In previous works we have developed a method to convert solar X-ray data , collected with the Yohkoh/SXT , into templates of stellar coronal observations .
Here we apply the method to several solar flares , for comparison with stellar X-ray flares .
Eight flares , from weak ( GOES class C5.8 ) to very intense ones ( X9 ) are selected as representative of the flaring Sun .
The emission measure distribution vs. temperature , EM ( T ) , of the flaring regions is derived from Yohkoh/SXT observations in the rise , peak and decay of the flares .
The EM ( T ) is rather peaked and centered around T \approx 10 ^ { 7 } K for most of the time .
Typically , it grows during the rise phase of the flare , and then it decreases and shifts toward lower temperatures during the decay , more slowly if there is sustained heating .
The most intense flare we studied shows emission measure even at very high temperature ( T \approx 10 ^ { 8 } K ) .
Time-resolved X-ray spectra both unfiltered and filtered through the instrumental responses of the non-solar instruments ASCA/SIS and ROSAT/PSPC are then derived .
Synthesized ASCA/SIS and ROSAT/PSPC spectra are generally well fitted with single thermal components at temperatures close to that of the EM ( T ) maximum , albeit two thermal components are needed to fit some flare decays .
ROSAT/PSPC spectra show that solar flares are in a two-orders of magnitude flux range ( 10 ^ { 6 } -10 ^ { 8 } erg cm ^ { -2 } s ^ { -1 } ) and a narrow PSPC hardness ratio range , however higher than that of typical non-flaring solar-like stars .