Scientists may have discovered the speed limit for a brown dwarf rotation

Shane McGlaun - Apr 8, 2021, 7:09am CDT
Scientists may have discovered the speed limit for a brown dwarf rotation

Brown dwarfs are also known as failed stars and can spin at extremely high velocities. Scientists know that a brown dwarf can spin as fast as 200,000 mph, but researchers believe there may be a limit to how fast they can rotate. NASA scientists have used data from the Spitzer Space Telescope to identify the three fastest-spinning brown dwarf stars ever discovered.

The three brown dwarfs are believed to be approaching a spin speed limit for all brown dwarfs. If they spun any faster, researchers believe they would break apart. The trio of fast rotating brown dwarfs are all roughly the same diameter as Jupiter but between 40 and 70 times more massive. Each of them rotates completely once each hour.

NASA researchers say that the next-fastest known brown dwarfs rotate only once every 1.4 hours. For comparison, Jupiter spins once every 10 hours. The largest of three brown dwarfs would spin at more than 60 miles per second or about 220,000 miles per hour based on the size. The brown dwarfs were initially discovered by the ground-based Two Micron All Sky Survey in operation through 2001.

As soon as they are created, brown dwarfs are spinning, and as they cool and contract, they spin faster. The spin rate of approximately 80 brown dwarfs has been measured with a spin rate variance from less than two hours to tens of hours.

The trio of speedy brown dwarfs in the latest study all have almost the same spin rate, and scientists don’t believe that is a coincidence. The speed of rotation can’t be attributed to the brown dwarfs forming together or being at the same stage in their development since they’re all physically different. Scientists believe the trio are all at the spin speed limit, and beyond their current speed, they would break apart.


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