Science

More than half of the objects at the edge of the solar system are from interstellar space 

Comet 2I/Borisov was the second interstellar object ever discovered when it was spotted it in 2019. However, there may be as many as 100 trillion interstellar objects like this in the solar system, significantly more common than first thought, a new study suggests. 

Astronomers Amir Siraj and Avi Loeb at Harvard University’s Center for Astrophysics suggest that approximately one percent of carbon and oxygen in the Milky Way could be locked in interstellar objects, with many of them located in the Oort cloud.

‘There should be about a hundred trillion Borisov-like interstellar comets out to the edge of the Oort cloud,’ Loeb wrote in an email to DailyMail.com 

Scientists believe there may be 100 trillion interstellar objects like Comet 2I/ Borisov in the solar system in the Oort cloud. The Oort cloud is a theoretical concept of icy objects at the farthest parts of the solar system

Comet 2I/Borisov (pictured) was discovered in August 2019 by astronomer Gennady Borisov

Comet 2I/Borisov (pictured) was discovered in August 2019 by astronomer Gennady Borisov

The Oort cloud is a theoretical concept of icy objects at the farthest reaches of the solar system, according to NASA

Scientists believe it’s possible that the Oort cloud could have as many as 10 quadrillion objects in it, though that number is up for debate, given it has never actually been observed.  

Siraj and Loeb speculate that the number of interstellar objects outnumber solar system objects in the Oort cloud. 

‘Before the detection of the first interstellar comet, we had no idea how many interstellar objects there were in our solar system, but theory on the formation of planetary systems suggests that there should be fewer visitors than permanent residents,’ said Siraj, the lead author of the study, in a statement

The Oort cloud is a theoretical concept of icy objects at the farthest parts of the solar system

The Oort cloud is a theoretical concept of icy objects at the farthest parts of the solar system

‘Now we’re finding that there could be substantially more visitors.’ 

Discovered in August 2019 by astronomer Gennady Borisov, Comet 2I/Borisov is believed to have come from a twin star system 13-light years from Earth, starting its journey nearly 1 million years ago.  

‘Let’s say I watch a mile-long stretch of railroad for a day and observe one car cross it. I can say that, on that day, the observed rate of cars crossing the section of railroad was one per day per mile,’ Siraj explained. 

‘But if I have a reason to believe that the observation was not a one-off event—say, by noticing a pair of crossing gates built for cars—then I can take it a step further and begin to make statistical conclusions about the overall rate of cars crossing that stretch of railroad.’  

The research suggests ~1% of carbon and oxygen in the Milky Way are in interstellar objects

The research suggests ~1% of carbon and oxygen in the Milky Way are in interstellar objects

Despite their supposed abundance, only two interstellar objects – Borisov and the much-debated ‘Oumuamua – have been spotted.

When asked if any of the interstellar objects emanating from the Oort cloud could be similar in nature to ‘Oumuamua, Loeb told DailyMail.com that since it was not made of carbon or oxygen, it leaves open the possibility the object it is ‘artificial’ or extraterrestrial, in origin. 

Siraj believes that is because humanity does not have the technology yet, when factoring in that the Oort cloud is anywhere between 200 billion to 100 trillion miles away from the sun and the objects in the cloud don’t produce their own light. 

Senior astrophysicist Matthew Holman, who was not involved in the study, said the research could have broader implications much closer to Earth and help humanity understand the solar system better. 

‘These results suggest that the abundances of interstellar and Oort cloud objects are comparable closer to the Sun than Saturn,’ Holman explained in the statement. ‘This can be tested with current and future solar system surveys.’

‘When looking at the asteroid data in that region, the question is: are there asteroids that really are interstellar that we just didn’t recognize before?’ he asked.

‘We think they are asteroids, then we lose them without doing a detailed look.’ 

Siraj hopes that next-generation technology, such as the launch of the Vera C. Rubin Observatory – scheduled for 2022 – will help in the discovery of more interstellar objects.

Other telescopes, such as the Transneptunian Automated Occultation Survey, which may come online later this year, may also help humanity find more interstellar objects and debris left over from when planets formed.

‘Our findings show that interstellar objects can place interesting constraints on planetary system formation processes, since their implied abundance requires a significant mass of material to be ejected in the form of planetesimals,’ Siraj explained.

‘Together with observational studies of protoplanetary disks and computational approaches to planet formation, the study of interstellar objects could help us unlock the secrets of how our planetary system—and others—formed.’

The research has been published in the Monthly Notices of the Royal Astronomical Society

WHAT IS 2I/BORISOV?

2I/Borisov is a comet that came from outside the solar system.

It is believed to have a core that is around 0.9–4.1 miles (1.4–6.6 kilometres) in diameter.

The interstellar comet 2I/Borisov, pictured, which is currently visiting our solar system is harbouring water that came from another star system, a study has found

The comet was spotted by amateur astronomer Gennady Borisov from Crimea’s MARGOT observatory on August 30, 2019.

It will make its closest pass to the Sun on December 8, 2019 — but will not get close to any of the planets in the solar system. 

2I/Borisov will leave the solar system in the direction of the constellation of Telescopium.

According to Polish researchers, it likely originated from the binary red dwarf star system Kruger 60.

The comet is only the second interstellar visit to have been spotted.

The first was the cigar-shaped asteroid 1I/’Oumuamua, which was detected on October 19, 2017. 


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