Determine the H2O/CO ratio in the coma of 3I/ATLAS

Determine the water-to-carbon monoxide (H2O/CO) abundance ratio in the coma of the interstellar comet 3I/ATLAS by detecting and quantifying CO and CO2 emissions or production rates, in order to assess whether the current activity is driven primarily by water-ice sublimation or by super-volatile outgassing from the subsurface.

Background

The authors detect water ice signatures in the near-infrared spectrum of 3I/ATLAS and infer that activity may be driven by sublimation at heliocentric distances around 4 au. However, no gas emissions have yet been observed from 3I/ATLAS, and super-volatiles such as CO or CO2 could also be responsible for activity.

Establishing the H2O/CO ratio is critical for constraining the dominant volatiles driving the activity and for understanding the formation region and thermal processing history of 3I/ATLAS. The authors emphasize the need for targeted searches for CO and CO2 with ground- and space-based facilities to resolve this uncertainty.