1993年3月19日SN/C5.6级耀斑的二维光谱分析

2D SPECTRA ANALYSIS OF A SN/C5.6 FLARE ON 19 MARCH 1993

利用南京大学太阳塔的ＣＣＤ二维成像光谱观测系统，于１９９３年３月１９日得到了一个ＳＮ级耀斑区域的Ｈα光谱资料．由线心强度分布显示，该耀斑带有三个明显发射区，它们的形态、结构、演化情况都不同；而线翼呈现明显的红不对称性．基于Ｈα谱线的红不对称性，我们导出了两维色球速度场，结果发现不同区域具有不同速度，有的区域向下最大速度可达３０～４０ｋｍ／ｓ，而有的区域只有１０ｋｍ／ｓ左右；此外，色球物质向下运动的持续时间也不等，有的仅约１ｍｉｎ，而有的长达６ｍｉｎ之久．最后我们还证实了红不对称性仅发生在线翼，而线心几乎无位移．

On 19 March 1993, a SN/C5.6 flare occurred near the center of the solar disk at￣02:19 UT. Two dimensional H α spectra were obtained by using an imaging spectrograph installed at the Solar Tower Telescope of Nanjing University. The 2D line center intensity contours show that the flare has three main kernels (marked with 'A','B','C' in Figure 1). Their morphology, structure and evolution are different. While the red asymmetry at the H α wings is common for the three regions. Based on the asymmetries of the H α lines, we derive a time series of 2D velocity fields for the flare. The results indicate that the inferred downward velocities are various in different regions. In fact, in the frames of velocity fields, it seems to have four sites marked with 'A1','A2','B1' and 'C1', respectively (Figure 2). The maximum velocity at A1 is about 30￣40km/s, the velocity in the region C1 is the least, only about 10km/s. Moreover, the duration of the mass motion velocities in these regions are also distinctly different: A1 and A2 are about 6 minutes, B1￣2 minutes, C1￣1 minute. Finally, we give the velocity distributions derived at different emission levels of H α line prefiles for the time of 02:18:51 UT. It shows that the H α line asymmetries for this flare only occur at the line wings, while the line centers are nearly no shift.