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arXiv 1503.00979astro-ph.SR
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在非等温假设下的RESIK太阳X射线耀斑元素丰度

RESIK Solar X-ray flare element abundances on a non-isothermal assumption

B. Sylwester, K. J. H. Phillips, J. Sylwester, A. Kepa

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摘要：

本文分析了33次太阳耀斑的太阳X射线谱（谱段\em CORONAS-F），计算了Si、S、Ar和K的丰度，其中Si、S、Ar和K的发射谱线在谱中占有重要地位。对于每个光谱，该方法首先优化元素丰度，然后根据Sylwester等人和Withbroe给出的程序导出作为温度函数的差分发射测量。这与我们以前使用等温假设的RESIK光谱分析形成对比。在分析中，所有耀斑的平均修正丰度（以$A({\rm H}) = 12$的对数标度表示）为$A({\rm Si}) = 7.53 \pm 0.08$（以前的$7.89 \pm 0.13$）、$A({\rm S}) = 6.91 \pm 0.07$（$7.16 \pm 0.17$）、$A({\rm Ar}) = 6.47 \pm 0.08$（$6.45 \pm 0.07$）和$A({\rm K}) = 5.73 \pm 0.19$（$5.86 \pm 0.20$），几乎没有证据表明每个耀斑演化过程中丰度随时间变化。因此，我们以前的估计的Ar和K耀斑丰度证实了这一分析，但Si和S的减少。这表明耀斑中Si和Ar的丰度与光球丰度或太阳代用指标非常接近，而S明显小于光球丰度，K丰度远高于光球丰度。这些估计在某种程度上不同于那些单一的增强因子适用于第一电离势小于10 eV的元素。

英文摘要：

Solar X-ray spectra from the RESIK crystal spectrometer on the {\em CORONAS-F} spacecraft (spectral range $3.3-6.1$~Å) are analyzed for thirty-three flares using a method to derive abundances of Si, S, Ar, and K, emission lines of which feature prominently in the spectra. For each spectrum, the method first optimizes element abundances then derives the differential emission measure as a function of temperature based on a procedure given by Sylwester et al. and Withbroe. This contrasts with our previous analyses of RESIK spectra in which an isothermal assumption was used. The revised abundances (on a logarithmic scale with $A({\rm H}) = 12$) averaged for all the flares in the analysis are $A({\rm Si}) = 7.53 \pm 0.08$ (previously $7.89 \pm 0.13$), $A({\rm S}) = 6.91 \pm 0.07$ ($7.16 \pm 0.17$), $A({\rm Ar}) = 6.47 \pm 0.08$ ($6.45 \pm 0.07$), and $A({\rm K}) = 5.73 \pm 0.19$ ($5.86 \pm 0.20$), with little evidence for time variations of abundances within the evolution of each flare. Our previous estimates of the Ar and K flare abundances are thus confirmed by this analysis but those for Si and S are reduced. This suggests the flare abundances of Si and Ar are very close to the photospheric abundance or solar proxies, while S is significantly less than photospheric and the K abundance is much higher than photospheric. These estimates differ to some extent from those in which a single enhancement factor applies to elements with first ionization potential less than 10~eV.

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