Derivation of the physical parameters for strong and weak flares from the Hα line

摘要

The two flares of 19 and 30 July 1999 were observed in the H α line using the multichannel flare spectrograph (MFS) at the Astronomical Institute in Ond?ejov, Czech Republic. We use a modified cloud method to fit the H α line profiles which avoids using the background profile. We obtain the four parameters of the two flares: the source function, the optical thickness at line center, the line-of-sight velocity and the Doppler width. The observed asymmetry profiles have been reproduced by the theoretical ones based on our model. A discussion is made about the results of strong and weak flares using the present method.