Astronomers utilized a new method of measuring wind speeds on distant objects. This new technique can potentially help astronomers comprehend giant planets around other stars in the future

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An artist impression of a brown dwarf - Image Credit: Nostalgia for infinity via Shutterstock- HDR tune by Universal-Sci

A brown dwarf is a celestial body with a mass smaller than that of a star, but more substantial than the mass of a gas giant. With a mass smaller than the lowest mass at which hydrogen fusion can be maintained (roughly 0.08 solar masses), brown dwarfs are classified as so-called substellar objects. Getting more detailed information about brown dwarf atmospheres might help astronomers comprehend giant planets around other stars.

Recently astronomers have been able to directly measure wind speed on a brown dwarf for the first time ever. In order to get to these measurements, the investigators utilized a new method (described in a paper in the journal Science) that can potentially also be applied to learn about the atmospheres of gas-dominated exoplanets.

For their study, the astronomers targeted a brown dwarf star situated approximately 32 light-years from our planet. It officially carries the name: 2MASS J10475385+2124234. The researchers identified wind speeds of almost 2300kmh whizzing around the entire planet. To put these speeds in perspective, a comparison with Neptune, the planet in our solar system with the fastest wind speeds, was made. Neptune's atmosphere features wind speeds of around 2,000 kmh, which is significantly slower.

Not as large as stars but more massive than planets. Brown dwarfs are classified as substellar objects - Image Credit: NASA/JPL-Caltech

To measure wind speed here on Earth, we clock the motion of our atmosphere in comparison to the planet's solid surface. The problem with brown dwarfs, however, is that they are almost entirely made of gas, so "wind" in this context relates to something somewhat different. Portions of the gas can move freely in the top layers of a brown dwarf. But at a specific depth, the pressure grows so intense that the gas begins to behave somewhat like a single, solid ball. This ball is deemed the brown dwarf's interior. While the interior turns, it pulls the top layers - the atmosphere -along with it so that the two are nearly in synchronization. In their study, the astronomers assessed the small variation in the speed of the brown dwarf's atmosphere relative to its interior.

Because of the hot interior of this particular brown dwarf in addition to its relatively close vicinity to Earth, the Spitzer space telescope was able to detect features in the brown dwarf's atmosphere rotating in and out of view. Using this phenomenon to their advantage, the science team was able to lock the atmospheric rotation speed. The turning velocity of the interior of the object was revealed trough its magnetic field. Recently it was discovered that interiors of brown dwarfs produce powerful magnetic fields. While the brown dwarf revolves, its magnetic field accelerates charged particles that, in turn, generate radio waves, which the researchers then identified with radio telescopes.

The team tested the accuracy of their method on Jupiter and found which confirmed its validity. The new method of measuring wind speeds on a distant object can potentially also be used to learn about the atmospheres of gaseous exoplanets.

Lead author Katelyn Allers stated that the research team thinks that this technique could be of great value in providing insight into the dynamics of exoplanet atmospheres. What really excites them is being able to learn about how the chemistry, the atmospheric dynamics and the environment around an object are interconnected, and the prospect of getting a very comprehensive view into these worlds.

Sources and further reading: Brown dwarf / NASA JPL press release