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Astronomers have detected a giant storm on the surface of a low mass L-dwarf star:
Astronomers have discovered what appears to be a tiny star with a giant, cloudy storm, using data from NASA's Spitzer and Kepler space telescopes. The dark storm is akin to Jupiter's Great Red Spot: a persistent, raging storm larger than Earth.
"The star is the size of Jupiter, and its storm is the size of Jupiter's Great Red Spot," said John Gizis of the University of Delaware, Newark. "We know this newfound storm has lasted at least two years, and probably longer." Gizis is the lead author of a new study appearing in The Astrophysical Journal.
While planets have been known to have cloudy storms, this is the best evidence yet for a star that has one. The star, referred to as W1906+40, belongs to a thermally cool class of objects called L-dwarfs. Some L-dwarfs are considered stars because they fuse atoms and generate light, as our sun does, while others, called brown dwarfs, are known as "failed stars" for their lack of atomic fusion.
[...] Spitzer has observed other cloudy brown dwarfs before, finding evidence for short-lived storms lasting hours and perhaps days.
In the new study, the astronomers were able to study changes in the atmosphere of W1906+40 for two years. The L-dwarf had initially been discovered by NASA's Wide-field Infrared Survey Explorer in 2011. Later, Gizis and his team realized that this object happened to be located in the same area of the sky where NASA's Kepler mission had been staring at stars for years to hunt for planets.
WISEP J190648.47+401106.8, also known as W1906+40.
Kepler Monitoring of an L Dwarf II. Clouds with Multiyear Lifetimes
(Score: 0) by Anonymous Coward on Monday December 14 2015, @09:39AM
We observe sunspots rather than clouds on the nearest star. Can anyone explain why they choose clouds over starspots as an explanation?
(Score: 2, Informative) by Drake_Edgewater on Monday December 14 2015, @11:55AM
From the article [nasa.gov], the infrared light detected using Spitzer allowed them to distinguish clouds over starspots
Follow-up observations with Spitzer, which detects infrared light, revealed that the dark patch was not a magnetic star spot but a colossal, cloudy storm with a diameter that could hold three Earths.
It seems that brown dwarfs are closer to a Jupiter-like object than a star https://en.wikipedia.org/wiki/Brown_dwarf#/media/File:BrownDwarfComparison-pia12462.jpg [wikipedia.org]
(Score: 3, Interesting) by khallow on Monday December 14 2015, @12:09PM
The subsequent identification of many field counterparts to GD 165B ultimately led Kirkpatrick and others to the definition of a new spectral class, the L dwarfs, defined in the red optical region not by weakening metal-oxide bands (TiO, VO), but strong metal hydride bands (FeH, CrH, MgH, CaH) and prominent alkali metal lines (Na I, K I, Cs I, Rb I).
The surface temperature of this particular star is a bit above 2000 C which means that it's around the boiling point of iron at 1% the pressure of atmosphere (see this diagram [wikipedia.org]). The diagram I just linked to also shows that iron also shows that iron's boiling/sublimation temperature varies greatly by pressure. If other metals do this as well, then that would explain how the cloud forms with condensation or freezing happening as soon as the pressure gets high enough or temperature low enough. I imagine the dynamics are radically different due to the huge temperature difference, the large variety of possible elements in the cloud, and the presence of strong magnetic fields.