Volume 654, October 2021
|Number of page(s)||5|
|Section||Letters to the Editor|
|Published online||08 October 2021|
Letter to the Editor
Tracing the ICME plasma with a MHD simulation⋆
University of Palermo, Physics and Chemistry Department, Piazza del Parlamento 1, 90134 Palermo, Italy
2 INAF-Turin Astrophysical Observatory, Via Osservatorio 20, 10025 Pino Torinese, TO, Italy
3 INAF-Palermo Astronomical Observatory, Piazza del Parlamento 1, 90134 Palermo, Italy
Accepted: 20 September 2021
The determination of the chemical composition of interplanetary coronal mass ejection (ICME) plasma is an open issue. More specifically, it is not yet fully understood how remote sensing observations of the solar corona plasma during solar disturbances evolve into plasma properties measured in situ away from the Sun. The ambient conditions of the background interplanetary plasma are important for space weather because they influence the evolutions, arrival times, and geo-effectiveness of the disturbances. The Reverse In situ and MHD APproach (RIMAP) is a technique to reconstruct the heliosphere on the ecliptic plane (including the magnetic Parker spiral) directly from in situ measurements acquired at 1 AU. It combines analytical and numerical approaches, preserving the small-scale longitudinal variability of the wind flow lines. In this work, we use RIMAP to test the interaction of an ICME with the interplanetary medium. We model the propagation of a homogeneous non-magnetised (i.e. with no internal flux rope) cloud starting at 800 km s−1 at 0.1 AU out to 1.1 AU. Our 3D magnetohydrodynamics (MHD) simulation made with the PLUTO MHD code shows the formation of a compression front ahead of the ICME, continuously driven by the cloud expansion. Using a passive tracer, we find that the initial ICME material does not fragment behind the front during its propagation, and we quantify the mixing of the propagating plasma cloud with the ambient solar wind plasma, which can be detected at 1 AU.
Key words: magnetohydrodynamics (MHD) / Sun: abundances / Sun: coronal mass ejections (CMEs) / solar-terrestrial relations
Movie associated with Fig. 1 is available at https://www.aanda.org
© ESO 2021
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