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Confined X-class Flares vs. Eruptive ones Non-CME associated X-class Flares vs.

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

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Confined X-class Flares vs. Eruptive ones Non-CME associated X-class Flares vs.

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  1. Confined X-class Flares vs. Eruptive ones Non-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

  2. (Adapted from Shibata et al. 1995)

  3. Flux rope catastrophe model Lin et al., 2004 Breakout model Lin & Forbes, 2000 Antiochos et al., 1999

  4. An incomplete list of the CME association of flares

  5. 11 (~10%) X-class flares were confined (not associated with CMEs). 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? 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.

  6. Select 4 eruptive flares similar to the confined flares in soft X-ray for comparison.

  7. 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.

  8. Identify the source regions of flares in MDI magnetograms

  9. 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.

  10. 4 eruptive events displacement

  11. ≤ 17 Mm Close to center Close to edge ≥ 22 Mm

  12. 1.5 Rs 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. High corona 1.1 Rs Low corona 1.0 Rs

  13. An eruptive event

  14. Confined Events

  15. Eruptive Events

  16. ≤ 5.68 ≥ 7.11

  17. 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. eruptive confined

  18. 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?

  19. A statistical comparison between CME and non-CME flares 78 available ARs from Andrews (2003) 229 events All non-CME flares do not exceed X-class |alpha| Coronal Helicity What does the helicity stand for? [Nindos & Andrews 2004]

  20. Next step • Extend to M-class flares • Investigate more parameters

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