A recent study suggests that the interstellar comet 3I/ATLAS formed around an old, metal-poor star located in the outer region of Via Láctea. The conclusion comes from the detailed analysis of the chemical composition of the object during its passage through Sistema Solar. Pesquisadores observed high isotopic proportions of nitrogen and carbon in the gases released, which differs from the patterns found in local comets.
The comet was discovered in July 2025 by the ATLAS system, at Chile, and quickly classified as interstellar due to its hyperbolic trajectory. Ele became the third object of its type detected visiting our region, after 1I/ʻOumuamua and 2I/Borisov. Astrônomos took advantage of the close proximity to Sol to collect precise spectroscopic data.
The evaporation of ice by solar heat allowed the release of gases, facilitating the identification of elements and isotopes. Observações with Very Large Telescope, in Chile, highlighted isotope values that align more with ancient star environments than with today’s Sistema Solar.
Origin linked to ancient stars
The chemical composition of 3I/ATLAS has high proportions of isotopes such as 14N/15N and 12C/13C. Esses values exceed those measured in Sistema Solar comets and approach patterns observed in cold, ancient molecular clouds.
Studies indicate that such isotopic signatures arise under conditions of low metallicity, typical of stars formed at the beginning of galactic evolution. The comet may have originated in a distant protoplanetary disk, where low temperatures preserved volatile compounds.
Analysis of the trajectory reinforces the possibility that it belongs to the thick disk of Via Láctea, a region rich in old stars and with a lower abundance of heavy elements.
Differences from other interstellar visitors
3I/ATLAS stands out for offering favorable conditions for chemical observation, unlike its predecessors. 1I/ʻOumuamua did not exhibit significant cometary activity, while 2I/Borisov was closer in composition to solar comets.
Gases such as carbon dioxide and carbon monoxide dominate in the object’s coma, along with traces of water and other molecules. Essa mixing suggests formation in cold regions beyond the ice line of volatile compounds.
Astronomers have recorded emissions of cyanide and nickel atomic vapor in concentrations comparable to those of local comets, but with unique isotopic particularities that point to a primordial environment.
Observations with advanced telescopes
Ground- and space-based telescopes captured data during the comet’s perihelion passage, which occurred in October 2025.
Activity increased as the object approached Sol, allowing accurate measurements of gas production rates. Esses data continues to be processed to refine models about the source.
The comet is now moving away toward the constellation Gêmeos, reducing the opportunity for new direct observations in the coming years.
Composition reveals training environment
The presence of a high nitrogen isotope ratio suggests chemical processes at very low temperatures, compatible with ancient protoplanetary disks. Modelos of galactic chemical evolution indicate that the object may have formed billions of years ago.
Heavy elements appear in limited quantities, reinforcing the hypothesis of low metallicity in the progenitor star. Essa characteristic differentiates 3I/ATLAS from bodies formed in more recent, metal-rich systems.
The analysis contributes to understanding how primitive stellar systems produced ice-rich and volatile planetesimals.
Trajectory and galactic implications
The comet’s speed and direction of arrival indicate its origin in the galaxy’s thick or thin disk. Componentes of galactic velocity show tilted motion with respect to the galactic plane, typical of ancient stellar populations.
Kinematic studies of galactic analogues support the connection with subsolar metallicity stars. The ejection of the original system likely occurred through gravitational interactions with giant planets or stellar perturbations.
This information expands knowledge about the diversity of interstellar materials that reach Sistema Solar.
Data continues to be analyzed
Researchers continue to examine the datasets collected during the passage. Novas chemical and dynamic modeling can clarify whether the origin is exclusively in the outer disk or whether there are contributions from other regions.
3I/ATLAS offers a rare window to study matter from another star system without the need for interstellar travel. The findings reinforce the importance of monitoring visiting objects to advance galactic astrophysics.
