Apr 13, 2021 - Science

Discoveries point to a speed limit on how fast "failed stars" can rotate

Artist's illustration of a brown dwarf. Photo: NASA/JPL-Caltech
Artist's illustration of a brown dwarf. Photo: NASA/JPL-Caltech

Scientists have discovered the three fastest spinning "failed stars" yet found, suggesting there might be a speed limit to how fast they can rotate.

The big picture: These objects — called brown dwarfs — are thought to be "failed stars" that didn't collect enough mass to ignite fusion in their cores needed to be considered a star and too large to be a gas giant planet like Jupiter.

  • By learning more about these fast-moving brown dwarfs, researchers hope to figure out more about their evolution and formation.

What they found: A new study in the Astronomical Journal shows that the three brown dwarfs each rotate fully about once per hour despite being in very different environments.

  • Researchers think that if these brown dwarfs rotated faster than this "speed limit," it might cause them to break apart.
  • "It would be pretty spectacular to find a brown dwarf rotating so fast it is tossing its atmosphere out into space," Megan Tannock, an author of the new study, said in a NASA statement
  • "But so far, we haven’t found such a thing. I think that must mean that either something is slowing the brown dwarfs down before they hit that extreme or that they can’t get that fast in the first place."

The intrigue: The new study also shows that old, out-of-service telescopes can find new life after death.

  • The researchers used data collected by NASA's Spitzer Space Telescope, which was turned off in January 2020, to find the spin rates of the brown dwarfs and then followed up with ground-based telescopes to gather more information.
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