The EUV spectrum of the Sun: Quiet- and active-Sun irradiances and chemical composition
The EUV spectrum of the Sun: Quiet- and active-Sun irradiances and chemical composition
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DOI：
10.1051/0004-6361/201834842
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发表时间：
2019-01
影响因子：
6.5
通讯作者：
G. Del Zanna
中科院分区：
文献类型：
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作者：
G. Del Zanna
我们根据从极端紫外线(EUV)的中等分辨率安静太阳光谱中获得的一系列辐照度，对新的原子数据进行基准测试，范围从60到1040？我们使用了太阳动力学天文台极端紫外线变率实验(EVE)的原型(PEVE)在2008年4月14日太阳活动最小期间测量的辐照度作为基线。我们使用飞行前夕数据和从太阳和日球层天文台(SOHO)日冕诊断光谱仪(CDS)获得的辐照度，考虑了PEVE数据中的一些不一致之处。我们进行了一次差分发射测量，发现在大多数情况下，预测和测量的辐照度之间的总体一致性非常好(在观测的准确性内，约为20%)，尽管我们指出了目前可用的离子电荷态分布中的几个问题。我们使用了Asplund等人的光球化学丰度。(2009，ARA&A，47,481)。对于中等分辨率的辐照度光谱，新的原子数据在这个光谱范围内几乎是完整的。最后，我们利用1969年对活跃太阳的观测表明，在这种情况下，直到1MK的日冕成分也几乎是光球状的。对于在活动区内发射的较高温度的等离子体，存在因子为2的变化。这些结果与我们之前的发现非常一致。
We benchmark new atomic data against a selection of irradiances obtained from medium-resolution quiet-Sun spectra in the extreme ultraviolet (EUV), from 60 to 1040 Å. We used as a baseline the irradiances measured during solar minimum on 2008 April 14 by the prototype (PEVE) of the Solar Dynamics Observatory Extreme ultraviolet Variability Experiment (EVE). We took into account some inconsistencies in the PEVE data, using flight EVE data and irradiances we obtained from Solar and Heliospheric Observatory (SoHO) Coronal Diagnostics Spectrometer (CDS) data. We performed a differential emission measure and find overall excellent agreement (to within the accuracy of the observations, about 20%) between predicted and measured irradiances in most cases, although we point out several problems with the currently available ion charge-state distributions. We used the photospheric chemical abundances of Asplund et al. (2009, ARA&A, 47, 481). The new atomic data are nearly complete in this spectral range for medium-resolution irradiance spectra. Finally, we used observations of the active Sun in 1969 to show that the composition of the solar corona up to 1 MK is nearly photospheric in this case as well. Variations of a factor of 2 are present for higher-temperature plasma, which is emitted within active regions. These results are in excellent agreement with our previous findings.