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arXiv 0812.1441astro-ph
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宁静太阳的Ly-alpha轮廓和中心到边缘的变化

The Ly-alpha profile and center-to-limb variation of the quiet Sun

W. Curdt, H. Tian, L. Teriaca, U. Schuehle, P. Lemaire

摘要:

本文研究了宁静太阳中氢原子莱曼-α谱线的辐射、中心-边缘变化(CLV)和辐射强度分布。我们还比较了准同时Ly-a和Ly-b线轮廓。我们使用SUMER光谱仪的高光谱和空间分辨率,并在磁盘的各个位置完成光栅扫描。我们第一次使用了一种方法,通过部分关闭孔径门将入射光子通量降低到20%的水平。我们还在太阳中心以坐立凝视模式对Ly-a和Ly-b进行了准同时观测。我们推断的流动特性的Ly-a地图中的变化,在校准的1206硅III线的质心。我们提出的平均配置文件的Ly-a,它的辐射分布,其CLV的行为,和签名的线轮廓上的流量。在Ly-a线的剖面中观察到很小的CLV和没有临边增亮。与所有其他的莱曼系,其中有一个更强的红角线,Ly-a有一个主导的蓝角不对称。似乎存在亮度与不对称性的关系。一个类似的,甚至更清楚的趋势是观察到的下降流不对称的关系。这一重要结果与包括流动的模型的预测一致。然而,在剖面中没有清晰的CLV可能更能指示各向同性场而不是径向流。看来,无处不在的氢的行为类似于一个过滤器,抑制所有的签名线形成的过程中的色球层和过渡区。

英文摘要:

We study the emission of the hydrogen Lyman-a line in the quiet Sun, its center-to-limb variation (CLV), and its radiance distribution. We also compare quasi-simultaneous Ly-a and Ly-b line profiles. We used the high spectral and spatial resolution of the SUMER spectrometer and completed raster scans at various locations along the disk. For the first time, we used a method to reduce the incoming photon flux to a 20%-level by partly closing the aperture door. We also performed a quasi-simultaneous observation of both Ly-a and Ly-b at Sun center in sit-and-stare mode. We infer the flow characteristic in the Ly-a map from variations in the calibrated 1206 Si III line centroids. We present the average profile of Ly-a, its radiance distribution, its CLV behaviour, and the signature of flows on the line profiles. Little CLV and no limb brightening are observed in the profiles of the Ly-a line. In contrast to all other lines of the Lyman series, which have a stronger red-horn, Ly-a has a dominating blue-horn asymmetry. There appears to be a brightness-to-asymmetry relationship. A similar and even clearer trend is observed in the downflow-to-asymmetry relationship. This important result is consistent with predictions from models that include flows. However, the absence of a clear CLV in the profiles may be more indicative of an isotropic field than a radial flow. It appears that the ubiquitous hydrogen behaves similar to a filter that dampens all signatures of the line formation by processes in the chromosphere and transition region.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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