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GLOBAL ENERGETICS OF FLARES

GLOBAL ENERGETICS OF FLARES. Gordon Emslie (for a large group of people). Initial Study (Emslie et al. 2004). Methodologies. Magnetic Energy U B =. Methodologies. Thermal Plasma U th = 3 n e V kT = 3 k T [EM . V] 1/2 erg

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GLOBAL ENERGETICS OF FLARES

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  1. GLOBAL ENERGETICS OF FLARES Gordon Emslie (for a large group of people)

  2. Initial Study (Emslie et al. 2004)

  3. Methodologies Magnetic Energy UB =

  4. Methodologies Thermal Plasma Uth = 3 ne V kT = 3 k T [EM . V]1/2 erg • Emission measure (EM) and temperature (T) obtained from both RHESSI and GOES soft X-ray observations. • Source volumes (V) were obtained from RHESSI 12 – 25 keV images using V = f Vapparent = f A3/2 where f is the filling factor (assumed to be 1) and A is the area inside the contour at 50% of the peak value.

  5. Figure 1. RHESSI image at the impulsive peak of the 2 Nov. 2003 flare.Contours: blue: 12 – 25 keV (50%), magenta: 50 – 100 keV (30 & 70%)

  6. Methodologies CME UK = ½ Mv2 U = -GMM/R • M determined from scattered brightness • V determined from rate of change of position R

  7. Methodologies Electrons UE = A E0 F0(E0) dE0 dt • F0(E0) determined from collisional thick target interpretation of HXR spectrum • Depends on lower energy “cutoff” EC

  8. The Electron “Problem” • Efficiency of bremsstrahlung production ~ 10-5 (ergs of X-rays per erg of electrons) Electron flux ~ 105 hard X-ray flux • Electron energy can be 1032 – 1033 ergs in large events • Total number of accelerated electrons up to 1040 (cf. number of electrons in loop ~1038). • replenishment and current closure necessary

  9. Electrical Current Issue • Rate of e- acceleration in large flares  1037 s-1 • Associated Current  1037 e- s-1 1018 A • Width of Channel ~ 107 m • Ampère law B = oI/2r ~ 104 T = 108 G • Faraday law V = L dI/dt ~ (o) I/ ~ 1019 V • These are impossibly large: • e.g., (B2/8) dV ~ 1042 ergs • Dynamic pressure ~ (nv)(mv) • ~ 10 dyne cm-2 (cf. 2nkT ~ 10 dyne cm-2)

  10. Resolution? – Multiple Channels • Current density j ~ 104 A m-2 • Maximum radius of current channel from (Ampère)  B ~ B/r = o j r = B/ o j ~ 10 m (Faraday)V=o L(r2j)/r ~ 1 m (!) •  Number of channels ~ 1012 (1014) • Operating simultaneously!?

  11. Methodologies Ions Ui = A  E0 F0(E0) dE0 dt • AF0(E0)dt determined from fit to gamma-ray observations • Also depends on lower energy “cutoff” EC (~ 1 MeV?) • Electrical current issues not as large • Impulse-momentum issues much more important - dynamic pressure ~ (nv)(mv) • 100 dyne cm-2 (cf. 2nkT ~ 10 dyne cm-2)

  12. Electron vs. Ion Acceleration gives equality of ion acceleration and escape times ED ~ 10-8 n(cm-3)/T(K) V cm-1 ~ 10-4 V cm-1 maximum electron energy ~ 1 MeV??

  13. Methodologies SEPs • UP determined from direct observations of SEP fluences at 1 AU • Assumptions: • solid-angle extent • number of particles crossings

  14. Results (Emslie et al. 2004)

  15. Results (Emslie et al. 2004)

  16. July 23, 2002 Summary

  17. Refinement (Emslie, Dennis, Holman, Hudson 2005) • Include Optical/EUV Continuum • Recognize Primary Intermediate Final modes of energy

  18. Refinement (Emslie, Dennis, Holman, Hudson 2005) • Include Optical/EUV Continuum • Recognize Primary Magnetic Field Intermediate Final modes of energy

  19. Refinement (Emslie, Dennis, Holman, Hudson 2005) • Include Optical/EUV Continuum • Recognize Primary Magnetic Field Intermediate Electrons, Ions Final modes of energy

  20. Refinement (Emslie, Dennis, Holman, Hudson 2005) • Include Optical/EUV Continuum • Recognize Primary Magnetic Field Intermediate Electrons, Ions Final Kinetic Energy, Radiation modes of energy

  21. Revised Numbers

  22. Revised Numbers

  23. Revised Numbers

  24. Revised Numbers

  25. Conclusion • CME energy still dominant by factor of ~4 BUT • Within uncertainties, rough equipartition amongst • Flare intermediate • Flare final • CME • SEP shock acceleration <~ 10% efficient

  26. Extension to Oct/Nov 2003 Flares (RHESSI/SOHO/TRACE group) • Thermal and CME energetics by B. Dennis et al., N. Gopalswamy • Electron/ion energetics to follow

  27. Figure 5.

  28. Figure 5.

  29. Figure 5.

  30. Figure 5.

  31. Figure 5.

  32. Figure 5.

  33. Figure 5.

  34. Figure 6. Flare Energies vs. Upeak

  35. Conclusions • Flare and CME energies are correlated for the Oct/Nov 2003 period. • Total Flare and CME energies are comparable to within a factor of 10. • Peak energy in SXR-emitting plasma is only ~1% of total flare energy in some cases. • Energy radiated by SXR-emitting plasma is only ~10% of total flare energy in some cases. • Energy in nonthermal electrons and ions can be a large fraction of the total flare energy. • Dominant flare energy in impulsive phase may be electrons and/or ions leading to early peak in total solar irradiance increase seen with SORCE/TIM.

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