34th Solar Physics Division Meeting, June 2003
Session 7 Photosphere and Chromosphere I
Poster, Monday, June 16, 2003, 3:30-5:00pm, Mezzanine

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[7.09] Chirality of Chromospheric Filaments

A. A. Pevtsov, K. S. Balasubramaniam (National Solar Observatory), J. W. Rogers (2001 NSF/NSO RET, Cloudcroft Elementary and Middle Schools)

We use the chromospheric full disk H\alpha observations to study chirality (sign of helicity) of 2310 filaments from 2000--2001. For each filament we identify the spine and its barbs and determine the filament chirality as fraction of dextral/sinistral barbs of total number of barbs. We find that 80.2% (558 out of 696) of quiescent filaments in northern hemisphere are dextral, and 85.5% (633 out of 740) of filaments in southern hemisphere are sinistral, in agreement with well known hemispheric helicity rule. Our data also show that the active region filaments follow the same rule, though the hemispheric dependence is weaker; 74.9% (338 out of 451) of active region filaments in northern hemisphere are dextral, and 76.7% (297 out of 387) of filaments in southern hemisphere are sinistral. We show that quiescent filaments formed on leading and returning arms of the same switch-back exhibit the same chirality. We also investigate a possible change in the hemispheric rule with polarity reversal of the polar field and we find no such change.

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