Scientists have a new idea to explain the strange behavior of ‘Oumuamua, the first known interstellar visitor in our solar system.
In October 2017, astronomers stumbled upon the object as it flew back into interstellar space in a slingshot orbit around the Sun, passing through our solar system. The brief flyby provided researchers with only a few weeks to study ‘Oumuamua. Oumuamua then disappeared forever, leaving more questions than answers. More than five years after his discovery of the object, researchers still struggle to make sense of the precious observations made. Against all expectations, the object somehow “hit the gas” on departure. It was like a frightened driver speeding away from a seedy part of town.
By the way, in the paper published on March 22, NatureThe two researchers concluded that ‘Oumuamua’s unexpected acceleration could have been caused, after all, by colliding with the gas. It is a natural celestial body like a comet, rather than an object in space (or even a derelict alien spaceship).”
“This scenario seemed to start with something more normal-looking, like a comet in our solar system, and still have a sort of final phenomenon that explains this non-gravitational acceleration,” said Jennifer Bergner. say. California, Berkeley, and lead author of the new study.
The study puts a new twist on previous ideas that suggested that ‘Oumuamua could have been a plume-erupting mass with solid hydrogen or nitrogen volatilities that are less robust than water ice. increase. Many experts cannot form in the first place whether such fragile objects can survive the perilous journey through the solar system. “It’s a good idea, and I don’t know if I can prove it,” said an astronomer at the University of Hawaii. One Karen Meech says he wasn’t involved in the new research.
In a new paper, Bergner and her co-author Darryl Seligman, an astrophysicist who co-authored a 2020 paper postulating the hydrogen ice hypothesis, said the intruder was another planetary system, mostly elastic. proposed to have formed as a mundane comet composed of some water ice. , exactly like those in our own stellar neighborhood. If we got too close to an alien planet or star, the object could have flew into interstellar space and been on its way to us.
In fact, our solar system’s comets are rich in water ice and are regularly kicked by larger celestial bodies. Tufts University astronomer Jane Lu points out that sunshine is enough to show zero-gravity acceleration. “Comets do it all the time,” Lou says of this acceleration. “It’s like a rocket, right? They release gas, and when they spew something out, Newton’s laws say you go the opposite way.
But previous research has shown that water ice sublimation alone cannot provide enough force to explain Oumuamua’s anomalous acceleration, so the authors of the new paper add an extra step. As the object moved through interstellar space, high-energy cosmic rays smashed through its surface, dissolving some of the water ice to form hydrogen, they write. Rather than escaping into space, most of the hydrogen remained trapped in the surrounding ice. It was released from the ice cage, resulting in extra acceleration.
This theory could address a key piece of the ‘Oumuamua puzzle. Outgassing comets have a distinctive feature called a coma, a bright but vague halo of light-scattering dust carried away by outgassing. should be wrapped in Observers, however, have never seen a coma around Oumuamua. This is a key conundrum in explaining that acceleration.
“We’ve never seen ice release gas without dust. Never,” Lou says. “Usually dust and ice go together.”
But according to Bergner and Seligman’s work, “‘Oumuamua’s dust could have remained trapped in the ice even as the hydrogen escaped.” Overall, the matrix should still be intact. says Bergner. “So we think it’s possible that the dust is still embedded in the water ice.”
But the paper doesn’t understand ‘Oumuamua’s strange, splinter-like shape, says Meech. “It’s a great model, but it doesn’t tell the whole story,” she says. Bergner agrees that the new study does not directly address the object’s shape, but Seligman’s previous work found that if a circular or disk-shaped hydrogen iceberg were present, it would be weathered by cosmic rays to a rectangular shape. points out that it may become
Bergner says that if astronomers can see a comet the size of ‘Oumuamua make its first inward journey from a reservoir in the outer solar system, scientists will eventually be able to see what’s happening in our own solar system. We hope to see phenomena similar to the scenario in the paper in comets. Bergner says we should receive enough cosmic radiation to do so.The trick is to find them. Astronomers may change with the Vera C. Rubin Observatory, which is set to begin extensive surveys in early 2025, but they’ve never seen a native comet as small as ‘Oumuamua.
As for ‘Oumuamua itself, Meech, Luu, and Bergner all say, frustratingly, that the icy invaders are long gone, so how to really test the claims offered by this (or any other) new study? “At this point, it doesn’t matter what you say about this object, because you’ll never see it again,” Luu said.
