云南天文台太阳光谱望远镜加Stokes光电偏振分析器的考虑

云南天文台太阳光谱望远镜是无偏振对称光路系统,经过重新装调望远镜空间分辨率在１”以内,光谱上的空间分辨率在１”～２”,跟踪精度在５ 分钟内１”,以上光学参数达到可以加装Ｓｔｏｋｅｓ 偏振分析器,用于参加２３ 周太阳峰年矢量磁场的光谱轮廓研究     

上海天文台1．56米望远镜斑点干涉成像实验进展

斑点干涉成像技术是克服大气湍流影响,提高地面大口径望远镜分辨本领的有效途径之一。该技术利用斑点相机拍摄一系列的短曝光像,使得大气湍流冻结,再经过图像处理获得高分辨率重建像。该技术设备简单,易于实现,很快在观测天文学中得到了广泛的应用,尤其是对双星的研究。首先回顾了天文高分辨率重建技术的发展,并介绍了相关研究成果。描述了几种典型的斑点干涉成像处理方法及其优缺点。对图像噪声类型及滤波方法进行了分析。在上海天文台1．56m望远镜上开展了双星斑点干涉观测实验,目标星等4～7mag,双星目标星等差小于2。分别采用斑点干涉术和迭代位移叠加法成功实现了双星目标的高分辨率成像,初步证明了在1．56m望远镜上进行斑点干涉成像实验,能够达到接近望远镜衍射极限的分辨率水平。     

The Self-Inversion of the Sign of Circular Polarization in “Halo” Microwave Sources

The large active region AR NOAA 5200 from October 1988 is used to investigate the concept of the “halo,” a magnetosphere-like structure above the active region. This structure is studied by using radio spectral polarization observations with high spatial resolution obtained mainly with the radio telescope RATAN-600. In the case of AR 5200 the halo emission accounted for >50% of the total AR emission. The results of the analysis of the observational data and of the model calculations allow us to reach the following conclusions: (1) The halo is a large, nonstructured, source of emission with a size of the total AR, with the emission centered at the dividing (neutral) line of polarities of the bipolar sunspot group. (2) The emission spectrum allows us to distinguish two components: a thermal part and a nonthermal part. The presence of two components implies that there are two populations of particles with different energy levels in the emission region. The phenomenon of inversion of the polarized halo radio emission could be explained by the influence of propagation conditions inside the source. The term “self-inversion” is introduced. The maximum in the halo density flux spectrum at wavelengths of 5 –10 cm may be explained by scattering resulting from the strong suppression of the emissivity of nonthermal electrons at these and longer wavelengths.