The Origin of ‘Oumuamua revealed: Mystery object came from the Pleiades

The year 2017 was of great importance as numerous groundbreaking discoveries were made in outer space. One of the highlights of 2017 was the arrival of the first interstellar object, first thought to be a comet, an asteroid, and then an alien spaceship. Discovered by a Hawaiian astronomer, it was quickly named ‘Oumuamua, which means “a messenger from afar arriving first,” reflecting the origin of the mystery object. However, the exact origin of the mystery rock remained a mystery, at least until now.

Astronomers believe they have finally tracked down the origin of the interstellar object.

According to experts, the cigar-shaped asteroid originated from the nearby “Pleiades moving group” of young stars, one of the closest to Earth and best perceived by the naked eye.

Astronomers believe how ‘Oumuamua was most likely expelled from its home star system, and sent out towards interstellar space.

Astronomers already know that the mystery object is composed of ice with a carbon-rich surface and has an extremely unusual orbit, and is traveling at around 26 km/ s, and will soon leave our solar system.

The hyperbolic trajectory of ʻOumuamua through the inner Solar System, with the Sun at the focus, showing its position every 7 days. The planet positions are fixed at the perihelion on September 9, 2017. Shown from a three-quarter perspective, roughly aligned to the plane of ʻOumuamua’s path.

‘Oumuamua was scanned using the Green Bank Telescope by astronomers from the Breakthrough Listen research program for any signs of alien signals, however, of intelligent signals have been identified so far, though further observations are planned, notes an article by the Conversation.

Now, a recent study published at arXiv gives us a glimpse of exactly where ‘Oumuamua may have originated from.

By reconstructing the object’s motion, Fabo Feng, a postdoctoral researcher at the University of Hertfordshire indicates how ‘Oumuamua most likely originated from the nearby “Pleiades moving group” of young stars, also known as the “Local Association”.

Astronomers believe it was likely ejected from its home solar system and sent out to travel interstellar space.

‘Oumuamua’s journey. Image Credit: The Conversation.

Based on the trajectory of ‘Oumuamua, this scientist simulated how ‘Oumuamua traveled through the galaxy and compared it to the movements of nearby stars. The conclusion is that the object passed 109 stars at a distance of 16 light years.

Five of these stars corresponded to the Pleiades or Local Association (a group of young stars that probably formed together), at a very slow speed in relation to their movement.

The study notes how it is likely that when Oumuamua was first expelled into outer space, it would have traveled at just enough speed to separate itself from the gravity of its home star, rather than at a much faster speed that would require even more energy.

An artist’s impression of the ‘Oumuamua asteroid, which scientists scanned for signs of intelligent life. Photograph: ESO/M Kornmesser/PA

This means, according to the new research, that we would expect the object to move relatively slowly at the start of its interstellar travel, so it’s slow encounters with these five stars suggest that it was expelled from one of the groups.

Usually, stars move with an average speed as they form and gradually change velocity when encountering very large cosmic objects, such as massive stars and molecular clouds, and are therefore affected by their gravity.

“Unlike most nearby stars, Oumuamua moves very slowly compared to the average movement of the rest of the galaxy. This suggests that it has only been traveling in interstellar space for a relatively short time and has not had the opportunity to find many massive objects that accelerate it, “the study emphasizes.

As to what the asteroid ejected from initially, this study considers as a plausible scenario that Oumuamua was ejected from a binary star system consisting of two stars orbiting closely together, explains Feng in an article written in The Conversation.

“Objects orbiting one of the stars in a binary system will be strongly affected by the gravity of the other and so can be more easily ejected from the system than if it had just one star.”

Furthermore, Feng indicates how ‘Oumuamua is probably just the tip of the iceberg. And that there are likely more than 46m similar interstellar objects crossing the solar system every year.

Source: arXiv

Reference: The Conversation

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