THE TRANSITION REGION RESPONSE TO A CORONAL NANOFLARE: FORWARD MODELING AND OBSERVATIONS IN SDO/AIA
THE TRANSITION REGION RESPONSE TO A CORONAL NANOFLARE: FORWARD MODELING AND OBSERVATIONS IN SDO/AIA
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过渡区对日冕纳米耀斑的响应：SDO/AIA 中的正演建模和观测
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
J. Klimchuk
中科院分区：
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作者：
N. Viall;J. Klimchuk
日冕和过渡区（TR）基本上是通过热传导和质量交换过程耦合的。不可能理解一个而不理解另一个。然而，在脉冲加热事件（如日冕纳米耀斑）之后，来自这两个位置的温度依赖性排放表现得非常不同。而电晕冷却顺序，发射第一次在较高的温度，然后在较低的温度，TR是多热和发射在所有温度一致的反应。我们以前应用的自动时间滞后技术的Viall和Klimchuk磁盘观测的活动区（AR）的大气成像组件（AIA）的太阳动力学天文台。穿过日冕等离子体的视线显示了纳米耀斑后冷却的明确证据，而与日冕链TR足点相交的视线显示出零时间滞后。在本文中，我们使用EBTEL流体动力学代码来证明，这正是预期的行为时，电晕加热纳米。我们还首次将时滞技术应用于AR的离肢观测。由于TR辐射不存在以上的肢体，零时间滞后的发生大大减少，支持的结论，零时间滞后的磁盘上测量的TR等离子体。最后，我们表明，在AIA的“冠状”通道可以由明亮的TR发射占主导地位。当以物理上有意义的方式定义时，TR达到通量管中峰值温度的大约60%的温度。由脉冲加热产生的TR可以延伸到3 MK和更高，正好在“冠状”AIA通道的范围内。
The corona and transition region (TR) are fundamentally coupled through the processes of thermal conduction and mass exchange. It is not possible to understand one without the other. Yet the temperature-dependent emissions from the two locations behave quite differently in the aftermath of an impulsive heating event such as a coronal nanoflare. Whereas the corona cools sequentially, emitting first at higher temperatures and then at lower temperatures, the TR is multithermal and the emission at all temperatures responds in unison. We have previously applied the automated time lag technique of Viall & Klimchuk to disk observations of an active region (AR) made by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. Lines of sight passing through coronal plasma show clear evidence for post-nanoflare cooling, while lines of sight intersecting the TR footpoints of coronal strands show zero time lag. In this paper, we use the EBTEL hydrodynamics code to demonstrate that this is precisely the expected behavior when the corona is heated by nanoflares. We also apply the time lag technique for the first time to off-limb observations of an AR. Since TR emission is not present above the limb, the occurrence of zero time lags is greatly diminished, supporting the conclusion that zero time lags measured on the disk are due to TR plasma. Lastly, we show that the ‘‘coronal'' channels in AIA can be dominated by bright TR emission. When defined in a physically meaningful way, the TR reaches a temperature of roughly 60% the peak temperature in a flux tube. The TR resulting from impulsive heating can extend to 3 MK and higher, well within the range of the ‘‘coronal'' AIA channels.