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Properties of High-Frequency Type II Radio Bursts and Their Relation to the Associated Coronal Mass Ejections
Solar Physics ( IF 2.7 ) Pub Date : 2021-01-29 , DOI: 10.1007/s11207-020-01743-8
A. C. Umuhire , N. Gopalswamy , J. Uwamahoro , S. Akiyama , S. Yashiro , P. Mäkelä

Solar radio bursts are often early indicators of space weather events such as coronal mass ejections (CMEs). In this study, we determined the properties of a sample of 40 high-starting-frequency (≥ 150 MHz) type II radio bursts and the characteristics of the associated CMEs such as width, location and speed during 2010–2016. The high starting frequency implies shock formation closer to the solar surface, which has important ramifications for the analysis of particle acceleration near the Sun. We found the CME heliocentric distances at the onset time of metric type II bursts range from 1.16 to 1.90 solar radii (Rs). The study was also extended to 128 metric type II bursts to include lower-starting-frequency events for further analysis. The projected CME heights range from 1.15 to 2.85 Rs. The lower starting frequency correspond to shocks forming at larger heights. A weak correlation was found between the type-II starting frequency and CME heights, which is consistent with the density decline in the inner corona. The analysis confirmed a good correlation between the drift rate and the starting frequency of type II bursts (correlation coefficient ∼ 0.8). Taking into account the radial variation of CMEs speeds from the inner corona to the interplanetary medium, we observed the deviations from the universal drift-rate spectrum of type II bursts and confirmed the previous results relating type II bursts to CMEs.



中文翻译:

高频II型无线电爆发的特性及其与相关冠状物质抛射的关系

太阳无线电爆发通常是诸如冠状物质抛射(CME)等太空天气事件的早期指标。在这项研究中,我们确定了2010-2016年间40个高起始频率(≥150 MHz)的II型无线电突发的样本的属性以及相关CME的特征,例如宽度,位置和速度。高起始频率意味着更靠近太阳表面的冲击形成,这对于分析太阳附近的粒子加速度具有重要的影响。我们发现,公制II型爆发爆发时CME的日心距为1.16至1.90太阳半径(Rs)。该研究还扩展到128个II型公制突发,以包括较低的启动频率事件以进行进一步分析。预计的CME高度范围为1.15至2.85 Rs。较低的启动频率对应于在较大高度处形成的冲击。在II型起始频率和CME高度之间发现了弱的相关性,这与内部电晕的密度下降相一致。分析证实,漂移率与II型猝发的起始频率之间具有良好的相关性(相关系数约为0.8)。考虑到CME的速度从内部电晕到行星际介质的径向变化,我们观察到与II型爆发的普遍漂移率谱之间的偏差,并确认了将II型爆发与CME相关的先前结果。分析证实,漂移率与II型猝发的起始频率之间具有良好的相关性(相关系数约为0.8)。考虑到CME的速度从内部电晕到行星际介质的径向变化,我们观察到与II型爆发的普遍漂移率谱之间的偏差,并确认了将II型爆发与CME相关的先前结果。分析证实,漂移率与II型猝发的起始频率之间具有良好的相关性(相关系数约为0.8)。考虑到CME的速度从内部电晕到行星际介质的径向变化,我们观察到与II型爆发的普遍漂移率谱之间的偏差,并确认了将II型爆发与CME相关的先前结果。

更新日期:2021-01-29
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