Joint X-Ray, EUV, and UV Observations of a Small Microflare
Joint X-Ray, EUV, and UV Observations of a Small Microflare
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DOI：
10.3847/1538-4357/ab2dfa
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发表时间：
2019-08-20
影响因子：
4.9
通讯作者：
Smith, David M.
中科院分区：
文献类型：
--
作者：
Hannah, Iain G.;Kleint, Lucia;Smith, David M.
我们提出了一个小的微耀斑在X射线与核光谱望远镜ARray（努斯塔），在紫外线与界面区成像光谱仪（IRIS），并在极紫外线与太阳动力学天文台/大气成像组件（SDO/AIA）的第一次联合观测。这些综合观测使我们能够研究来自微耀斑的热日冕和较冷的色球/过渡区发射。这个小的微耀斑在2016年7月26日23：35至23：36 UT期间达到峰值，在努斯塔，SDO/AIA和IRIS中。在空间上，这对应于SDO/AIA Fe XVIII发射中可见的一个小环，这与SJI 1330和1400 A中IRIS在太阳大气中看到的类似结构相匹配。2.5-4和4-6 keV的努斯塔发射位于该环路位置的源中。IRIS狭缝位于微耀斑环的上方，拟合结果显示Mg II的变化很小，但强度增加，宽度略有增强，Si IV和0 IV的红移，这表明这个微耀斑在上色球层和以上最有意义。努斯塔微耀斑光谱与5.1 MK和6.2 x 10（44）cm（-3）的热分量很好地拟合，这对应于1.5 x 10（26）erg的热能，使其比以前研究的活动区微耀斑小得多。未检测到非热发射，但这可能是由于观察的有效暴露时间有限。这一观察表明，即使是在紫外线中看到的普通特征也可以明显地具有在X射线中清晰可见的较高能量成分。
We present the first joint observation of a small microflare in X-rays with the Nuclear Spectroscopic Telescope ARray (NuSTAR), in UV with the Interface Region Imaging Spectrograph (IRIS), and in EUV with the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA). These combined observations allow us to study the hot coronal and cooler chromospheric/transition region emission from the microflare. This small microflare peaks from 2016 July 26 23:35 to 23:36 UT, in both NuSTAR, SDO/AIA, and IRIS. Spatially, this corresponds to a small loop visible in the SDO/AIA Fe XVIII emission, which matches a similar structure lower in the solar atmosphere seen by IRIS in SJI1330 and 1400 A. The NuSTAR emission in both 2.5-4 and 4-6 keV is located in a source at this loop location. The IRIS slit was over the microflaring loop, and fits show little change in Mg II but do show intensity increases, slight width enhancements, and redshifts in Si IV and 0 IV, indicating that this microflare had most significance in and above the upper chromosphere. The NuSTAR microflare spectrum is well fitted by a thermal component of 5.1 MK and 6.2 x 10(44) cm(-3), which corresponds to a thermal energy of 1.5 x 10(26) erg, making it considerably smaller than previously studied active region microflares. No non-thermal emission was detected but this could be due to the limited effective exposure time of the observation. This observation shows that even ordinary features seen in UV can remarkably have a higher-energy component that is clear in X-rays.