The Speed Of Interstellar Object Oumuamua Is Helping Astronomers To Tell Where It Actually Came From

Astronomers have been able to determine where the interstellar object Oumuamua came from and its properties using the speed at which it entered our solar system. Astronomers have detected only two Interstellar objects in our solar system, which are Oumuamua and 2I/Borisov. These two objects may look similar but Oumuamua has no cometary tail, while Borisov appears like a typical comet.

What Researchers found about Interstellar Object, Oumuamua

During a recent interview with, Matthew Hopkins, a graduate student of the University of Oxford in England reveals his view about this latest study.

“The properties of their home planetary systems are imprinted on both of them,” Hopkins told “Because they come from other stars, their properties are going to correlate with those stars,” he added.

Hopkins carried out new research on the interstellar object and presented his study to the United Kingdom’s National Astronomy meeting in early July. Only two interstellar objects have indeed been spotted so far. However, scientists believed that there are still a good number of them that pass through our solar system at intervals.

They may seem to be too far from us to detect them. However, most of these ISOs likely started life as comets around the stars before coming into contact with a fly-by star or a planet, sized like Jupiter which exported them into interstellar space.

“In our solar system for every one comet that Jupiter and Neptune pushed into the Oort Cloud, it completely ejected 10, and there are a trillion objects in the Oort Cloud,” Hopkin says and if you calculate it, you will come to a conclusion that ISOs are the most numerous objects in the Milky Way galaxy” he added.

Why Interstellar Objects Moving in Groups

Each star moves around the galaxy at its specific pace. With this pattern of movement, they form groups that correspond to their point of origin and their inherited chemical composition. Our sun is abundant in heavy elements. Stars that are abundant in heavy elements reside in the thin disk of the Galaxy. This region forms a flat plane within the spiral arms and it has a thickness of 400 light years approximately.

Beyond it, is a thick disk with its elasticity about 1,000 light-years above the galactic plane. The thick disk houses mainly older stars that bear fewer heavy elements. There are different speed distributions for every population of stars belonging to each disk. This is because the ISOs that they export have a similar speed as their parent star which is related to the sun. This makes them remain in the same moving group but these moving groups continually intersect the path of the sun.

“The sun is essentially running into them,” said Hopkins. Consequently, we can anticipate a higher likelihood of observing ISOs originating from the “solar apex, representing the direction of the sun’s movement concerning other neighboring stars. Oumuamua was very close to the solar apex,” Hopkins said. “Borisov was slightly farther away but still quite near [to the solar apex], and that’s where we expect most of them to come from,” he added.

Why Interstellar Objects Can Be Spotted Easily

When these ISOs come from this specific direction, they will get to their closest proximity to the sun. This will make them very easy to detect. Vera Rubin Observatory will be observing the Southern Hemisphere sky for a survey, The good news is that this is the same region the ISOs will align.

Therefore, it is anticipated that the Vera Rubin Observatory will find numerous new ISOs which is possible to amount to hundreds of discoveries.

Why There Is Less Water In Slower ISOs

ISOs with lower velocity compared to the sun can be detected easily because they may fall into the inner solar system, while the fast ones will zoom past the inner solar system and won’t experience any form of attraction from the sun’s gravity.

You can identify an ISO’s parent star easily with its relative velocity. This is because they have the same relative velocity as their parent star. With their relative velocity, you can distinguish a star that originates from a thin disk with more heavy elements from a star that originates from a thick disk which fewer heavy elements.

“My results show that the velocity of an ISO correlates with its composition, and because of this we can get a handle on the types of stars they may have come from,” said Hopkins.

IOSs with lower velocities compared to that of the sun originate from the thin disk of the Galaxy, this area is well known for its numerous stars and planetary systems which are formed from gas and dust that are rich in heavy elements. Therefore, there will be ISOs with a smaller fraction of water content if there is a high amount of heavy elements in the gas and dusk disk because this disk gives rise to planets and comets.

This happens because of the presence of a protoplanetary disk rich in heavy elements, especially carbon. Keep in mind that carbon plays an important role in the composition of ISOs. In such disks, carbon efficiently binds with available oxygen atoms and carbon dioxide molecules in pairs. The remaining oxygen atoms are used for water formation. Therefore, ISOs that originate within such disk possess a lower fraction of water because a large amount of oxygen is bound with carbon, leaving a small amount of oxygen for water molecule creation.

Why There is Absence of Cometary Tail on the interstellar object Oumuamua

Could this absence of water be the reason behind the lack of cometary tail on Oumuamua? Let’s find out

“Because it had a lower velocity relative to the sun, it probably did come from a thin disk star with more heavy elements,” said Hopkins.

Nevertheless, he emphasized the caveat that Oumuamua’s history is not yet certain. Maybe the object lost its water and other weak elements through other means. For example, cosmic rays could have stripped them away during their journey through interstellar space or must have been eroded by several close encounters with its parent star before being exported. On the contrary, Borisov shows a moderate level of water content as inferred from spectral observations of its tail.

Currently, it is challenging to draw a definite conclusion as only two ISOs are known. However, the situation is expected to change when Vera Rubin Observatory begins its survey later this decade. Its expected discovery of hundreds of ISOs will help to understand their origin and chemical compositions.

If there’s a bias towards ISOs moving similarly to the sun falling into the inner solar system, then we would expect to see more ISOs from the thin disk,” said Hopkins.

That means we are likely to see more objects that look like Oumuamua rather than Borisov. Time will determine the authenticity of that prediction.


Oumuamua, the interstellar object is one of the most mysterious space rocks ever spotted in space. The recent study conducted by scientists will likely reveal more facts about the strange interstellar object. What do you think about this latest study?

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