HR: 1340h
AN: SH23A-0320 [Abstracts]
TI: Solar Energetic Particle Composition, Energy Spectra and Timing in the January 20, 2005
Event
AU: * Mewaldt, R A
EM: rmewaldt@srl.caltech.edu
AF: California Institute of Technology, MC 220-47, Pasadena, CA 91125
United States
AU: Cohen, C M
SH23A-0320
AF: California Institute of Technology, MC 220-47, Pasadena, CA 91125
United States
AU: Leske, R A
SH23A-0320
AF: California Institute of Technology, MC 220-47, Pasadena, CA 91125
United States
AU: Labrador, A W
SH23A-0320
AF: California Institute of Technology, MC 220-47, Pasadena, CA 91125
United States
AU: Mason, G M
SH23A-0320
AF: Applied Physics Laboratory, Johns Hopkins University, Johns Hopkins Rd., Laurel, MD 20723
United States
AU: Haggerty, D K
SH23A-0320
AF: Applied Physics Laboratory, Johns Hopkins University, Johns Hopkins Rd., Laurel, MD 20723
United States
AU: Looper, M D
SH23A-0320
AF: Aerospace Corporation, P.O. Box 92957, Los Angeles, CA 90009
United States
AU: Mazur, J E
SH23A-0320
AF: Aerospace Corporation, P.O. Box 92957, Los Angeles, CA 90009
United States
AU: Selesnick, R S
SH23A-0320
AF: Aerospace Corporation, P.O. Box 92957, Los Angeles, CA 90009
United States
AU: Desai, M I
SH23A-0320
AF: Southwest Research Institute, PO Drawer 28510
6220 Culebra Rd, San Antonio, TX 78228
United States
AB:
The solar energetic particle event of January 20, 2005 was, by some measures, the most intense in 30 years. The >100 MeV
proton intensity exceeded that of the October 1989 event and also broke the so-called "streaming limit" by a factor of
~4. In addition it was the largest ground-level neutron monitor event in 49 years. Another surprising aspect of this
event was the speed of its onset, the first particles arrived within 13 minutes of the flare onset and the intensity-maximum
for >100 MeV protons was much faster than any other large SEP event that we have been able to identify. Using data from
five instruments on the ACE, GOES, and SAMPEX spacecraft, we have measured the energy spectra of H, He, and heavier nuclei
over the energy range from ~0.1 to several hundred MeV/nuc, and electrons from 0.03 to 8 MeV. All species can be
characterized by power laws, with spectral indices of -2.2 to -2.5 extending from ~1 MeV/nucleon to at least 400
MeV/nucleon in the case of protons. We report on the time evolution of the composition and energy spectra in an effort to
identify whether there are separate flare-accelerated and shock-accelerated components contributing to this event. We will
also report on a comparison of the ion and electron arrival times at 1 AU with the timing of the CME, flare, and other
electromagnetic signatures. This event poses a challenge to shock-acceleration theory - apparently particles with energies
>1 GeV were accelerated within ~5 to10 minutes, while the CME was still very low in the corona.
DE: 2114 Energetic particles (7514)
DE: 7513 Coronal mass ejections (2101)
DE: 7519 Flares
DE: 7924 Forecasting (2722)
DE: 7984 Space radiation environment
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005