So far we only know two interstellar objects (ISO) to visit our solar system. They are ‘Oumuamua and 2I / Borisov. There is a third possible ISO called CNEOS 2014-01-08, and research suggests that there should be many more.
But a new research letter shows that cosmic ray erosion limits the lifespan of frozen ISOs, and while there may be many more, they just don’t last as long as thought.
If true, probably “Oumuamua was substantially older when he began his journey, wherever he went.
The title of the research letter is “Erosion of interstellar objects frozen by cosmic rays and implications for ‘Oumuamua’.” It is available on the prepress site arxiv.org and has not yet been peer-reviewed. The lead author is Vo Hong Minh Phan, from Aachen University in Germany.
The research team examined four different types of ice cream: nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4).
They then considered the cosmic rays of the interstellar medium (ISM) and their effect of erosion on ice cream. They also considered the erosion that collisions between frozen ISOs and ISM ambient gas would have on ISOs.
The research takes into account many variables. The CR flux can vary widely and the erosion time of a given frozen ISO can vary depending on the strength of the cosmic rays. The same goes for gas encounters at the ISM. And different types of ice cream also erode at different rates.
There are many things we do not know about ‘Oumuamua. In fact, we know almost nothing about it.
We don’t know what it’s made of, we only have interval estimates for its size and we don’t know where it comes from. There is little evidence to prove this conclusively.
But anyway, there are some intriguing possibilities.
Previous research suggested that ‘Oumuamua could be a fragment of N2 ice from a Pluto-like body in another solar system. This scenario has ‘Oumuamua coming from somewhere in Perseus’ arm about 0.5 Gyr ago.
In this scenario, the initial size of Oumuamua would have been between 10-50 km (6-31 miles). The actual size within this range would be determined primarily by the force of the cosmic rays to which it was subjected.
The researchers also looked at it differently. If the formation mechanisms of different ISOs indicate the initial radius of the object, they can set distance limits for its origin depending on the speed of the object.
The higher the speed of an ISO, the greater the erosion effect of gas collisions inside the ISM. And on the other hand, the slower an ISO moves, the more time it spends exposed to cosmic rays, i.e. it should erode more quickly.
This type of research is in the early stages. The authors point out that we need to know more about the variable force of cosmic rays in the Milky Way to advance further.
“It is also clear from this example that a more detailed study of the spatial profile of galactic CRs could help shed light on the origin of ISOs passing through the solar system,” they write.
We only know about ‘Oumuamua for four years. The study of ISOs is in its infancy. With only two ISOs known so far, there isn’t much hard data to follow.
As advanced observation facilities such as the Vera Rubin Observatory go online in the coming years, we will surely discover more.
Hopefully, we will discover them at a greater distance and have more time to study them. There is even talk of a mission that can visit an ISO as it makes its way through our solar system.
ESA plans to launch the Comet Interceptor mission in 2029. The interceptor would park at the L2 Sun-Earth point and wait. He can sit there for three years and wait for a long-lived comet to arrive.
It could then be sent to study the comet. If no suitable comet arrives, it is rumored that the Interceptor could be used to study an ISO if a suitable one arrives.
And the initiative for interstellar studies has begun its own potential ISO mission called Project Lyra. Lyra is a spacecraft that could be sent to visit ISO using a slingshot past Jupiter or using advanced systems such as nuclear propulsion.
But missions take a long time to plan and implement. And many things must go well.
Meanwhile, the authors think that the best way to expand our knowledge is to increase our understanding of the strength of cosmic rays throughout the Milky Way. With this, we could at least build a better understanding of ISO origins. Who knows what we will learn?
The researchers conclude their letter with the following: “It would be interesting to incorporate a detailed modeling of the CR distribution in the galactic disk to establish stricter restrictions on the birthplace of known ISOs and this could help better clarify its origin.”
This article was originally published by Universe Today. Read the original article.