Download presentation
Presentation is loading. Please wait.
Published byBernadette Harrison Modified over 8 years ago
1
On Coronal Mass Ejections and Configurations of the Ambient Magnetic Field Yang Liu Stanford University 3/17/2016 1 COSPAR 2008
2
Outline This talk includes two topics: This talk includes two topics: does the background field affect CMEs’ occurrence? does the background field affect CMEs’ occurrence? does the background field influence CMEs’ propagation? does the background field influence CMEs’ propagation? 3/17/2016 2COSPAR 2008
3
CMEs’ occurrence: Motivation 3/17/2016 3COSPAR 2008 TRACE 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)
4
CMEs’ occurrence: Motivation 3/17/2016 4COSPAR 2008 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?
5
CMEs’ occurrence: Motivation MHD simulations (FE vs KI) MHD simulations (FE vs KI) 3/17/2016 5COSPAR 2008 Courtesy: Kliem & Torok
6
CMEs’ occurrence: Motivation MHD simulations (FE vs KI) MHD simulations (FE vs KI) 3/17/2016 6COSPAR 2008 Courtesy: Kliem & Torok
7
CMEs’ occurrence: Motivation MHD simulation (KI vs TI) MHD simulation (KI vs TI) 3/17/2016 7COSPAR 2008 Fan & Gibson (2007)
8
CMEs’ occurrence: Motivation 3/17/2016 8COSPAR 2008 FE versus KI KI versus TI suggest gradient of the overlying field decides eruptions n(FE)<n(KI)<n(TI)
9
CMEs’ occurrence: Methodology Select erupted filaments in active regions; Select erupted filaments in active regions; Calculate background field using a potential field source surface model; Calculate background field using a potential field source surface model; At each height, compute overlying field by averaging horizontal field along the magnetic neutral line on the photosphere; At each height, compute overlying field by averaging horizontal field along the magnetic neutral line on the photosphere; Derive decay index. Derive decay index. 3/17/2016 9COSPAR 2008
10
CMEs’ occurrence: Sample We collect events from literature, and found: We collect events from literature, and found: 4 failed eruption (FE) cases (Green et al. 2007); 4 failed eruption (FE) cases (Green et al. 2007); 4 kink-instability (KI) full eruption cases (Green et al. 2007; Williams, et al. 2005); 4 kink-instability (KI) full eruption cases (Green et al. 2007; Williams, et al. 2005); 2 torus-instability (TI) full eruption cases (Schrijver et al. 2008). 2 torus-instability (TI) full eruption cases (Schrijver et al. 2008). 3/17/2016 10COSPAR 2008
11
Result IDTypeFlareDate, Time (dd/mm/yy) ARFlux (e22 Max) nB_t @ 42 Mm (Gauss) 1FEX1.106/06/00 133090265.931.5158.4 2FE------19/07/00 233090776.761.6544.2 3FE------27/05/02 180599576.981.7151.3 4FEM1.002/05/03 024703456.711.6299.3 5KIC6.807/04/97 135080271.121.7512.6 6KIC1.312/05/97 044280380.881.8812.3 7KIM6.315/06/01 095295021.991.8528.3 8KIX2.510/11/04 015606964.652.2535.9 9TIM4.016/06/05 191007753.702.0426.4 10TIM3.727/07/05 030007924.561.7433.0 3/17/2016 11COSPAR 2008 Decay index shows a clearly dividing line between failed eruptions and full eruptions, supportive of MHD simulations.
12
Result n(FE)<n(KI) & n(FE)<n(TI) support MHD results; n(FE)<n(KI) & n(FE)<n(TI) support MHD results; n(KI)~n(TI) not support MHD results; n(KI)~n(TI) 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) big active regions? F(FE)>F(KI) & F(FE)>F(TI) 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. 12 TypeFlux (e22 Max) nB_t (Gauss) FE6.60±0.331.62±0.0563.3±18.0 KI2.16±1.251.93±0.1522.3±9.8 TI4.13±0.431.89±0.1529.7±3.3 KI+TI2.81±1.481.91±0.1524.7±8.2 3/17/2016 COSPAR 2008
13
CMEs’ occurrence: Summary MHD simulations suggest: n(FE)<n(KI)<n(TI). MHD simulations suggest: n(FE)<n(KI)<n(TI). This work indicates: This work indicates: n(FE)<n(KI) & n(FE)<n(TI); but n(FE)<n(KI) & n(FE)<n(TI); but n(KI)~n(TI); n(KI)~n(TI); Field strength at low altitude is much stronger for failed eruption than for full eruptions. Field strength at low altitude is much stronger for failed eruption than for full eruptions. 3/17/2016 13COSPAR 2008
14
Outline This talk includes two topics: This talk includes two topics: does the background field affect CMEs’ occurrence? does the background field affect CMEs’ occurrence? does the background field influence CMEs’ propagation? does the background field influence CMEs’ propagation? 3/17/2016 14COSPAR 2008
15
3/17/2016 COSPAR 2008 CMEs’ propagations: Introduction Purpose: The purpose of this research is to study influence of background field for propagation of halo CMEs. Purpose: The purpose of this research is to study influence of background 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 15
16
3/17/2016 COSPAR 2008 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. 16
17
3/17/2016 COSPAR 2008 current-sheet boundary Non-current-sheet boundary 17
18
18 3/17/2016 COSPAR 2008 3D MHD simulation shows that type 2 and 3 CMEs are faster than type 1 (from Liu & Hayashi 2006). 3D MHD simulation shows that type 2 and 3 CMEs are faster than type 1 (from Liu & Hayashi 2006). Can observation support this result? Can observation support this result?
19
19 3/17/2016 COSPAR 2008 CMEs’ propagation: Methodology Methodology: we classify the halo CMEs by the magnetic field computed based on the Potential Field Source Surface model, and then compare speed distributions of those three type CMEs. Methodology: we classify the halo CMEs by the magnetic field computed based on the Potential Field Source Surface model, and then compare speed distributions of those three type CMEs. Assumption: we assume that, statistically, these three types of halo CMEs should have a similar speed distribution in the initial phase. The initial speed of a CME is suggested to be related with characteristic of the associated flare (e. g. Moon et al. 2002, Cheng et al. 2003, Zhang et al. 2004, Qiu et al. 2004). Assumption: we assume that, statistically, these three types of halo CMEs should have a similar speed distribution in the initial phase. The initial speed of a CME is suggested to be related with characteristic of the associated flare (e. g. Moon et al. 2002, Cheng et al. 2003, Zhang et al. 2004, Qiu et al. 2004).
20
20 3/17/2016 COSPAR 2008 CMEs’ propagation: Data We select the halo CME events from the CMEs catalog of Gopalswamy’s group. 99 halo CMEs in the period from 2000 to 2004 were chosen. The solar sources were identified by that group, and were confirmed by other groups/works. We select the halo CME events from the CMEs catalog of Gopalswamy’s group. 99 halo CMEs in the period from 2000 to 2004 were chosen. The solar sources were identified by that group, and were confirmed by other groups/works.
21
21 3/17/2016 COSPAR 2008 Examples of the three types of CMEs Type 1 Type 2 Type 3
22
3/17/2016 COSPAR 2008 CMEs’ propagation: Result Type 1Type 2Type 3 number394614 Percentage39%47%14% Median speed (km/s)72812081443 Mean speed (km/s)883±4031345±5961530±736 22
23
3/17/2016COSPAR 2008 Open: type 1 Filled: type 2 + type 3
24
3/17/2016 COSPAR 2008 Distribution of CMEs versus flare class.
25
25 3/17/2016 COSPAR 2008 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.
26
26 3/17/2016 COSPAR 2008 CMEs’ propagation: Summary Types 2 & 3 CMEs appear to be significantly faster than type 1. This effect is not biased by flare importance. Types 2 & 3 CMEs appear to be significantly faster than type 1. This effect is not biased by flare importance. It is shown that the background magnetic configuration associated with halo CMEs does play a role in deciding the speeds of the CMEs. It is shown that the background magnetic configuration associated with halo CMEs does play a role in deciding the speeds of the CMEs. A correlation was found between the speed of type 3 CMEs and the peak of X-ray flux of the associated flares. A correlation was found between the speed of type 3 CMEs and the peak of X-ray flux of the associated flares.
27
Conclusion In this talk, I shall try to answer two questions: In this talk, I shall try to answer two questions: does the background field affect CMEs’ occurrence? does the background field affect CMEs’ occurrence? does the background field influence CMEs’ propagation? does the background field influence CMEs’ propagation? Yes, configuration of background magnetic field influences occurrence and propagation of CMEs. Yes, configuration of background magnetic field influences occurrence and propagation of CMEs. 3/17/2016 27COSPAR 2008
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.