A comet so massive that it was initially mistaken for a dwarf planet that is on an inward-bound trajectory from the outer Solar System.
There is no cause for concern – C/2014 UN271 (Bernardinelli-Bernstein), as the comet is called, will never get closer to the Sun than outside the orbit of Saturn. But its large size and relative proximity will provide a rare opportunity to study an ancient object from the Oort Cloud and gain new information about the formation of the Solar System.
“We’ve had the privilege of discovering perhaps the largest comet ever observed – or at least larger than any well-studied comet – and caught close enough for people to see it Because it approaches and heats up,” co-discoverer and astronomer Gary Bernstein of the University of Pennsylvania said earlier this year.
“It hasn’t visited the Solar System in more than 3 million years.”
The outer solar system, overall, is a somewhat mysterious place. It is far away, and quite dark, and the objects in it are quite small, so it is quite challenging to see what lies outside the orbit of Neptune.
We have a general idea of the architecture of that region of space, which consists of small icy bodies in the Kuiper Belt, and then the Oort Cloud at much greater distances, but the specifics are hard to drill down.
We’re getting more information from an unexpected source, though: the Dark Energy Survey (DES), which ran between August 2013 and January 2019.
It looked over the southern sky in the infrared and near-infrared over the course of several hundred nights, studying objects such as supernovae and galaxy clusters, to try to calculate the acceleration of the expansion of the universe, which is thought to be influenced by dark energy. .
The depth, breadth and accuracy of the survey proved to be very good for identifying objects, even in the outer Solar System, beyond the orbit of Neptune at about 30 astronomical units from the Sun. Earlier this year, a team of astronomers revealed that they had discovered 461 previously unknown objects in the outer solar system in DES data.
One of those objects, observed by Bernstein and fellow astronomer Pedro Bernardinelli of the University of Pennsylvania, was c/2014 UN271 (Bernardinelli-Bernstein). Now, he and his colleagues describe the comet in more detail in a preprint paper that has been accepted The Astrophysical Journal Letters.
“We conclude that C/2014 UN271 (Bernardinelli-Bernstein) is a ‘new’ comet in the sense that there is no evidence of a previous approach to the Sun closer to 18 AU since the ejection in the Oort cloud,” the researchers write.
“Indeed, it may be the most ancient comet we’ve ever detected before orbiting Uranus, and it may never have done so in a previous orbit.”
According to the team’s analysis, C/2014 UN271 (Bernardinelli-Bernstein) began its inner journey at a distance of about 40,400 astronomical units from the Sun. It is very much in the Oort cloud region, a vast region of icy objects that span anywhere from about 2,000 to 100,000 astronomical units.
When it was discovered, the comet was at a distance of about 29 astronomical units from the Sun. The closest to the Sun will be in 2031, when it will reach a distance of 10.97 astronomical units; For reference, the average distance of Saturn’s orbit is 9.5 astronomical units.
155 kilometers (96 mi) in diameter, C/2014 UN271 (Bernardinelli-Bernstein) is a complete chunker, but still, would not be visible to the naked eye at that distance.
However, scientists will take every opportunity to study it using telescopes. They hope that learning more about its structure will give us more information about the early Solar System and its far-flung regions.
That’s because icy rocks from the far edge of our planetary system are thought to be more or less unchanged since their formation, about 4.5 billion years ago. The volatiles locked in the comet’s ice should therefore contain information about the chemistry of the outer solar system during its formation.
Scientists have already observed signs of a coma, the comical atmosphere seen as a comet approaches the Sun. The rising heat stirs up the ice on the comet’s surfaces, creating the visible coma and, at close range, the tail of the comet. A spectral analysis of these features will tell us a lot about what lies inside the C/2014 UN271 (Bernardinelli-Bernstein).
Since we know very little about the Oort cloud and the objects in it, C/2014 UN271 (Bernardinelli-Bernstein) Space represents a very rare window into this bucolic area of our home.
research has been accepted The Astrophysical Journal Letters, and is available on arXiv.