Observational evidence of ring current in the magnetosphere of Mercury

J-T Zhao; Q-G Zong; C Yue; W-J Sun; H Zhang; X-Z Zhou; G Le; R Rankin; J A Slavin; J M Raines; Y Liu; Y Wei

doi:10.1038/s41467-022-28521-3

Observational evidence of ring current in the magnetosphere of Mercury

Nat Commun. 2022 Feb 17;13(1):924. doi: 10.1038/s41467-022-28521-3.

Authors

J-T Zhao¹, Q-G Zong^#^{2

3}, C Yue^#⁴, W-J Sun⁵, H Zhang⁶, X-Z Zhou¹, G Le⁷, R Rankin⁸, J A Slavin⁵, J M Raines⁵, Y Liu¹, Y Wei⁹

Affiliations

¹ Institute of Space Physics and Applied Technology, Peking University, Beijing, 100871, China.
² Institute of Space Physics and Applied Technology, Peking University, Beijing, 100871, China. qgzong@pku.edu.cn.
³ Polar Research Institute of China, Shanghai, 200136, China. qgzong@pku.edu.cn.
⁴ Institute of Space Physics and Applied Technology, Peking University, Beijing, 100871, China. yuechao@pku.edu.cn.
⁵ Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
⁶ Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA.
⁷ ITM Laboratory, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, 675, USA.
⁸ Department of Physics, University of Alberta, Edmonton, AB, T6G2R3, Canada.
⁹ Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China.

^# Contributed equally.

Abstract

The magnetic gradient and curvature drift of energetic ions can form a longitudinal electric current around a planet known as the ring current, that has been observed in the intrinsic magnetospheres of Earth, Jupiter, and Saturn. However, there is still a lack of observational evidence of ring current in Mercury's magnetosphere, which has a significantly weaker dipole magnetic field. Under such conditions, charged particles are thought to be efficiently lost through magnetopause shadowing and/or directly impact the planetary surface. Here, we present the observational evidence of Mercury's ring current by analysing particle measurements from MErcury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft. The ring current is bifurcated because of the dayside off-equatorial magnetic minima. Test-particle simulation with Mercury's dynamic magnetospheric magnetic field model (KT17 model) validates this morphology. The ring current energy exceeds [Formula: see text] J during active times, indicating that magnetic storms may also occur on Mercury.