Abstract


  MULTIWAVELENGTH ANALYSIS OF SIGMOID STRUCTURES

  V. Aparna, IUCAA, aparna2884@gmail.com
  D. Tripathi, IUCAA, durgesh@iucaa.ernet.in

Sigmoids are an important mode for studying the flux ropes in the solar atmosphere. Flux ropes are an integral part of coronal mass ejections and understanding their nature is necessary in order to unravel the processes of initiation and evolution of eruptions. Sigmoids are popularly thought to be regions where flux ropes commonly form. This study focuses upon sigmoidal regions on the Sun in order to identify flux rope structures and depict their formation and evolution. A sigmoidal region active for more than half a rotation of the Sun is tracked since its appearance on the east limb until it disappears over the west limb. The evolution of the region into showing the typical S structure of a sigmoid which is not seen initially is discussed. In addition, cooler emission corresponding to around ~1MK is removed from AIA 94 A images in order to detect the presence of hot flux ropes corresponding to FeXVIII emissions. Further, IRIS data is utilized to observe the regions corresponding to sigmoids in the higher atmosphere to understand the properties in the lower atmosphere. The identification of the temperature regimes of the S shaped structures and the study of the evolution of the structure will help determine the formation of the flux ropes.