2018/08/27 by Ju Jing, Chang Liu, Jeongwoo Lee +4 · 59 citations
Physics and Astronomy · #Astro and Planetary Science #Coronal mass ejection #Halo #Instability #Ionosphere and magnetosphere dynamics #Kink instability #Magnetic field #Magnetohydrodynamics #Solar and Space Plasma Dynamics #Solar flare #Solar prominence #Torus #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/aad6e4
published in The Astrophysical Journal 864(2), 138 (IOP Publishing) · 20 pages, 5 figures
arxiv created 2018/08/27 · openalex created_date 2018/08/31 · openalex publication_date 2018/09/10 · arxiv updated 2018/09/19 · openalex updated_date 2026/08/06
Abstract A recent laboratory experiment of ideal magnetohydrodynamic instabilities revealed four distinct eruption regimes readily distinguished by the torus instability (TI) and helical kink instability (KI) parameters. To establish its observational counterpart, we collected 38 solar flares (stronger than GOES -class M5 in general) that took place within 45° of disk center during 2011–2017, 26 of which are associated with a halo or partial halo coronal mass ejection (CME; i.e., ejective events), while the others are CME-less (i.e., confined events). This is a complete sample of solar events satisfying our selection criteria detailed in the paper. For each event, we calculate a decay index n of the potential strapping field above the magnetic flux rope (MFR) in and around the flaring magnetic polarity inversion line (a TI parameter) and the unsigned twist number T w of the nonlinear force-free field lines forming the same MFR (a KI parameter). We then construct an n – T w diagram to investigate how the eruptiveness depends on these parameters. We find that (1) T w appears to play little role in discriminating between confined and ejective events; (2) the events with n ≳ 0.8 are all ejective, and all confined events have n ≲ 0.8. However, n ≳ 0.8 is not a necessary condition for eruption because some events with n ≲ 0.8 also erupted. In addition, we investigate the MFR’s geometrical parameters, apex height, and distance between footpoints, as a possible factors for the eruptiveness. We briefly discuss the difference of the present result for solar eruptions with that of the laboratory result in terms of the role played by magnetic reconnection.