Magnetic helicity and eruptivity in active region 12673
Magnetic helicity and eruptivity in active region 12673
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DOI：
10.1051/0004-6361/201935870
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发表时间：
2019-07
影响因子：
6.5
通讯作者：
K. Moraitis;X. Sun;E. Pariat;L. Linan
中科院分区：
文献类型：
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作者：
K. Moraitis;X. Sun;E. Pariat;L. Linan
上下文2017年9月，第24个太阳活动周期最大的X级耀斑发生在该周期最活跃的区域AR 12673。由于其独特的形态学和进化特征，引起了人们的广泛关注。在AR中检查的参数是磁螺旋度，但要么只是近似的，或间歇的，或两者兼而有之。目标。我们在这里研究的相对磁螺旋度和它的分解，非潜在的两个组成部分的演变，和体积线程的一个，在时间间隔周围的AR 12673的最高活动。我们特别关注的非潜在的总螺旋度，这是最近提出的AR喷发的指标的比率。方法.我们首先用两种不同的基于优化的外推程序来近似AR的日冕磁场，并选择在每个时刻产生最可靠的螺旋度值的方法。此外，在这些方法之一中，我们加权优化的不确定性估计来自日震和磁成像仪（HMI）仪器的第一次。然后，我们遵循一种精确的方法来计算所有感兴趣的量。结果第一次观测确定的非潜在的总螺旋度比的演变似乎证实了质量，它在指示喷发。这个比率在AR 12673的主要耀斑之前增加，之后放松到较低的值。此外，我们还讨论了AR 12673的各种螺旋度和能量收支的演化模式，并与其他工作的结果进行了比较。
Context. In September 2017, the largest X-class flare of solar cycle 24 occurred from the most active region (AR) of this cycle, AR 12673. This AR attracted much interest because of its unique morphological and evolution characteristics. Among the parameters that were examined in the AR was magnetic helicity, but either only approximately, or intermittently, or both. Aims. We here study the evolution of the relative magnetic helicity and of the two components of its decomposition, the non-potential, and the volume-threading one, in the time interval around the highest activity of AR 12673. We especially focus on the ratio of the non-potential to total helicity, which has recently been proposed as an indicator of AR eruptivity. Methods. We first approximated the coronal magnetic field of the AR with two different optimization-based extrapolation procedures, and chose the method that produced the most reliable helicity value at each instant. Moreover, in one of these methods, we weighted the optimization by the uncertainty estimates derived from the Helioseismic and Magnetic Imager (HMI) instrument for the first time. We then followed an accurate method to compute all quantities of interest. Results. The first observational determination of the evolution of the non-potential to total helicity ratio seems to confirm the quality it has in indicating eruptivity. This ratio increased before the major flares of AR 12673 and afterwards relaxed to lower values. Additionally, we discuss the evolution patterns of the various helicity and energy budgets of AR 12673 and compare them with results from other works.