太阳光谱线轮廓在日面上的变化和宁静太阳大气模型

本文利用在美国基特峰国家天文台观测得到的氢和电离钙多条谱线轮廓,以及PANDORA大气模型计算程序,对宁静太阳VAL-C'大气模型进行了诊断。文中首先讨论了模型大气中不同层次的辐射特性,着重指出H巴尔末谱线同Call共振线和红外线的源函数具有与温度不同的耦合关系。其次,通过计算得到了各条谱线在日面不同点的出射轮廓,并将其同观测轮廓相比较,存在的系统差别有:(1)Hβ和λ8498红外线线心的剩余强度较观测值高,而CaIIH和K线线翼的剩余强度则明显比观测值低;(2)Hβ及caII各条谱线在△λ=0.5?处的剩余强度值的临边增大系数较观测值大。除上所述及某些观测误差以外,计算值同观测值符合得较好。最后,文章分析了导致计算和观测不符的可能原因,并进而提出了对VAL-C'模型改进的意见。 

CENTER-TO-LIMB VARIATION OF SPECTRAL LINES AND QUIET SUN ATMOSPHERIC MODEL

In this paper, the spectral lines of hydrogen and ionized calcium, as well as their center-to-limb variations, observed at Kitt Peak National Solar Observatory, are used to diagnose the VAL-C', quiet Sun atmospheric model. The PANDORAcomputer program is used to perform the detailed non-LTEmodel calculations, especially for hydrogen and calcium. The main discrepancies between the computed spectral lines and the observed data are: (1) The residual intensity in Hβ andλ8498 line centers is evidently higher, while that in CaII Hand Klines are relatively lower than the observed values; (2) The center-to-limb enhancement coefficient of the residual intensities of Hβ, and all the CaIIlines (resonance and infrared lines) near Δλ = 0.5? is a little larger than indicated by the observation. However, all other spectral features observed can be reproduced fairly well. Finally, the possible causes which can make the computed values deviate from the observed ones is discussed, and a comment on revising the VAL-C' model is given.