Comet 3I/ATLAS has been transformed by billions of years of space radiation, James Webb Space Telescope observations reveal
Comet 3I/ATLAS is extremely irradiated by billions of years of cosmic ray bombardment, new research using observations from the James Webb Space Telescope (JWST) has revealed.
The comet absorbed so many galactic cosmic rays during its interstellar journey through the Milky Way that it developed a deep irradiated crust that no longer resembles the material of its original star system, the new research suggests.
Galactic cosmic rays — a kind of space radiation composed of high-energy particles from outside the solar system — strike carbon monoxide (CO) in space to convert it to carbon dioxide (CO2). In our solar system, the heliosphere — the enormous bubble of radiation emitted by the sun — protects Earth and its neighbors from the majority of this cosmic radiation. But in interstellar space, where 3I/ATLAS spent most of its life, no such protection exists.
The authors of the new study concluded that over billions of years, cosmic rays significantly altered the physical state of the ice of comet 3I/ATLAS, down to a depth of about 50 to 65 feet (15 to 20 meters).
“It’s very slow, but over billions of years, it’s a very powerful effect,” lead author of the study Romain Maggioloresearch scientist at the Royal Belgian Institute of Space Aeronomy, told Live Science.
The results, which the researchers described as a “paradigm shift” for the study of interstellar objects, suggest that objects like Comet 3I/ATLAS are primarily made of cosmic ray-processed galactic material rather than pristine material representative of the environments in which they formed.
In other words, Comet 3I/ATLAS is now a product of its interstellar travel rather than its origin – at least externally.
Track the interstellar visitor
Comet 3I/ATLAS is currently orbiting the sun. The comet has reached perihelion (its closest point to our star) Thursday (October 29). Comets heat up as they approach stars, causing ices on their surfaces to sublimate into gas. The new findings suggest that before perihelion, all of the gas ejected from the comet simply came from its irradiated outer shell. This is likely to continue after perihelion, but Maggiolo noted that while this is unlikely, solar erosion could be strong enough to expose pristine material from the comet’s home star that is locked in its core.
“It will be very interesting to compare the observations before perihelion, so the first observation we had when it arrived in the solar system, with the observations made after perihelion, when there was some erosion,” Maggiolo said. “Perhaps by looking at these differences we can get some insight into its initial composition.”
Since its discovery In July, researchers used different telescopes to learn as much as possible about 3I/ATLAS. Their findings so far indicate that the comet is passing through our solar system at speeds above 130,000 mph (210,000 km/h) at an unusual speed. flat and straight trajectory. 3I/ATLAS could also be the the oldest comet ever seenwith one study suggesting it is around 3 billion years older than our 4.6 billion year old. solar system.
The new research builds on previous work that documented comet 3I/ATLAS is rich in CO2based on the first images of the interstellar visitor taken by JWST in August, and observations from NASA’s SPHEREx orbiteralso carried out in August.
Maggiolo and his colleagues were studying irradiation from a house comet (comet 67P), which passes between the orbits of Jupiter and Earth, and adapted their models from a 2020 study published in Letters from the astrophysical journal to be applied to comet 3I/ATLAS.
The team modeled the cumulative effects of exposure to galactic cosmic rays on ice structure and chemical composition after 1 billion years of irradiation. The method relies on laboratory experiments simulating the effects of galactic cosmic rays and therefore may not be completely representative of interstellar conditions. Still, the study says, the tests offer a strong indicator of what comets experience during their billion-year solitary journeys through interstellar space.
The simulations showed that a billion years of irradiation was enough for comet 3I/ATLAS to form its deep irradiated crust. Maggiolo noted that Comet 3I/ATLAS is still full of interesting information, but it has aged and changed, which researchers will need to take into account in their analyses.
“We have to be careful and take into account aging processes, so it’s more work for scientists, but [3I/ATLAS] remains very interesting,” Maggiolo said.
