SH039-10
Solar Orbiter Observations of Waves and Structures from the Tail of Comet ATLAS
Monday, 14 December 2020: 12:06
Virtual
Lorenzo Matteini1, Timothy Simon Horbury1, Lloyd David Woodham1, Stuart D Bale2,3, Petr Hellinger4, Marina F Galand3, Geraint H Jones5, Helen O'Brien1, Vincent Evans3, Virginia Angelini3, Milan Maksimovic6, Thomas Chust7, Yuri Khotyaintsev8, Vladimir Krasnoselskikh9, Matthieu Kretzschmar10, Eric Lorfevre11, Dirk Plettemeier12, Jan Soucek13, Manfred Steller14, Stepan Stverak15, Pavel Travnicek16,17, Andris Vaivads18, Antonio Vecchio6, Roberto Bruno19, Andrei Fedorov20, Stefano A Livi21, Philippe Louarn22 and Christopher John Owen23, (1)Imperial College London, Department of Physics, London, SW7, United Kingdom, (2)University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, United States, (3)Imperial College London, Department of Physics, London, United Kingdom, (4)Astronomical Institute, CAS, Ondrejov/Prague, Czech Republic, (5)UCL Mullard Space Science Laboratory, Centre for Planetary Sciences at UCL/Birkbeck, Holmbury St. Mary, Dorking, Surrey, United Kingdom, (6)LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Meudon, France, (7)Laboratoire de Physique des Plasmas (UMR7648), CNRS/Ecole Polytechnique/UPMC/Univ. Paris Sud/Obs. de Paris, Paris, France, (8)IRF Swedish Institute of Space Physics, Uppsala, Sweden, (9)LPC2E, CNRS and University of Orléans, Orléans, France, (10)CNRS and University of Orléans, LPC2E, Orléans, France, (11)CNES French National Center for Space Studies, Toulouse Cedex 09, France, (12)Dresden University of Technology, Dresden, Germany, (13)Inst. of Atmospheric Physics, Praha 4, Czech Republic, (14)Space Research Institute, Austrian Academy of Sciences, Graz, Austria, (15)Astronomical Institute AS CR, Prague, Czech Republic, (16)University of California, Berkeley, Space Sciences Laboratory, Berkeley, United States, (17)Astronomical Institute of the Academy of Sciences, Prague, Czech Republic, (18)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (19)IAPS-INAF, Rome, Italy, (20)CNRS-IRAP, Toulouse, France, (21)SwRI, San Antonio, TX, United States, (22)IRAP, CNRS, Toulouse, France, (23)University College London, Mullard Space Science Laboratory, Dorking, United Kingdom
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.
