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Abstract

In preparation of the ESA-JAXA mission Bepi Colombo we reconsidered the electron acceleration near Mercury. We first reviewed the existing observations starting from NASA’s Mariner-10 (1974–1975). Some of them later were shown to be inaccurate. Recently NASA’s Messenger mission newly observed energetic electrons including bursts of energies up to 100–200 keV. This by far exceeds the electron energies in the upstream solar wind. The acceleration mechanisms are, however, still not well understood. We derive models of electron acceleration near Mercury by passing strong interplanetary shocks, by reconnection at the magnetopause and in the Hermean magnetotail. We obtained the resulting electron energies and spectra in the near-Mercury MHD- and kinetic plasma turbulence as well as due to electric field structures by means of test particle calculations and also by fully self-consistent kinetic two- and three-dimensional PIC-code simulations whose results and, therefore, the acceleration mechanisms should be verified by the coming ESA-JAXA Bepi-Colombo mission to Mercury.