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arXiv 0910.5191astro-ph.SRastro-ph.IM
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宁静太阳中普遍存在的高速过渡区和日冕上升流

Ubiquitous High Speed Transition Region and Coronal Upflows in the Quiet Sun

Scott W. Mcintosh, Bart De Pontieu

备注：
10 pages, 15 figures. In press ApJ. Higher resolution figures, and movies supporting them, can be found at http://download.hao.ucar.edu/pub/mscott/papers/QS/
发表信息：
Astrophys.J.707:524-538,2009
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摘要：

我们研究了在典型的太阳宁静区观测到的一系列过渡区（TR）发射线的谱线轮廓。在磁网络区，Si IV 1402 nm，C IV 1548 nm，N V 1238 nm，O VI 1031 nm和Ne VIII 770 nm谱线在发射线轮廓的蓝翼显示出明显的不对称性。我们将TR下部和上部的这些高速上升流解释为最近在谱区上方的低日冕中发现的上升流的安静太阳等效物（Hara等人，2008年）。后者已被证明与高速色球针状体直接相关，这些针状体（部分）被加热到日冕温度，并在为活动区日冕提供热等离子体方面发挥重要作用（DePontieu等人，2009年）。我们发现，一个类似的过程可能占主导地位的安静的太阳网络。我们提供了一个新的解释所观察到的安静的太阳TR发射的色球层和日冕之间的无情的质量传输-从动态的情节加热和质量注入到日冕以及从以前充满，缓慢冷却，日冕等离子体的混合物的发射。对观测到的上升流分量的分析表明，它携带了足够的热等离子体，在宁静日冕的能量和质量平衡中发挥了重要作用。我们确定的温度依赖性的上升流速度来约束的加速和加热机制，驱动这些上升流。我们还表明，这些上升流的时间特性表明，有时会导致准周期信号的一个情节驱动程序。我们认为，至少有一些的准周期性观测日冕成像仪和光谱仪，以前被解释为传播磁声波，而不是这些上升流造成的。

英文摘要：

We study the line profiles of a range of transition region (TR) emission lines observed in typical quiet Sun regions. In magnetic network regions, the Si IV 1402Å, C IV 1548Å, N V 1238Å, O VI 1031Å, and Ne VIII 770Å spectral lines show significant asymmetry in the blue wing of the emission line profiles. We interpret these high-velocity upflows in the lower and upper TR as the quiet Sun equivalent of the recently discovered upflows in the low corona above plage regions (Hara et al., 2008). The latter have been shown to be directly associated with high-velocity chromospheric spicules that are (partially) heated to coronal temperatures and play a significant role in supplying the active region corona with hot plasma (DePontieu et al., 2009}. We show that a similar process likely dominates the quiet Sun network. We provide a new interpretation of the observed quiet Sun TR emission in terms of the relentless mass transport between the chromosphere and corona - a mixture of emission from dynamic episodic heating and mass injection into the corona as well as that from the previously filled, slowly cooling, coronal plasma. Analysis of the observed upflow component shows that it carries enough hot plasma to play a significant role in the energy and mass balance of the quiet corona. We determine the temperature dependence of the upflow velocities to constrain the acceleration and heating mechanism that drives these upflows. We also show that the temporal characteristics of these upflows suggest an episodic driver that sometimes leads to quasi-periodic signals. We suggest that at least some of the quasi-periodicities observed with coronal imagers and spectrographs that have previously been interpreted as propagating magnetoacoustic waves, may instead be caused by these upflows.

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