HR: 15:20h
AN: SH53B-07 INVITED    [Abstracts]
TI: MHD Simulations and Kinetic Analyses of Solar ³He-Rich Events
AU: * Zhang, T
EM: tianxi.zhang@aamu.edu
AF: Alabama A & M University, 4900 Meridian Street, Normal, AL 35762, United States
AU: Wu, S
EM: wus@cspar.uah.edu
AF: University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, AL 35899, United States
AU: Tan, A
EM: arjun.tan@aamu.edu
AF: Alabama A & M University, 4900 Meridian Street, Normal, AL 35762, United States
AU: Winebarger, A
EM: amy.winebarger@aamu.edu
AF: Alabama A & M University, 4900 Meridian Street, Normal, AL 35762, United States
AB: The origin and magnetic topology of solar impulsive (or ³He-rich) events are numerically simulated by using a three-dimensional axisymmetric time-dependent self-consistent magnetohydrodynamic (MHD) model. The results indicate that, when a magnetic flux of opposite polarity is emerged from the photosphere at the open field line region near a coronal hole boundary, the magnetic topology that leads to solar impulsive events is formed. Magnetic reconnections at the coronal base due to emergences of photospheric magnetic flux strongly disturb the magnetic fields in the solar corona and interplanetary space, and generate fast jet-like plasma outflows (or non- flux-rope coronal mass ejections). The magnetic field line disturbances scatter charged particles and therefore accelerate them to high energies through the Fermi acceleration mechanism. In terms of our previously developed two-stage acceleration model, the Fermi acceleration of a certain species (e.g. ³He) of ions can lead to the abundance enhancement of this species of ions in high-energy particles relative to the solar corona, if they are preferentially heated. The magnetic reconnections at the coronal base can generate the high-frequency Alfvén waves, which can heat heavy ions with low charge-mass ratios, especially ultraheavy ions with Z > 50. The electrostatic and electromagnetic ion-cyclotron waves including ⁴He-cyclotron waves and H-cyclotron waves generated by electron beams, electric currents, and the low-frequency global MHD modes can significantly heat ³He, electrons, and heavy ions with appropriate charge states via the harmonic cyclotron and Landau resonances. In this presentation, we will present our new MHD simulations for solar impulsive events including the origin; magnetic topology, reconnection, and fluctuations; jet-like fast plasma outflows and non-flux-rope coronal mass ejections (CMEs); properties of CME-driven quasi-parallel shocks; and mechanisms of acceleration. We will also overview the kinetic analyses in accord with the two-stage acceleration model for the impulsive (or ³He-rich) events including plasma wave excitations, heating of particles by waves, acceleration of particles via the Fermi acceleration mechanism; and abundance enhancements and energy spectra of high- energy particles.
DE: 7509 Corona
DE: 7513 Coronal mass ejections (2101)
DE: 7514 Energetic particles (2114)
DE: 7519 Flares
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting