The root of a comet tail - Rosetta ion observations at comet 67P/Churyumov--Gerasimenko

Abstract

The first 1000 km of the ion tail of comet 67P/Churyumov-Gerasimenko were explored by the European Rosetta spacecraft, 2.7 au away from the Sun. We characterised the dynamics of both the solar wind and the cometary ions on the night-side of the comet's atmosphere. We analysed in situ ion and magnetic field measurements and compared the data to a semi-analytical model. The cometary ions are observed flowing close to radially away from the nucleus during the entire excursion. The solar wind is deflected by its interaction with the new-born cometary ions. Two concentric regions appear, an inner region dominated by the expanding cometary ions and an outer region dominated by the solar wind particles. The single night-side excursion operated by Rosetta revealed that the near radial flow of the cometary ions can be explained by the combined action of three different electric field components, resulting from the ion motion, the electron pressure gradients, and the magnetic field draping. The observed solar wind deflection is governed mostly by the motional electric field.

arXiv comment11 pages, 7 figures

References in corpus (7)

• The birth and growth of a solar wind cavity around a comet -- Rosetta observations
• Observation of a New Type of Low Frequency Waves at Comet 67P/Churyumov-Gerasimenko
• Mass loading at 67P/Churyumov-Gerasimenko: a case study
• The 67P/Churyumov-Gerasimenko observation campaign in support of the Rosetta mission
• Solar wind dynamics around a comet - A 2D semi-analytical kinetic model
• Hall Effect in the coma of 67P/Churyumov-Gerasimenko
• Solar wind dynamics around a comet: The paradigmatic inverse-square-law model

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• Plasma densities, flow and Solar EUV flux at comet 67P - A cross-calibration approach
• The Reduced Proper Motion selected halo: methods and description of the catalogue
• Solar wind dynamics around a comet: The paradigmatic inverse-square-law model
• Interaction between the turbulent solar wind and a planetary magnetosphere: a 2D comet example
• Probing Coronal Magnetic Fields with Sungrazing Comets: \hi\ Ly$\alpha$ from Pickup Ions