Spatial distribution of low-energy plasma around comet 67P/CG from Rosetta measurements

Abstract

We use measurements from the Rosetta plasma consortium (RPC) Langmuir probe (LAP) and mutual impedance probe (MIP) to study the spatial distribution of low-energy plasma in the near-nucleus coma of comet 67P/Churyumov-Gerasimenko. The spatial distribution is highly structured with the highest density in the summer hemisphere and above the region connecting the two main lobes of the comet, i.e. the neck region. There is a clear correlation with the neutral density and the plasma to neutral density ratio is found to be about 1-2x10^-6, at a cometocentric distance of 10 km and at 3.1 AU from the sun. A clear 6.2 h modulation of the plasma is seen as the neck is exposed twice per rotation. The electron density of the collisonless plasma within 260 km from the nucleus falls of with radial distance as about 1/r. The spatial structure indicates that local ionization of neutral gas is the dominant source of low-energy plasma around the comet.

arXiv comment7 pages, 3 figures

Cited by in corpus (18)

• The Rosetta mission orbiter Science overview the comet phase
• CME impact on comet 67P/Churyumov-Gerasimenko
• Measurements of the electrostatic potential of Rosetta at comet 67P
• Mass-loading of the solar wind at 67P/Churyumov-Gerasimenko -- Observations and modelling
• Changes in the physical environment of the inner coma of 67P/Churyumov-Gerasimenko with decreasing heliocentric distance
• Solar wind interaction with comet 67P: impacts of corotating interaction regions
• Solar wind dynamics around a comet - A 2D semi-analytical kinetic model
• Cold electrons at comet 67P/Churyumov-Gerasimenko
• A charging model for the Rosetta spacecraft
• Plasma Density Structures at Comet 67P/Churyumov-Gerasimenko
• Plasma densities, flow and Solar EUV flux at comet 67P - A cross-calibration approach
• Momentum and pressure balance of a comet ionosphere
• The evolution of the electron number density in the coma of comet 67P at the location of Rosetta from 2015 November through 2016 March
• Constraining spatial pattern of early activity of comet 67P/C-G with 3D modeling of the MIRO observations
• Near-UV OH Prompt Emission in the Innermost Coma of 103P/Hartley 2
• Solar flares observed by Rosetta at comet 67P
• A photochemical model of ultraviolet atomic line emissions in the inner coma of comet 67P/Churyumov-Gerasimenko
• Modeling the Plasma Composition of 67P/C-G at different Heliocentric Distances