Intriguing ‘Oumuamua origin hypothesis

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(ORDO NEWS) — A few years ago, astronomers discovered a bizarre object called ‘Oumuamua, which not only defied conventional classification, but was also the first object to fly to us from another star system.

Researchers at Arizona State University (ASU) have proposed a new origin story that explains all the observed oddities of this cosmic body – it may be part of an “exo-Pluto”.

Astronomers claim that they have picked up a “genuine hypothesis” of the origin of the mysterious object, explaining all the unusual features of its behavior

‘Oumuamua was discovered by the Pan-STARRS observatory in October 2017, and its speed and trajectory indicated that it came from outside our solar system, making it the first interstellar object known to science to make such a journey.

It was originally classified as an asteroid, but ‘Oumuamua’s light signature pulsed regularly, indicating that it was not an ordinary rounded piece of space rock.

Instead, astronomers hypothesized that it was a cigar-shaped body about 400 m long, rotating around its axis. When viewed through a telescope, this rotation will create a variable light signature as the asteroid’s brightness is uneven.

But then the strangeness began. ‘Oumuamua accelerated as it orbited the Sun. This “rocket effect” is often seen in comets, where the heat of a star causes the ice to evaporate and turn into gas, creating a plume that accelerates the object. But ‘Oumuamua did not have a characteristic gas plume – so what’s the matter?

Astronomers have put forward a number of explanations for these strange features. Some suggest that it was a fragment of a rocky planet, torn into elongated pieces in a collision with a star. Of course, the hypothesis of an alien ship surfaced, but it was quickly dismissed.

In a new study , ASU scientists have put forward a new explanation that at least clearly explains all the observed phenomena. Astronomers say it’s a piece of nitrogen ice, possibly ejected from a Pluto-like body after a catastrophic cosmic collision with another object.

The team looked at a number of different types of ice, calculating how quickly they would lose mass to the Sun’s heat and how big the “rocket effect” would be.

Scientists evaluated the mass and shape of these objects, as well as the degree of reflection of the ice. Of all the types studied, it is nitrogen ice that is best suited to explain the strange behavior of ‘Oumuamua.

“We knew we had the right idea when we completed the calculation of what albedo (i.e., how much light is reflected by the body) would make ‘Oumuamua’s movement match the observations,” says Alan Jackson, co-author of the study.

“This value turned out to be the same as we observe on the surface of Pluto or Triton – cosmic bodies covered with nitrogen ice.”

The team says the most likely scenario is that ‘Oumuamua was torn from the body of an exoplanet about 500 million years ago in a collision, after which it was ejected from its home system and began to drift towards us.

The scientists also recalculated the size and shape of the object. Rather than a spindle hundreds of meters long, the team believes it is more of a flat and wide “pancake” shape, measuring approximately 45 x 44 meters and 7.5 meters thick (see image below title).

Intriguing Oumuamua origin hypothesis 2
Scheme of Omuamua’s journey and its gradual metamorphoses

“Frozen nitrogen also explains the unusual shape of ‘Oumuamua,” says Jackson. “As the outer layers of nitrogen ice evaporated, the shape of the body gradually became flatter, like a bar of soap as the outer layers are worn away during use.”

The new hypothesis is very similar to another proposed by scientists from Yale University. They suggested that it was a hydrogen iceberg frozen in a dense molecular cloud in deep space. However, this kind of object is entirely hypothetical, so a piece of nitrogen ice seems more plausible.

Either way, the team says future telescopes will help keep an eye on new interstellar “boundary trespassers” that could become priceless time capsules from other star systems. A second interstellar comet has already been discovered, so it’s probably quite common.


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