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2014 January 24




Sigmoids on Parade!

Sigmoids are a type of active region that has an 'S' (or 'reversed-S') shape because of their bending or twisted magnetic field structures. Since such distorted structures are unstable, sigmoids often erupt and sometimes become a source of big flares and coronal mass ejections (CMEs).

Although there are days and weeks when sigmoids are rarely seen, they sometimes appear in herds and adorn the solar disk. Early January of 2014 was such a period. We observed at least 6 different sigmoids in the first 15 days of the month. Below is information on each sigmoid appearing in the image above:
  • Top left : 1-Jan-2014 06:04:18, South of Disk Center, AR11938.
  • Top right : 9-Jan-2014 06:04:20, South-West of DC, AR11944.
  • Bottom left : 5-Jan-2014 05:38:48, North of DC, AR11942.
  • Bottom center upper : 4-Jan-2014 18:27:36, South-West of DC, West of AR11944, source region of the M4.0 flare at 19:05.
  • Bottom center lower : 15-Jan-2014 05:59:25, South of DC, AR11949.
  • Bottom right : 14-Jan-2014 05:59:25, North-East of DC, East of AR11950.


Keywords: Sigmoid
Filters: Be_thin


(Prepared by Aki Takeda)

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