If there is lots of mass wouldn't that mean brown dwarfs have enough gravitational force to ignite nuclear fusion? are brown dwarfs just unable to ignite nuclear fusion because there is not enough heat?
Illustration by Jon Lomberg, University of Toronto
Published September 13, 2011
A colossal storm grander than anything yet seen in our solar system may have been discovered on a cool brown dwarf, according to a new study.
Sitting about 47 light-years away, the brown dwarf is considered to be a failed star—a transitional object between gas-giant planets and stars.
Even though they range from 10 to 80 times Jupiter's mass, brown dwarfs aren't massive enough to sustain nuclear fusion and shine like stars.
"There has been some debate about how to picture a brown dwarf atmosphere and about whether clouds are mostly uniform or patchy," Radigan said.
"This work shows that at least some brown dwarf atmospheres have complex cloud patterns, perhaps similar to those on Jupiter."
In fact, the failed star appears to have a dark storm akin to Jupiter's Great Red Spot.
Brown Dwarf Boasts Cosmic Hurricane?
Using a telescope fitted with an infrared camera at the Carnegie Institution of Washington's Las Campanas Observatory in Chile, astronomers took pictures over several hours of the brown dwarf, dubbed 2MASS J21392676+0220226.
In that relatively short time span, the team recorded a 30-percent change in the object's brightness—the largest light variation yet seen on a brown dwarf.
Radigan and her team have not been able to make an image of the object's surface. But they believe that the observed brightness variations may be evidence of temperature gradients associated with large-scale cloud features, such as swirling storms.
"If we attribute all the variability to a single spot—a hurricane-like feature, for example—it would have to cover 15 to 35 percent of a visible hemisphere, so possibly quite a bit bigger than Jupiter's Great Red Spot," Radigan said.
(Related picture: "Jupiter Gains New Red Spot.")
Tracking Weather on Other Worlds
The discovery of such an extreme storm could affect our understanding of atmospheric dynamics not only on brown dwarfs but also on giant planets outside the solar system.
For instance, studies of the brown dwarf could help astronomers figure out where exactly cloud bands form in brown-dwarf and alien-planet atmospheres, as well as refine theories of atmospheric winds and circulation, Radigan said.
Tracking down stormy weather patterns on extrasolar planets, however, will be challenging with current technology.
"Because the light [signatures] of these planets are washed out by light from the host stars, they are much more difficult to observe," Radigan said.
"Nonetheless, for a small number of the brightest and widest-separation planets"—those orbiting farther from their stars—"detection of a 30-percent variation in brightness would certainly be possible using current eight- to ten-meter class telescopes."
The research on the brown dwarf's huge storm will be presented at the Extreme Solar Systems II meeting, held this week in Moran, Wyoming.
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