The professors were able to shed light on the structure of brown dwarfs.
Dim astronomical objects called brown dwarfs, less massive than our Sun but more massive gas giant Jupiter. They have the atmosphere with strong winds and massive clouds spotted form and consisting mainly of droplets of molten iron and silicate dust. Recently, it was found that these giant clouds can very quickly (in less than one earth day) to build up and just as quickly dissipate. But the researchers don’t understand why this is happening.
In the framework of the new analysis of data collected by space telescope “Spitzer”, an international group of scientists could create a model explaining how clouds brown dwarfs move and change its shape. Objects created by these giant waves start very large-scale motion of the particles in the atmosphere of brown dwarfs, changing the thickness of silicate clouds. This researchers reported in the journal Science. The report also assumes that these clouds congregate together at different heights, moving at different speeds and direction.
“We first observed atmospheric flows and waves in brown dwarfs,” said the study’s author, Daniel Apai, associate Professor of astronomy and planetary science the University of Arizona.
Waves can be formed not only on the water, as, for example, in our seas and oceans but in the atmosphere of the planets. If you take our planet, it is very long wave mixed cold air of the polar regions with air masses in the middle latitudes, which often leads either to the appearance or the dissipation of clouds.
The distribution and movement of clouds in brown dwarfs, which became the objects of this study were most similar to those that scientists observed on Jupiter, Saturn and Neptune. The latter also has several air streams which move in the opposite direction, but they consist mainly of ice. Observation of Neptune with a space telescope “Kepler” was the key in this comparison between planets and brown dwarfs.
“Atmospheric wind brown dwarfs is very similar to Jupiter’s belts and zones than on the chaotic atmospheric formation observed in the Sun and many other stars,” adds study co-author mark Marley of the Ames Research center of NASA.
Brown dwarfs can be considered as failed stars, because their mass is too small to support chemical reactions of elements in their cores. But they can also be seen as “superplanet”, as they are more massive than Jupiter, but have approximately the same diameter. As gas giants, brown dwarfs are mostly composed of hydrogen and helium, but they are quite often found outside any planetary system. And in 2014, in the framework of the research conducted with the use of a space telescope “Spitzer” scientists have found that brown dwarfs are quite often raging atmospheric storms.
Due to their similarity to giant exoplanets brown dwarfs can be a window into other planetary systems. However, these objects are much easier to study because they usually don’t have a real bright star, difficult observation, as is often the case with exoplanets.
“It is possible that those atmospheric flows, and waves that we found in brown dwarfs, it be frequent for the more ordinary giant exoplanets”, adds API.
Using “Spitzer”, scientists have been observing the change of luminosity of the six brown dwarfs for almost a year and a half, after witnessing the 32 revolutions around its axis of each of them. As the rotation of the brown dwarf it clouds appear, then disappear in the hemisphere, is watching in the telescope that changes its brightness. Due to this, scientists were able to analyze these changes in light to determine how the distribution of silicate clouds in the atmosphere of such objects.
Previously, scientists had assumed that brown dwarfs would be elliptical storm similar to the Great red spot of Jupiter, caused and maintained by the zones of high pressure. The spot is on Jupiter for over a hundred years and during that time little has changed. But these “spots” are unable to explain such rapid changes in brightness, that was observed by scientists in the study of brown dwarfs. Note the changes occurred in less than one earth day.
To get to the truth, scientists had to reconsider their assumption. And the best model that would explain such behavior, and sudden changes in luminosity, turned out to be the one that describes a huge atmospheric waves, which manifests itself with different intervals. These waves cause the atmospheric flow to rotate in opposite directions. A supercomputer and a new computer algorithm helped the researcher Arizona state University Theodore, Karaleti to create a map of the movement of the clouds in brown dwarfs.
“When the peaks of two waves shifted, during the day there is two points maximum brightness. When the waves are synchronized, it turns out one of the peak brightness (one wave), which makes brown dwarfs are twice as bright,” says Karaleti.
These results fully explain the strange change in brightness that was observed by scientists during the study of brown dwarfs. The next step will be to attempt to better understand what creates waves that trigger the movement of atmospheric masses of these objects.