Eruptive Flare, CME, and Shock Wave in the 25 August 2001 High-Energy Solar Event

• Published in: Solar physics Vol. 298; no. 3; p. 49
• Main Authors: Grechnev, V. V., Kochanov, A. A., Uralov, A. M.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.03.2023; Springer Nature B.V
• Subjects: Astrophysics and Astroparticles; Atmospheric Sciences; Coronal mass ejection; Emissions; Fluctuations; Frequency drift; Gamma emission; Gamma rays; Hard X-rays; Kinematics; Magnetic flux; Magnetic reconnection; Particle acceleration; Physics; Physics and Astronomy; Shock waves; Solar energy; Solar physics; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Spacecraft; X ray sources; X-rays; Coronal mass ejections; Magnetic reconnection; X-ray bursts; Radio bursts, Type II; Waves, shock; Flares
• ISSN: 0038-0938; 1573-093X
• DOI: 10.1007/s11207-023-02144-3

The major SOL2001-08-25 event produced a fast coronal mass ejection (CME: 1430 km s −1 ), strong flare emissions in hard X-rays and γ -rays extending to high energies, and neutrons detected both on spacecraft and by a low-latitude neutron monitor. To supplement the probable picture of this outstanding event, we reconstruct kinematic plots of the eruption and the shock-wave history. The hard X-ray and γ -ray emissions exhibited soft-hard-soft evolution. The emissions were strongest and hardest during a two-minute interval soon after the highest change rate of the magnetic flux within the flare ribbons of 2.6 × 10 19  Mx s −1 , which was simultaneous with the reconstructed acceleration of the erupting flux rope. We reveal an indication of accelerated electrons injected into the erupting flux rope that then precipitated far from the main flare site, producing a hard X-ray source that moved along the footprint of a stretching flux-rope leg. These results suggest that the particle acceleration was governed by magnetic reconnection during the eruption. As in a typical situation, a piston shock was excited early in the impulsive phase and gradually transformed into a bow shock later. The frequency drift of a Type-II burst is shown to be proportional to a power of frequency f , d f / d t ∝ − f ϵ , with a typical range of ϵ being between 5/3 and 2. Overall, the SOL2011-08-25 event was a typical eruptive two-ribbon flare. Its strength was determined mainly by the intensity of the reconnection processes.