Scientists determine the origin of outdoor sun object ‘Oumuamua

Scientists determine the origin of outdoor sun object 'Oumuamua

This painting by William K. Hartmann, a senior scientific emeritus at the Planetary Science Institute in Tucson, Arizona, is based on a commission from Michael Belton and shows a concept of the ‘Oumuamua object as a pancake-shaped disk. Credit: William Hartmann

In 2017, the first interstellar object from outside our solar system was discovered via the Pan-STARRS astronomical observatory in Hawaii. It was called ‘Oumuamua’, which in Hawaiian means ‘scout’ or ‘messenger’. The object was like a comet, but with features that were just strange enough to withstand classification.

Two Arizona State University astrophysicists, Steven Desch and Alan Jackson of the School of Earth and Space Exploration, tried to explain the strange features of ‘Oumuamua’ and determined that it was probably a piece of a Pluto-like planet from a other solar system is. Their findings were recently published in several articles in the AGU Journal of Geophysical Research: Planets.

“In many ways, ‘Oumuamua looked like a comet, but in many ways it was strange enough that the mystery surrounded its nature, and speculations abounded about what it was,'” said Desch, a professor in the School of Earth and Space Exploration is.

From observations of the object, Desch and Jackson determined several properties of the object that differed from what would be expected of a comet.

In terms of speed, the object has penetrated the solar system at a speed slightly lower than expected, indicating that it has been traveling 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.

They also noted that although the object received a slight push from the sun (a ‘rocket effect’ common in comets while sunlight evaporates the ice of which they are composed), the push was stronger than could be taken into account. word. Eventually, the object lacked an observable escaping gas that is usually visibly depicted by the tail of a comet. In total, the object was much like a comet, but unlike any comet ever observed in the solar system.

Desch and Jackson then assume that the object consists of different ices and they calculate how fast this ice would sublimate (which changes from a solid to a gas) while ‘Oumuamua passes by the sun. From there, they calculate the rocket effect, the mass and shape of the object, and the reflection of the ice.






Credit: Arizona State University

“It was an exciting moment for us,” Desch said. “We realized that a piece of ice would be much more reflective than humans assume, which means it could be smaller. The same rocket effect would then give ‘Oumuamua greater pressure, larger than comets usually experience.’

Desch and Jackson in particular found one ice cream – solid nitrogen – that exactly matches all of the objects’ characteristics 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 were getting the right idea when we completed the calculation for what albedo (how reflective the body is) would make the movement of ‘Oumuamua match the observations,'” says Jackson, a researcher and explorer. at ASU. “The value appears to be the same as what we observe on the surface of Pluto or Triton, bodies covered with nitrogen ice.”

They then calculate 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,” Jackson said. “Being frozen nitrogen also explains the unusual shape of ‘Oumuamua. As the outer layers of nitrogen ice evaporated, the shape of the body would gradually become more flattened, just like a bar of soap when the outer layers are rubbed off. use. “

Could ‘Oumuamua have been alien technology?

Although the comet-like nature of Oumuamua was quickly recognized, the inability to explain it in detail immediately led to speculation that it was a piece of strange technology, as in the recently published book “Extraterrestrial: The First Signs of Intelligent Life Beyond Earth” “by Avi Loeb of Harvard University.

Scientists determine the origin of outdoor sun object 'Oumuamua

Illustration of a plausible history for ‘Oumuamua: Origins in its parent system about 0.4 billion years ago; erosion by cosmic rays during its journey to the solar system; and passage through the solar system, including its closest approach to the sun on September 9, 2017, and its discovery on 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. Credit: S. Selkirk / ASU

This has sparked a public debate about the scientific method and the responsibility of scientists not to come to unfounded conclusions.

“Everyone is interested in aliens, and it was inevitable that this first object outside the solar system would make people think of aliens,” Desch said. “But it’s important in science not to come to conclusions. It took two or three years to figure out a natural explanation – a piece of nitrogen ice – that matches everything we know about ‘Oumuamua’. “It’s not so long in science, and too soon to say we’ve exhausted all natural explanations.”

Although there is no evidence that it is an alien technology, as a fragment of a Pluto-like planet, Oumuamua scientists have offered a special opportunity to look at extrasolar systems in a way they could not before do not. As more objects like ‘Oumuamua’ are found and studied, scientists can continue to expand our understanding of what other planetary systems look like and how they are similar to or different from our own solar system.

“This research is exciting in that we probably solved the mystery that ‘Oumuamua is’ and that we can reasonably identify it as a piece of an ‘exo-Pluto’, a Pluto-like planet in another solar system,” said Desch. “Until now, we had no way of knowing if other solar systems had Pluto-like planets, but now we have seen a part of the earth pass by.”

Desch and Jackson hope that future telescopes, such as those at the Vera Rubin Observatory / Large Synoptic Survey Telescope in Chile, which will be able to examine the entire southern sky on a regular basis, will be able to find even more interstellar objects that they and other scientists can further test their ideas.

“It is hoped that in a decade or so we will be able to obtain statistics on what types of objects pass through the solar system, and whether nitrogen particles are scarce or as common as we have calculated,” Jackson said. “Either way, we need to be able to learn a lot about other solar systems and whether they have undergone the same collision history as ours.”


‘Oumuamua probably comes from a binary galaxy


More information:
Alan P. Jackson et al. 1I / ‘Oumuamua as an N 2 ice fragment of an exo – Pluto surface: I. Size and compositional limitations, Journal of Geophysical Research: Planets (2021). DOI: 10.1029 / 2020JE006706

S. J Desch et al. 1I / ‘Oumuamua as an N 2 ice fragment from an exo – pluto surface II: Generation of N 2 ice fragments and the origin of’ Oumuamua, Journal of Geophysical Research: Planets (2021). DOI: 10.1029 / 2020JE006807

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