JWST Examines Interstellar Comet 3i/Atlas in Detail

3I/Atlas, an interstellar visitor, is noted for being one of the most carbon-rich comets observed, suggesting a formation in an environment vastly different from our solar system.

Since July, astronomers have been monitoring 3I/Atlas. While many findings indicate it resembles typical comets, several peculiar features hint at a more exotic origin, including the emission of water gas at distances from the sun typically unobserved in solar system comets.

Martin Codinner from NASA’s Goddard Space Flight Center in Maryland, along with his team, has utilized the James Webb Space Telescope to capture some of the most intricate observations of the comet.

Codinner’s team studied 3I/Atlas in early August, when they were approximately three times the distance from the sun compared to typical comets. At this distance, temperatures rise enough for water to transition from ice to gas, resulting in comets usually generating water vapor and dust, known as a coma.

However, their findings revealed that the coma of 3I/Atlas contains a significantly higher amount of carbon dioxide relative to water, with an 8:1 ratio. This is 16 times more than what is generally seen in other comets from our solar system at this distance from the Sun.

High carbon dioxide levels could imply that comets formed in planetary systems where carbon dioxide ice is more prevalent than water ice, suggests Matthew Genge from Imperial College London. “This may indicate a fundamental difference in planetary system formation compared to ours,” Genge adds.

When planetary systems initially form, there are differing quantities of dust, gas, and water vapor found at varying distances from stars. Over time, stars expel gas, leaving behind solid materials. If the progenitor star of 3I/Atlas expelled water vapor from locations where comets developed earlier than in our solar system, it could account for its unique composition, Genge articulates.

The scarcity of water vapor may also be attributed to previous close encounters with other stars, Genge notes. Codinner offers that water could be concealed deep within the comet’s crust, thus insulated from higher temperatures, which is indeed unusual.

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