Thermodynamic evolution of a sigmoidal active region with associated flares

ABSTRACT Active regions often show S-shaped structures in the corona called sigmoids. These are highly sheared and twisted loops formed along polarity inversion line. They considered to be one of best pre-eruption signatures for CMEs. Here, we investigate thermodynamic evolution an on-disc sigmoid observed during 2015 December 24–28. For this purpose, have employed Emission Measure (EM) filter-ratio techniques on observations recorded by Atmospheric Imaging Assembly (AIA) on-board Solar Dynamics Observatory (SDO) X-ray Telescope (XRT) Hinode. The EM analysis showed multithermal plasma provided a peak temperature ?10–12.5 MK all flares. sigmoidal structure emission from Fe xviii (93.93 Å) xxi (128.75 lines AIA 94 131 Å channels, respectively. Our results that hot is confined very strands. obtained was found good agreement with using XRT, AIA, GOES methods. provide important constraints modelling core active regions. Moreover, study also benchmarks different available estimation solar coronal structures.