Webb telescope detects changing water clouds on coldest known brown dwarf 7.5 light-years away
A team led by Brittany Miles of the University of Arizona Steward Observatory used the James Webb Space Telescope to watch WISE 0855, the coldest known brown dwarf, over 11 hours. The study, published in The Astrophysical Journal, reports the first direct confirmation that water clouds on another body thicken and thin over time, alongside deep gases churned upward by convection. The researchers say the two signals could now be separated, which older telescopes could not do.
Bottom line — Miles argues the Jupiter-like physics seen on WISE 0855 may apply to gas giant exoplanets now being studied with Webb.
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Miles said that before Webb, observations gave only photometry, which mixed the effects of clouds, chemistry and temperature together.
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Co-author Mark Marley, of the University of Arizona's Lunar and Planetary Laboratory, compared the atmosphere to a screen door that filters the light astronomers see.
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The researchers tracked carbon monoxide and phosphine, whose fluctuations they attribute to heat from the object's interior churning gases upward.
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Miles described the paper as a generational milestone, crediting Marley's mentorship and the atmospheric models that were benchmarked against Jupiter.
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Miles plans further baseline observations with Webb to refine WISE 0855's rotation and three-dimensional atmospheric movement.