Pick‐Up Ion Cyclotron Waves Around Mercury
Daniel Schmid, Yasuhito Narita, Ferdinand Plaschke, M. Volwerk, R. Nakamura, W. Baumjohann
Abstract
Abstract Mercury is host to a rich and highly dynamic plasma environment, resulting from the interaction of the solar wind with Mercury's intrinsic magnetic field and tenuous exosphere. Ion cyclotron waves generated by the pick‐up of freshly photoionized neutrals are a common physical phenomenon in the exosphere of weakly and/or unmagnetized bodies. Here we study the properties of cyclotron waves generated by proton pick‐up, the so‐called proton cyclotron waves (PCWs), at Mercury. We surveyed 4 years of MESSENGER magnetometer data and identified 5455 PCW events observed over a wide spatial range, where ∼73% of the observed PCWs are located in the solar wind and ∼27% in the magnetosheath. By associating the wave properties with their spatial distribution, we evaluate the characteristics and differences of the PCWs in the two regions.