TY - JOUR
T1 - Statistical Analysis of Torus and Kink Instabilities in Solar Eruptions
AU - Jing, Ju
AU - Liu, Chang
AU - Lee, Jeongwoo
AU - Ji, Hantao
AU - Liu, Nian
AU - Xu, Yan
AU - Wang, Haimin
N1 - Funding Information:
We thank the anonymous referee for constructive comments. We thank the NASA SDO team for HMI and AIA data. HMI and AIA are instruments on board SDO, a mission for NASA’s Living with a Star program. We thank CDAW Data Center at Goddard Space Flight Center for providing the CME catalog, which is supported by NASA’s Living with a Star program and the SOHO project. We thank Dr. Rui Liu for developing the code to calculate the twist number. J.J., N.L., Y.X., C.L., and H.W. were supported by NASA grants NNX16AF72G, 80NSSC17K0016 (Grand Challenge) and 80NSSC18K0673 (GI), NSF grants AGS 1408703, and 1539791. J.L. was supported by the BK21 plus program through the National Research Foundation (NRF) funded by the Ministry of Education of Korea to Kyung Hee University.
Funding Information:
J.J., N.L., Y.X., C.L., and H.W. were supported by NASA grants NNX16AF72G, 80NSSC17K0016 (Grand Challenge) and 80NSSC18K0673 (GI), NSF grants AGS 1408703, and 1539791. J.L. was supported by the BK21 plus program through the National Research Foundation (NRF) funded by the Ministry of Education of Korea to Kyung Hee University.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved.
PY - 2018/9/10
Y1 - 2018/9/10
N2 - 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.
AB - 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.
KW - Sun: activity
KW - Sun: coronal mass ejections (CMEs)
KW - Sun: flares
KW - Sun: magnetic fields
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U2 - 10.3847/1538-4357/aad6e4
DO - 10.3847/1538-4357/aad6e4
M3 - Article
AN - SCOPUS:85053409743
SN - 0004-637X
VL - 864
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 138
ER -