太阳耀斑CaIIK线不对称性的观测和分析

OBSERVATION AND ANALYSIS OF CalIK LINE ASYMMETRY OF SOLAR FLARES

本文分析了南京大学太阳塔观测到的8个耀斑CaIIK线轮廓的不对称性特征,指出一般耀斑的CaIIK线表现出明显的红不对称性,即红翼K_1的强度大于蓝翼K_1的强度,红翼K_1到线心的距离也比蓝翼K_1的大.这种红不对称性在K线线心强度达到极大前最为显著,但K线线心却无明显的多普勒位移.根据有速度场时的Non-LTE大气模型和K线轮廓计算结果,提出用耀斑温度极小区附近的物质运动来解释K线的红不对称性特征,对1982年12月2日耀斑还得出了速度为20公里/秒的结果.此外,本文的统计也表明:耀斑越强,温度极小区受到的加热越厉害,温度极小区也移向更深层.

The Call K line spectra for eight flares are analysed in this paper. It is found that the red asymmetry is common for all flares, i.e., the intensity of red wing K_(1r) is stronger than that of the blue wing K_(1b) and the distance of the K line center from K_(1r) is larger than that from K_(1b). Such red asymmetry becomes most obvious around the maximum of the Call K line intensity. However the CalI K line center does not showobvious Doppler shift for all flares studied here. By use of non-LTE theory to calculate model atmosphere and Call K line profile, it is shown that the asymmetry observed may be explained by the motion of material around the temperature minimum region. The velocity, in one sample, can be as large as 20 km/s. Besides, a statistical study also showed that the tempera,ure and the depth of the temperature minimum region are proportional to the maximum intensity of the flare emission.