Metis Observations of Alfvénic Outflows Driven by Interchange Reconnection in a Pseudostreamer

This study presents observations of a large pseudostreamer solar eruption and, in particular, the post-eruption relaxation phase, as captured by Metis, on board the Solar Orbiter, on 2022 October 12, during its perihelion passage. Utilizing total-brightness data, we observe the outward propagation of helical features up to 3 solar radii along a radial column that appears to correspond to the stalk of the pseudostreamer. The helical structures persisted for more than 3 hr following a jet-like coronal mass ejection associated with a polar crown prominence eruption. A notable trend is revealed: the inclination of these features decreases as their polar angle and height increase. Additionally, we measured their helix pitch. Despite the 2 minute time cadence limiting direct correspondence among filamentary structures in consecutive frames, we find that the Metis helical structure may be interpreted as a consequence of twist (nonlinear torsional Alfvén waves) and plasma liberated by interchange reconnection. A comparison was performed between the helix parameters as outlined by fine-scale outflow features and those obtained from synthetic white-light images derived from the high-resolution magnetohydrodynamics simulation of interchange reconnection in a pseudostreamer topology by P. F. Wyper et al. A remarkable similarity between the simulation-derived images and the observations was found. We conjecture that these Metis observations may represent the upper ends of the spatial and energy scales of the interchange reconnection process that has been proposed recently as the origin of the Alfvénic solar wind.