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arXiv 2001.02259astro-ph.SR
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长寿命冕洞的差分发射测量等离子体诊断

Differential Emission Measure Plasma Diagnostics of a Long-Lived Coronal Hole

Jonas Saqri, Astrid M. Veronig, Stephan G. Heinemann, Stefan J. Hofmeister, Manuela Temmer, Karin Dissauer, Yang Su

摘要:

我们使用太阳动力学天文台(SDO)/大气成像组件(AIA)的数据重建等离子体的性质从差分发射测量(DEM)分析以前研究的长寿命,低纬度冕洞(CH)在其寿命的10个太阳旋转。我们最初得到一个非等温DEM分布的主导成分集中在0.9 MK和次要较小的组件在1.5 - 2.0 MK。我们发现,去卷积的数据与仪器点扩散函数(PSF)占远程散射光减少了二次热分量。使用2012年金星凌日和2013年月食来测试这种去卷积的效率,在被掩盖的区域发现了大量的残留杂散光。考虑到不同AIA滤波器的误差预算中的这种杂散光,进一步减少了二次热发射,产生了接近等温的CH DEM分布,主要贡献集中在0.9 MK左右。基于这些DEM,我们分析了CH的寿命期间的发射测量(EM),密度和平均温度的演变。我们发现,一旦CH在EUV图像中被清楚地观察到,大部分的CH等离子体揭示了一个相当恒定的状态,即温度和密度没有显示出重大的变化,而总的CH面积和光球磁精细结构内的CH显示出一个独特的演化模式。这些研究结果表明,CH等离子体的性质大多是“设置”在CH形成或/和所有CH具有类似的等离子体性质。

英文摘要:

We use Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) data to reconstruct the plasma properties from differential emission measure (DEM) analysis for a previously studied long-lived, low-latitude coronal hole (CH) over its lifetime of ten solar rotations. We initially obtain a non-isothermal DEM distribution with a dominant component centered around 0.9 MK and a secondary smaller component at 1.5 - 2.0 MK. We find that deconvolving the data with the instrument point spread function (PSF) to account for long-range scattered light reduces the secondary hot component. Using the 2012 Venus transit and a 2013 lunar eclipse to test the efficiency of this deconvolution, significant amounts of residual stray light are found for the occulted areas. Accounting for this stray light in the error budget of the different AIA filters further reduces the secondary hot emission, yielding CH DEM distributions that are close to isothermal with the main contribution centered around 0.9 MK. Based on these DEMs, we analyze the evolution of the emission measure (EM), density, and averaged temperature during the CH's lifetime. We find that once the CH is clearly observed in EUV images, the bulk of the CH plasma reveals a quite constant state, i.e. temperature and density reveal no major changes, whereas the total CH area and the photospheric magnetic fine structure inside the CH show a distinct evolutionary pattern. These findings suggest that CH plasma properties are mostly "set" at the CH formation or/and that all CHs have similar plasma properties.

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