NARROW-LINE-WIDTH UV BURSTS IN THE TRANSITION REGION ABOVE SUNSPOTS OBSERVED BY IRIS

作者：Hou, Zhenyong; Huang, Zhenghua^*; Xia, Lidong; Li, Bo; Madjarska, Maria S.; Fu, Hui; Mou, Chaozhou; Xie, Haixia

来源：Astrophysical Journal Letters, 2016, 829(2): L30.

DOI：10.3847/2041-8205/829/2/L30

• line: profiles
• methods: observational
• Sun: atmosphere
• Sun: transition region
• sunspots Supporting material: animations

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 one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two data. sets (a raster and a sit-and-stare data. set). Among these, four events are short-lived with a duration of similar to 10 minutes, while two last for more than 36 minutes. All NUBs have Doppler shifts of 15-18 km s(-1), while the NUB found in sit-and-stare data possesses an additional component at similar to 50 km s(-1) 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.

• 出版日期2016-10-1
• 单位山东大学