The Drivers of Active Region Outflows into the Slow Solar Wind
The Drivers of Active Region Outflows into the Slow Solar Wind
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DOI：
10.3847/1538-4357/ab8a4c
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发表时间：
2020-05-01
影响因子：
4.9
通讯作者：
Walsh, Robert
中科院分区：
文献类型：
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作者：
Brooks, David H.;Winebarger, Amy R.;Walsh, Robert
从活动区边缘流出的等离子体被认为是缓慢太阳风的一个可能来源。光谱测量表明，这些外流具有增强的元素组成，这是慢风的明显特征。然而，目前的光谱观测没有足够的空间分辨率来区分正在测量的结构或确定外流的驱动因素。高分辨率日冕成像仪(Hi-C)于2018年5月搭载探空火箭飞行，观测到活动区以有史以来最高的空间分辨率(250公里)流出。在这里，我们使用Hi-C数据来解开Hinode卫星在飞行过程中观测到的外流成分特征。我们发现流出辐射有两种成分：一种是从活动区核心的闭合环中排出的膨胀等离子体的实质性贡献，另一种是活动区斑块动态活动的贡献，其成分特征反映了太阳光球层的丰度。这两个相互竞争的外流驱动力可能解释了缓慢的太阳风的不同组成。
Plasma outflows from the edges of active regions have been suggested as a possible source of the slow solar wind. Spectroscopic measurements show that these outflows have an enhanced elemental composition, which is a distinct signature of the slow wind. Current spectroscopic observations, however, do not have sufficient spatial resolution to distinguish what structures are being measured or determine the driver of the outflows. The High-resolution Coronal Imager (Hi-C) flew on a sounding rocket in 2018 May and observed areas of active region outflow at the highest spatial resolution ever achieved (250 km). Here we use the Hi-C data to disentangle the outflow composition signatures observed with the Hinode satellite during the flight. We show that there are two components to the outflow emission: a substantial contribution from expanded plasma that appears to have been expelled from closed loops in the active region core and a second contribution from dynamic activity in active region plage, with a composition signature that reflects solar photospheric abundances. The two competing drivers of the outflows may explain the variable composition of the slow solar wind.