YNAO OpenIR  > 太阳物理研究组
太阳活动区磁场测量和非势特征研究
其他题名RESEARCH ON THE MEASUREMENTS OF SOLAR MAGNETIC FIELDS AND THE NONPOTENCIALITY OF SOLAR ACTIVITY REGIONS
敦金平
学位类型博士
导师张柏荣 ; 李如风 ; 张洪起
2002-09-17
学位授予单位中国科学院研究生院(云南天文台)
学位授予地点北京
学位专业天体物理
关键词太阳活动 磁场测量 磁场非势特征
摘要磁场在太阳活动中扮演者最主要的角色,太阳表面上各种活动现象(如太阳黑子、耀斑爆发和日冕物质抛射等)都和太阳磁场有关。因此,太阳活动区磁场测量和非势特征的研究对理解太阳表面上各种活动现象的物理机制和动力学过程有着十分重要的意义。本文主要在这两方面进行了一些研究,主要内容包括以下四部分:1.法拉第效应对怀柔磁场望远镜横场方位角测量的影响。理论上,在谱线的远线翼观测时,法拉第效应的影响远远小于在谱线线心观测时的影响。我们利用国家天文台怀柔太阳磁场望远镜分别在工作谱线线心和线翼(偏离线心-0.15A)处观测的70组矢量磁图,通过对线心和线翼处测量的横场方位角的统计比较,结果表明:对于总磁场强度小于1000高斯的区域,法拉第效应的影响是比较小的。但对于总磁场强度大于1000高斯的区域,法拉第效应的影响明显变大。在γ<30°的倾角范围内,可以认为法拉第效应的影响很小:在30°≤γ<60°的倾角范围内,法拉第效应的影响明显变大:当倾角γ≥75°后,法拉第效应的影响又明显减小。法拉第效应对怀柔磁场望远镜横场观测中方位角的平均影响为130。2.法拉第效应对利用怀柔磁场望远镜观测的矢量磁场计算电流螺度的影响。我们通过对磁场望远镜分别在工作谱线线心和线翼(偏离线心-0.15A)处观测的70组矢量磁图计算的平均电流螺度值的比较,得到:在总磁强度小于1000高斯的范围内,法拉第效应对平均电流螺度计算值的影响非常小,随着总磁场强度的增大,法拉第效应的影响越来越明显。在倾角下小于30°和大于75°的两个范围内,法拉第效应对平均电流螺度计算值的影响非常轻微,而在30°到75°的范围内,法拉第效应的影响随倾角的增加而变得越来越强。3.太阳23周活动上升期磁场剪切角和非势能的演化。我们利用国家天文台怀柔太阳磁场望远镜在1995到1998年观测数据中234个活动区的共700幅矢量磁图,计算了每幅磁图的纵向磁场通量、磁场剪切角和非势能并给出了它们的月平均值随时间的演化。我们得到如下结论:从太阳活动低年到太阳活动峰年,太阳上活动区的数目、活动区的面积、纵向磁场通量和磁场所蕴含的磁能都在增强,而且日面上单位体积内所蕴含的磁场能量和潜在的、可以供给各种太阳活动现象(如耀斑、日面物质抛射等)的非势能量也在增加,磁场剪切角的变化虽然没有上述随时间的演化趋势.但是在太阳活动的土升期,磁场剪切角的符号和大小在剧烈的变化,从另一个角度反映了太阳上活动区的非势性随着太阳活动峰年的即将到来而变得强烈、复杂。4.太阳23周活动上升期磁场剪切角的统计分布。我们利用国家天文台怀柔太阳望远镜在1996年到2000年观测数据中274个活动区的共759幅矢量磁图,计算了每幅磁图的磁场剪切角,分别做了南半球、北半球和所仃活动区的磁场剪切角的统计分布直方图。这些统计分布都近似为正态高斯分布,可用高斯曲线的得到很好的拟合。磁场剪切角具有南北半球符号的反对称手征性,在南半球有53%的活动区的磁场剪切角是正的,而在北半球有62%是负的。
其他摘要Magnetic field plays central role in solar activity. Almost all kinds of solar activities, such as sunspot, solar flare and coronal mass ejection, are associated with solar magnetic field. The measurement of solar magnetic field and the non-potential characteristic of solar activity are important to explain the physical mechanism and dynamical process of solar activity. In this dissertation the both are studied. The main results are as follows: The effect of Faraday rotation on the azimuths of transverse fields observed by the Solar Magnetic Field Telescope at the Huairou Solar Observing Station. It is believed that the Faraday rotation is insignificant in the far wing of the line in the theoretical analysis. We make a comparison between the azimuths of 70 couples of transverse fields observed at line center and in the wing of the working spectral line of the telescope. From the comparison we found that the influence of Faraday rotation is slight for the weak magnetic fields (less than l000Gauss) and becomes significant for the strong fields (bigger than lOOOGauss). And the influence of Faraday rotation is insignificant when the incline angle γ is less than 30°. It becomes significant when 30 °≤γ<60°and becomes slight when the incline angle γ is bigger than 75°. The average influence of Faraday rotation on the measurements of the azimuths of transverse fields observed by the telescope is 13° The effect of Faraday rotation on the helicity computation using observations from the Solar Magnetic Field Telescope at the Huairou Solar Observing Station. The helicities derived from 70 couples of vector magnetograms obtained at the line center and in the wing of the line were compared. The results show that the influence of Faraday rotation on the helicity computation is insignificant when the strength of magnetic fields is less than 1000 Gauss and becomes significant as the increase in the strength of magnetic fields. The influence is insignificant when the incline angle y is less than 30° or bigger than 30°. And when 30°≤γ<75°, the influence increases with the value of the incline angle. The evolution of the magnetic shear angles and the non-potential energies in the ascending phase of solar cycle 23. We selected 700 vector magnetograms of 234 active regions observed from 1995 to 1998 by the Solar Magnetic Field Telescope at the Huairou Solar Observing Station. The flux of longitudinal magnetic fields, the magnetic shear angle and the non-potential energy of these vector magnetograms are calculated. And the evolutions of the monthly mean values of above parameters are derived. The results show that from the minimum of solar cycle 22 to the ascending phase of solar cycle 23, not only the number and area of solar active regions, the flux of longitudinal magnetic fields and the total energy of the active regions are increased, but also the density of non-potential energy of the solar active regions is increased. Although the evolution of magnetic shear angle has not such trend, the sign and value of the magnetic shear angle change slow at the minimum of solar cycle 22 and change rapidly in the ascending phase of solar cycle 23, which show that the non-potentiality becomes more and more complicated as the coming of solar maximum years. The statistical distribution of magnetic shear angle in the ascending phase of solar cycle 23. We selected 759 vector magnetograms of 274 active regions observed from 1996 to 2000 by the Solar Magnetic Field Telescope at the Huairou Solar Observing Station and calculated their magnetic shear angles. The histograms of magnetic shear angles of the total active regions, the active regions in the north hemisphere and the active regions in the south hemisphere are derived. The distributions were fitted well by Gaussian curves. And the distribution of the magnetic shear angles exhibits the hemisphere sign rule as the asymmetry of helicity. In our dataset, 53% of the active regions in the south hemisphere have positive shear angle and 62% in the north hemisphere have negative shear angle.
学科领域天文学
页数72
语种中文
文献类型学位论文
条目标识符http://ir.ynao.ac.cn/handle/114a53/6584
专题太阳物理研究组
推荐引用方式
GB/T 7714
敦金平. 太阳活动区磁场测量和非势特征研究[D]. 北京. 中国科学院研究生院(云南天文台),2002.
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