Hα, Extreme-Ultraviolet, and Microwave Observations of the 2000 March 22 Solar Flare and Spontaneous Magnetic Reconnection
Hα, Extreme-Ultraviolet, and Microwave Observations of the 2000 March 22 Solar Flare and Spontaneous Magnetic Reconnection
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2000 年 3 月 22 日太阳耀斑和自发磁重联的 Hα、极紫外和微波观测
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发表时间：
2003
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通讯作者：
H. Yun
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作者：
Jeongwoo Lee;P. Gallagher;D. Gary;G. Nita;G. Choe;S. Bong;H. Yun
利用欧文斯谷太阳阵列（OVSA）、大熊太阳天文台（BBSO）、过渡区和日冕探测器（TRACE）以及太阳和日光层天文台（SOHO）上的迈克尔逊多普勒成像仪（MDI）的观测资料，讨论了2000年3月22日发生在NOAA活动区8910的一次GOES X1.1级太阳耀斑的演变。在脉冲阶段，TRACE 171 Å （~1 × 106 K）波段可见一组日冕环，这些日冕环被限制在大的βγδ型活跃区中心的一个小体积内。紧接着是明亮的Hα带的出现，与EUV发射一致。射电图像显示，在5 GHz波段，单个源包围着Hα带，但在更高的频率，在紧凑的Hα和EUV发射的区域内，可以看到双源。我们用受限耀斑的概念来解释观测结果，而不是更常被引用的爆发耀斑。我们使用基于MDI磁图的磁重联几何原理图表明，EUV回路显示分离矩阵的某些部分，并且射电源和α源分别与分离矩阵的整个部分及其脚点重合。首先，它解释了为什么这个耀斑缺乏α带的分离运动，α带是爆发耀斑的标志。其次，在这种情况下，尽管有大量的软x射线通量，但微波爆发的持续时间很短是可以解释的，因为在受限磁结构中通过自发重联释放的能量可以非常迅速。第三，从OVSA微波光谱推断，受限磁几何也被认为有利于保持色球蒸发和等离子体湍流。此外，本文还简要讨论了LASCO日冕仪在耀斑发生后观测到的一次日冕物质抛射。
The evolution of a GOES class X1.1 solar flare, which occurred in NOAA Active Region 8910 on 2000 March 22, is discussed using observations from the Owens Valley Solar Array (OVSA), Big Bear Solar observatory (BBSO), Transition Region and Coronal Explorer (TRACE), and the Michelson Doppler Imager (MDI) on board Solar and Heliospheric Observatory (SOHO). During the impulsive phase, a set of coronal loops are visible in the TRACE 171 Å (~1 × 106 K) wavelength band, which is confined to a small volume in the center of the large βγδ-type active region. This is rapidly followed by the emergence of bright Hα ribbons that coincide with the EUV emission. Radio images show a single source encompassing the Hα ribbons at 5 GHz, but at higher frequencies a double source is seen within the area bounded by the compact Hα and EUV emissions. We interpret the observation under the idea of the confined flare in contrast with the more commonly cited, eruptive flare. We use a schematic magnetic reconnection geometry based on the MDI magnetogram to suggest that the EUV loops show some parts of a separatrix, and that the radio and Hα sources coincide with the whole part of the separatrix and its footpoints, respectively. First of all, it explains why this flare lacks the separating motion of Hα ribbons, a signature for eruptive flares. Second, the very short duration of microwave bursts in spite of the large amount of soft X-ray flux is explicable under this scenario, since energy release via spontaneous reconnection in a confined magnetic structure can be very rapid. Third, the confined magnetic geometry is also considered favorable for preserving chromospheric evaporation and plasma turbulence as inferred from the OVSA microwave spectrum. In addition, a coronal mass ejection as detected in the LASCO coronagraph after this flare is briefly discussed in relation to the above flare model.