The second ever-known interstellar object to visit our solar system — the comet 2I/Borisov — came from a twin star system 13 light years away, experts found.
The interstellar visitor was first identified by Crimea-based amateur astronomer Gennady Borisov, who spotted the comet using a telescope on August 30.
The comet — identified as such through its distinctive cloud of dust and gas — is 0.9–4.1 miles (1.4–6.6 km) in diameter and began its journey a million years ago.
It will make its closest pass to the Sun on December 8, 2019 — but will not get close to any of the solar system’s planets.
2I/Borisov is the second-known visitor from outside our solar system — joining the cigar-shaped asteroid 1I/’Oumuamua, which was detected on October 19, 2017.
Unlike with 2I/Borisov, however, astronomers were not able to determine exactly where 1I/’Oumuamua had come from.
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The second ever-known interstellar object to visit our solar system — the comet 2I/Borisov, pictured — came from a twin star system 13 light years away, experts found
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 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.
Astronomer Piotr Dybczyński of the Adam Mickiewicz University in Poznań, Poland, and colleagues extrapolated back the course that 2I/Borisov likely took before it arrived in our solar system.
Its projected trajectory passes through a binary red dwarf star system that scientists refer to as Kruger 60, which lies 13.15 light years from the Earth.
When 2I/Borisov traversed that system, around one million years ago, it passed within just 5.7 light years from the centre of Kruger 60.
When it did so, it would have been moving at just 2.13 miles per second (3.43 kilometres per second).
According to the researchers, this relatively slow speed and proximity to the binary star system indicates that the comet likely originated from there, rather than having merely passed through Kruger 60 from elsewhere in the cosmos.
‘If you have an interstellar comet and you want to know where it came from, then you want to check two things,’ University of Maryland comet expert Ye Quanzhi, who was not involved in the present study, told Live Science.
‘First, has this comet had a small pass distance from a planetary system? Because if it’s coming from there, then its trajectory must intersect with the location of that system.’
2I/Borisov’s 5.7 light year clearance with Kruger 60 counts as small for such considerations — despite being almost 357,000 times bigger than the separation between the Earth and the Sun — Dr Ye explained.
‘Second, usually comets are ejected from a planetary system due to gravitational interactions with major planets in that system,’ he added.
2I/Borisov’s projected trajectory passes through a binary red dwarf star system (pictured here with the comet) that scientists refer to as Kruger 60, which lies 13.15 light years from the Earth
At one time, 2I/Borisov would have orbited the twin stars of Kruger 60 much like comets orbit the Sun in our system — until another planet’s influence knocked it flying off into space
‘This ejection speed has a limit. It can’t be infinite because planets have a certain mass,’ Dr Ye said, noting that a planet’s mass determines how hard it can eject a comet out into interstellar space.
‘Jupiter is pretty massive, but you can’t have a planet that’s 100 times more massive than Jupiter because then it would be a star.’
The interstellar visitor was first identified by Crimea-based amateur astronomer Gennady Borisov, who spotted the comet using a telescope on August 30. Pictured, the trajectories of comet 2I/Borisov and 1I/’Oumuamua as they passed through the solar system
For astronomers, the appeal of investigating interstellar visitors like 2I/Borisov and 1I/’Oumuamua comes in the potential to study pieces of solar systems beyond our own in far closer detail than would otherwise be possible.
For example, anything scientists learn about Comet 2I/Borisov has the potential to shine light on the make-up of its home star system Kruger 60.
A pre-print of the article, which has not yet been peer-reviewed, can be read on the arXiv repository.
For astronomers, the appeal of investigating interstellar visitors like 2I/Borisov and 1I/’Oumuamua, pictured in this artist’s impression, comes in the potential to study pieces of solar systems beyond our own in far closer detail than would otherwise be possible
WHAT IS ‘OUMUAMUA AND WHAT DO WE KNOW ABOUT IT?
A cigar-shaped asteroid named ‘Oumuamua sailed past Earth at 97,200mph (156,428km/h) in October.
It was first spotted by a telescope in Hawaii on 19 October, and was observed 34 separate times in the following week.
It is named after the Hawaiian term for ‘scout’ or ‘messenger’ and passed the Earth at about 85 times the distance to the moon.
It was the first interstellar object seen in the solar system, and it baffled astronomers.
Initially, it was thought the object could be a comet.
However, it displays none of the classic behaviour expected of comets, such as a dusty, water-ice particle tail.
The asteroid is up to one-quarter mile (400 meters) long and highly-elongated – perhaps 10 times as long as it is wide.
That aspect ratio is greater than that of any asteroid or asteroid observed in our solar system to date.
But the asteroid’s slightly red hue — specifically pale pink — and varying brightness are remarkably similar to objects in our own solar system.
Around the size of the Gherkin skyscraper in London, some astronomers were convinced it was piloted by aliens due to the vast distance the object traveled without being destroyed – and the closeness of its journey past the Earth.
Alien hunters at SETI – the Search for Extra-terrestrial Intelligence based at Berkeley University, California said there was a possibility the rock was ‘an alien artefact’.
But scientists from Queen’s University Belfast took a good look at the object and said it appears to be an asteroid, or ‘planetesimal’ as originally thought.
Researchers believe the cigar-shaped asteroid had a ‘violent past’, after looking at the light bouncing off its surface.
They aren’t exactly sure when the violent collision took place, but they believe the lonely asteroid’s tumbling will continue for at least a billion years.