XRT Picture of the Week (XPOW)

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2015 September 01

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Sigmoid Evolution

Hinode XRT tracked the spunky active region, AR12831, for several days in early July. Initially, the hot x-ray loops form straight lines connecting regions of opposite polarity. As the active region evolves, the endpoints become twisted forming a backward S. This shape is called a sigmoid.

Sigmoidal active regions are more likely to erupt than other active regions. Therefore, understanding their formation could lead to predicting solar flares and coronal mass ejections.

Hinode along with the Solar Dynamics Observatory (SDO) maintain a sigmoid catalog so that scientists can easily access these events.

This XPOW was brought to you by the letter S.

Keywords: Sigmoid, AR Tracking
Filters: Be_thin

(Prepared by Kathy Reeves, Nicole Schanche, and Patricia Jibben)

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