The research team used the Webb telescope's Near-Infrared Spectrograph (NIRSpec) instrument to observe Chiron in July 2023. The instrument split Chiron's reflected sunlight into its component colors, creating a detailed spectrum that reveals the chemical composition of both its surface and surrounding gas. The observations were made using three different wavelength ranges to provide complete coverage from 0.97 to 5.27 micrometers in the infrared portion of the spectrum. The team took multiple exposures and carefully processed the data to remove background noise and create clear spectral signatures of the various chemical components.
The observations revealed multiple new discoveries: the first-ever detection of methane gas emission from a centaur at such distances, the presence of frozen carbon dioxide and various hydrocarbons on the surface, and evidence of chemical processing by radiation. The team also observed that the methane gas forms a distinct fan-shaped pattern extending outward from Chiron's surface, suggesting a localized source of the emission.
The study was limited to a single set of observations at one point in time, making it impossible to track how these emissions might change as Chiron moves along its orbit. Additionally, the observing mode wasn't optimized for studying extended gas emissions, potentially limiting the detail in which the coma could be analyzed.
The findings suggest that bodies in the outer solar system can maintain significant activity through mechanisms previously unknown. The presence of various processed chemicals indicates that Chiron's surface has undergone substantial modification since its formation. This helps astronomers understand how similar bodies evolve over time and provides clues about conditions in the early solar system.
The research involved scientists from multiple institutions across several countries, including Spain, the United States, France, and Italy. The work was supported by various organizations, including NASA, CNRS (France), and multiple universities. The observations were part of the James Webb Space Telescope's Guaranteed Time Observations Program 1273, led by Cornell University.