Dr Lea Ferellec, a Research Fellow based in Northumbria's School of Engineering, Physics and Mathematics
Photo Credit: Courtesy of Northumbria University
Scientific Frontline: Extended "At a Glance" Summary: 3I/ATLAS Interstellar Object
The Core Concept: 3I/ATLAS is a rare, comet-like interstellar object that formed around a distant star and traveled for millions of years before entering our solar system. It is only the third such object ever detected by astronomers.
Key Distinction/Mechanism: By analyzing the plasma streaming from the object as it moved away from the Sun, researchers identified five distinct charged molecules. A high ratio of dinitrogen gas to carbon monoxide indicates that the object formed in extremely cold conditions (below -240 degrees Celsius), suggesting an origin in the icy outer reaches of its native stellar system.
Major Frameworks/Components:
- WEAVE Spectrography: Researchers utilized the William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE) in the Canary Islands to capture high-resolution spectral data of the object.
- Plasma Tail Analysis: As solar plasma swept the object's charged particles into a tail, astronomers measured the chemical composition and spatial changes of the gases traveling outward.
- Molecular Ratios: The comparative abundance of dinitrogen to carbon monoxide served as a primary temperature proxy to determine the environmental conditions present during the object's formation.
Branch of Science: Astronomy, Astrophysics, and Planetary Science.
Future Application: The advanced spectroscopic techniques used to analyze 3I/ATLAS will improve the profiling of future interstellar visitors, refining current models of exoplanetary system formation and interstellar chemistry.
Why It Matters: Because interstellar objects carry pristine material from other parts of the galaxy, studying them provides scientists with a rare, direct glimpse into the chemical and environmental conditions that govern planetary formation around other stars.
A Northumbria University astronomer has helped uncover new clues about a rare icy object from outside our solar system, revealing that it formed in extremely cold conditions, far from any star.
Every so often, a large icy rock, similar to a comet, arrives from beyond our solar system, having formed around a different star entirely and then traveling for millions of years before reaching us.
These are called interstellar objects, and only three have ever been spotted. The most recent, known as 3I/ATLAS, was discovered in July 2025 as it sped past the sun and back out into deep space.
Because these objects formed in a completely different part of the galaxy, studying them gives scientists a rare glimpse into how planets and comets form around other stars, not just our own.
Dr. Lea Ferellec, a research fellow based in Northumbria's School of Engineering, Physics, and Mathematics, led a study analyzing the charged particles streaming off 3I/ATLAS as it moved away from the sun.
Using WEAVE (the William Herschel Telescope Enhanced Area Velocity Explorer), a new-generation spectrograph on a powerful telescope in the Canary Islands, the team was able to identify five different charged molecules in this stream simultaneously—an achievement rarely accomplished for a comet, let alone an object of this type.
By measuring the abundance of dinitrogen gas relative to carbon monoxide, the researchers determined that 3I/ATLAS formed somewhere extremely cold, likely colder than −240°C.
This suggests it formed far from its home star, in the outer, icier edges of wherever its solar system took shape. Discussing the findings, Dr. Ferellec said, “This object gives us a rare chance to study material that formed somewhere completely different from our own solar system.
“Finding that it's so rich in nitrogen tells us it likely formed in extremely cold conditions, far from its home star.
“Every one of these objects we study helps us understand a little more about how planets form around other stars.”
The team also analyzed how the charged gases changed the farther they traveled along 3I/ATLAS's tail, which forms when plasma streaming from the sun sweeps the object's charged particles out behind it. This is the first time this level of detail has been captured for an object of this type.
Published in journal: Monthly Notices of the Royal Astronomical Society.
Title: Ion abundances in the plasma tail of 3I/ATLAS show that it is N2-rich
Authors: L Ferellec, C Opitom, and C Snodgrass
Source/Credit: Northumbria University
Edited by: Scientific Frontline
Reference Number: astr090826_01