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arXiv 1402.6554astro-ph.SR
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来自Hinode/EIS的热无耀斑日冕的热结构

Thermal structure of hot non-flaring corona from Hinode/EIS

A. Petralia, F. Reale, P. Testa, G. Del Zanna

摘要:

在以往的研究中,人们曾通过SDO/AIA三个不同窄带通道的图像诊断出太阳活动区存在一个非常热的等离子体成分。这种诊断从EUV成像数据也支持了匹配形态的发射在热的Ca XVII线,与Hinode/EIS观察。这一证据是有争议的,因为未知的分布的排放措施沿视线。在这里,我们详细调查的热分布的一个这样的区域使用EUV光谱数据。在SDO/AIA,Hinode/EIS和XRT观测到的活动区域中,我们选择了一个具有非常热的等离子体成分的子区域和另一个较冷的子区域进行比较。提取两者的平均光谱,并选择14条强谱线进行分析,这些谱线均匀地探测5.5 < log T < 7的温度范围。从这些线的发射测量分布与MCMC方法重建。结果进行交叉检查与比较的两个分区,用不同的反演方法,与图像的形态,并与从窄和宽带成像仪测量的通量。我们发现,而冷区域具有平坦且无特征的分布,其在温度log T >= 6.3时下降,热区域的分布在log T = 6.6处显示出明确的峰值,并且在两侧上逐渐减小趋势,从而支持用成像仪诊断的热分量的非常热的性质。其他交叉检查与此结果一致。这项研究提供了一个完整的活动区组件的分析,并由此产生的方案支持在核心的一个小的非常热的等离子体组件的存在,与温度log T > 6.6。

英文摘要:

In previous studies a very hot plasma component has been diagnosed in solar active regions through the images in three different narrow-band channels of SDO/AIA. This diagnostic from EUV imaging data has also been supported by the matching morphology of the emission in the hot Ca XVII line, as observed with Hinode/EIS. This evidence is debated because of unknown distribution of the emission measure along the line of sight. Here we investigate in detail the thermal distribution of one of such regions using EUV spectroscopic data. In an active region observed with SDO/AIA, Hinode/EIS and XRT, we select a subregion with a very hot plasma component and another cooler one for comparison. The average spectrum is extracted for both, and 14 intense lines are selected for analysis, that probe the 5.5 < log T < 7 temperature range uniformly. From these lines the emission measure distributions are reconstructed with the MCMC method. Results are cross-checked with comparison of the two subregions, with a different inversion method, with the morphology of the images, and with the addition of fluxes measured with from narrow and broad-band imagers. We find that, whereas the cool region has a flat and featureless distribution that drops at temperature log T >= 6.3, the distribution of the hot region shows a well-defined peak at log T = 6.6 and gradually decreasing trends on both sides, thus supporting the very hot nature of the hot component diagnosed with imagers. The other cross-checks are consistent with this result. This study provides a completion of the analysis of active region components, and the resulting scenario supports the presence of a minor very hot plasma component in the core, with temperatures log T > 6.6.

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