AI 中文总结
研究日冕暗化事件能否产生类日冕洞特性，通过比较多卫星观测数据，发现暗化区域发射强度等变化，仅在部分方面呈现类日冕洞特性，为日冕暗化大气结构研究提供新见解。
AI 中文摘要
日冕暗化，即瞬变日冕洞，表现为极紫外（EUV）和X射线辐射的突然减少，常伴随太阳爆发。我们通过比较太阳轨道飞行器、日出号、IRIS和SDO在暗化之前及期间的成像和光谱观测，研究暗化事件是否能产生类日冕洞等离子体特征。暗化区域的SDO/AIA 193 Å发射强度在11小时内降至与相邻日冕洞相同水平。用Fe XII（日冕）测量的多普勒速度从\(-0.34^{+0.37}_{-0.27}\) km/s降至主要向上流动的\(-3.2^{+0.4}_{-0.6}\) km/s。首次电离势（FIP）偏差向光球值降低。我们发现SDO/AIA 193 Å中暗化边界附近自动检测到的EUV增亮数量增加，这可能是磁重联的迹象。在较冷的SDO/AIA 171 Å或太阳轨道飞行器HRI_EUV 174 Å通道中未观察到这种增加。日冕亮点（CBPs）似乎相对不受暗化形成的影响。Mg II \(k_3\)（色球层）多普勒速度不变，除了弱磁场（\(<20\) G）区域暗化向上流动略有降低。我们发现暗化仅表现出部分类日冕洞特性；具体而言，在日冕发射线和温度\(>1\) MK时。我们认为这是由于暗化仅在较高高度由等离子体耗尽导致。由于CBPs未受暗化显著影响，我们将其磁环高度（\(\sim 10\) Mm）用作暗化高度的下限。我们的发现为日冕暗化的大气结构提供了新见解。
英文摘要
Coronal dimmings, or transient coronal holes, are manifested as a sudden reduction in extreme ultraviolet (EUV) and X-ray emission, often following solar eruptions. We investigate whether a dimming event can produce coronal hole-like plasma characteristics by comparing imaging and spectroscopic observations from Solar Orbiter, Hinode, IRIS, and SDO prior and during the dimming. The SDO/AIA 193 Å emission intensity in the dimming region was reduced to the same level as the neighbouring coronal hole within 11 hours. The Doppler velocity measured with Fe XII (corona) decreased from $-0.34^{+0.37}_{-0.27}$ km/s towards a predominant upflow of $-3.2^{+0.4}_{-0.6}$ km/s. The first ionisation potential (FIP) bias was reduced towards photospheric values. We found an increase in the number of automatically detected EUV brightenings near the dimming boundary in SDO/AIA 193 Å which could be a sign of magnetic reconnection. In the cooler SDO/AIA 171 Å or Solar Orbiter HRI_EUV 174 Å channel, we did not observe such an increase. Coronal bright points (CBPs) appeared relatively unaffected by the formation of the dimming. The Mg II $k_3$ (chromosphere) Doppler velocities were unchanged, except for a small reduction in the dimming upflows in areas with weak magnetic fields ($<20$ G). We find that the dimming only shows partial coronal hole-like properties; specifically, in the coronal emission lines and at temperatures of $>1$ MK. We suggest that this is due to the dimming resulting from plasma depletion only at higher altitudes. Since the CBPs were not significantly impacted by the dimming, we used their magnetic loop heights ($\sim 10$ Mm) as the lower limit to the dimming height. Our findings provide new insights into the atmospheric structure of coronal dimmings.
CommentsAccepted for publication in Astronomy & Astrophysics (A&A)
DOI：10.1051/0004-6361/202660557
