Fate of escaping O+ ions during unshocked solar wind

Determine the eventual fate of oxygen ions (O+) observed escaping from Earth's magnetosphere into the unshocked solar wind during the April 24, 2023 coronal mass ejection Alfvén wing state, specifically whether these ions propagate with the magnetic cloud or return to the magnetosphere due to their large gyro-radius and the near-tangential configuration of the magnetic cloud field lines relative to the magnetosphere.

Background

MMS observed bidirectional O+ flux with dominant parallel components (2–20 keV in the O+ rest frame) in the unshocked solar wind, alongside energetic electrons and protons, consistent with escape signatures during the Alfvén wing state.

While these observations confirm O+ escape, the authors explicitly note that the ions’ final trajectories and destinations are uncertain, given the geometry and gyroradius effects near magnetic cloud field lines. Clarifying this fate is important for understanding heavy ion loss processes during sub-Alfvénic interactions.