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1I / ‘Oumuamua, a strange object of extrasolar origin discovered on October 19, 2017 by the Pan-STARRS 1 telescope, was small, about half the length of a block and as thick as a three-story building, but he was very brilliant; its brightness is about the same as the surfaces of Pluto and Triton, which are covered with exotic ice. In new research, a duo of astrophysicists from Arizona State University looked at several different ice creams and the push they would give to “ Oumuamua when they evaporated and found that the best ice is there. nitrogen, which would explain a lot of things researchers know about interstellar. object. They also suggest that “Oumuamua was probably cast out of a young planetary system about half a billion years ago.
An artist’s impression of ‘Oumuamua as a piece of almost pure nitrogenous ice. Image credit: William Hartmann / Arizona State University.
“In many ways, ‘Oumuamua looked like a comet, but it was quite strange in several ways that the mystery surrounded his nature, and speculation raged on who he was,” said Professor Steven Desch, researcher at Arizona State University School of Land and Space Exploration.
From ‘Oumuamua’s observations, Professor Desch and his colleague, Dr Alan Jackson, determined several characteristics of the interstellar object that differed from what one would expect from a comet.
In terms of speed, the object entered the solar system at a speed somewhat slower than expected, indicating that it had not traveled interstellar space for over a billion years or so.
In terms of size, its pancake shape was also more flattened than any other known object in the solar system.
Scientists also observed that while ‘Oumuamua acquired a slight thrust away from the Sun, the thrust was stronger than could be explained.
Finally, the object lacked a detectable escaping gas, which is usually visibly represented by the tail of a comet.
In all, “Oumuamua looked a lot like a comet, but was unlike any comet ever seen in the solar system.
The authors hypothesized that the object was made of different exotic ice creams, and they calculated how quickly these ice creams would sublimate when Oumuamua passed in front of the sun.
From there, they calculated the rocket effect, the object’s mass and shape, and the reflectivity of the ice.
“It was an exciting time for us. We realized that a piece of ice would be much more reflective than people thought, which meant it could be smaller, ”Prof Desch said.
“The same rocket effect would then give ‘Oumuamua a greater thrust, greater than that of comets usually.”
Illustration of a plausible story for ‘Oumuamua: origin in its parent system around 400 million years ago; erosion by cosmic rays on its journey to the solar system; and the passage through the solar system, including its closest approach to the Sun on September 9, 2017, and its discovery in October 2017. At each point in its history, this illustration shows the predicted size of ‘Oumuamua, and the ratio between its longest and the shortest dimensions. Image credit: S. Selkirk / Arizona State University.
The team found one particular ice – solid nitrogen – that exactly matched all of the object’s characteristics simultaneously.
And since solid nitrogen ice can be seen on Pluto’s surface, it’s possible that a comet-like object could be made of the same material.
“We knew we had come up with the right idea when we finished calculating the albedo that would match Oumuamua’s motion to the observations,” Dr Jackson said.
“This value appeared to be the same as that which we observe on the surface of Pluto or Triton, bodies covered with nitrogenous ice.”
The researchers then calculated the rate at which pieces of solid nitrogen ice would have been thrown onto the surfaces of Pluto and similar bodies early in the history of our solar system.
And they calculated the likelihood of chunks of solid nitrogen ice from other solar systems reaching ours.
“It was probably knocked down by an impact about half a billion years ago and thrown out of its parent system,” Dr. Jackson said.
“Being made of frozen nitrogen also explains the unusual shape of ‘Oumuamua.
“As the outer layers of nitrogenous ice evaporated, the shape of the body would have gradually flattened, just like a bar of soap does when the outer layers are washed away with use.”
The team’s two papers were published in the Journal of Geophysical Research: Planets.
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Alan P. Jackson and Steven J. Desch. 1I / ‘Oumuamua as a fragment of ice N2 of an exo-Pluto surface: I. Constraints of size and composition. Journal of Geophysical Research: Planets, published online March 16, 2021; do I: 10.1029 / 2020JE006706
Alan P. Jackson and Steven J. Desch. 1I / ‘Oumuamua as N2 ice fragment of an exo-Pluto II surface: Generation of N2 ice fragments and origin of’ Oumuamua. Journal of Geophysical Research: Planets, published online March 16, 2021; do I: 10.1029 / 2020JE006807
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