Astronomers discover brown dwarfs with record fast rotation

Astronomers discover brown dwarfs with record fast rotation
Astronomers discover brown dwarfs with record fast rotation

Three distant brown dwarfs are spinning on their axis at an incredible speed of 370 thousand kilometers per hour - just a little more - and they would be torn apart by centrifugal forces.


Brown dwarfs are objects located on the border between planets and real stars. They are noticeably larger than the planets, and for some time thermonuclear reactions even take place in their bowels. However, to start the fusion of protons, the mass of the dwarfs is not enough, and after the rest of the light elements run out, they begin to slowly cool down without shining.

A team of scientists led by Megan Tannock of the University of Western Ontario in Canada has discovered three brown dwarfs that rotate unusually fast. It takes only a few hours for them to complete a revolution around the axis. Calculations show that this speed is close to the limit, after which the dwarf will simply be torn apart by centrifugal forces. Scientists write about this in an article preparing for publication in the new issue of the Astronomical Journal.

For observations, astronomers used the Spitzer space infrared telescope, as well as ground-based instruments: the Gemini North telescope operating in Hawaii and the Chilean Magellan Baade telescope. Spitzer made it possible to accurately track the fluctuations in the brightness of brown dwarfs: as these bodies turn to us in one direction or another, their brightness changes depending on spots and other details on the surface. Other telescopes recorded rotation along the periodic shift of the spectral lines of molecules in the atmospheres of distant objects.

This work allowed us to find three brown dwarfs (2MASS J04070752 + 1546457, 2MASS J12195156 + 3128497 and 2MASSJ03480772-6022270), whose rotation speed at the equator reaches an astounding 370,000 kilometers per hour - an order of magnitude greater than even the rapidly rotating Jupiter. They make a complete revolution around the axis in only a little more than an hour. "The relatively weak gravity of the dwarfs has difficulty keeping them intact," says one of the authors of the find, Sandy Leggett.

Scientists speculate that these brown dwarfs acquired this speed gradually. Such objects are born, like stars, during the collapse of a gas and dust cloud and initially keep its rotation. However, with age, after completing thermonuclear reactions, the dwarf cools and contracts, decreasing in size. According to the law of conservation of angular momentum, this leads to an acceleration of rotation - like an athlete-skater who, twisting, presses his hands closer to his body.

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