Brown Dwarf Weather Map Shows A Stormy Atmosphere
January 9, 2013

NASA Space Telescopes Used To Create Detailed Brown Dwarf Weather Map

redOrbit Staff & Wire Reports - Your Universe Online

By using the Hubble and Spitzer space telescopes, NASA officials say they have managed to complete the most detailed weather map to date for the cool, planet-like stars known as brown dwarfs.

Brown dwarfs, which are also sometimes known as failed stars, form out of condensing gas but do not have the mass in order to fuse hydrogen atoms and produce energy, officials from the US space agency explained in a recent statement. As a result, they tend to have atmospheres that are complex and varied, much like gas planets.

“The new research is a stepping stone toward a better understanding not only of brown dwarfs, but also of the atmospheres of planets beyond our solar system,” NASA added.

In an attempt to compile the weather map, astronomers turned their space telescopes to a brown dwarf known as 2MASSJ22282889-431026. They discovered that the light it gave off varied, getting brighter or dimmer every 90 minutes or so as the star rotated. Furthermore, the researchers found that the timing of that change depended upon which wavelengths of infrared light they were using to view it.

The variations are reportedly caused by different areas of material, swirling around the brown dwarf in windy storms said to be as large as our entire planet. The two space telescopes, however, can see different layers of the atmosphere because some types of infrared wavelengths are blocked by methane and water vapor, while others emerge from deeper layers.

Principle investigator Daniel Apai, from the University of Arizona, compared the process to the way doctors use different types of imaging techniques to study different types of human tissue.

Apai presented the team´s findings Tuesday at a meeting of the American Astronomical Society in Long Beach, California. A paper detailing the research also appears in The Astrophysical Journal Letters.

Even though brown dwarfs are said to be cool stars, they are actually quite hot in comparison to what we´re used to here on Earth, the researchers explained. Their subject, 2MASSJ22282889-431026, reached temperatures of 1,100 to 1,300 degrees Fahrenheit (600 to 700 degrees Celsius), lead researcher Esther Buenzli said.

“Unlike the water clouds of Earth or the ammonia clouds of Jupiter, clouds on brown dwarfs are composed of hot grains of sand, liquid drops of iron, and other exotic compounds," Mark Marley, a research scientist at NASA's Ames Research Center and a co-author of the paper, said in a separate statement. "So this large atmospheric disturbance found by Spitzer and Hubble gives a new meaning to the concept of extreme weather."

"What we see here is evidence for massive, organized cloud systems, perhaps akin to giant versions of the Great Red Spot on Jupiter," added research participant Adam Showman, also of the University of Arizona. "These out-of-sync light variations provide a fingerprint of how the brown dwarf's weather systems stack up vertically. The data suggest regions on the brown dwarf where the weather is cloudy and rich in silicate vapor deep in the atmosphere coincide with balmier, drier conditions at higher altitudes -- and vice versa."

The team now plans to use Spitzer and Hubble to study the atmosphere of several other brown dwarfs in the same region. According to NASA Spitzer Program scientist Glenn Wahlgren, studies like these will help the US space agency “learn much about this important class of objects, whose mass falls between that of stars and Jupiter-sized planets“¦ This technique will see extensive use when we are able to image individual exoplanets."

Image 2 (below): This artist's conception illustrates the brown dwarf named 2MASSJ22282889-431026. NASA's Hubble and Spitzer space telescopes observed the object to learn more about its turbulent atmosphere. Brown dwarfs are more massive and hotter than planets but lack the mass required to become sizzling stars. Their atmospheres can be similar to the giant planet Jupiter's. Image credit: NASA/JPL-Caltech