两种日珥光谱分析方法的比较

A COMPARISON BETWEEN TWO SPECTRAL ANALYSIS METHODS FOR SOLAR FROMINENCES

本文将完全线性化方法同非局部热动平衡计算方法进行了比较,考察了用完全线性化方法确定光谱参数的可靠性,并研究了光谱分析中经常用的“共空间发射”等假设的合理性。本文研究结果表明,用完全线性化方法可以唯一确定谱线多普勒宽度,线心光学厚度和源函数线性变化系数,其中多普勒宽度和源函数线性变化系数反映了日珥中H_a和CaⅡH. K线线翼附近所对应形成区的物理状况。H_a线同C_aⅡ H. K线是共空间发射的,从共空间发射求出的温度反映了日珥中上述区域的运动温度。本文结果还表明,一般来说,日珥中CaⅢ粒子数大于CaⅡ粒子数,从CaⅡ H、K线求氢原子密度必须考虑两次电离钙的贡献。

The Non-local thermodynamic equilibrium (Non-LTE) method and line inversion method are often used in the spectral analysis of solar prominences. As we know, the Non-LTE method has wide applications in stellar and solar physics. It demands few assumptions. On the other hand, a line inversion method is proposed to treat a specific active phenomenon and contains more simplification. In some cases, the simplification is true. But sometimes, it is not, and causes a discrepancy in results. In this paper, we choose the complete linearization method to compare with the Non-LTE calculation. By simu lating H_a, CaⅡ H and K line profiles, we study the reliability and physical significance of the Doppler width, the opacity at a line center, and the damping width determined by the linearization method. In addition, the reliability of H_a, and CaⅡ H, K co-spatial emission and the method of deducing hydrogen density from Call H and K line optical depths are checked. This paper reveals that: The Doppler width, the optical depth at line center, and the linear variation coefficient of the line source function determined by the complete linearization method are dependable and unique. Due to observational error and theoretical simplification, the damping width can hardly be deduced accurately with this method. Generally, the formation region of Haline is only about 150 km deeper than that of CaII H and K lines. Hence, the assumption of H_and Call H, K line co-spatial emission is reasonable. The Doppler width and linear variation coefficient of the source function calculated with the complete linearization method represent the physical condition of the region where line wings (around) are formed. The temperature determinded by the Doppler widths of H_and Call H, K lines represents the kinetic temperature in this region. Because prominences are illuminated by incident radiation from the surrounding atmosphere, the number density of CaⅢ is generally greater that that of CaⅡ. Therefore, if one wants to derive the hydrogen number density from the CaⅡ H and K line opacities, the contribution of the CaⅢ population to the calcium number density must be taken into account. Otherwise the resulting hydrogen density will be much smaller than its real value.