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Post Info TOPIC: WISE J085510.83-071442.5
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RE: WISE J085510.83-071442.5
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Title: A New Parallax Measurement for the Coldest Known Brown Dwarf
Author: K. L. Luhman, T. L. Esplin

WISE J085510.83-071442.5 was recently discovered as the coldest known brown dwarf based on four epochs of images from the Wide-field Infrared Survey Explorer and the Spitzer Space Telescope. We have improved the accuracy of its parallax measurement by obtaining two additional epochs of Spitzer astrometry. We derive a parallactic distance of 2.31±0.08 pc, which continues to support its rank as the fourth closest known system to the Sun when compared to WISE J104915.57-531906.1 AB (2.02±0.02 pc) and Wolf 359 (2.386±0.012 pc). The new constraint on the absolute magnitude at 4.5um indicates an effective temperature of 235-260 K based on four sets of theoretical models. We also show the updated positions of WISE J085510.83-071442.5 in two color-magnitude diagrams. Whereas Faherty and coworkers cited its location in MW2 versus J-W2 as evidence of water clouds, we find that those data can be explained instead by cloudless models that employ non-equilibrium chemistry.

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First Evidence for Water Ice Clouds Found outside Solar System

A team of scientists led by Carnegie's Jacqueline Faherty has discovered the first evidence of water ice clouds on an object outside of our own Solar System. Water ice clouds exist on our own gas giant planets--Jupiter, Saturn, Uranus, and Neptune--but have not been seen outside of the planets orbiting our Sun until now.
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Title: Indications of Water Clouds in the Coldest Known Brown Dwarf
Author: Jacqueline K. Faherty, C.G. Tinney, Andrew Skemer, Andrew J. Monson
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Title: Indications of Water Clouds in the Coldest Known Brown Dwarf
Author: Jacqueline K. Faherty, C.G. Tinney, Andrew Skemer, Andrew J. Monson

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+0.33 -0.53 (J_MKO=25.0+0.33-0.53) at 2.6sigma -- or equivalently an upper limit of J3 > 23.8 (J_MKO > 24.0) at 5sigma makes W0855 the reddest brown dwarf ever categorized (J_MKO - W2 = 10.984+0.33 - 0.53 at 2.6sigma -- or equivalently an upper limit of J_MKO - W2 > 9.984 at 5sigma) and refines its position on color magnitude diagrams. Comparing the new photometry with chemical equilibrium model atmosphere predictions, we demonstrate that W0855 is 4.5sigma 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.

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NASA's Spitzer and WISE Telescopes Find Close, Cold Neighbour of Sun

NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope have discovered what appears to be the coldest "brown dwarf" known -- a dim, star-like body that, surprisingly, is as frosty as Earth's North Pole.
Images from the space telescopes also pinpointed the object's distance to 7.2 light-years away, earning it the title for fourth closest system to our sun. The closest system, a trio of stars, is Alpha Centauri, at about 4 light-years away.
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