For the first time astronomers were able to measure the average speed of the winds, surging at the equator a brown dwarf. She was 2293 kilometers per hour, which is an order of magnitude greater than in the case of Jupiter, which is consistent with theoretical predictions. Article published in the journal Science.
Brown dwarfs belong to the class of objects whose mass is much larger than gas giants but not sufficient to sustain thermonuclear “burning” of hydrogen, characteristic of the stars. However, they occur in fusion reactions involving the nuclei of deuterium and lithium. Typically, the masses of such objects are enclosed in the range from 13 to 72 Jupiter masses, and the typical temperature characteristic of the outer layers of brown dwarfs, does not exceed two thousand Kelvin, and sometimes can be less than 500 degrees Kelvin, so they have a deep red color (hence their name).
Periods of rotation around its own axis brown dwarfs ranges from several hours to days, which allows you to track the movement of various structures in the upper layers of their atmospheres, which will cause quasi-periodic changes in the brightness of the dwarf. For single brown dwarfs of spectral types L and T such changes can be seen in observations in the middle infrared range. Scientists are interested in the relationship between the zonal winds and the characters of atmospheric currents with the internal structure of the dwarf and how effectively it cools the atmosphere by radiation, such data needed to build models, both brown dwarfs and exoplanets.
A team of astronomers headed by Kathleen Allers (Katelyn Houston janowicz) reports the results of observations of brown dwarfs 2MASS J10475385+2124234, which is located 34 light-years from the Sun, using a system of radio telescopes VLA (Very Large Array) and the space infrared telescope “Spitzer”. This object is about the same size as Jupiter, but is 40 times more massive than him.
To determine the speed of the winds in the atmosphere dwarf the researchers used a method that was previously used for Jupiter. Its essence lies in the fact that the rotation period of a gas giant that is defined according to observations in the radio band, is interpreted as the rotation period of the magnetosphere of Jupiter. If we consider that the magnetic field of the gas giant is generated in the inner layers, which behave as a rigid body, it can be argued that the period of rotation of the inner layers of the planet. The period of rotation of planets is determined by the speed of movement visible in its atmosphere structures in the optical and infrared ranges, gives, in turn, the rotation period of the planet’s atmosphere. Knowing these two parameters we can calculate the average wind speed in the Equatorial region of the planet. The radio emission of brown dwarfs is due to the same physical processes as in the case of Jupiter, therefore, this technique can be extended to these objects.
In the case of 2MASS J10475385+2124234 the wind speed amounted to 2293 km / h in the direction from West to East. For comparison, the average wind speed in the Equatorial region of Jupiter is 370 kilometers per hour. These results are consistent with theoretical predictions and data from simulations that assume a more powerful wind and weather on brown dwarfs due to atmospheric currents and/or weak resistance of the medium in the lower part of the atmosphere of the dwarf.
Earlier we talked about where found the largest population of brown dwarfs and how astronomers found in the “desert brown dwarfs,” a massive brown dwarf.