Current Sheets in Comet 67P/Churyumov-Gerasimenko's Coma

Abstract:

A cometary coma collects the time history of the solar wind magnetic field (IMF). Around the outgassing nucleus a conducting plasma envelope will be created through ionization of the neutrals coming from the comet. Through this layer the IMF cannot freely move, but is hung-up because the magnetic diffusion speed is much slower than the solar wind speed. Changes in IMF direction will therefore be layered in this hang-up region. Rosetta, moving at slow speed through 67P/CG’s coma, measures the magnetic field and observes strong rotations of the field over short (minutes) time scales. These strong rotations have to be accompanied by local current sheets, which should display themselves in the plasma instruments. We will show examples where these rotations are indeed accompanied by an increase in the ion or electron signatures in their respective time-energy spectrograms.