The interstellar comet 3I/ATLAS showed a change in the composition of its coma after its closest passage to Sol. The object, the third confirmed origin outside Sistema Solar, was observed by Telescópio Subaru on January 7, 2026. The analysis focused on the colors of the gas cloud surrounding the core.
Pesquisadores estimated the ratio of carbon dioxide to water released by the comet. The value recorded on that date was below that indicated by previous observations made by space telescopes. Perihelion occurred on October 29, 2025.
Análise used oxygen emission lines
The team led by Yoshiharu Shinnaka, from Instituto to Ciências Espaciais Koyama at Universidade Kyoto Sangyo, applied techniques developed for Sistema Solar comets. The Subaru, an 8.2-meter telescope on the Havaí, captured spectroscopic data.
Scientists measured forbidden oxygen lines in the coma. Esse method allowed calculating the CO2/H2O ratio indirectly. The result pointed to a significant reduction compared to data collected before perihelion.
The change suggests that different layers of the nucleus contributed to the release of gases as the comet heated. Solar radiation causes the ice to sublimate, releasing material that forms the coma.
- Observações of Subaru occurred more than two months after perihelion
- Razão CO2/H2O measured in January 2026 was lower than that indicated by data from August 2025
- Equipe compared the object with Sistema Solar’s known comets
- Estudo will be published in The Astronomical Journal magazine on April 22, 2026
Estrutura internal may differ from surface
The observed variation indicates that the composition of the interior of 3I/ATLAS is not identical to that of the outer layer. Objetos interstellar cells travel for long periods exposed to cosmic radiation. Isso can change the surface before approaching a star.
Quando the comet approached Sol, the heating removed more volatile material from the outside. Gases from deeper layers started to escape. The ratio measured after perihelion best reflects the original internal composition.
Cometas from Sistema Solar often show predictable trends in volatile release with distance from Sol. 3I/ATLAS had already shown high CO2 values in initial observations. The subsequent fall reinforces the unique character of this visitor.
Comparação with other interstellar objects
3I/ATLAS is the third interstellar object detected, after 1I/’Oumuamua and 2I/Borisov. Cada one offers clues about conditions in other star systems.
Astrônomos use these bodies as samples of materials formed around other stars. The chemical evolution observed in 3I/ATLAS helps to understand sublimation processes and nuclear structure in different environments.
Previous Observações by instruments such as James Webb and the JUICE probe have also mapped the comet’s activity. Elas recorded release of water, carbon dioxide and other compounds.
Importância for planetary formation studies
Objetos interstellar systems allow you to directly compare raw materials from different star systems. The 3I/ATLAS study contributes to models about how planetesimals and planets form.
Pesquisadores hopes new survey telescopes will discover more similar visitors in the coming years. Cada observation adds data on chemical diversity in other systems.
The team highlighted that consolidated techniques for local comets can now be extended to these rare objects. Isso expands the possibilities of comparative analysis.
Comet 3I/ATLAS continues to move away from Sol. Novas observations may provide more details about its trajectory and future activity.