VLT Study Reveals Dramatic Nickel Emission and CN Outgassing in Interstellar Comet 3I/ATLAS

Summary

Astronomers using the Very Large Telescope (VLT) have conducted spectroscopic observations of interstellar comet 3I/ATLAS (C/2025 N1) as it approaches the Sun from 4.4 to 2.85 astronomical units. The study reveals a dust-dominated coma with a red optical continuum and reports the first detection of CN emission and numerous Nickel (Ni I) lines, while finding no evidence of other common cometary species like oxygen, carbon compounds, or ammonia. The research shows dramatic increases in nickel and CN production rates as the comet approaches perihelion, with nickel production scaling as r_h^-8.43 and CN as r_h^-9.38. The findings suggest nickel release mechanisms inconsistent with direct sublimation, instead favoring low-activation-energy processes like photon-stimulated desorption or thermolysis of metalated organics, potentially including nickel-carbonyl complexes.