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تسجيل مستخدم جديدFlarelike brightenings of active region loops observed with SUMER
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Coronal loops on the east limb of the Sun were observed by SUMER on SOHO for several days. Small flare-like brightenings are detected very frequently in the hot flare line Fe~{small XIX}. We find that the relatively intense events are in good coincidence with the transient brightenings seen by Yohkoh/SXT. A statistical analysis shows that these brightenings have durations of 5-84 min and extensions along the slit of 2-67 Mm. The integrated energy observed in Fe~{small XIX} for each event is in the range of $3times10^{18}-5times10^{23}$ ergs, and the estimated thermal energy ranges from $10^{26}-10^{29}$ ergs. Application of the statistical method proposed by Parnell & Jupp (2000) yields a value of 1.5 to 1.8 for the index of a power law relation between the frequency of the events and the radiated energy in Fe~{small XIX}, and a value of 1.7 to 1.8 for the index of the frequency distribution of the thermal energy in the energy range $>10^{27}$ ergs. We examine the possibility that these small brightenings give a big contribution to heating of the active region corona.
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