HR: 1340h
AN: SH23A-0318    [Abstracts]
TI: What is Unusual About the 2005 January 20 SEP Event?
AU: * Gopalswamy, N
EM: gopals@fugee.gsfc.nasa.gov
AF: NASA Goddard Space Flight center, Bldg 21, Rm 260, Code 695, Grrenbelt, MD 20771 United States
AU: Xie, H
SH23A-0318 AF: The Catholic University of America, 200 Hannan Hall 1 Cardinal Station, Washington, DC 20064 United States
AU: Yashiro, S
EM: yashiro@ssedmail.gsfc.nasa.gov
AF: The Catholic University of America, 200 Hannan Hall 1 Cardinal Station, Washington, DC 20064 United States
AU: Usoskin, I
EM: ilya.usoskin@oulu.fi
AF: Sodankyla Geophysical Observatory (Oulu unit), P.O.Box 3000 FIN-90014 University of Oulu, Oulu, FIN-90014 Finland
AB: We report on the solar energetic particle (SEP) event of 2005 January 20 that had an associated ground level enhancement (GLE). The Solar and Heliospheric Observatory (SOHO) spacecraft observed a CME, which was among the fastest of cycle 23 CMEs. This event is consistent with the results that the GLE-associated CMEs represent the fastest known population of CMEs. A metric type II burst started before the proton injection time, suggesting that a coronal shock was formed before high-energy protons were released at the Sun. These 2005 January 20 event is consistent with the current paradigm that large SEP events originate in CME-driven shocks. We also determined the height of the CME at two time marks: the metric type II onset (2.1 Rs) and the proton injection time (4.5 Rs). At a height of 4.5 Rs the CME should have attained the maximum speed, thus driving the strongest shocks. We discuss the estimation of the CME speed given that the coronagraph observations were hampered by the SEPs arriving at the SOHO spacecraft. We also discuss the arrival of the CME-associated plasma and shock at 1 AU. Work supported by NASA/LWS and NSF/SHINE programs.
UR: http://cdaw.gsfc.nasa.gov
DE: 7513 Coronal mass ejections (2101)
DE: 7514 Energetic particles (2114)
DE: 7519 Flares
DE: 7845 Particle acceleration
DE: 7851 Shock waves (4455)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005