arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.08584astro-ph.SR
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太阳软X射线光谱的新结果

Coronal Elemental Abundance: New Results from Soft X-ray Spectroscopy of the Sun

S. Narendranath, P. Sreekumar, Netra S Pillai, S. Panini, K. Sankarasubramanian, Juhani Huovelin

摘要:

太阳日冕中的元素丰度与在太阳光球层中观测到的元素丰度不同。日冕与光球丰度的比值显示出对元素第一电离势(FIP)的依赖。我们估计FIP的偏见,从软X射线光谱的元素丰度的直接测量数据,从多个空间任务,涵盖了一系列的太阳活动水平。这一全面的分析表明,有明确的证据表明,在FIP偏差减少周围的最大强度的X射线耀斑与日冕丰度短暂倾向于光球值和缓慢的恢复作为耀斑衰减。低FIP元素Ca、Fe和Si与日冕丰度的偏离大于具有中等FIP值的S。分馏程度的这些变化可能为耀斑期间通过色球层的波传播模型提供输入。

英文摘要:

Elemental abundances in the solar corona are known to be different from those observed in the solar photosphere. The ratio of coronal to photospheric abundance shows a dependence on the first ionisation potential (FIP) of the element. We estimate FIP bias from direct measurements of elemental abundances from soft X-ray spectra using data from multiple space missions covering a range of solar activity levels. This comprehensive analysis shows clear evidence for a decrease in FIP bias around maximum intensity of the X-ray flare with coronal abundances briefly tending to photospheric values and a slow recovery as the flare decays. The departure from coronal abundances are larger for the low FIP elements Ca, Fe and Si than for S which have a mid FIP value. These changes in the degree of fractionation might provide inputs to model wave propagation through the chromosphere during flares.

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