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[37.16] Magnetic Helicity Injection By Transient Photospheric Shear Flows in Flares and Prominences

H. S. Yun (Seoul National University), J. Chae (Chungnam National University), Y.-J. Moon (BBSO/NJIT, KAO), H. Wang, P. R. Goode (BBSO/NJIT)

There has been increasing interest in magnetic helicity since it is a well-conserved measure of the non-potentiality of solar magnetic fields. Magnetic helicity in the solar corona may change when magnetic helicity is transported either across the photosphere or out of the Sun. Of our specific interest is the magnetic helicity change due to transient shear flows in the photosphere. We have developed a method of determining its rate from a time series of magnetograms, and have applied it to several active regions. We present one example showing that transient shear flows may inject significant amount of magnetic helicity for several days during the formation of a prominence, and other examples showing that magnetic helicity injection by shear flows may occur impulsively during strong flares. We do not know the physical nature of transient shear flows, but there is a possibility that they may represent the photospheric velocity field of low frequency, large-scale torsional Alfvén waves passing through the solar surface.

This work was supported by the US-Korea Cooperative Science Program (KOSEF 995-0200-002-2, NSF INT-98-16267), and the the National Research Laboratory project M10104000059-01J000002500 and the BK21 project of the Korean Government.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.