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arXiv 1608.04892astro-ph.SR
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IRIS观测到的太阳黑子过渡区的窄线宽UV爆发

Narrow-line-width UV bursts in the transition region above Sunspots observed by IRIS

Zhenyong Hou, Zhenghua Huang, Lidong Xia, Bo Li, Maria S. Madjarska, Hui Fu, Chaozhou Mou, Haixia Xie

摘要:

太阳活动区上方的大气中存在着大量的小尺度结构,它们对太阳活动区的动力学和演化起着重要的作用。我们报告一类新的小尺度过渡区结构的活动区,其特征在于强发射,但极窄的硅IV线剖面中发现的观察与界面区域成像光谱仪(IRIS)。这些结构位于太阳黑子上方,由一个或多个亚弧秒尺度的致密亮核组成,被称为窄线宽紫外暴(NUB)。我们在两个数据集中发现了六个NUB(一个栅格数据集和一个静坐凝视数据集)。其中,4起事件持续时间短,持续时间为$\sim$ 10分钟,2起事件持续时间超过36分钟。所有NUB都有15- 18 km/s的多普勒频移,而在坐立凝视数据中发现的NUB具有仅在C II和Mg II谱线中发现的$\sim$ 50 km/s的附加分量。鉴于这些事件被发现在局部动力学中发挥作用,重要的是要进一步研究产生这些现象的物理机制及其在太阳黑子质量传输中的作用。

英文摘要:

Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si IV line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as Narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise of one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two datasets (a raster and a sit-and-stare dataset). Among these, four events are short-living with a duration of $\sim$10 mins while two last for more than 36 mins. All NUBs have Doppler shifts of 15--18 km/s, while the NUB found in sit-and-stare data possesses an additional component at $\sim$50 km/s found only in the C II and Mg II lines. Given that these events are found to play a role in the local dynamics, it is important to further investigate the physical mechanisms that generate these phenomena and their role in the mass transport in sunspots.

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