Mapping of the cometary plasma density around comet CG/67P at perihelion.

Abstract : In August 2015, comet 67P/Churyumov-Gerasimenko, target of the ESA’s Rosetta mission, reached its perihelion at 1.3 AU from the Sun. The Rosetta Plasma Consortium (RPC) onboard the Rosetta spacecraft offers a unique opportunity to analyze the plasma environment during this period. Combining observations from the Mutual Impedance probe (RPC-MIP) and the Langmuir probes (RPC-LAP), we estimate the cometary plasma density. We will present its spatial distribution around the comet when close to perihelion. Combined Mutual impedance and Langmuir probes density measurements are also compared to the density derived from particle measurements (RPC-ICA and RPC-IES). In addition, we will focus on localised, strong variations of the cometary plasma density over short timescales (~ minutes to seconds) observed during this period. These strong plasma density enhancements are interpreted taken into account the electron energy spectrum measured by the Ion and Electron Spectrometer (RPC-IES). Possible correlations of these plasma enhancements with variations in the magnetic field direction measured from the Magnetometer (RPC-MAG) will be discussed.