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3D Global MHD Simulations of Flux Rope Driven Coronal Mass Ejections

3D Global MHD Simulations of Flux Rope Driven Coronal Mass Ejections. W. Manchester 1 , T. Gombosi 1 , I. Roussev 1 , M. Opher 2 , D. DeZeeuw 1 , G. Toth 3 , I. Sokolov 1 , K. Powell 1 1 University of Michigan, 2 JPL, 3 Eotvos University SHIINE Conference Banff, August 18-23, 2002.

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3D Global MHD Simulations of Flux Rope Driven Coronal Mass Ejections

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  1. 3D Global MHD Simulations of Flux Rope Driven Coronal Mass Ejections W. Manchester1, T. Gombosi1, I. Roussev1, M. Opher2, D. DeZeeuw1, G. Toth3, I. Sokolov1, K. Powell1 1University of Michigan, 2JPL, 3Eotvos University SHIINE Conference Banff, August 18-23, 2002

  2. Outline • Introduction • Insertion of the Gibson-Low flux rope into a numerical MHD coronal model • Expansion of the flux rope driving a CME • Acceleration curves • Energy budget • Synthetic Thomson-scattered white-light coronagraph images of the CME • View of the CME at the limb • View of the CME from the pole • View of a halo CME • CME approaching 1 A.U. • Pile up of plasma and flattening of the flux rope • Reconnection of open field lines with the flux rope • Future Research

  3. The Gibson-Low Flux Rope • The 3D self-similar CME model of Gibson and Low, 1998 ApJ, volume 493, pages 460-473 • Model has a complex magnetic topology of a spheromak flux rope distorted into a 3D tear drop shape • Model possesses a 3-part density structure associated with CMEs including a dense front, a cavity and a dense core • Magnetic field supports the weight of the plasma, consequently the magnetic field possess significant free energy • Entire flow is self-similar, characterized by a radial outflow whose speed increases linearly with distance from the origin • No interaction of the CME with a background solar wind

  4. The Ambient Solar Wind • Global steady-state model of the heliosphere • Heating in the polar corona • High-latitude coronal holes with high speed wind • Low latitude helmet streamer with low speed wind

  5. The Computational Grid • 7 levels of refinement • 1 million cells • 1/32 Rsun to 2 Rsun

  6. 3D View of the Flux Rope in the Corona

  7. Properties of the Initial State

  8. Temperature Structure at 1 hour • Shock heated plasma • M = 4.75 at z = 0 • M = 2.0 at z = 5 • Streamer cusp heated by magnetic reconnection

  9. Shock, flux rope front and flux rope back positions as functions of time

  10. Velocity of the front and back of the flux rope as a function of time

  11. Velocity of the front of the flux rope as a function of height • V(t) = V1 + (V0 - V1)e-t/tau • V0 = 1500 km/sec V1 = 755 km/sec tau = 1.05 hrs

  12. Total system kinetic, thermal and gravitational energy as a function of time

  13. Large Scale CME Simulation

  14. Features of the Model • System is initially in force imbalance • Flux rope with dense core and cavity contained in a helmet streamer • Kinetic energy of 1032 ergs • Ejected mass of ~ 1016 grams • Deceleration closes matches observations (Sheeley et al. 1999) • Shock formation and interaction with the bi-modal solar wind • Thomson-scattered white-light images showing complex structure

  15. Future Investigations • Flux rope parameter study with application to fast and slow CMEs • Shock structure study • Long term evolution of the CME • Plasma swept up in the CME • Tangential discontinuities in B • Effects on space weather

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