34th Solar Physics Division Meeting, June 2003
Session 16 Flares and Microflares II
Poster, Wednesday, June 18, 2003, 3:30-5:00pm, Mezzanine

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[16.06] The nature of impulsive solar energetic particle events

N. V. Nitta (LMSAL), H. S. Hudson (UCB), M. L. DeRosa (LMSAL)

Impulsive solar energetic particle (SEP) events, as opposed to gradual SEP events, are usually thought to originate from flares in the well-connected regions. In order to test this idea, we compute the solar locations of the field lines that cross the spacecraft encountering particles from SEP events, and compare them with the flare locations. We combine two frequently used techniques, i.e., the ballistic approximation for the interplanetary magnetic field and the potential-field source-surface model for the coronal field. Such comparisons are made for selected impulsive SEP events during 1995-2001. We check the validity of the techniques using Yohkoh SXT and SOHO EIT images, which often show coronal holes on the disk. Furthermore, we study the properties of the flares that are identified with impulsive SEP events, and compare them with those of other flares in the well-connected areas but without impulsive SEP events. This will give us a clue as to the importance of the flare processes relative to the magnetic field connectivity on the detection of impulsive SEP events.

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.