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Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT

Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT. Background.

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Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT

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  1. Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT

  2. Background • Magnetic reconnection at low corona is the drive of flares. Recent observations have provided indirect evidence of magnetic reconnection as depicted by the standard (eruptive) flare model. • The rate of magnetic reconnection may be derived from flare observations using sound assumptions and approximations. • Current sheet is the most important structure in the magnetic reconnection process.

  3. How do scientists “observe” magneticReconnection and Current Sheet, the driver of solar flares?

  4. (Courtesy of Terry Forbes ) “observe” magnetic reconnection in a standard flare configuration

  5. flare loop arcade and two ribbons in EUV TRACE Fe 19.5nm

  6. two-ribbon flare observed in different wavelengths

  7. Signatures of magnetic reconnection and Current sheet in the corona: satellite observations

  8. Masuda flare: hard X-ray source above the loop top (Masuda et al. 1994) Here put a couple of figures from satellite Observations. YOHKOH

  9. soft X-ray jet as indication of reconnection outflow (Shimizu 1994) soft X-ray high temperature ridges along outer or newly formed loops (Tsuneta 1996) YOHKOH

  10. SOHO high temperature structure indicative of current sheet (Ko et al. 2003)  X-ray sources at two ends of current sheet (Sui et al. 2003)  RHESSI

  11. The rate of magnetic reconnection can be inferred from some sorts of observations using sound assumptions and approximations.

  12. corona surface Magnetic reconnection is the driver of solar flares.   E field Magnetic reconnection rate is deduced by measuring expansion offlare ribbons across magnetic fields.

  13. l V11 Physical approach : Forbes & Lin (2000) Ec: electric field along the reconnecting current sheet (RCS) at the corona

  14. M1.0 flare on 2000 September 12

  15. Ribbon 1 Ribbon 2 electric field (V/cm) voltage drop (Mx/s)

  16. .8 .6 .4 .2 .0 4 3 2 1 0 flare soft X-ray emission rate E field (V/cm) flux rate (1e+18 Mx/s) 11 12 13 14 hr magnetic reconnection rate and flare emission

  17. X1.6 flare on 2001 October 19

  18. Ribbon 1 Ribbon 2 Electric field (v/cm) Voltage drop (Mx/s)

  19. 6 4 2 0 7.5 5.0 2.5 0.0 flare microwave emission at 10 GHz E field (V/cm) flux rate (1e+18 Mx/s) 16:20 16:30 16:40 16:50 17:00 Magnetic reconnection rate and flare non-thermal emission

  20. event 1 flare flare rate of total magnetic flux reconnected E field E field flux rate 11 12 13 14 event 2 flare flare rate of total magnetic flux reconnected E field E field flux rate 16:10 16:20 16:30 16:40 16:50 17:00 0.8 0.4 0.0 two ways to measure the magnetic reconnection rate 7.5 5.0 2.5 0.0 Either way, it evolves along with flare high-energy emission.

  21. Coronal mass ejections are often accompanied by filament eruptions and flares. They are all driven magnetically.

  22. flare  CME correlation between mass flight and flare emission (Zhang et al. 2001) In some flare-CME events, acceleration of CMEs and magnetic reconnection that drives flares are closely related.

  23. CME filament two-ribbon flare (Lin et al. 2004) A schematic flux rope model for CME and flare

  24. mass acceleration magnetic reconnection flare emission

  25. Strong Correlation Between Magnetic Reconnection Rate and Filament Acceleration (Jing et al., 2004, Ap.J. to be submitted)

  26. Weaker Correlation Between Magnetic Reconnection Rate and CME Acceleration (Jing et al., 2004, Ap.J. to be submitted)

  27. The derived magnetic reconnection rate is temporally correlated with flare non-thermal emission and mass acceleration of core flux rope ejection.

  28. SUMMARY Indirect Evidence of Current Sheets and Magnetic Reconnection • High temperature region in Helmet Structure • Plasma outflow above flare loop • Loop top HXR source • Organized separation of flare ribbons

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