Is Oumuamua Alien Space Junk, an asteroid, or a comet? Study sheds light on mysterious visitor

Was it space junk? One asteroid Wander among the stars? or one comet stranger than another sun? Since 2017, when astronomers were in Hawaii They discovered something they called it Oumuamua (“beater”) cross Solar System, they argued about what it was. Telescopes saw only a moving blob that was already heading into the interstellar darkness. Astronomers deduced that it was reddish, cigar- or pancake-shaped, and probably a few hundred meters across. To date, all comets observed in our solar system have ranged from half a mile to hundreds of kilometers in diameter. (Comet Haley It is about 11 kilometers wide).

Initially classified as an asteroid, ‘Oumuamua showed none of the hisses and flashes typical of comets. (Comets are essentially sloppy snowballs; when heated by sunlight, they emit jets of steam, carbon dioxide, and dust, creating glowing tails or comas.) There was no evidence of gas or dust surrounding the object, and telescopes did not hear radio anything similar.

But further analysis revealed that something was causing ‘Oumuamua to accelerate as it exited the solar system, leaving scientists with a delicious puzzle.

Now, two astronomers have discovered what they call a “surprisingly simple explanation” for Oumuamua’s behavior: The object was a comet after all, propelled by tiny amounts of hydrogen gas gushing from an icy core.

Written by Jennifer Bergner, an astrophysicist at the University of California, Berkeley, and Daryl Z. . This provides further evidence that ‘Oumuamua originated as a planetary impact much like solar system comets.

In a statement from the University of California, Berkeley, Seligman said, “The beautiful thing about Jenny’s idea is that this is exactly what should happen with interstellar comets. We had all these stupid assumptions like hydrogen icebergs and other crazy things, and that’s just more of an explanation.” generality.”

In an email, Karen Meek, a comet expert at the University of Hawaii’s Institute for Astronomy who has studied ‘Oumuamua extensively, called the paper “a very interesting explanation.” “I’m not prepared to say that solves things – the final proof will be the spectroscopic detection of hydrogen,” she added. But this is very plausible, and if another ‘Oumuamua-like object is detected, all of these models and interpretations provide a lot of guidance for the observations. I’m amazed at how much work has gone into explaining this single thing – so much creative effort has been put into getting the best possible understanding.”

The controversy isn’t likely to go away anytime soon. Avi Loeb, the Harvard astronomer who suggested Oumuamua could be a solar sail or some other alien artifact, was quick to discuss the new study. “The authors of the new paper claim it was a water-ice comet, although we did not see the comet’s tail,” Loeb said in an email. “It’s like saying an elephant is a zebra without stripes,” he added.

Bergner and Seligman began collaborating to find a solution to the “Oumuamua mystery” as postdoctoral fellows at the University of Chicago. “We’ve never seen a comet in the solar system that didn’t have a dust coma,” Seligman said. “So the non-gravity acceleration was really weird.”

Bergner, who specializes in the chemistry of ice in outer space, wondered if molecular hydrogen gas, the lightest, most abundant and most volatile element in the universe, could be responsible for propelling the comet. But where does the gas come from? He found that laboratory experiments conducted since the 1970s showed that when ice collided with high-energy particles, their molecules could break apart, leaving small bubbles of hydrogen gas trapped several meters deep in the ice. “A comet traveling through the interstellar medium is essentially cooked by cosmic radiation, creating hydrogen,” Bergner said in a statement from the University of California, Berkeley.

She added in an email: “Water ice in its amorphous form has a thin structure that contains pockets where other volatile molecules can get trapped. When the ice is heated, it realigns itself into a more stable and cohesive structure.” This process “leads to the collapse of these pockets and the formation of channels within the ice through which trapped gas can escape,” she said.

For a full-sized comet, Bergner said, such outgassing would have little effect. “But because ‘Oumuamua was so small, we think he already produced enough force to power that acceleration.”

And any dust in the ice would get stuck there, removing much of the show away from the comet’s tail. Indeed, in recent years, astronomers like Seligman and his colleagues have discovered half a dozen “dark” comets: small bodies that show acceleration but no observable comas or tails. Perhaps the hydrogen jets are not the cause in all cases, Bergner said, but together they “reveal that there is much to learn about the nature of small bodies in the solar system.”