PARTIAL ERUPTION OF A FILAMENT WITH TWISTING NON-UNIFORM FIELDS
PARTIAL ERUPTION OF A FILAMENT WITH TWISTING NON-UNIFORM FIELDS
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具有扭曲非均匀场的细丝的部分爆发
DOI：
10.1088/0004-637x/805/1/48
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发表时间：
2015-05-20
影响因子：
4.9
通讯作者：
Liu, Weiwei
中科院分区：
文献类型：
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作者：
Bi, Yi;Jiang, Yunchun;Liu, Weiwei
丝状体以扭结状的方式喷发通常被认为是扭结不稳定性的标志。然而，扭结不稳定性阈值的灯丝的磁结构并没有得到广泛的理解。利用新真空太阳望远镜的Ha观测，我们提出了一个部分爆发的灯丝。在喷发过程中，细丝似乎从中间分裂，并以扭结状的方式爆发。在这一时期，剩余的暗条物质停留在下方，并在之后没有扭结运动的情况下爆发。与暗条相关的日冕磁力线是利用太阳动力学天文台上的日震和磁成像仪（HMI）的12分钟节奏矢量磁图通过非线性无力场外推获得的。我们研究了通过磁倾角的外推场线，与观测到的暗条符合得很好。磁力线是不均匀扭曲的，似乎是由两个扭曲的磁通绳缠绕在一起。其中一个比另一个有更高的扭曲度，并且具有更高扭曲度的通量绳在其喷发开始时与扭结的喷发线对齐。此外，在爆发之前，具有较高扭曲的磁通绳被发现以近似恒定的场扭曲膨胀。此外，从HMI磁图推导出的螺旋度通量图显示，一些螺旋度被注入到上覆的磁拱中，但没有显著的螺旋度被注入到通量绳中。因此，我们认为，当不稳定性阈值随着磁绳的膨胀而下降时，高扭曲磁绳成为扭结不稳定。
The eruption of a filament in a kinklike fashion is often regarded as a signature of kink instability. However, the kink instability threshold for the filament's magnetic structure is not widely understood. Using Ha observations from the New Vacuum Solar Telescope, we present a partial eruptive filament. During the eruption, the filament thread appeared to split from its middle and to break out in a kinklike fashion. In this period, the remaining filament material stayed below and erupted without the kinking motion later on. The coronal magnetic field lines associated with the filament are obtained from nonlinear force-free field extrapolations using the twelve-minute-cadence vector magnetograms of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory. We studied the extrapolated field lines passing through the magnetic dips which are in good agreement with the observed filament. The field lines are non-uniformly twisted and appear to be composed of two twisted flux ropes winding around each other. One of them has a higher twist than the other, and the flux rope with the higher twist has its dips aligned with the kinking eruptive thread at the beginning of its eruption. Before the eruption, moreover, the flux rope with the higher twist was found to expand with an approximately constant field twist. In addition, the helicity flux maps deduced from the HMI magnetograms show that some helicity is injected into the overlying magnetic arcade, but no significant helicity is injected into the flux ropes. Accordingly, we suggest that the highly twisted flux rope became kink unstable when the instability threshold declined with the expansion of the flux rope.