Study of Plasma Heating Processes in a Coronal Mass Ejection-driven Shock Sheath Region Observed with the Metis Coronagraph

0584793 - ASÚ 2025 RIV GB eng J - Journal Article
Frassati, F. - Bemporad, A. - Mancuso, S. - Heinzel, Petr … Total 27 authors
Study of Plasma Heating Processes in a Coronal Mass Ejection-driven Shock Sheath Region Observed with the Metis Coronagraph.
Astrophysical Journal. Roč. 964, č. 1 (2024), č. článku 15. ISSN 0004-637X. E-ISSN 1538-4357
Institutional support: RVO:67985815
Keywords : II radio-bursts * white-light * physical parameters
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 4.9, year: 2022
Method of publishing: Open access

On 2021 September 28, a C1.6 class flare occurred in active region NOAA 12871, located approximately at 27 degrees S and 51 degrees W on the solar disk with respect to Earth's point of view. This event was followed by a partial halo coronal mass ejection (CME) that caused the deflection of preexisting coronal streamer structures, as observed in visible-light coronagraphic images. An associated type II radio burst was also detected by both space- and ground-based instruments, indicating the presence of a coronal shock propagating into interplanetary space. By using H i Ly alpha (121.6 nm) observations from the Metis coronagraph on board the Solar Orbiter mission, we demonstrate for the first time the capability of UV imaging to provide, via a Doppler dimming technique, an upper limit estimate of the evolution of the 2D proton kinetic temperature in the CME-driven shock sheath as it passes through the field of view of the instrument. Our results suggest that over the 22 minutes of observations, the shock propagated with a speed decreasing from about 740 +/- 110 km s-1 to 400 +/- 60 km s-1. At the same time, the postshock proton temperatures peaked at latitudes around the shock nose and decreased with time from about 6.8 +/- 1.01 MK to 3.1 +/- 0.47 MK. The application of the Rankine-Hugoniot jump conditions demonstrates that these temperatures are higher by a factor of about 2-5 than those expected from simple adiabatic compression, implying that significant shock heating is still going on at these distances.
Permanent Link: https://hdl.handle.net/11104/0353185