Astronomers bring together more indices on the interstellar comet 3i / Atlas

The telescopes formed on the interstellar comet 3i / Atlas revealed that it looks very much like comets found in the external parts of our own solar system. However, confusing characteristics, such as an surprisingly large quantity of water which even comes out of the sun, could give us clues to the old star system from which it originates.

The objects of the other systems which pass through ours are extremely rare: 3i / Atlas, discovered in July, is only the third interstellar visitor known after the Oumuamua Comets in 2017 and Borisov in 2019.

So far, scientists have used its speed to deduce that it could come from a star system for billions of years more than ours. The first observations also suggested that it was approximately 20 kilometers wide, but there was little information on the vast plume of water or gas, or both, which he leaves in his wake, called his tail, which can tell us about the composition of the comet itself.

Toni Santana-Ros at the University of Barcelona in Spain and his colleagues have now used several telescopes on the ground to observe the comet and its tail, and found that it contains a relatively low to moderate amount of dust. The amount of dust in its tail also seems to be developing as it approaches the sun and warms up, which is similar to the behavior of the comets of the external solar system. “It is an ordinary object. There is nothing particularly bizarre on it, ”explains Santana-Ros.

Astronomers have also observed the comet from space. The researchers working with the Hubble space telescope found that it could be much smaller than it seemed first, perhaps between 320 meters and 5.6 kilometers wide.

Compets often contain ice, which is sprayed as they approach the sun, producing water vapor in the tail. Using the satellite of the Swift observatory of Neil Gehrels, Zexi Xing at the University of Auburn, in Alabama, and his colleagues detected the presence of water in the tail of the comet, at distances much further from the sun than what is typical. To produce the amount of water they have detected, around 20% of the comet surface should produce it, which is larger than the comets of the typical solar system.

Producing as much water so far from the sun could adapt to the idea that 3i / Atlas comes from a star system much older than our sun, explains Cyrielle Opitom at the University of Edinburgh, in the United Kingdom. Indeed, older star systems tend to have more water compared to other molecules. “It may have more water than other molecules simply because it was formed earlier. It could be revealing of that, but I think it is still too early to say.”

Astronomers also dig older data to see if the telescopes may have accidentally picked up the comet. Adina Feinstein at Michigan State University and her colleagues found that the Satellite space telescope (Tess) Transiting Exoplanet, which is looking for planets around other stars, picked up the comet by chance between May 7 to June 3. “It was just that, at this ideal moment, Tess [was] Just look where 3i / Atlas was, ”explains Feinstein.

They found that it was surprisingly shiny during this period, which implies that he released water or gases from his surface at distances far from the sun. “He had not entirely crossed the region in our solar system where you expect the water to react,” explains Feinstein.

In this distant area, it is relatively unlikely that it is water and more likely to have been gases such as carbon monoxide or carbon dioxide, explains Opitom. “This happens all the time with comets of the solar system; They can be active very far because of these volatiles. ”

But the fact that he was active so far from the sun could suggest that it is a comet who was not exposed to a lot of starry light in his life, which is in accordance with an origin in the external parts of his own stars system, says Matthew Genge to the Imperial College of London.

“What all this ultimately suggests is that it is a comet who was disturbed from the periphery of another solar system,” explains Genge. It will be difficult to know exactly what caused its release, but it can be the gravity of a star who passed who put it on a course towards us, he says.

We will soon have even more detailed observations of 3i / Atlas, known as Opitom, like the James Webb space telescope has just finished the observations of it, which will be analyzed by astronomers in the coming weeks.

The comet will reach her point closest to the sun in October, when exposed to the highest intensity of sunlight, allowing astronomers to measure the gases he produces. This could tell us exactly what molecules are in its active tail, and therefore also in the comet itself, but also the relationships of various molecules, which could refer to the way in which 3i / Atlas was formed originally, explains Opitom.

As with previous interstellar objects, people have hypothesized that it could be foreign technology, but Santana-Ros sees no evidence of this. “If you take a photo on vacation and you see something that is big and with a long neck and four legs, you can always think that it is a stranger, but it is very likely that it is a giraffe,” explains Santana-Ros. “Since we have no evidence that it is a strange thing, and that we see nothing really bizarre, there is no reason to think that it is something abnormal.”

The world capital of astronomy: Chile

Discover the astronomical strengths of Chile. Visit some of the most technologically advanced observatories in the world and Stargaze under some of the clearest heavens on the earth.