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Confined X-class Flares vs. Eruptive ones Non-CME associated X-class Flares vs. CME-associated ones Yuming Wang 1, 2 & Jie Zhang 1 1 Computational & data Science, College of Science, George Mason University, Fairfax, VA 22030, USA - PowerPoint PPT Presentation
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Confined X-class Flares vs.
Eruptive onesNon-CME associated X-class Flares
vs. CME-associated ones
Yuming Wang1, 2 & Jie Zhang1
1 Computational & data Science, College of Science, George Mason University, Fairfax, VA 22030, USA
2 School of Earth & Space Sciences, University of Science & Techonology of China,Hefei, Anhui 230026, P. R. China
2007 September
Lin & Forbes, 2000
Flux rope catastrophe model
Antiochos et al., 1999
Breakout model
Lin et al., 2004
C M X
15% 24% 100% Harrison, 1995
290 flares, 86-87
55% 100% Andrews, 2003
229 flares, 96-99
16-25% 42-55% 90-92%4 events
Yashiro et al., 2005
1301 flares, 96-01
89%11 events
Wang & Zhang, 2007
104 X flares, 96-04
An incomplete list of the CME association of flares
Question
Why could strong energy releases in corona be either confined or eruptive?
Why are not some X-class flares associated with coronal mass ejections?
11 (~10%) X-class flares were confined (not associated with CMEs).
Some cases were reported by Feynman & Hundhausen (1994), Green et al. (2002), Yashiro et al. (2005) and so on.
Another question: Why these confined X-class flares occurred only in solar maximum and decline phase? At least, it is true for the last solar cycle.
Two sets of events have similar profiles in soft X-ray flux recorded by GOES.
The rise time is no more than 13 minutes.
The intensity is no stronger than X2.0.
4 confined events
Segmented MDI magnetogram remapped on Carrington rotation map.
Red asterisks, diamonds, and blue lines denote the flare site, centroid of magnetic flux, and associated neutral line, respectively.
A confined event
PFSS model is used to extrapolate coronal magnetic field, in which MDI synoptic charts with resolution of 3600x1080 are adopted as input boundary condition and spheric harmonic coefficients are calculated to 225 order.
1.0 Rs
1.1 Rs
1.5 Rs
Low corona
High corona
confined
eruptive
Conclusions:
(1) The displacement for all the confined events is smaller than that for eruptive events, which implies that the overlying arcades are weaker in the edge of an active region than in the center.
(2) The flux ratio of low-corona to high-corona is smaller for confined events than eruptive events (no significant difference between the two sets of events in individual values of coronal fluxes), which means that there probably is a critical point, above/below which a flare is eruptive/confined.
The inner flux rope has a tendency to erupt due to Lorentz self-force (hoop force).
It is suggested that the magnetic gradient along the height in the overlying field may decide whether the flux rope instability leads to a confined event or to a CME.
A weak gradient favors confinement.
[Torok & Kliem, 2005].
Initial configuration (Adapted from Torok & Kliem, 2007)
Question: If there is only a flare but no CME, what happens to the inner flux rope or what is its fate?
[Nindos & Andrews 2004]
|alpha| Coronal Helicity
A statistical comparison between CME and non-CME flares78 available ARs from Andrews (2003) 229 events
All non-CME flares do not exceed X-class
What does the helicity stand for?
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