The previously unreconciled acceleration of 1I/2017 U1 ‘Oumuamua, a strange object of extrasolar origin discovered on October 19, 2017 by the Pan-STARRS 1 telescope, was due to the production of hydrogen gas from ice reserves, according to new research.
In 2017, a mysterious object dubbed ‘Oumuamua fired the imaginations of scientists and the public alike.
It was the first known visitor from outside our Solar System, it had no bright coma or dust tail, like most comets, and a peculiar shape — something between a cigar and a pancake — and its small size more befitted an asteroid than a comet.
But the fact that it was accelerating away from the Sun in a way that astronomers could not explain perplexed scientists, leading some astronomers to suggest that it was an alien spaceship.
In a new model developed by University of California, Berkeley astrochemist Jennifer Bergner and Cornell University astronomer Darryl Seligman, the acceleration of ‘Oumuamua is attributed to the release of trapped molecular hydrogen from within the object.
This hydrogen has been formed through energetic processing of water-rich ice as the body passed close to the Sun, and is subsequently released from the object, slightly bending its path through our Solar System.
Such reactions have been demonstrated in existing experimental work, showing that molecular hydrogen is known to be produced and subsequently expelled under such conditions.
Importantly, this model helps the astronomers understand ‘Oumuamua’s unusual properties without requiring further fine-tuning.
“For a comet several kilometers across, the outgassing would be from a really thin shell relative to the bulk of the object, so both compositionally and in terms of any acceleration, you wouldn’t necessarily expect that to be a detectable effect,” Dr. Bergner said.
“But because ‘Oumuamua was so small, we think that it actually produced sufficient force to power this acceleration.”
The findings support…
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