Magnetosheath plasmoids at Earth and Mercury
Recently there has been an increased interest in transient, localized increases in plasma density and flow velocity in Earth’s magnetosheath. Such enhancements have been studied under several different designations, e.g. magnetosheath jets or plasmoids. The latter designation specifically refers to the presence of clear magnetic signatures associated with localized density increases. These transients have been suggested to be universally present in planetary magnetospheres. As a first check of that hypothesis, we present results from the Mercury magnetosheath and near solar wind, using MESSENGER magnetic field data from the MAG instrument (and ion data from the Fast Imaging Plasma Spectrometer (FIPS) instrument for contextual information). We discuss the findings and some of their consequences pertaining to the different nature of the quasi-parallel bow shocks at Mercury and Earth.