Coronal Plasma Characterization via Coordinated Infrared and Extreme Ultraviolet Observations of a Total Solar Eclipse
Coronal Plasma Characterization via Coordinated Infrared and Extreme Ultraviolet Observations of a Total Solar Eclipse
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DOI：
10.3847/1538-4357/ab2b3c
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发表时间：
2019-01
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影响因子：
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通讯作者：
C. Madsen;J. Samra;G. del Zanna;E. DeLuca
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作者：
C. Madsen;J. Samra;G. del Zanna;E. DeLuca
我们利用极紫外成像光谱仪（EIS）和机载红外光谱仪（AIR-Spec）对2017年8月21日日全食进行了协调的日冕观测。这些仪器在两个不同的波长范围内提供了前所未有的日冕视图，即极紫外（EUV）和近中红外（IR），为表征复杂的日冕等离子体环境开辟了新的途径。在日全食期间，AIR-Spec在赤道西翼附近采集了日冕红外光谱，在1.4-4 μm的两个通带内探测到Mg viii、S xi、Si ix和Si x的强源。我们应用强度比诊断的强共振Fe十二线对所产生的协调EIS观测。这导致在整个共享的EIS/AIR-Spec视场中的电子密度的高分辨率图。电子密度测量使我们能够使用发射测量（EM）轨迹分析产生类似的等离子体温度图，应用于27条EIS发射线，提供沿着肢体的温度为106.12 ± 103.5 K，向外约100″的温度为106.19 ± 103.5 K。将EM轨迹分析应用于AIR-Spec IR光谱，在两个31″宽的范围内，以距离肢体30″和100″的两个位置为中心，产生与EIS数据一致的温度，尽管存在适度的不确定性。无论如何，我们证明了EUV光谱数据是有价值的限制日冕红外辐射模型，并将是未来的红外太阳观测站，特别是DKIST的有力补充。
We present coordinated coronal observations of the 2017 August 21 total solar eclipse with the Extreme-ultraviolet Imaging Spectrometer (EIS) and the Airborne Infrared Spectrometer (AIR-Spec). These instruments provide an unprecedented view of the solar corona in two disparate wavelength regimes, the extreme ultraviolet (EUV) and the near- to mid-infrared (IR), opening new pathways for characterizing the complex coronal plasma environment. During totality, AIR-Spec sampled coronal IR spectra near the equatorial west limb, detecting strong sources of Mg viii, S xi, Si ix, and Si x in two passbands encompassing 1.4–4 μm. We apply an intensity-ratio diagnostic to a strong resonant Fe xii line pair arising from the coordinated EIS observations. This results in a high-resolution map of electron density throughout the shared EIS/AIR-Spec field of view. Electron density measurements allow us to produce a similar map of plasma temperature using emission measure (EM) loci analysis as applied to 27 EIS emission lines, providing temperatures of 106.12 ± 103.5 K along the limb and 106.19 ± 103.5 K at about 100″ outward. Applying EM loci analysis to AIR-Spec IR spectra coadded over two 31″ wide ranges centered at two locations, 30″ and 100″ from the limb, produces temperatures consistent with the EIS data, albeit suffering from moderate uncertainties. Regardless, we demonstrate that EUV spectral data are valuable constraints to coronal IR emission models, and will be powerful supplements for future IR solar observatories, particularly DKIST.