In a First, NASA Measures Wind Speed on a Brown Dwarf

Not quite planets and not quite stars, brown dwarfs are cosmic in-betweeners. Learning about their atmospheres could help us understand giant planets around other stars.

For the first time, scientists have directly measured wind speed on a brown dwarf, an object larger than Jupiter (the largest planet in our solar system) but not quite massive enough to become a star. To achieve the finding, they used a new method that could also be applied to learn about the atmospheres of gas-dominated planets outside our solar system.

Described in a paper in the journal Science, the work combines observations by a group of radio telescopes with data from NASA’s recently retired infrared observatory, the Spitzer Space Telescope, managed by the agency’s Jet Propulsion Laboratory in Southern California.

Officially named 2MASS J10475385+2124234, the target of the new study was a brown dwarf located 32 light-years from Earth – a stone’s throw away, cosmically speaking. The researchers detected winds moving around the planet at 1,425 mph (2,293 kph). For comparison, Neptune’s atmosphere features the fastest winds in the solar system, which whip through at more than 1,200 mph (about 2,000 kph).

Measuring wind speed on Earth means clocking the motion of our gaseous atmosphere relative to the planet’s solid surface. But brown dwarfs are composed almost entirely of gas, so “wind” refers to something slightly different. The upper layers of a brown dwarf are where portions of the gas can move independently. At a certain depth, the pressure becomes so intense that the gas behaves like a single, solid ball that is considered the object’s interior. As the interior rotates, it pulls the upper layers – the atmosphere -along so that the two are almost in synch.

Brown dwarfs are more massive than planets but not quite as massive as stars. Generally speaking,

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