Interstellar visitor 3I/ATLAS carries clues from the frozen outskirts of another star system

UK astronomers have uncovered new clues about the origin of 3I/ATLAS, the third known interstellar object ever spotted. The study, published in Monthly Notices of the Royal Astronomical Society, reveals that the comet formed in extremely cold conditions, far from any star. Researchers used the WHT Enhanced Area Velocity Explorer (WEAVE) instrument on the William Herschel Telescope to analyze the ionized gases streaming off 3I/ATLAS. The observations were made using WEAVE's LIFU mode, which allowed the detection of five different ions in the comet's stream. This is a rare achievement for any comet and a remarkable first for an interstellar object of this nature. The team measured the abundance of dinitrogen gas compared with carbon monoxide, determining that 3I/ATLAS formed somewhere extremely cold, likely colder than -240°C (-400°F). This suggests it formed in the outer, icy edges of another star system.

The findings indicate that 3I/ATLAS is a rare sample from another system, providing scientists with a unique opportunity to study material that formed in completely different conditions from our own solar system. The study shows that the comet is rich in nitrogen, suggesting it formed in extremely cold conditions far from its home star. The WEAVE instrument, which was developed with support from the Science and Technology Facilities Council, enabled the researchers to capture detailed data about the comet's ionized gases. The research team, including scientists from the University of Edinburgh, also analyzed how the ions changed as the comet traveled, capturing the first detailed data on this level for an interstellar object.

This discovery highlights the importance of studying interstellar objects, as they offer a rare glimpse into how planets and comets form around other stars. The findings contribute to our understanding of how planets form in different parts of the galaxy and provide valuable insights into the formation of our own solar system. The study emphasizes the role of advanced instruments like WEAVE in enabling such detailed observations, and it underscores the value of scientific collaboration in advancing our knowledge of the universe.

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