Fig. 42.
![Evolution of sigmoidal active regions observed by XRT showing the three phases of evolution from flux emergence to sheared arcade, to “double J”-shaped loops, and then finally the continuous S-shaped threads of the sigmoid. Top row: AR 10930. Second row: AR 8005. Third row: Unnumbered region observed on the disk during 2007 February. Bottom row: AR 10977. [Reproduced from Green and Kliem (2014).] (Color online)](https://oup.silverchair-cdn.com/oup/backfile/Content_public/Journal/pasj/71/5/10.1093_pasj_psz084/2/pasj_71_5_r1_f37.jpeg?Expires=1749925731&Signature=PRcYK~YidqlOU7KnokOYOA~-7kZVypiiFX3BIMLHMesIPNm4xoPfbQHIFYy7KI77tZL8dA6dpjbnNvur0ko25F4IZjm7F5r15Gt2s054rk0vZ1Bbhh~mo9Pv319C0p8BFicOoQkU1OJOSdc62WFcg22ySVin0B1R1NMObD2b-c6OzC3GOfRDtrlSFqt6si1bETsiSwlUsGPJAjMqwE6KLAm5N0YpIUUHMuQ9hVCU7qtOpylM~0R1~fZQdfAIheP7DPcAAaxkjEjxWSztTLJLCThE2M5TzZl4DE~DBi6UxGwgDGMz69c50a3utQ8J53EvG2R2h3XEnFC9hLHpnM4frA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Evolution of sigmoidal active regions observed by XRT showing the three phases of evolution from flux emergence to sheared arcade, to “double J”-shaped loops, and then finally the continuous S-shaped threads of the sigmoid. Top row: AR 10930. Second row: AR 8005. Third row: Unnumbered region observed on the disk during 2007 February. Bottom row: AR 10977. [Reproduced from Green and Kliem (2014).] (Color online)
