1. Solar Orbiter Observations of Waves and Structures from the Tail of Comet ATLAS
- Author
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Matteini, L., Horbury, T. S., Woodham, L. D., Bale, S. D., Hellinger, P., Galand, M. F., Jones, G. H., O'Brien, H., Evans, V., Angelini, V., Maksimovic, M., Chust, Thomas, Khotyaintsev, Y., Krasnoselskikh, V., Kretzschmar, Matthieu, Lorfevre, E., Plettemeier, D., Soucek, J., Steller, M., Stverak, S., Travnicek, P., Vaivads, A., Vecchio, A., Bruno, R., Fedorov, A., Livi, S. A., Louarn, P., Owen, C. J., and POTHIER, Nathalie
- Subjects
ASTROPHYSICS ,[SDU] Sciences of the Universe [physics] ,General or miscellaneous ,Instruments and techniques ,ASTRONOMY ,SOLAR PHYSICS - Abstract
Comet ATLAS disintegrated into several fragments while reaching its most recent perihelion at approximately 0.25AU in April 2020. Solar Orbiter is predicted to have crossed both the ion and dust tails of the comet between 31 May and 6 June 2020, when the spacecraft was close to 0.5AU. This constituted a unique opportunity to make in situ measurements of distinct cometary fragments at such a close distance from the Sun and to study the interaction of cometary pick-up ions with the solar wind plasma. In this study, we present and discuss possible signatures of this interaction as seen in various Solar Orbiter in situ sensors (MAG, RPW, SWA). We mainly focus on properties of a wide range of both structures and low-frequency electromagnetic waves that are supposedly driven by cometary pick-up ion instabilities and intermittently observed over several days during the encounter. These include trains of phase-steepened Alfvén waves propagating in both directions along the magnetic field, sharp discontinuities and current sheets, and precessing linearly polarised waves possibly suggesting the presence of non-gyrotropic sources of heavier pick-up ions. Observed wave properties are discussed and compared with expectations from linear theory and numerical simulations.
- Published
- 2020