NEW OBSERVATIONS OF THE SOLAR 0.5–5 KEV SOFT X-RAY SPECTRUM
NEW OBSERVATIONS OF THE SOLAR 0.5–5 KEV SOFT X-RAY SPECTRUM
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太阳 0.5–5 KEV 软 X 射线光谱的新观测
DOI：
10.1088/2041-8205/802/1/l2
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
H. Warren
中科院分区：
文献类型：
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作者：
A. Caspi;T. Woods;H. Warren
日冕比下面的光球层热几个数量级，但日冕如何达到如此高的温度仍然不清楚。软X射线（SXR）发射为高温日冕中的热过程提供了重要的诊断，也是地球电离层动力学的重要驱动因素。在0.2keV和0.4keV之间有一个至关重要的观测差距，超出了现有光谱仪的范围。我们提出了一个新的SXR光谱仪，Amptek X123-SDD，测量空间积分太阳光谱辐照度从0.5keV到0.5keV，0.15keV的FWHM分辨率，在探空火箭飞行2012年6月23日和2013年10月21日的观测。这些测量结果表明，即使只有微弱的活动，高度可变的SXR发射量也比2009年的深极小期大几个数量级。观测到的光谱显示出显着的高温（5-10 MK）发射，并与指数为10.6的简单幂律温度分布很好地拟合，接近日冕加热的纳米耀斑模型的预测。在2013年更活跃的飞行期间进行的观测表明，低第一电离势元素的富集度仅为1.16，低于通常观测到的1.14，这表明丰度变化可能与日冕加热过程有关。XUV光度计系统4级数据产品是一种源自综合宽带测量的光谱辐照度模型，它显着高估了两次飞行的光谱，这表明需要修改其非耀斑参考光谱，这对研究地球电离层动力学具有重要意义由太阳SXR驱动。
The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the high-temperature corona, and is also an important driver of ionospheric dynamics at Earth. There is a crucial observational gap between ∼0.2 and ∼4 keV, outside the ranges of existing spectrometers. We present observations from a new SXR spectrometer, the Amptek X123-SDD, which measured the spatially integrated solar spectral irradiance from ∼0.5 to ∼5 keV, with ∼0.15 keV FWHM resolution, during sounding rocket flights on 2012 June 23 and 2013 October 21. These measurements show that the highly variable SXR emission is orders of magnitude greater than that during the deep minimum of 2009, even with only weak activity. The observed spectra show significant high-temperature (5–10 MK) emission and are well fit by simple power-law temperature distributions with indices of ∼6, close to the predictions of nanoflare models of coronal heating. Observations during the more active 2013 flight indicate an enrichment of low first-ionization potential elements of only ∼1.6, below the usually observed value of ∼4, suggesting that abundance variations may be related to coronal heating processes. The XUV Photometer System Level 4 data product, a spectral irradiance model derived from integrated broadband measurements, significantly overestimates the spectra from both flights, suggesting a need for revision of its non-flare reference spectra, with important implications for studies of Earth ionospheric dynamics driven by solar SXRs.