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arXiv 1104.4334astro-ph.SR
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大尺度日冕亮锋的减速和色散

Deceleration and Dispersion of Large-scale Coronal Bright Fronts

David M. Long, Peter T. Gallagher, R. T. James McAteer, D. Shaun Bloomfield

摘要:

太阳活动最引人注目的表现之一是在太阳大气的极紫外(EUV)图像中观察到的大规模日冕亮锋(CBF)。到目前为止,CBF的能量学和运动学仍然知之甚少,这是由于以前的EUV成像仪的低图像节奏和灵敏度以及用于提取特征的有限方法。在本文中,CBFs的轨迹和形态的确定,以调查CBFs的样品的变化特性,包括它们的运动学和脉冲形状,色散和耗散。我们已经开发了一种半自动强度分析技术,从STEREO/EUVI中提取2.5-10分钟节奏图像中CBFs的形态和准确位置。该技术被应用到序列的171 A和195 A的图像从STEREO/EUVI为了测量四个单独的CBF事件的波特性。在以~240- 450 km ^{-1}的速度发射后,所研究的四个事件中的每一个都显示出显著的负加速度,范围从~ -290到-60 ms ^{-2}。CBF的空间和时间宽度分别从~50 μ m增加到~200 μ m和~100 s增加到~1500 s,表明它们在本质上是分散的。位置-角度平均脉冲积分强度随传播的变化在所研究的四个事件中没有显示出明显的趋势。这些结果与CBF是色散磁声波最一致。

英文摘要:

One of the most dramatic manifestations of solar activity are large-scale coronal bright fronts (CBFs) observed in extreme ultraviolet (EUV) images of the solar atmosphere. To date, the energetics and kinematics of CBFs remain poorly understood, due to the low image cadence and sensitivity of previous EUV imagers and the limited methods used to extract the features. In this paper, the trajectory and morphology of CBFs was determined in order to investigate the varying properties of a sample of CBFs, including their kinematics and pulse shape, dispersion, and dissipation. We have developed a semi-automatic intensity profiling technique to extract the morphology and accurate positions of CBFs in 2.5-10 min cadence images from STEREO/EUVI. The technique was applied to sequences of 171A and 195A images from STEREO/EUVI in order to measure the wave properties of four separate CBF events. Following launch at velocities of ~240-450kms^{-1} each of the four events studied showed significant negative acceleration ranging from ~ -290 to -60ms^{-2}. The CBF spatial and temporal widths were found to increase from ~50 Mm to ~200 Mm and ~100 s to ~1500 s respectively, suggesting that they are dispersive in nature. The variation in position-angle averaged pulse-integrated intensity with propagation shows no clear trend across the four events studied. These results are most consistent with CBFs being dispersive magnetoacoustic waves.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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