The Temperature Difference between Eruptive and Confined Solar Flares

Eruptive and confined flares are distinguished by their coronal mass ejection (CME) association. From 1996 January to 2023 December, we found 1,748 flares with definite CME association (eruptive flares) and 7,288 flares that lacked CMEs (confined flares) using the coronagraph observations by SOHO/LASCO and STEREO/SECCHI. Flare temperatures, which are measured from the GOES short/long wavelength ratio, increase with the peak X-ray intensity. Average maximum temperature is 10 MK at C3.0 and 24 MK at X10 level. [Kay et∼al., 2003] examined a total of 69 eruptive and confined flares and found that eruptive flares tend to have lower temperatures than the confined ones. By analyzing a 100 times larger data set, we confirmed that result and found that, for a given X-ray flare intensity, the average maximum temperature of eruptive flares is approximately 0.9 MK cooler than that of the confined ones.