Nola Taylor Redd has a December 13, 2017 article at Scientific American
on how ‘Oumuamua, could be a bonanza for researchers.
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Originally Posted by Nola Taylor Redd, Scientific American
Telescopes swiftly targeted the object, with most researchers expecting to see a cometary tail trailing from an icy visitor as it approached the sun. But to their surprise, ‘Oumuamua showed none. Instead, it looked more like an asteroid. “It does not a resemble a comet—it had no tail whatsoever," says Karen Meech, who studies comets at the University of Hawai’i at Mnoa. Meech used NASA’s Hubble Space Telescope and other observatories to examine the mysteriously inert space tourist.
Asteroid or comet—why does it matter? The answer ties into our understanding of how planetary systems grow over time in their natal “protoplanetary” disks around young stars. Newborn giant planets can jostle one another, using their gravity to push each other around. They also lord their size over their smaller neighboring worlds—and especially over the kilometer-scale objects called “planetesimals” left behind as debris from the planet-forming process. When a giant planet throws its weight around, more than half of these planetesimals can wind up hurled from the system. Because most of a typical protoplanetary disk is icy—in 2016 Meech used solar system observations to estimate there were as many as 10,000 icy objects for every rocky object—icy objects should dominate the ejecta.
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Quote:
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Originally Posted by Nola Taylor Redd, Scientific American
‘Oumuamua’s oddball spin could be related to its origins as well. According to new research posted on the preprint server arXiv.org, the visitor is tumbling willy-nilly rather than smoothly rotating on its axis. The researchers, who declined to comment due to embargo concerns, state in their paper “1I/‘Oumuamua was likely set tumbling within its parent planetary system, and will remain tumbling well after it has left ours.” ‘Oumuamua’s motion, they speculate, could be due to a long-ago collision with another body or the extreme tidal torqueing it may have experienced during its ejection from its parent planetary system. Alternatively, its spin could come from the jetlike outgassing of icy material vaporizing in sunlight—the process that creates a cometary tail.
But, again, the object did not appear to sprout a tail when it closely approached our sun. If indeed ‘Oumuamua is an icy body, how did it avoid growing a cometary tail? David Jewitt, an astronomer at the University of California, Los Angles, suspects any ice might be buried under a layer of material damaged by the charged particles known as cosmic rays that bombarded ‘Oumuamua while it traveled through space.
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https://www.scientificamerican.com/a...etary-science/