In our own Milky Way galaxy alone, 100 billion brown dwarfs are said to exist: “failed” stars whose mass is insufficient for the nuclear fusion of hydrogen to ignite within them. So it only glows faintly and is more difficult to notice than real stars. Megan Tannock of the University of Western Ontario and her colleagues observed three private specimens of these brown dwarves. They also write for The Astronomical Magazine and submit on arXiv, These samples are orbiting at the equator at about 100 kilometers per second – the highest value so far recorded in brown dwarfs and close to the maximum that can be considered possible for such elementary stars.
It only took the three brown dwarves between 1.08 and 1.23 hours for a full revolution. This is about a third faster than previous measurements showed. Tanuck and his colleagues discovered the trio while they were evaluating data from the Spitzer Space Telescope. Then they compared these with the values of two other telescopes. A comparison with Earth shows just how fast the rotation can be: at the equator, it rotates at about 1650 kilometers per hour, while brown dwarves rotate at 360,000 kilometers per hour.
The second fastest brown dwarf needs 1.4 hours for one revolution. Despite the extensive search, the group did not find any other samples with the same frequency. So Tanok suspects her team may have discovered the maximum possible rotational speed. Because with the speed of rotation, the centrifugal forces, which counteract the force of gravity, also increase. At some point things can be torn apart.
Another reason for the kind of speed limit is that the noticeable three brown dwarves differ in terms of hot, old, and gigantic amounts. However, it rotates at the same speed. So you can actually move on the edge of what is physically possible.
However, this conflicts with the model’s calculations that such large, heavy brown dwarves can be 50 to 80 percent faster, the researchers write. Further studies should clarify what is slowing down organisms or whether there are actually faster samples in space. The high pressure inside the brown dwarfs may cause a braking effect: it ensures that the hydrogen becomes a conductive metal, which in turn generates electromagnetic fields, which can then reduce the velocity. But so far this is only speculation.
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