRIUM; ICE; MASS; METALLICITY; PHOTOMETRY; PROPER MOTION; SOLAR SYSTEM; STAR MODELS; STARS; STELLAR ATMOSPHERES; WATER