Astronomers have discovered three brown dwarfs that spin faster than any others ever observed. Scientists discovered three of the fastest-spinning brown dwarfs ever discovered in a new study published in the Astronomical Journal. Data from NASA’s Spitzer Space Telescope was used to make the discovery.
In the study, scientists measured the speed of these quasars for the first time. They also contended that these three rapid rotators might be approaching a spin speed limit for all brown dwarfs, beyond which they would disintegrate. The discovery of the fastest-spinning brown dwarfs ever discovered may point to a cosmic speed limit.
These brown dwarfs are all roughly the same size as Jupiter but 40 to 70 times more massive. They spin once every 1.08, 1.14, and 1.23 hours, respectively, while the next-fastest known brown dwarfs spin once every 1.4 hours and Jupiter spins once every 10 hours. Based on their size, the largest of the three brown dwarfs travels at a speed of more than 100 km per second (60 miles per second).
In a new study appearing in the Astronomical Journal, scientists reported the three fastest-spinning brown dwarfs ever found. The discovery was made using data from NASA‘s Spitzer Space Telescope.
The diameter of these rapidly rotating stars is the same as that of Jupiter, but they are 40 to 70 times more massive. They each spin once every hour, while the next-fastest known brown dwarfs spin once every 1.4 hours and Jupiter spins once every 10 hours.
Given their size, this implies that the largest of the three brown dwarfs travels at more than 60 miles per second (100 kilometers per second), or approximately 220,000 miles per hour (360,000 kilometers each hour). The fact that these fastest brown dwarfs have nearly the same spin rate as each other astounded scientists.
Because the three worlds are at different temperatures, the new research suggests that they are approaching a speed limit beyond which brown dwarfs would break apart, flinging their contents out into space due to an overload of centrifugal force. According to NASA, similar natural “braking mechanisms” have been discovered in other astronomical objects, such as stars, to prevent them from spinning too fast and bursting.
This cannot be attributed to the brown dwarfs framing together or being at a similar stage in their development because they are distinct: One is a warm brown dwarf, one is cold, and the other is somewhere in between. Because brown dwarfs improve with age, the temperature contrasts indicate that these brown dwarfs are of varying ages.
In stars and planets, the rotation of the objects generates centripetal force, which threatens to throw riders from their seats. Surprisingly, it has the ability to tear the thing apart. Before being separated, it will frequently begin to bulge around its midsection as it deforms under pressure. This is referred to as an oblation. Based on their known properties, brown dwarfs are likely to have similar degrees of oblation.
“We appear to have discovered a speed limit on the rotation of brown dwarfs,” said first author Megan Tannock, a Ph.D. candidate at the University of Western Ontario’s Department of Physics and Astronomy. “Despite extensive searches by our team and others, no brown dwarfs with faster rotation have been discovered. In fact, faster spins may cause a brown dwarf to tear apart.”
“It would be pretty spectacular to find a brown dwarf rotating so fast that it is tossing its atmosphere out into space,” Megan Tannock, a Ph.D. candidate at Western University in London, Ontario, said. But we haven’t seen anything like it so far. That must imply that either something is slowing the brown dwarfs down before they reach that extreme, or that they are incapable of reaching that speed in the first place. Our paper’s findings support some kind of rotation rate limit, but we’re not sure why.”
“Brown dwarfs, like planets with atmospheres, can experience large weather storms that affect their visible brightness,” said co-author Dr. Stanimir Metchev, an astronomer at Western University’s Institute for Earth and Space Exploration. “The observed brightness variations show how frequently the same storms are seen as the object spins, revealing the spin period of the brown dwarf.”
The Astronomical Journal will publish a paper describing the findings. More observations are needed to determine whether the brown dwarfs described in the paper have reached a point where their spinning stops accelerating, or if there are still faster brown dwarfs out there waiting to be discovered.vvvvvvvvy
