The microwave radiation of the corona above a large single sunspot in right- and left-circular polarization
The microwave radiation of the corona above a large single sunspot in right- and left-circular polarization
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单个大太阳黑子上方的日冕微波辐射呈右旋和左旋圆偏振
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
T. P. Borisevich
中科院分区：
文献类型：
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作者：
N. Topchilo;N. Peterova;T. P. Borisevich
报告了对 2002 年 9 月观察到的 NOAA 10105 活动区域中一个大太阳黑子上方的日冕的研究结果，该太阳黑子的半影大小约为 70 英寸。使用 NoRH、SSRT 和 RATAN-600 望远镜的观测数据构建了活性区域和发射光谱图。确定太阳黑子上方微波发射的大小和亮度温度。对 SOHO/MDI 和 Kitt Peak 磁图以及在 Meudon 天文台获得的 CaII K 线图像进行了比较。假设磁场具有偶极结构，导出的特性被解释为热等离子体的回旋发射。在短波长下并且仅在普通发射模式下观察到太阳黑子中心的稳定变暗。在普通发射模式下，由于尺寸和光谱通量密度的增加，观察到太阳黑子源的结构出现跳跃式变化。这些结果需要对太阳黑子上方回旋加速器发射源的模型概念进行根本性修正，因为它们与最初的假设不一致。有人认为，在过渡区的顶部，回旋发射源可能仅由第三陀螺水平代表，但在异常和普通发射模式下观察到（与普遍接受的模型相反，该模型具有第二和第三陀螺水平的组合）。考虑到新的观测数据，我们可以改进太阳黑子上方日冕等离子体主要参数（电子温度和密度）的模型分布以及有关磁场特征的信息。
Results of a study of the corona above a large sunspot in the active region NOAA 10105 with a penumbra size of ∼70″ observed in September 2002 are reported. Maps of the active region and emission spectra were constructed using observational data from the NoRH, SSRT, and RATAN-600 telescopes. The sizes and brightness temperatures of the microwave emission above the sunspot are determined. SOHO/MDI and Kitt Peak magnetograms, as well as CaII K line images obtained at the Meudon Observatory, are compared. The derived characteristics are interpreted as cyclotron emission of thermal plasma, assuming a dipole structure for themagnetic field. A stable darkening at the sunspot center observed at short wavelengths and only in the ordinary emission mode was detected. A jump-like change was observed in the structure of the sunspot source in the ordinary emission mode, due to an increase in the size and spectral flux density. These results demand a fundamental correction of model concepts about cyclotron emission sources above sunspots, since they are at variance with the initial assumptions. It is suggested that, at the top of the transition region, the cyclotron emission source may be represented only by the third gyrolevel, but is observed in the extraordinary and ordinary emission modes (in contrast to the generally accepted model, which has a combination of the second and third gyrolevels). Taking into account the new observational data may allow us to refine model distributions of the main parameters of the coronal plasma above sunspots (the electron temperature and density) and information about the character of the magnetic field.