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Evolution of twist-shear and dip-shear in flaring active region NOAA 10930

Published online by Cambridge University Press:  26 August 2011

Sanjay Gosain  and
P. Venkatakrishnan
Sanjay Gosain
Affiliation:
Udaipur Solar Observatory, Physical Research Laboratory, P. Box No. 198, Udaipur 313001, Rajasthan, India email: [email protected]
P. Venkatakrishnan
Affiliation:
Udaipur Solar Observatory, Physical Research Laboratory, P. Box No. 198, Udaipur 313001, Rajasthan, India email: [email protected]
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Abstract

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We study the evolution of magnetic shear angle in a flare productive active region NOAA 10930. The magnetic shear angle is defined as the deviation in the orientation of the observed magnetic field vector with respect to the potential field vector. The shear angle is measured in horizontal as well as vertical plane. The former is computed by taking the difference between the azimuth angles of the observed and potential field and is called the twist-shear, while the latter is computed by taking the difference between the inclination angles of the observed and potential field and is called the dip-shear. The evolution of the two shear angles is then tracked over a small region located over the sheared penumbra of the delta sunspot in NOAA 10930. We find that, while the twist-shear shows an increasing trend after the flare the dip-shear shows a significant drop after the flare.

Keywords

Sunspotsflares
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S273: The Physics of Sun and Star Spots , August 2010 , pp. 212 - 215
Copyright
Copyright © International Astronomical Union 2011

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