Comet 3I/ATLAS Extremely irradiated from billions of years of cosmic ray bombardment, new study using observations from space James Webb Space Telescope (JWST) reported.
The comet absorbed so many galactic cosmic rays during its interstellar journey through Milky Way New research hints that it has developed a deep irradiated crust that no longer resembles the material of its home star system.
Galactic cosmic rays – kind of cosmic radiation consists of high energy particles coming from beyond solar system – releasing carbon monoxide (CO) into space to convert it into carbon dioxide (CO2). In our solar system heliosphere – a huge bubble of radiation emitted by the Sun – protects the Earth and its neighbors from most of this cosmic radiation. But in interstellar space, where 3I/ATLAS has spent most of its life, such protection does not exist.
The authors of the new study concluded that over billions of years, cosmic rays significantly altered the physical state of the ice on comet 3I/ATLAS, down to depths 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,” said the study's lead author. Romain Maggioloresearcher at the Royal Belgian Institute of Space Aeronomy, told Live Science.
The results, which the researchers called a “paradigm shift” for the study of interstellar objects, suggest that objects such as Comet 3I/ATLAS are largely composed of material processed by galactic cosmic rays rather than primordial material that is representative of the environment in which they formed.
In other words, Comet 3I/ATLAS is now a product of its interstellar journey, rather than the place it came from—at least from the outside.
Tracking the interstellar visitor
Comet 3I/ATLAS is currently orbiting the Sun. The comet has reached perihelion (the closest point to our star) on Thursday (October 29). Comets heat up as they approach their stars, causing the ice on their surfaces to sublimate into gas. The new results show that before perihelion, any gases ejected by the comet simply came from its irradiated outer shell. This is likely to continue beyond perihelion, but Maggiolo noted that, while unlikely, solar erosion could be severe enough to expose the comet's primordial home star materials that are locked in its core.
“It would be very interesting to compare observations before perihelion, which is the first observation we made when it arrived in the solar system, with observations made after perihelion, when some erosion had occurred,” Maggiolo said. “Perhaps by looking at these differences we can gain some insight into its original composition.”
Since its opening In July, researchers used a variety of telescopes to learn everything they could about 3I/ATLAS. Their results indicate that the comet is moving through our solar system at an unusual speed in excess of 130,000 mph (210,000 km/h). smooth and straight path. 3I/ATLAS can also be oldest comet ever seenwith one study suggesting it is about 3 billion years older than our 4.6 billion-year-old creature. solar system.
The new study builds on previous work that documented comet 3I/ATLAS is rich in CO2based on the first images of the interstellar guest taken by JWST in August, and observations from NASA's SPHEREx orbiteralso taken in August.
Maggiolo and his colleagues studied the radiation of a house comet (comet 67P), which passes between the orbits of Jupiter and Earth, and adapted their models based on a 2020 study published in the journal Letters from an Astrophysical Journal apply to Comet 3I/ATLAS.
The team modeled the cumulative effects of galactic cosmic ray exposure on the structure and chemistry of ice after 1 billion years of irradiation. This method is based on laboratory experiments simulating the effects of galactic cosmic rays, and therefore may not fully reflect interstellar conditions. However, according to the study, these tests provide a reliable indicator of what comets experience during their lonely, multibillion-year journeys through interstellar space.
Simulations showed that 1 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 is outdated and has changed, which researchers will need to take into account during their analysis.
“We have to be careful and take into account the aging process, so it's more work for scientists, but [3I/ATLAS] remains very interesting,” Maggiolo said.
