SH039-06
The Low-Energy Ion Event on 19 June 2020 Measured by Solar Orbiter
Monday, 14 December 2020: 11:50
Virtual
Angels Aran1, Daniel Pacheco2, Nicolas Wijsen3, Evangelia Samara3,4, Raul Gomez-Herrero5, Monica Laurenza6, Simone Benella6, Blas Sanahuja1, Stefaan Poedts3, Johan Lauritz Freiherr von Forstner2, Lars Berger7, Glenn M Mason8, Robert Colby Allen8, Helen O'Brien9, Vincent Evans10, Virginia Angelini10, Timothy Simon Horbury9, George C Ho8, Robert F Wimmer-Schweingruber2 and Javier Rodriguez-Pacheco11, (1)Universitat de Barcelona, Física Quàntica i Astrofísica, Institut de Ciències del Cosmos (ICCUB), Barcelona, Spain, (2)University of Kiel, Institute for Experimental and Applied Physics, Kiel, Germany, (3)KU Leuven, Centre for mathematical Plasma-Astrophysics, Leuven, Belgium, (4)Observatoire Royal de Belgique, Brussel, Belgium, (5)University of Alcala, Alcala de Henares, Spain, (6)INAF-Istituto di Astrofisica e Planetologia Spaziali, Roma, Italy, (7)Institute for Experimental and Applied Physics (IEAP), Christian-Albrechts-University of Kiel, Kiel, Germany, (8)Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (9)Imperial College London, Department of Physics, London, SW7, United Kingdom, (10)Imperial College London, Department of Physics, London, United Kingdom, (11)University of Alcalá, Space Research Group, Alcalá de Henares, Spain
Abstract:
Shortly after reaching the first perihelion, the Energetic Particle Detector (EPD) onboard Solar Orbiter measured a small particle event. The observed ion intensity enhancement extended from few keV(/nuc) to <1 MeV(/nuc) and had different durations depending on the particles’ energy. The increase above pre-event intensity levels was detected at the beginning of June 19 for ions in the energetic particle range (~50 keV to ~MeV) and lasted up to the noon of June 20. In contrast, the particle event lasted from the 18th to the ~21st of June in the energy range from ~10 keV to < 40 keV, corresponding to the highest energies of the suprathermal particle population in the solar wind. This low-energy increase coincides with a decrease in the count rates of ions with energies > 17 MeV/nuc. On the other hand, no electron increases were detected.
In this work, we present and analyse the particle data gathered by the EPD instruments during this event and discuss its possible sources. To interpret the particle data, we also use interplanetary magnetic field data from the MAG instrument. As seen from 1 AU, there is no clear evidence of solar activity from the visible disk associated with this ion event; it might, however, have a possible association with solar activity erupting from behind the limb and/or with a source of interplanetary origin. We further discuss on the latter scenario by using three-dimensional simulations for both the solar wind and the particles’ transport and acceleration. For the former, we employ the magnetohydrodynamic model EUHFORIA (EUropean Heliospheric FORecasting Information Asset) while for the particles’ transport and acceleration we use the PARADISE (PArticleRadiation Asset Directed at Interplanetary Space Exploration) model.
