非爆发性伪流中的热非平衡循环
Thermal Non-equilibrium Cycles in a Non-eruptive Pseudo-Streamer
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中文总结 AI 辅助
研究发现伪流中存在持续2.5天的热非平衡循环，其不仅发生在闭合场还发生在开放场，支持了热非平衡可存在于开-闭边界的数值结论，为太阳大气热非平衡研究提供新视角。
中文摘要 AI 辅助
热非平衡（TNE）是一种著名的热力学机制，通常在日冕环中研究。这种蒸发和凝结循环由准稳态分层加热诱导，长周期极紫外（EUV）脉冲和日冕雨是TNE的两种表现形式。循环的准周期性是TNE的显著特征，因为系统围绕一个无法达到的平衡位置动态演化。近期有报道称在扇-脊拓扑和伪流等开-闭边界处存在日冕雨，但关于驱动这些日冕雨事件的物理机制尚未得出明确结论。我们报告利用太阳动力学天文台（SDO）上的大气成像组件（AIA）观测到的伪流中长周期EUV脉冲和共空间重复出现的日冕雨阵雨。结合势场源表面（PFSS）模型和EUV动力学，详细研究了伪流的磁拓扑和演化。这个持续2.5天的事件展现了此前在日冕环中报道的所有TNE特征：不同波段依次出现周期性EUV脉冲，遵循其温度响应峰值的排序，且日冕雨阵雨在这些循环末期出现。我们进一步表明，伪流中的TNE循环不仅发生在闭合场中，也发生在开放场中。我们的观测支持近期数值研究的结果，即TNE也可发生在开放场区域和开-闭边界处。同时，如EUV中所见，交换重联沿开-闭边界持续且非脉冲式发生。TNE与交换重联之间的相互作用有待未来工作详细研究。这一观测为理解太阳大气中的TNE及其对太阳风的潜在影响开辟了新视角。
英文摘要
Thermal non-equilibrium (TNE) is a well-known thermodynamic mechanism, generally studied in coronal loops. These evaporation and condensation cycles are induced by a quasi-steady and stratified heating. Long-period EUV pulsations and coronal rain are two manifestations of TNE. The quasi-periodicity of the cycles is a strong characteristic of TNE as the system dynamically evolves around an equilibrium position that is not reachable. There are recent reports of coronal rain at open-closed boundaries such as fan-spine topologies and pseudo-streamers. However, no definite conclusions were drawn on the physical mechanisms driving these coronal rain events. We report the detection of long-period EUV pulsations and co-spatial recurring coronal rain showers in a pseudo-streamer observed with AIA on board SDO. The magnetic topology and evolution of the pseudo-streamer are studied in detail using a combination of PFSS modeling and EUV dynamics. The 2.5-day event exhibits all the characteristic features of previous TNE events reported in coronal loops: periodic EUV pulses appearing sequentially in the different channels, following the ordering of the peaks in their temperature response, and coronal rain showers appearing toward the end of these cycles. We further show that the TNE cycles in the pseudo-streamer occur not only in the closed field but also in the open field. Our observations support the findings of recent numerical studies showing that TNE can also occur in open field regions and at open-closed boundaries. In parallel, interchange reconnection occurs continuously and non-impulsively all along the open-closed boundary as seen in EUV. The interplay between TNE and interchange reconnection should be studied in detail in future works. This observation opens further perspectives for the understanding of TNE in the solar atmosphere and its potential implications for the solar wind.
