Multiwavelength study of 20 jets that emanate from the periphery of active regions
Multiwavelength study of 20 jets that emanate from the periphery of active regions
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DOI：
10.1051/0004-6361/201527473
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发表时间：
2016-01
影响因子：
6.5
通讯作者：
Sargam M. Mulay;D. Tripathi;G. Zanna;H. Mason
中科院分区：
文献类型：
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作者：
Sargam M. Mulay;D. Tripathi;G. Zanna;H. Mason
目标。我们提出了一个多波长分析的20 EUV射流发生在活动区的外围靠近太阳黑子。我们讨论了喷流的物理参数及其与H α涌、非热III型射电爆发和硬X射线（HXR）辐射等现象的关系。方法.这些喷流是在2010年8月至2013年6月期间由太阳动力观测站（SDO）上的大气成像组件（AIA）仪器观测到的。我们选择了在太阳盘面上+/-60°纬度范围内观测到的事件。利用对日冕温度敏感的AIA波长通道，利用视线差分辐射测量（DEM）技术研究了喷流中的温度分布。我们还研究了光球磁场的作用，使用LOS磁图数据从太阳地震和磁成像仪（HMI）机载SDO。结果据观察，大多数喷流起源于活动区的西部边缘。它们的寿命为5 ~ 39 min，平均为18 min，速度为87 ~ 532 km·s-1，平均为271 km·s-1。所有喷流都与H α涌同时相关。大多数喷流与Wind/WAVES航天器在20 kHz至13 MHz频率范围内观测到的第三类非热射电爆发同时。我们使用位场源表面（PFSS）技术确认这些爆发的源区。利用拉马迪高能太阳光谱成像仪（RHESSI）的观测，我们发现一半的喷流产生了HXR辐射，并且它们通常与HXR辐射（6 - 12 keV）共享同一个源区。20个事件中有10个事件表明，射流起源于通量抵消区域，6个射流起源于通量出现区域。四个事件表明通量出现，然后取消在射流的演变。DEM分析表明，对于大多数的螺旋射流，DEM峰值在log T [K] = 6.2/6.3（~2 MK）左右。此外，我们还导出了发射测度和电子密度的下限（射流1：log EM = 28.6，Ne = 1.3 × 10 10 cm-3;射流2：log EM = 28.6，Ne = 1.3 × 10 10 cm-3）logEM = 28.0，Ne = 8.6 × 109 cm-3）和足点（射流1 -logEM = 28.6，Ne = 1.1 × 1010 cm-3;射流2：logEM = 28.1，Ne = 8.4 × 109 cm-3）。这些结果与先前通过研究单个活动区射流所获得的结果一致。结论.通量抵消的观测，与HXR发射和非热III型射电爆发的发射的关联，表明启动，因此，加热发生在喷流的底部。这也得到了射流足点中DEM分析所揭示的高温等离子体的支持（DEM中log T [K] = 6.5处的峰值）。我们的研究结果提供了大量的约束条件的理论建模的射流和它们的热力学性质。
Aims. We present a multiwavelength analysis of 20 EUV jets which occurred at the periphery of active regions close to sunspots. We discuss the physical parameters of the jets and their relation with other phenomena such as H α surges, nonthermal type-III radio bursts and hard X-ray (HXR) emission. Methods. These jets were observed between August 2010 and June 2013 by the Atmospheric Imaging Assembly (AIA) instrument that is onboard the Solar Dynamic Observatory (SDO). We selected events that were observed on the solar disk within +/–60° latitude. Using AIA wavelength channels that are sensitive to coronal temperatures, we studied the temperature distribution in the jets using the line of sight (LOS) differential emission measure (DEM) technique. We also investigated the role of the photospheric magnetic field using the LOS magnetogram data from the Helioseismic and Magnetic Imager (HMI) onboard SDO. Results. It has been observed that most of the jets originated from the western periphery of active regions. Their lifetimes range from 5 to 39 min with an average of 18 min and their velocities range from 87 to 532 km s -1 with an average of 271 km s -1 . All the jets are co-temporally associated with H α surges. Most of the jets are co-temporal with nonthermal type-III radio bursts observed by the Wind/WAVES spacecraft in the frequency range from 20 kHz to 13 MHz. We confirm the source region of these bursts using the potential field source surface (PFSS) technique. Using Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations, we found that half of the jets produced HXR emission and they often shared the same source region as the HXR emission (6−12 keV). Ten out of 20 events showed that the jets originated in a region of flux cancellation and six jets in a region of flux emergence. Four events showed flux emergence and then cancellation during the jet evolution. DEM analyses showed that for most of the spires of the jets, the DEM peaked at around log T [K] = 6.2/6.3 (~2 MK). In addition, we derived an emission measure and a lower limit of electron density at the location of the spire (jet 1: log EM = 28.6, N e = 1.3 × 10 10 cm -3 ; jet 2: log EM = 28.0, N e = 8.6 × 10 9 cm -3 ) and the footpoint (jet 1 – log EM = 28.6, N e = 1.1 × 10 10 cm -3 ; jet 2: log EM = 28.1, N e = 8.4 × 10 9 cm -3 ). These results are in agreement with those obtained earlier by studying individual active region jets. Conclusions. The observation of flux cancellation, the association with HXR emission and emission of nonthermal type-III radio bursts, suggest that the initiation and therefore, heating is taking place at the base of the jet. This is also supported by the high temperature plasma revealed by the DEM analysis in the jet footpoint (peak in the DEM at log T [K] = 6.5). Our results provide substantial constraints for theoretical modeling of the jets and their thermodynamic nature.