Magnetic Field Overlying Solar Eruptive Regions and Kink

Magnetic Field Overlying Solar Eruptive Regions and Kink and Torus Instabilities Yang Liu Stanford University 2/25/2021 AGU/SPD 2008 1

Motivation Confined eruption Fulleruptionofof of kink instability. kink torusinstability. (FE hereafter) (KI (TIhereafter) 2/25/2021 AGU/SPD 2008 TRACE EIT TRACE 195 1600 171 A. movie. Courtesy of L. Green of Schrijver 2

Motivation Full eruption of Failed eruption of kink instability (FE) kink instability (KI) Full eruption of torus instability (TI) Q: what causes these different types of eruptions? 2/25/2021 AGU/SPD 2008 3

Motivation n MHD simulations (FE vs KI) 2/25/2021 AGU/SPD 2008 & Torok Courtesy: Kliem 4

Motivation n MHD simulation (KI vs TI) 2/25/2021 AGU/SPD 2008 Fan & Gibson (2007) 5

Motivation FE versus KI KI versus TI suggest gradient of the overlying field decides eruptions n(FE)<n(KI)<n(TI) 2/25/2021 AGU/SPD 2008 6

Methodology Select erupted filaments in active regions; n Calculate background field using a potential field source surface model; n At each height, compute overlying field by averaging horizontal field along the magnetic neutral line on the photosphere; n Derive decay index. AGU/SPD 2008 2/25/2021 n 7

Sample n We collect events from literature, and found: 4 failed eruption (FE) cases (Green et al. 2007); n 4 kink-instability (KI) full eruption cases (Green et al. 2007; Williams, et al. 2005); n 2 torus-instability (TI) full eruption cases (Schrijver et al. 2008). n 2/25/2021 AGU/SPD 2008 8

AR Flux Result (e 22 Max) ID Type Flare Date, Time (dd/mm/yy) n B_t @ 42 Mm (Gauss) 1 FE X 1. 1 06/06/00 1330 9026 5. 93 1. 51 58. 4 2 FE ------ 19/07/00 2330 9077 6. 76 1. 65 44. 2 3 FE ------ 27/05/02 1805 9957 6. 98 1. 71 51. 3 4 FE M 1. 0 02/05/03 0247 0345 6. 71 1. 62 99. 3 5 KI C 6. 8 07/04/97 1350 8027 1. 12 1. 75 12. 6 6 KI C 1. 3 12/05/97 0442 8038 0. 88 12. 3 7 KI M 6. 3 15/06/01 0952 9502 1. 99 1. 85 28. 3 8 KI X 2. 5 10/11/04 0156 0696 4. 65 2. 25 35. 9 9 TI M 4. 0 16/06/05 1910 0775 3. 70 2. 04 26. 4 10 TI M 3. 7 27/07/05 0300 0792 4. 56 1. 74 33. 0 Decay index shows a clearly dividing line between failed eruptions and full eruptions, supportive of MHD simulations. AGU/SPD 2008 2/25/2021 9

Type FE KI TI KI+TI n n n Flux n Result (e 22 Max) 6. 60± 0. 33 1. 62± 0. 05 2. 16± 1. 25 1. 93± 0. 15 4. 13± 0. 43 1. 89± 0. 15 2. 81± 1. 48 1. 91± 0. 15 B_t (Gauss) 63. 3± 18. 0 22. 3± 9. 8 29. 7± 3. 3 24. 7± 8. 2 n(FE)<n(KI) & n(FE)<n(TI) support MHD results; n(KI)~n(TI) not support MHD results; B(FE)>B(KI) & B(FE)>B(TI), due to probably, F(FE)>F(KI) & F(FE)>F(TI) large active regions? Large active regions usually produce more events: n n Eruptions may be caused by other mechanisms; Initial heights of filaments are higher. 10

Conclusions MHD simulations suggest: n(FE)<n(KI)<n(TI). n This work indicates: n n(FE)<n(KI) & n(FE)<n(TI); but n n(KI)~n(TI); n Field strength at low altitude is much stronger for failed eruption than for full eruptions. n 2/25/2021 AGU/SPD 2008 11