ON THE INJECTION OF HELICITY BY THE SHEARING MOTION OF FLUXES IN RELATION TO FLARES AND CORONAL MASS EJECTIONS
ON THE INJECTION OF HELICITY BY THE SHEARING MOTION OF FLUXES IN RELATION TO FLARES AND CORONAL MASS EJECTIONS
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DOI：
10.1088/0004-637x/761/2/86
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发表时间：
2012-02
期刊：
影响因子：
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通讯作者：
P. Vemareddy;A. Ambastha;R. Maurya;J. Chae
中科院分区：
文献类型：
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作者：
P. Vemareddy;A. Ambastha;R. Maurya;J. Chae
利用太阳动力学观测站上的日震和磁成像仪获得的视线磁场观测资料，对NOAA 11158和11166两个活动区进行了光球剪切运动对螺旋度注入的研究。我们从微分仿射速度估计（DAVE）技术推导出AR中的水平速度。在这两个AR中观测到沿磁极反转线以0.6-0.9 km s-1沿着的最大速度的持续强烈剪切运动和从太阳黑子外围区域向外的流动。NOAA 11158和11166在其6天演化期间注入的螺旋度估计分别为14.16 × 1042 Mx2和9.5 × 1042 Mx2。通过将磁图之间的时间间隔从12分钟增加到36分钟，估计的注入率降低了13%，通过将DAVE窗口大小从21 × 18像素2减小到9 × 6像素2，估计的注入率增加了9%，导致累积螺旋度变化10%。在这两个AR中，耀斑倾向区域（R2）的螺旋度通量分布不均匀，混合的两个符号和日冕物质抛射（CME）倾向区域的螺旋度通量几乎均匀的分布占主导地位的一个符号。在某些耀斑/CME期间，由于负螺旋度注入到正螺旋度通量的主导区域，螺旋度注入的时间剖面表现出脉冲变化。定量分析揭示了一个轻微的显着关联的螺旋度通量与日冕物质抛射体，但不是耀斑在AR 11158，而AR 11166，我们发现一个轻微的显着关联的螺旋度通量与耀斑，但不是日冕物质抛射体，提供证据的螺旋度注入的作用在本地网站的事件。这些短期变化的螺旋度通量进一步讨论，鉴于可能的耀斑相关的影响。这项研究表明，磁通量运动和螺旋度注入的空间分布是重要的理解的复杂性质的磁通量系统的AR，以及它如何能够导致有利于喷发事件的条件。
An investigation of helicity injection by photospheric shear motions is carried out for two active regions (ARs), NOAA 11158 and 11166, using line-of-sight magnetic field observations obtained from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. We derived the horizontal velocities in the ARs from the differential affine velocity estimator (DAVE) technique. Persistent strong shear motions at maximum velocities in the range of 0.6–0.9 km s−1 along the magnetic polarity inversion line and outward flows from the peripheral regions of the sunspots were observed in the two ARs. The helicities injected in NOAA 11158 and 11166 during their six-day evolution period were estimated as 14.16 × 1042 Mx2 and 9.5 × 1042 Mx2, respectively. The estimated injection rates decreased up to 13% by increasing the time interval between the magnetograms from 12 minutes to 36 minutes, and increased up to 9% by decreasing the DAVE window size from 21 × 18 to 9 × 6 pixel2, resulting in 10% variation in the accumulated helicity. In both ARs, the flare-prone regions (R2) had inhomogeneous helicity flux distribution with mixed helicities of both signs and coronal mass ejection (CME) prone regions had almost homogeneous distribution of helicity flux dominated by a single sign. The temporal profiles of helicity injection showed impulsive variations during some flares/CMEs due to negative helicity injection into the dominant region of positive helicity flux. A quantitative analysis reveals a marginally significant association of helicity flux with CMEs but not flares in AR 11158, while for the AR 11166, we find a marginally significant association of helicity flux with flares but not CMEs, providing evidence of the role of helicity injection at localized sites of the events. These short-term variations of helicity flux are further discussed in view of possible flare-related effects. This study suggests that flux motions and spatial distribution of helicity injection are important to understanding the complex nature of the magnetic flux system of the AR, and how it can lead to conditions favorable for eruptive events.