On Coronal Mass Ejections and Configurations of the Ambient Magnetic Field
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On Coronal Mass Ejections and On Coronal Mass Ejections and Configurations of the Ambient Configurations of the Ambient Magnetic Field Magnetic Field Yang Liu Yang Liu Stanford University Stanford University 06/13/22 1 COSPAR 2008
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On Coronal Mass Ejections and Configurations of the Ambient Magnetic Field. Yang Liu Stanford University. Outline. This talk includes two topics: does the background field affect CMEs’ occurrence? does the background field influence CMEs’ propagation?. CMEs’ occurrence: Motivation. - PowerPoint PPT Presentation
Transcript of On Coronal Mass Ejections and Configurations of the Ambient Magnetic Field
On Coronal Mass Ejections and On Coronal Mass Ejections and Configurations of the Ambient Configurations of the Ambient
Magnetic FieldMagnetic Field
Yang LiuYang LiuStanford UniversityStanford University
04/22/23 1COSPAR 2008
OutlineOutline
This talk includes two topics:This talk includes two topics:
does the background field affect CMEs’ does the background field affect CMEs’ occurrence? occurrence?
does the background field influence does the background field influence CMEs’ propagation? CMEs’ propagation?
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CMEs’ occurrence: CMEs’ occurrence: Motivation Motivation
04/22/23 3COSPAR 2008TRACE 171 movie. Courtesy of SchrijverEIT 195TRACE 1600 A. Courtesy of
L. Green
Confined eruption of kink instability.(FE hereafter)
Full eruption of kink instability.(KI hereafter)
Full eruption of torus instability.(TI hereafter)
CMEs’ occurrence: CMEs’ occurrence: Motivation Motivation
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Failed eruption of kink instability (FE)
Full eruption of kink instability (KI)
Full eruption of torus instability (TI)
Q: what causes these different types of eruptions?
CMEs’ occurrence: CMEs’ occurrence: MotivationMotivation
MHD simulations (FE vs KI)MHD simulations (FE vs KI)
04/22/23 5COSPAR 2008Courtesy: Kliem & Torok
CMEs’ occurrence: CMEs’ occurrence: MotivationMotivation
MHD simulations (FE vs KI)MHD simulations (FE vs KI)
04/22/23 6COSPAR 2008Courtesy: Kliem & Torok
nexternalpoloidal hB
CMEs’ occurrence: CMEs’ occurrence: MotivationMotivation
MHD simulation (KI vs TI)MHD simulation (KI vs TI)
04/22/23 7COSPAR 2008Fan & Gibson (2007)
CMEs’ occurrence: CMEs’ occurrence: MotivationMotivation
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FE versus KI
KI versus TI
suggest gradient of the overlying field decides eruptions
nexternalpoloidal hB n(FE)<n(KI)<n
(TI)
CMEs’ occurrence: CMEs’ occurrence: MethodologyMethodology
Select erupted filaments in Select erupted filaments in active regions;active regions;
Calculate background field Calculate background field using a potential field using a potential field source surface model;source surface model;
At each height, compute At each height, compute overlying field by averaging overlying field by averaging horizontal field along the horizontal field along the magnetic neutral line on the magnetic neutral line on the photosphere;photosphere;
Derive decay index.Derive decay index.04/22/23 9COSPAR 2008
CMEs’ occurrence: CMEs’ occurrence: SampleSample
We collect events from literature, We collect events from literature, and found:and found: 4 failed eruption (FE) cases (Green et 4 failed eruption (FE) cases (Green et
al. 2007);al. 2007); 4 kink-instability (KI) full eruption cases 4 kink-instability (KI) full eruption cases
(Green et al. 2007; Williams, et al. (Green et al. 2007; Williams, et al. 2005);2005);
2 torus-instability (TI) full eruption 2 torus-instability (TI) full eruption cases (Schrijver et al. 2008).cases (Schrijver et al. 2008).
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Result Result ID Type Flare Date, Time(dd/mm/yy)
AR Flux(e22 Max)
n B_t @ 42 Mm
(Gauss)
1 FE X1.1 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 M1.0
02/05/03 0247
0345
6.71 1.62
99.3
5 KI C6.8 07/04/97 1350
8027
1.12 1.75
12.6
6 KI C1.3 12/05/97 0442
8038
0.88 1.88
12.3
7 KI M6.3
15/06/01 0952
9502
1.99 1.85
28.3
8 KI X2.5 10/11/04 0156
0696
4.65 2.25
35.9
9 TI M4.0
16/06/05 1910
0775
3.70 2.04
26.4
10
TI M3.7
27/07/05 0300
0792
4.56 1.74
33.0
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Decay index shows a clearly dividing line between failed eruptions and full eruptions, supportive of MHD simulations.
Result Result
n(FE)<n(KI) & n(FE)<n(TI) n(FE)<n(KI) & n(FE)<n(TI) support MHD support MHD results;results;
n(KI)~n(TI) n(KI)~n(TI) not support MHD results; not support MHD results; B(FE)>B(KI) & B(FE)>B(TI), probably due to,B(FE)>B(KI) & B(FE)>B(TI), probably due to, F(FE)>F(KI) & F(FE)>F(TI)F(FE)>F(KI) & F(FE)>F(TI)big active regions?big active regions? Big active regions usually produce more events:Big active regions usually produce more events:
Eruptions may be caused by other mechanisms;Eruptions may be caused by other mechanisms; Initial heights of filaments are higher.Initial heights of filaments are higher.
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Type Flux(e22 Max)
n B_t(Gauss)
FE 6.60±0.33
1.62±0.05
63.3±18.0
KI 2.16±1.25
1.93±0.15
22.3±9.8
TI 4.13±0.43
1.89±0.15
29.7±3.3
KI+TI 2.81±1.48
1.91±0.15
24.7±8.2
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CMEs’ occurrence: CMEs’ occurrence: Summary Summary
MHD simulations suggest: MHD simulations suggest: n(FE)<n(KI)<n(TI).n(FE)<n(KI)<n(TI).
This work indicates:This work indicates: n(FE)<n(KI) & n(FE)<n(TI); butn(FE)<n(KI) & n(FE)<n(TI); but n(KI)~n(TI);n(KI)~n(TI); Field strength at low altitude is much Field strength at low altitude is much
stronger for failed eruption than for full stronger for failed eruption than for full eruptions.eruptions.
04/22/23 13COSPAR 2008
OutlineOutline
This talk includes two topics:This talk includes two topics:
does the background field affect CMEs’ does the background field affect CMEs’ occurrence? occurrence?
does the background field influence does the background field influence CMEs’ propagation? CMEs’ propagation?
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CMEs’ propagations: CMEs’ propagations: Introduction Introduction
Purpose: The purpose of this research Purpose: The purpose of this research is to study influence of background is to study influence of background field for propagation of halo CMEs.field for propagation of halo CMEs.
The background field was found to have two different configurations: current sheet and non-current sheet (see, e. g. Shultz 1973; Wilcox et al. 1980; Neugebauer et al. 2002, 2004).
Current-sheet boundary
Non-current-sheet boundary
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Current-sheet boundary
Non-current-sheet boundary
These two configurations were also successfully reproduced by Zhao & Webb (2003) based on a Potential Field Source Surface model.
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current-sheet boundary
Non-current-sheet boundary
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3D MHD simulation shows that type 2 and 3 CMEs 3D MHD simulation shows that type 2 and 3 CMEs are faster than type 1 (from Liu & Hayashi 2006).are faster than type 1 (from Liu & Hayashi 2006).
Can observation support this result?Can observation support this result?
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COSPAR 2008
CMEs’ propagation: CMEs’ propagation: MethodologyMethodology
Methodology: we classify the halo CMEs by Methodology: we classify the halo CMEs by the magnetic field computed based on the the magnetic field computed based on the Potential Field Source Surface model, and Potential Field Source Surface model, and then compare speed distributions of those then compare speed distributions of those three type CMEs.three type CMEs.
Assumption: we assume that, statistically, Assumption: we assume that, statistically, these three types of halo CMEs should have a these three types of halo CMEs should have a similar speed distribution in the initial phase. similar speed distribution in the initial phase. The initial speed of a CME is suggested to be The initial speed of a CME is suggested to be related with characteristic of the associated related with characteristic of the associated flare (e. g. Moon et al. 2002, Cheng et al. flare (e. g. Moon et al. 2002, Cheng et al. 2003, Zhang et al. 2004, Qiu et al. 2004).2003, Zhang et al. 2004, Qiu et al. 2004).
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CMEs’ propagation: Data CMEs’ propagation: Data We select the halo CME events from the We select the halo CME events from the
CMEs catalog of Gopalswamy’s group. 99 CMEs catalog of Gopalswamy’s group. 99 halo CMEs in the period from 2000 to halo CMEs in the period from 2000 to 2004 were chosen. The solar sources were 2004 were chosen. The solar sources were identified by that group, and were identified by that group, and were confirmed by other groups/works.confirmed by other groups/works.
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Examples of the three types of CMEsExamples of the three types of CMEs
Type 1 Type 2 Type 3
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CMEs’ propagation: CMEs’ propagation: ResultResult
Type 1 Type 2 Type 3
number 39 46 14
Percentage 39% 47% 14%
Median speed (km/s) 728 1208 1443
Mean speed (km/s) 883±403 1345±596 1530±736
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Open: type 1
Filled: type 2 + type 3
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Distribution of CMEs versus flare class.
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A correlation was found between the speed of type 3 CMEs and the peak X-ray flux of the associated flares. No such correlations are found for types 1 and 2 CMEs.
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CMEs’ propagation: CMEs’ propagation: SummarySummary
Types 2 & 3 CMEs appear to be significantly Types 2 & 3 CMEs appear to be significantly faster than type 1. This effect is not biased by faster than type 1. This effect is not biased by flare importance.flare importance.
It is shown that the background magnetic It is shown that the background magnetic configuration associated with halo CMEs does configuration associated with halo CMEs does play a role in deciding the speeds of the CMEs.play a role in deciding the speeds of the CMEs.
A correlation was found between the speed of A correlation was found between the speed of type 3 CMEs and the peak of X-ray flux of the type 3 CMEs and the peak of X-ray flux of the associated flares.associated flares.
ConclusionConclusion
In this talk, I shall try to answer two In this talk, I shall try to answer two questions:questions: does the background field affect CMEs’ does the background field affect CMEs’
occurrence? occurrence? does the background field influence CMEs’ does the background field influence CMEs’
propagation? propagation? Yes, configuration of background Yes, configuration of background
magnetic field influences magnetic field influences occurrence and propagation of occurrence and propagation of CMEs.CMEs.
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