VARIATIONS IN SOLAR WIND FRACTIONATION AS SEEN BY ACE/SWICS AND THE IMPLICATIONS FOR GENESIS MISSION RESULTS
VARIATIONS IN SOLAR WIND FRACTIONATION AS SEEN BY ACE/SWICS AND THE IMPLICATIONS FOR GENESIS MISSION RESULTS
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ACE/SWICS 观察到的太阳风分解变化及其对 Genesis 任务结果的影响
DOI：
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发表时间：
2015
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影响因子：
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通讯作者：
R. Wiens
中科院分区：
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作者：
P. Pilleri;D. Reisenfeld;T. Zurbuchen;S. Lepri;P. Shearer;J. Gilbert;R. Steiger;R. Wiens
我们利用先进成分探测器(ACE)/太阳风离子成分光谱仪(SWICS)的元素组成数据，比较了在最近一次太阳活动高峰(1999-2001年)、太阳活动极小期(2006-2009年)和创世号航天器收集太阳风(2001年末-2004年初)期间太阳风(SW)分馏的变化。我们区分了我们的分析在西南方向(即，起源于流间或日冕空穴流动，或日冕物质抛射)。丰度被归一化到低第一电离势(Low-FIP)离子镁，以揭示当归一化到高FIP离子时不明显的相关性。我们发现，相对于镁，其他低FIP元素存在可测量的分馏，但分馏程度在整个太阳周期内没有明显变化。对于高FIP离子，分馏在太阳周期内的变化是显著的：Ne/mg和C/mg最大，O/mg次之，He/mg最小。当丰度比作为西南方向速度的函数时，我们发现了很强的相关性，值得注意的是，分馏程度遵循与质量有关的趋势。我们讨论了将Genesis样本返回结果修正为光球层丰度的含义。
We use Advanced Composition Explorer (ACE)/Solar Wind Ion Composition Spectrometer (SWICS) elemental composition data to compare the variations in solar wind (SW) fractionation as measured by SWICS during the last solar maximum (1999–2001), the solar minimum (2006–2009), and the period in which the Genesis spacecraft was collecting SW (late 2001—early 2004). We differentiate our analysis in terms of SW regimes (i.e., originating from interstream or coronal hole flows, or coronal mass ejecta). Abundances are normalized to the low-first ionization potential (low-FIP) ion magnesium to uncover correlations that are not apparent when normalizing to high-FIP ions. We find that relative to magnesium, the other low-FIP elements are measurably fractionated, but the degree of fractionation does not vary significantly over the solar cycle. For the high-FIP ions, variation in fractionation over the solar cycle is significant: greatest for Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance ratios are examined as a function of SW speed, we find a strong correlation, with the remarkable observation that the degree of fractionation follows a mass-dependent trend. We discuss the implications for correcting the Genesis sample return results to photospheric abundances.