Hinode observations and 3D magnetic structure of an X-ray bright point
Hinode observations and 3D magnetic structure of an X-ray bright point
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Hinode 观测结果和 X 射线亮点的 3D 磁结构
DOI：
10.1051/0004-6361/201014045
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发表时间：
2011
影响因子：
6.5
通讯作者：
Alexander C
中科院分区：
文献类型：
--
作者：
Alexander C
目标我们展示了 2007 年 10 月 10 日、11 日观测到的 X 射线亮点 (XBP) 在其整个寿命（约 12 小时）内的日出太阳光学望远镜 (SOT)、X 射线望远镜 (XRT) 和 EUV 成像光谱仪 (EIS) 的完整观测结果。我们的目的是展示 XBP 的测量等离子体参数如何随时间变化，以及 X 射线发射与势磁场模型有何相似之处。方法使用 Hinode 上所有三个仪器的信息来研究其整个演变。 XRT 数据用于研究亮点的结构并测量 X 射线发射。 EIS 仪器用于测量 XBP 整个使用寿命期间的各种等离子体参数。最后，SOT 用于测量磁场强度，并为光球场的势场外推提供基础。执行这些操作，然后与观测到的日冕特征进行比较。结果 XBP 的尺寸约为 15 英寸，被发现形成于光球层磁通量合并和抵消区域的正上方。发现 X 射线发射率和总磁通量减少之间存在良好的相关性。人们发现 XBP 的磁性碎片会在非常短的时间尺度（分钟）内发生变化，但全局准双极结构在 XBP 的整个生命周期中保持不变。在大多数情况下，势场外推在视觉上与观察到的日冕环非常吻合，这意味着磁场与势态相差不太远。使用Fe xii的线比获得电子密度测量结果，发现平均密度为4.95×109cm-3，计算出体积等离子体填充因子的平均值为0.04。然后使用发射测量位点图来推断 logTe[K] ~ 6.1 的稳定温度。计算出的 Fe xii 多普勒频移显示亮点内及其周围 ±15 km s-1 的速度变化，观察到其变化时间尺度小于 30 分钟。
AimsWe present complete Hinode Solar Optical Telescope (SOT), X-Ray Telescope (XRT)and EUV Imaging Spectrometer (EIS) observations of an X-ray bright point (XBP) observed on the 10, 11 of October 2007 over its entire lifetime (~12 h). We aim to show how the measured plasma parameters of the XBP change over time and also what kind of similarities the X-ray emission has to a potential magnetic field model.MethodsInformation from all three instruments on-board Hinode was used to study its entire evolution. XRT data was used to investigate the structure of the bright point and to measure the X-ray emission. The EIS instrument was used to measure various plasma parameters over the entire lifetime of the XBP. Lastly, the SOT was used to measure the magnetic field strength and provide a basis for potential field extrapolations of the photospheric fields to be made. These were performed and then compared to the observed coronal features.ResultsThe XBP measured ~15″ in size and was found to be formed directly above an area of merging and cancelling magnetic flux on the photosphere. A good correlation between the rate of X-ray emission and decrease in total magnetic flux was found. The magnetic fragments of the XBP were found to vary on very short timescales (minutes), however the global quasi-bipolar structure remained throughout the lifetime of the XBP. The potential field extrapolations were a good visual fit to the observed coronal loops in most cases, meaning that the magnetic field was not too far from a potential state. Electron density measurements were obtained using a line ratio of Fe xii and the average density was found to be 4.95 × 109cm-3with the volumetric plasma filling factor calculated to have an average value of 0.04. Emission measure loci plots were then used to infer a steady temperature of logTe[K] ~ 6.1. The calculated Fe xii Doppler shifts show velocity changes in and around the bright point of ±15 km s-1which are observed to change on a timescale of less than 30 min.