Statistical Study of Magnetic Nonpotential Measures in Confined and Eruptive Flares
Statistical Study of Magnetic Nonpotential Measures in Confined and Eruptive Flares
复制标题
DOI：
10.3847/1538-4357/aac272
复制
发表时间：
2018-05
期刊：
影响因子：
--
通讯作者：
N. Vasantharaju;P. Vemareddy;B. Ravindra;V. H. Doddamani
中科院分区：
文献类型：
--
作者：
N. Vasantharaju;P. Vemareddy;B. Ravindra;V. H. Doddamani
利用太阳动力学观测站/日震观测站和磁成像仪的矢量磁场观测，研究了活动区(ARs)磁无势程度与观测到的耀斑/日冕物质抛射(CME)的关系。从77个耀斑/CME病例的样本中，我们发现一般情况下，无潜势的程度与耀斑强度和相关的CME速度呈正相关。由于耀斑带区的磁通量与重联关系较大，因此我们沿着耀斑带区手工追踪强梯度极性反转线(SGPIL)和Schrijver的R值。与没有耀斑带信息的自动跟踪的值相比，手动检测的SGPIL长度和R值与耀斑强度和CME速度显示出更高的相关性。这凸显了从耀斑预测模型中使用的耀斑前磁图先验地预测耀斑强度和日冕物质抛射速度的难度。虽然总势磁能指标与耀斑强度和CME速度呈弱正相关，但自由能的降低与耀斑强度和CME速度有较高的相关性(0.56)。此外，与受限耀斑相比，爆发耀斑具有SGPIL长度(31 Mm)、R值(1.6×1019Mx)和自由能降低(2×1031erg)的阈值。在90%的爆发耀斑中，衰变指数曲线较陡，达到42毫米以内，而70%的受限耀斑的衰变指数曲线超过了这个值。虽然我们的研究表明，用耀斑带信息预测AR爆发行为的统计能力有所改善，但我们的研究提供了耀斑爆发的阈值磁特性。
Using Solar Dynamics Observatory/Helioseismic and Magnetic Imager vector magnetic field observations, we studied the relation between the degree of magnetic non-potentiality with the observed flare/coronal mass ejection (CME) in active regions (ARs). From a sample of 77 flare/CME cases, we found in general that the degree of non-potentiality is positively correlated with the flare strength and the associated CME speed. Since the magnetic flux in the flare-ribbon area is more related to the reconnection, we trace the strong gradient polarity inversion line (SGPIL) and Schrijver’s R value manually along the flare-ribbon extent. Manually detected SGPIL length and R values show higher correlation with the flare strength and CME speed than automatically traced values without flare-ribbon information. This highlights the difficulty of predicting the flare strength and CME speed a priori from the pre-flare magnetograms used in flare prediction models. Although the total potential magnetic energy proxies show a weak positive correlation, the decrease in free energy exhibits a higher correlation (0.56) with the flare strength and CME speed. Moreover, eruptive flares have thresholds of SGPIL length (31 Mm), R value (1.6 × 1019 Mx), and free energy decrease (2 × 1031 erg) compared to confined flares. In 90% of eruptive flares, the decay-index curve is steeper, reaching within 42 Mm, whereas it is beyond this value in >70% of confined flares. While indicating improved statistics in the predictive capability of AR eruptive behavior with flare-ribbon information, our study provides threshold magnetic properties for a flare to be eruptive.