标题： NOAA 11942弱磁场区域中Sigmoid结构的形成与喷发 显示英文标题

标题： Formation and eruption of sigmoidal structure from a weak field region of NOAA 11942

摘要： 利用太阳动力学天文台的观测数据，我们研究了活动区（AR）11942的小尺度磁通量抵消区域中一个有趣的磁陀螺形成和爆发的例子。 通过对HMI和AIA观测数据的分析表明，最初该活动区紧凑且双极性，经过几天的时间演化为由反向J形环组成的剪切结构，这些环围绕着一个丝道。 通过追踪光球上的磁特征，发现剪切和汇聚运动在S形环的发展中起主导作用，进一步的磁通量抵消导致J形环的系绳切断重联。 这一阶段与1月6日21:32 UT时丝状体上升运动以及随后的磁陀螺爆发同时发生。 磁绳以缓慢（v$_{avg}$ = 26 km~s$^{-1}$）和快速（a$_{avg}$= 55 ms$^{-2}$）的两阶段上升运动上升，将该日冕物质抛射（CME）分类为慢速，并伴有弱C1.0级X射线耀斑。 耀斑带分离速度在耀斑峰值时间附近达到峰值，在此时刻最大重联速率（2.14 Vcm$^{-1}$）发生。 此外，131、171\AA 的EUV光曲线比94\AA 延迟了130分钟，这可以通过差分发射度来解释。 我们的分析表明，能量释放过程发生在较长的时间范围内，展示了由光球上汇聚和抵消的磁通量驱动的丝状体上升和最终爆发的开始。 与强烈的爆发事件不同，观测到的慢速CME和弱耀斑表明了缓慢的系绳切断重联，其中在爆发的扩展后阶段，大部分剪切拱被放松。 显示英文摘要

摘要： Using observations from Solar Dynamics Observatory, we studied an interesting example of a sigmoid formation and eruption from small-scale flux canceling regions of active region (AR) 11942. Analysis of HMI and AIA observations infer that initially the AR is compact and bipolar in nature, evolved to sheared configuration consisting of inverse J-shaped loops hosting a filament channel over a couple of days. By tracking the photospheric magnetic features, shearing and converging motions are observed to play a prime role in the development of S-shaped loops and further flux cancellation leads to tether-cutting reconnection of J-loops. This phase is co-temporal with the filament rise motion followed by sigmoid eruption at 21:32 UT on January 6. The flux rope rises in phases of slow (v$_{avg}$ = 26 km~s$^{-1}$) and fast (a$_{avg}$= 55 ms$^{-2}$) rise motion categorizing the CME as slow with an associated weak C1.0 class X-ray flare. The flare ribbon separation velocity peaks at around peak time of the flare at which maximum reconnection rate (2.14 Vcm$^{-1}$) occurs. Further, the EUV light-curves of 131, 171\AA~have delayed peaks of 130 minutes compared to 94\AA~and is explained by differential emission measure. Our analysis suggests that the energy release is proceeded in a much long time duration, manifesting the onset of filament rise and eventual eruption driven by converging and canceling flux in the photosphere. Unlike strong eruption events, the observed slow CME and weak flare are indications of slow runway tether-cutting reconnection where most of the sheared arcade is relaxed during the extended post phase of the eruption.