Development of a cometosheath at comet 67P/Churyumov-Gerasimenko: A case study comparison of Rosetta observations

Williamson, H. N., Nilsson, H., Stenberg Wieser, G., Moeslinger, A. and Goetz, Charlotte (2022) Development of a cometosheath at comet 67P/Churyumov-Gerasimenko: A case study comparison of Rosetta observations. Astronomy & Astrophysics, 660. A103. ISSN 0004-6361

aa42461-21.pdf - Published Version
Available under License Creative Commons Attribution 4.0.

Download (2MB) | Preview
Official URL:


Context. The ionosphere of a comet is known to deflect the solar wind through mass loading, but the interaction is dependent on cometary activity. We investigate the details of this process at comet 67P using the Rosetta Ion Composition Analyzer.

Aims. This study aims to compare the interaction of the solar wind and cometary ions during two different time periods in the Rosetta mission.

Methods. We compared both the integrated ion moments (density, velocity, and momentum flux) and the velocity distribution functions for two days, four months apart. The velocity distribution functions were projected into a coordinate system dependent on the magnetic field direction and averaged over three hours.

Results. The first case shows highly scattered H+ in both ion moments and velocity distribution function. The He2+ ions are somewhat scattered, but less so, and appear more like those of H2O+ pickup ions. The second case shows characteristic evidence of mass-loading, where the solar wind species are deflected, but the velocity distribution function is not significantly changed.

Conclusions. The distributions of H+ in the first case, when compared to He2+ and H2O+ pickup ions, are indicative of a narrow cometosheath on the scale of the H+ gyroradius. Thus, He2+ and H2O+, with larger gyroradii, are largely able to pass through this cometosheath. An examination of the momentum flux tensor suggests that all species in the first case have a significant non-gyrotropic momentum flux component that is higher than that of the second mass-loaded case. Mass loading is not a sufficient explanation for the distribution functions and momentum flux tensor in the first case, and so we assume this is evidence of bow shock formation.

Item Type: Article
Uncontrolled Keywords: plasmas, methods: data analysis, comets: individual: comet 67P, Churyumov-Gerasimenko
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 06 Oct 2022 15:01
Last Modified: 06 Oct 2022 15:15

Actions (login required)

View Item View Item


Downloads per month over past year

View more statistics