Sunspots, Starspots, and Elemental Abundances
Sunspots, Starspots, and Elemental Abundances
复制标题
太阳黑子、星黑子和元素丰度
DOI：
10.3847/1538-4357/aa7bea
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
H. Warren
中科院分区：
文献类型：
--
作者：
G. Doschek;H. Warren
太阳光球、色球、过渡区和日冕中的元素丰度是研究太阳风来源、估算平静日冕和太阳耀斑等动力事件中辐射损失的关键参数。根据元素的第一电离势(FIP)不同，日冕和光球层的丰度也不同。正常情况下，日冕中FIP值小于10 eV的丰度大约是光球层丰度的3-4倍。然而，最近在太阳黑子附近的小区域发现了逆FIP效应，在这些区域，FIP小于10 eV的元素相对于高FIP元素(EV)的丰度比它们在光球层中要少。这类似于具有大星斑的全对流恒星。逆FIP效应预计将发生在太阳黑子/恒星黑子附近。到目前为止，太阳异常丰度只在很小的空间范围内被发现。在这篇文章中，我们证明了在太阳黑子附近可能有相当大的区域，丰度介于日冕和光球丰度之间，有时只有光球丰度。在某些情况下，FIP效应往往会在太阳黑子附近关闭。我们检查了日诺航天器上的极紫外成像光谱仪在第24周期中观测到的几个具有相对较大太阳黑子的活动区域。
Element abundances in the solar photosphere, chromosphere, transition region, and corona are key parameters for investigating sources of the solar wind and for estimating radiative losses in the quiet corona and in dynamical events such as solar flares. Abundances in the solar corona and photosphere differ from each other depending on the first ionization potential (FIP) of the element. Normally, abundances with FIP values less than about 10 eV are about 3–4 times more abundant in the corona than in the photosphere. However, recently, an inverse FIP effect was found in small regions near sunspots where elements with FIP less than 10 eV are less abundant relative to high FIP elements ( eV) than they are in the photosphere. This is similar to fully convective stars with large starspots. The inverse FIP effect is predicted to occur in the vicinity of sunspots/starspots. Up to now, the solar anomalous abundances have only been found in very spatially small areas. In this paper, we show that in the vicinity of sunspots there can be substantially larger areas with abundances that are between coronal and photospheric abundances and sometimes just photospheric abundances. In some cases, the FIP effect tends to shut down near sunspots. We examine several active regions with relatively large sunspots that were observed with the Extreme-ultraviolet Imaging Spectrometer on the Hinode spacecraft in cycle 24.