用半经验模型研究耀斑大气的能量耗散

本文利用南京大学太阳塔多波段光谱资料推求出的两个耀斑(一个SB级,一个2B级)的半经验模型;计算了耀斑不同时刻的辐射损失速率,并与电子束轰击和X线作用下的产能率作了比较.结果表明,耀斑不同时刻的色球辐射损失变化可达一个量级以上;耀斑脉冲相前后电子束轰击加热相当有效;耀斑强度极大时,电子束轰击和X线加热都有作用;耀斑主相时,X线加热更能有效地平衡辐射损失.但是,尤其是对大耀斑来说,色球低层和光球上层的加热既不能用电子束轰击,也不能用X线的作用来解释;可能存在某种把能量从色球上层向低层转移的机制.研究也表明,耀斑随时间变化的半经验模型为研究耀斑的能量耗散过程提供了很好的工具. 

A Study of the Energy Deposits in Flaring Atmosphere with Semiempirical Models of Flares

Using the time-varying semiempirical models for two flares (one is classified as a SBflare and the other a 2Bflare), which were deduced from the spectral data obtained with the solar tower telescope of Nanjing University, the radiative loss at different phases of the flares are computed and compared with the energy deposits due to electron beam bombardment and X-ray radiation. The results show that the variation of chromospheric radiative loss during the flares is more than one order of magnitude. It is also shown that during the impulsive phase of the flares the heating due to the electron beam bombardment is very efficient, but for the gradual phase of the flares, the energy deposits mechanism due to X-ray is a better one than that due to electron beam in order to explain the observational results, whereas near the intensity maximum of the flares, both X-ray and electron beam have their contributions. The results indicate that the heating in the lower chromosphere and the upper photosphere, especially for large flares, can be caused neither by X-ray radiation nor by electron beam bombardment. It seems that there are some other mechanism to transpot the deposit energy from the upper part of the atmosphere to the lower part. This study also shows that time-varying models of flares are good tools in the investigation of the flare energy balance.