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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[16.03] RHESSI and Microwave Imaging Observations of Two Microflares

V.I. Garaimov, M.R Kundu (U. Maryland), P.C. Grigis (Institute of Astronomy, ETH Zurich, Switzerland)

We describe two microflares which occurred in the AR 9934 at 03:58 UT May 3, 2002 and at 05:08 UT May 4, 2002. AR~9934 was a complex region which contained a sunspot with a strong negative polarity of the magnetic field on the north side and a bipolar region on the south side. Analysis of the MDI images shows fast evolution of the south part of the region. TRACE images show many small loops in the south part of AR and the complex loop which connected the north sunspot to the south side of the region. We have observations of both of these events by Nobeyama Radio Heliograph and RHESSI. The NoRH 17 GHz maps show loop like structure of the radio source which has a maximum above the sunspot land it connects to the south side of AR. RHESSI maps superimposed on the NoRH maps show that X-ray emission in the range 3-25 keV are located inside the radio contours. During both events hard X-ray emission was located in the south part of the AR. RHESSI maps corresponding to the maximum X-ray emission during the event of May 3, 2002 clearly show an X-ray loop in the range 3-6 keV and two footpoints of the loop in the 6-12 and 12-25 keV ranges. These footpoints are located above opposite magnetic polarities as seen in overlays of hard X-ray images on the MDI image. Also hard X-ray emission seems to be brighter from the northern footpoint than from the other. The hard X-ray images of the event of May 4, 2002 shows a small X-ray loop (smaller than size of the loop in the previous event), located close to the same position relative to the active region. We calculated the hard X-ray spectrum, temperature and emission measure for both events.


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