Tests for coronal electron temperature signatures in suprathermal electron populations at 1 AU
Tests for coronal electron temperature signatures in suprathermal electron populations at 1 AU
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DOI：
10.5194/angeo-35-1275-2017
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发表时间：
2017-11
影响因子：
1.9
通讯作者：
A. Macneil;C. Owen;R. Wicks
中科院分区：
文献类型：
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作者：
A. Macneil;C. Owen;R. Wicks
摘要。关于太阳风的日冕起源如何影响其原位特性的知识的发展是理解太阳和日球层之间关系的关键之一。本文对ACE/SWICS和WIND/3DP数据进行了分析，并测试了太阳风超热电子分布的性质，以确定日冕温度在其起源处可能保持在1au的特征。特别地，我们重新检查了先前的建议，即这些性质与氧电荷态比O7+∕O6+有关，这是日冕电子温度的一个已建立的代理。我们发现在超热电子能含量与O7+∕O6+之间只有非常弱但可变的相关性。与先前的结果相反，相关性的弱性质使我们得出结论，与核心电子温度的初始关系可能存在于日冕中，但在大多数情况下，在1au的超热电子分布中没有留下强烈的特征。目前还不能确定这是由于日冕条件对这种关系的影响，还是由于太阳风在到达1au的过程中通过处理改变了电子分布。光晕种群和斯特拉种群的对比结果支持后一种解释。使用太阳轨道飞行器的数据（巡航和名义任务阶段）来验证这种关系的弱点是否在日心距离范围内持续存在是可能的。如果在靠近太阳的地方发现这种相关性增强，那么这将表明一种最初的关系正在减弱，可能是由于波粒相互作用，在到达观测者的途中。
Abstract. The development of knowledge of how the coronal origin of the solar wind affects its in situ properties is one of the keys to understanding the relationship between the Sun and the heliosphere. In this paper, we analyse ACE/SWICS and WIND/3DP data spanning > 12 years, and test properties of solar wind suprathermal electron distributions for the presence of signatures of the coronal temperature at their origin which may remain at 1 AU. In particular we re-examine a previous suggestion that these properties correlate with the oxygen charge state ratio O7+ ∕ O6+, an established proxy for coronal electron temperature. We find only a very weak but variable correlation between measures of suprathermal electron energy content and O7+ ∕ O6+. The weak nature of the correlation leads us to conclude, in contrast to earlier results, that an initial relationship with core electron temperature has the possibility to exist in the corona, but that in most cases no strong signatures remain in the suprathermal electron distributions at 1 AU. It cannot yet be confirmed whether this is due to the effects of coronal conditions on the establishment of this relationship or due to the altering of the electron distributions by processing during transport in the solar wind en route to 1 AU. Contrasting results for the halo and strahl population favours the latter interpretation. Confirmation of this will be possible using Solar Orbiter data (cruise and nominal mission phase) to test whether the weakness of the relationship persists over a range of heliocentric distances. If the correlation is found to strengthen when closer to the Sun, then this would indicate an initial relationship which is being degraded, perhaps by wave–particle interactions, en route to the observer.