The first known comet c2019 q4 which came to visit us from another star system has unusual makeup, according to new research. This mysterious c2019 q4 comet from the depths of space provided an unprecedented opportunity for astronomers to compare him to the comets that formed around the Sun.
New data suggests that it contains large amounts of carbon monoxide – a possible clue to where he was “born”. The results appear in two separate scientific articles published by Nature Astronomy.
In one of the documents, an international team led by Martin Cordiner and Stefanie Milam of the Goddard Space Flight Center of the American space agency (Nasa) in Greenbelt, Maryland, pointed the painting Atacama Large Millimeter / submillimeter Array (Alma) to the comet on December 15 and 16, 2019.
Alma consists of 66 antennas on the top of a mountain in Chile which observe the sky at wavelengths less than a millimeter.
In the other study, Dennis Bodewits of Auburn University in Alabama and his colleagues collected 2I / Borisov ultraviolet observations using the Hubble Space Telescope (HST) and the Neil Gehrels Swift Observatory.
Comets are made up of gas, ice and dust; they form swirling in the disc of matter which surrounds a star at the time of the birth of its planets. They can sow young worlds with the chemicals necessary for life and may have brought water to the beginning of the Earth.
The teams identified two molecules in the gas ejected by the comet: hydrogen cyanide (HCN) and carbon monoxide (CO).
HCN has already been detected in this interstellar c2019 q4 comet and is present in quantities similar to those found in comets in the solar system.
However, they were surprised to see large amounts of CO. The researchers using Alma for their observations estimated that the CO concentration of 2I / Borisov was between nine and 26 times higher than that of a medium comet in the solar system.
“This is the first time we have looked inside a comet from outside our solar system,” said Dr. Cordiner, “and it is radically different from most other comets we have seen before. “
Dr. Ye Quanzhi, an astronomer at the University of Maryland at College Park, called the results “very cool and surprising”.
The researcher, who was not involved in the studies, told BBC News: “We have learned in the past two months that Borisov is similar to the” dynamically new “comets in our solar system (ie say native comets that have formed at the edge of the solar system and tend to have a higher CO concentration), so a high CO abundance is expected [sort of], but such a high CO level (at least minus twice as high as the typical comets of the solar system) is very surprising – at least for me. “
He added: “It is nice to see that different teams of astronomers working at different wavelengths (Hubble in the ultraviolet, Alma on the radio) are able to confirm each other’s results”.
Carbon monoxide is common in space and is found inside most comets. But, for reasons that are not clear, there is a huge variation in the CO concentration in these frozen objects.
This could be partly related to where in a star system a comet formed. It can also be linked to the frequency with which the orbit of a comet brings it closer to its star and causes it to release its ice more easily evaporated.
Nevertheless, said Dr. Cordiner, “if the gases we observed reflect the composition of the birthplace of 2I / Borisov, it shows that it may have formed in a different way from our own comets in the solar system , in an extremely cold outer region of a distant planetary system. “
Dr. Milam commented: “The comet must have formed from a material very rich in CO ice, which is only present at the lowest temperatures in space, below -420F (-250C ). “
Dr. Cordiner added that Alma had previously observed disks of dust and gas – from which planets are formed – surrounding young, low-mass stars similar to the Sun.
“Many of these disks extend far beyond the region where our own comets would have formed and contain large quantities of extremely cold gas and dust. It is possible that 2I / Borisov originated from one of these disks bigger.”
Dr. Bodewits proposed a separate approach, claiming that the comet could have come from a red dwarf star, the most common type in the Milky Way galaxy. “These stars have exactly the low temperatures and luminosities where a comet could form with the type of composition found in Comet Borisov,” he said.
Based on its high speed (33 km / s; 21 miles / s), astronomers suspect that c2019 q4 or 2I / Borisov was projected out of its host system after a close encounter with a passing star or a giant planet.
It then spent millions or billions of years on a lonely journey through interstellar space before its discovery on August 30, 2019 by amateur astronomer Gennady Borisov.
Astronomers continue to study the intruder, and recent observations of the comet’s behavior suggest that it is fragmenting.
“I think Borisov split in two – HST observed the comet at two different times and the two showed the rupture,” said Ye Quanzhi. “Our follow-up observation (led by Qicheng Zhang of Caltech) was made a few days after the initial discovery and apparently showed some development of the event – it appears that one of the fragments was reduced to a drop of dust. “
c2019 q4 is only the second interstellar object to be detected in our solar system.
The first, known as “Oumuamua”, was discovered in October 2017, at that time, it was already at the top of our cosmic quarter. Although initially classified as a comet, it did not show any sign of the gas and dust explosions characteristic of these objects (and observed in 2I / Borisov).
A study published earlier in Nature Astronomy suggested that Oumuamua, which has a very elongated shape like a cigar, could be a splinter from a planet torn apart by the gravity of its host star.