论文标题
通过单个J形冠状环的滑动而形成乙状结肠
Sigmoid Formation Through Slippage of A Single J-shaped Coronal Loop
论文作者
论文摘要
迫在眉睫的太阳喷发的众所周知的前体是在活性区域（AR）中的热S形环（也称为Sigmoid）的外观。从经典上讲，这种S形环的形成被设想通过通过两个相对定向的J形环的磁重新连接来实现。但是，由于发射前阶段的发射和细微的演变，重新连接的细节难以捉摸。在本文中，我们调查了单个J形循环如何通过其在NOAA AR 11719在2013年4月11日在NOAA AR 11719中的一个脚步的打滑转变为S形的，在大约16分钟的间隔中，J形循环在爆发的峰值时以强大的峰值速度升至$ 1000 km^$^$^$^$^$^$^$^$^$^$^$^$^$^M^appeption j harp loop lop逐渐下降。正如非无线电场建模所暗示的，电流密度的增强表明，冠状血浆的“非理想性”在局部重要，这可能有助于磁重新连接。进行滑动运动的循环段加热；同时，由于环的延长和加热的组合效应，在固定的脚步冠状发射之上，后者表现在昏暗斜率的时间变化和发射度量的时间变化中。这些特征共同通过单个J形环的重新连接来支持Sigmoid形成的不对称场景，该环路与涉及双J形环系统的标准绑扎截面方案不同。
A well-known precursor of an imminent solar eruption is the appearance of a hot S-shaped loop, also known as sigmoid, in an active region (AR). Classically, the formation of such an S-shaped loop is envisaged to be implemented by magnetic reconnection of two oppositely oriented J-shaped loops. However, the details of reconnection are elusive due to weak emission and subtle evolution during the pre-eruptive phase. In this paper, we investigate how a single J-shaped loop transforms into an S-shaped one through the slippage of one of its footpoints in NOAA AR 11719 on 2013 April 11. During an interval of about 16 min, the J-shaped loop slips through a low-corona region of strong electric current density in a bursty fashion, reaching a peak apparent speed as fast as over 1000 km s$^{-1}$, at the slipping footpoint. The enhancement of electric current density, as suggested by non-linear force-free field modeling, indicates that the "non-idealness" of coronal plasma becomes locally important, which may facilitate magnetic reconnection. The loop segment undergoing slipping motions is heated; meanwhile, above the fixed footpoint coronal emission dims due to a combination effect of the lengthening and heating of the loop, the latter of which is manifested in the temporal variation of dimming slope and of emission measure. These features together support an asymmetric scenario of sigmoid formation through slipping reconnection of a single J-shaped loop, which differs from the standard tether-cutting scenario involving a double J-shaped loop system.
