1I / ‘Oumuamua, a foreign object of extra-solar origin discovered by the Pan-STARRS 1 telescope on October 19, 2017, was small, about half as long as a city block and as thick as a three-story building , but it was very shiny; its luster is about the same as the surfaces of Pluto and Triton, which are covered with exotic ice. In new research, a duo of astrophysicists at Arizona State University looked at different ice creams and the pressure they would give ‘Oumuamua while evaporating, and found that the best ice is nitrogen, which is much of the stuff that researchers at the interstate knows, would declare. objection. They also suggest that ‘Oumuamua was probably ejected from a young planetary system about half a billion years ago.
An Artist’s Impression Of ‘Oumuamua As A Piece Of Almost Pure Nitrogen Ice Image Credit: William Hartmann / Arizona State University.
“In many ways, ‘Oumuamua looked like a comet, but in different ways it was strange enough that the mystery surrounded its nature, and the speculation grew as to what it was,'” said Professor Steven Desch, a researcher. of the School of Earth and Space Exploration at Arizona State University.
From observations of ‘Oumuamua, Professor Desch and his colleague, dr. Alan Jackson, several properties of the interstellar object determine what differs from what would be expected of a comet.
In terms of speed, the object entered the solar system at a velocity that was slightly lower than expected, indicating that it has been moving in interstellar space for more than a billion years.
In terms of size, the shape of the pancake was also flatter than any other object in the solar system.
The scientists also noted that while ‘Oumuamua received a slight pressure from the sun, the pressure was stronger than could be accounted for.
Eventually, the object lacked an observable escaping gas that is usually visibly depicted by the tail of a comet.
In total, ‘Oumuamua was much like a comet, but unlike any comet ever observed in the solar system.
The authors assumed that the object consisted of various exotic ice creams and they calculated how fast this ice cream would sublimate if ‘Oumuamua passed by the sun.
From there, they calculate the rocket effect, the mass and shape of the object, and the reflection of the ice.
“It was an exciting moment for us. “We realized that a piece of ice would be much more reflective than people assume, which means it could be smaller,” said Professor Desch.
“The same rocket effect would then ‘give Oumuamua greater pressure, greater than comets usually experience.’
Illustration of a plausible history for ‘Oumuamua: origin in his parent system about 400 million years ago; erosion by cosmic rays during its journey to the solar system; and passage through the solar system, including the closest approach to the sun on September 9, 2017, and its discovery in October 2017. At every point in its history, this illustration shows the predicted size of ‘Oumuamua, and the relationship between the longest and shortest dimensions. Image Credit: S. Selkirk / Arizona State University.
The team found one ice in particular – solid nitrogen – that exactly matches all the functions of the object at once.
And since solid nitrogen ice can be seen on the surface of Pluto, it is possible that a comet-like object could be made of the same material.
“We knew we had the right idea when we completed the calculation for albedo that would make the ‘Oumuamua’s movement consistent with the observations,” Dr. Jackson said.
“The value appears to be the same as what we observe on the surface of Pluto or Triton, bodies covered with nitrogen ice.”
The researchers then calculated the rate at which pieces of solid nitrogen ice would be knocked off the surfaces of Pluto and similar bodies early in our solar system’s history.
And they calculated the probability that pieces of solid nitrogen ice from other solar systems would reach those of us.
“It was probably knocked off the surface about half a billion years ago by an impact and thrown out of its parent system,” said Dr. Jackson said.
‘Making frozen nitrogen also explains the unusual shape of’ Oumuamua. ‘
“As the outer layers of nitrogen ice evaporated, the body would gradually become flatter, just like a bar of soap if the outer layers were rubbed off by use.”
The team’s two papers are in the Journal of Geophysical Research: Planets.
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Alan P. Jackson and Steven J. Desch. 1I / ‘Oumuamua as an N2 Ice Fragment of an Exo-Pluto Surface: I. Size and Composition Limitations. Journal of Geophysical Research: Planets, Published March 16, 2021 online; doi: 10.1029 / 2020JE006706
Alan P. Jackson and Steven J. Desch. 1I / ‘Oumuamua as an N2 ice fragment from an exo-Pluto surface II: Generation of N2 ice fragments and the origin of’ Oumuamua. Journal of Geophysical Research: Planets, Published March 16, 2021 online; doi: 10.1029 / 2020JE006807