A view of the evolution of a coronal mass ejection and the associated wave trains at high spatial and temporal resolution.

The study of the kinematic and dynamic evolution of fast, eruptive events from the middle to the high solar corona is one of the primary scientific objectives of the Metis coronagraph on board the Solar Orbiter satellite. During the spacecraft's perihelion passages, Metis operates in an observational mode that acquires visible light images at a cadence of 20,seconds, achieving a spatial resolution of around 2000,km at a solar distance of 0.28,au. This capability enables the detailed capture of coronal structures and transient events, such as coronal mass ejections (CMEs), with unprecedented spatial and temporal resolution. Between October 8 and 9, 2022, an extensive CME was observed in the Metis plane of the sky while Solar Orbiter was at a distance of 0.3,au, allowing for a spatial resolution in the visible channel of 4.4⋅ 10^3,km/pixel. We aim to exploit the unprecedented high resolution of Metis observations to resolve multiple substructures within the CME front, revealing plasma elements propagating at different speeds and along distinct trajectories, enabling a detailed kinematic characterisation of the eruption. To highlight the complex morphology of the solar eruption observed in Metis images, a normalisation-based running difference enhancement algorithm was applied. Height-time diagrams were implemented to estimate the propagation speeds and frequency variations of newly emerging features. In addition, a three-dimensional reconstruction model of the flux rope structure, combined with data from other space-based coronagraphs and disk imagers, enabled tracking of the entire CME evolution from its early phase in the lower corona up to the middle corona (approximately 5 solar radii). Joint observations with Solar Orbiter/EUI-FSI provided insights into the eruption's initiation in the inner corona, while Metis' high resolution imaging captured its development into the middle corona, allowing a comprehensive view of CME kinematics across multiple coronal layers. The high spatial and temporal resolution observations provided by Metis make it possible to study the fine structure of the CME, highlighting the internal motions of the coronal plasma and characterising its kinematic evolution. The results obtained from this study contribute to a deeper understanding of the morphology and kinematics of CMEs. Furthermore, the detection of circular, fast-propagating wavefronts (travelling at ∼500,km/s with a characteristic period of ∼3 minutes) at the western flank of the CME front opens new interpretative scenarios, suggesting the involvement of wave excitation and magnetic field reconfiguration processes in shaping the CME evolution. Multiple interpretations are proposed for the observed coronal plasma wave trains, including the presence of quasi-periodic propagating fast modes, providing new insights into wave generation and energy transport in the solar corona.