与等离子体冷却相关的失败爆发中的太阳软X射线冕洞变暗
Solar Soft X-ray Coronal Dimming in a Failed Eruption Associated with Plasma Cooling
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中文总结 AI 辅助
研究发现与失败暗条爆发相关的M8.8级耀斑产生了无显著CME驱动质量损失的高温太阳软X射线冕洞变暗，其成因是高温等离子体冷却，为恒星变暗机制提供了新解释。
中文摘要 AI 辅助
冕洞变暗表现为太阳极紫外和X射线辐射的突然局域性减弱，传统上，1-2 MK温度形成的谱线出现显著变暗被视为日冕物质抛射（CMEs）的指标，反映等离子体逃逸到行星际空间造成的密度损耗。本文中，我们报告了一个特殊的深冕洞变暗事件，该事件主要在M8.8级受限太阳耀斑及伴随的失败暗条爆发后，于高温谱线中被观测到。来自地球静止环境业务卫星（Geostationary Operational Environmental Satellite）和极紫外变率实验（Extreme Ultraviolet Variability Experiment）的全日面恒星测量显示，软X射线（SXR）强度降低超过30%，且Fe XVIII（6.5 MK）和Fe XX（9.3 MK）出现可测量的下降。大气成像组件（Atmospheric Imaging Assembly）的空间分辨观测表明，该变暗起源于活动区核心，而日地关系天文台-A（Solar Terrestrial Relations Observatory-A）未发现CME驱动质量损失的证据。微分发射度分析显示，温度>5 MK的等离子体冷却至更低温度，支持等离子体冷却为高温波段变暗的主要贡献因素，而非CME相关的等离子体逃逸。该事件表明，在无显著CME驱动质量损失时也可出现深的高温SXR变暗，提示除常见推断的CME特征外，其他物理机制也可能解释未分辨的恒星变暗。
英文摘要
Coronal dimmings are observed as sudden and localized reductions in the extreme-ultraviolet and X-ray emission of the solar corona. Traditionally, significant dimmings of spectral lines formed at temperatures of 1-2 MK are regarded as indicators of coronal mass ejections (CMEs), reflecting the density depletion caused by plasma escaping into interplanetary space. In this Letter, we report a peculiar deep coronal dimming event predominantly observed in high-temperature spectral lines following an M8.8-class confined solar flare associated with a failed filament eruption. Sun-as-a-star measurements from the Geostationary Operational Environmental Satellite and the Extreme Ultraviolet Variability Experiment reveal intensity reductions exceeding 30% in soft X-ray (SXR) and measurable decreases in Fe XVIII (6.5 MK) and Fe XX (9.3 MK). Spatially resolved observations from the Atmospheric Imaging Assembly demonstrate that the dimming originates from the active region core, while the Solar Terrestrial Relations Observatory-A shows no evidence for CME-driven mass loss. Differential emission measure analysis reveals plasma at temperatures >5 MK cooling into lower temperatures, supporting plasma cooling as the dominant contributor to the hot-band dimming rather than CME-associated plasma escape. This event demonstrates that deep hot SXR dimmings can occur without substantial CME-driven mass loss, suggesting that alternative physical mechanisms may also account for unresolved stellar dimmings in addition to the commonly inferred CME signatures.
发表机构
- Peking University（北京大学）
- National Space Science Center, Chinese Academy of Sciences（中国科学院国家空间科学中心）
- Institute of Physics, University of Graz（格拉茨大学物理研究所）
- Kanzelhöhe Observatory for Solar and Environmental Research, University of Graz（格拉茨大学坎泽勒霍厄太阳与环境研究天文台）
- Yunnan University（云南大学）
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