Solar Physics Division Meeting 2000, June 19-22
Session 2. Corona, Solar Wind, Flares, CMEs, Solar-stellar, Instrumentation, Other
Display, Chair: J. Krall, Monday-Thursday, June 19, 2000, 8:00am-6:00pm, Forum Ballroom

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[2.42] Microwave/Millimeter Wavelength Bursts with Simple Spiky Time Profiles

M. R. Kundu, S. M. White (Astronomy Department, University of Maryland, College Park), K. Shibasaki (Nobeyama Radio Observatory, NAO, Japan), T. Sakurai (National Astronomical Observatory, Japan)

We report the detection at 17 and 34 GHz of microwave and millimeter bursts which have simple spiky time profiles similar to those found to be common at \lambda\,=\,3 mm. These bursts are of short duration, with fast 2 - 4 sec rise time to peak, followed by an exponential decay. These bursts can be of any intensity, from ~ 1 sfu to 10's of sfu; they are very strongly polarized (> 50%), and they have similar properties regardless of the nature of the active region in which the bursts originate. The bursts seem to originate in compact sources which are generally unresolved with 15" and 7" resolution of the Nobeyama Radio Heliograph at 17 and 34 GHz respectively. We provide both direct and indirect evidence that these compact sources are low-lying bipolar loops. The direct evidence follows from the physical appearance of the loop as well as from the bipolar nature of the loop. The indirect evidence follows from the offset in position of the footpoint emission in microwaves and hard X-rays, implying a compact asymmetric loop with microwaves originating from the stronger magnetic field foot point and the hard X-rays originating from the weaker field foot point.

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