HR: 09:40h
AN: SH21A-07 INVITED     [Abstracts]
TI: The 20 January 2005 Energetic Particle Event as a Test of Current Models
AU: * Kahler, S
EM: stephen.kahler@hanscom.af.mil
AF: Air Force Research Laboratory, AFRL/VSBXS 29 Randolph Rd, Hanscom AFB, MA 01731 United States
AB: The 20 January ground level event (GLE) was not only an unusually large event from a magnetically well connected solar region but was also accompanied by extensive solar observations that allow us to test current ideas of particle acceleration. A basic question is whether the GeV protons were produced in the flare or by a CME-driven coronal shock. If the protons were produced in a coronal shock, then the very high speed (~ 3000 km/s) of the CME suggests an early shock initiation at low heights, where the coronal Alfven speed is high. The question then is how fast particles can be accelerated to GeV energies and whether shock conditions appropriate for that acceleration can be achieved. In this event there is also an apparent observed violation of the streaming limits for high-energy protons, which is another challenge for shock acceleration. The energetic proton spectra and timings inferred from the flare observations can be compared with the GLE and space-based particle observations to test for a possible flare origin of the GLE. Near-relativistic electrons were released later than the protons, so we can ask whether the electrons were accelerated in the same or a different process. Unfortunately, the high CME speed means that the height-time profile for the CME and the shock will also have uncertainties that challenge our ability to obtain definitive answers to these questions.
DE: 7513 Coronal mass ejections (2101)
DE: 7514 Energetic particles (2114)
DE: 7519 Flares
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005