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首页> 外文期刊>Solar Physics >Transverse oscillations in coronal loops observed with TRACE – I. An Overview of Events, Movies, and a Discussion of Common Properties and Required Conditions
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Transverse oscillations in coronal loops observed with TRACE – I. An Overview of Events, Movies, and a Discussion of Common Properties and Required Conditions

机译：用TRACE观测到的冕环中的横向振荡-I.事件，电影概述以及共同特性和所需条件的讨论

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We study transverse loop oscillations triggered by 17flares and filament destabilizations; only 2 such cases have been reported in the literature until now. Oscillation periods are estimated to range over a factor of ∼15, with most values between 2 and 7 min. The oscillations are excited by filament destabilizations or flares (in 6% of the 255 flares inspected, ranging from about C3 to X2). There is no clear dependence of oscillation amplitude on flare magnitude. Oscillations occur in loops that close within an active region, or in loops that connect an active region to a neighboring region or to a patch of strong flux in the quiet Sun. Some magnetic configurations are particularly prone to exhibit oscillations: two active regions showed two, and one region even three, distinct intervals with loop oscillations. The loop oscillations are not a resonance that builds up: oscillations in loops that are excited along their entire length are likely to be near the fundamental resonance mode because of that excitation profile, but asymmetrically excited oscillations clearly show propagating waves that are damped too quickly to build up a resonance, and some cases show multiple frequencies. We discuss evidence that all oscillating loops lie near magnetic separatrices that outline the large-scale topology of the field. All magnetic configurations are more complicated than a simple bipolar region, involving mixed-polarities in the interior or vicinity of the region; this may reflect that the exciting eruptions occur only in such environments, but this polarity mixing likely also introduces the large-scale separatrices that are involved. Often the oscillations occur in conjunction with gradual adjustments in loop positions in response to the triggering event. We discuss the observations in the context of two models: (a) transverse waves in coronal loops that act as wave guides and (b) strong sensitivity to changes in the field sources for field lines near separatrices. Properties that favor model b are (1) the involvement of loops at or near separatrices that outline the large-scale topology of the field, (2) the combined occurrence of oscillations and loop translations, (3) the small period spread and similar decay time scale in a set of oscillating loops in one well-observed event, and (4) the existence of loops oscillating in antiphase with footpoints close together in two cases. All other properties are compatible with either model, except the fact that almost all of the oscillations start away from the triggering event, suggestive of an outward-pushing exciting wave more in line with model a. The spread in periods from event to event suggests that the oscillations may reflect the properties of some driver mechanism that is related to the flare or mass ejection.
机译：我们研究了由17喇叭口和细丝失稳引发的横向环路振荡；迄今为止，文献中仅报道了2起此类病例。估计振荡周期的范围约为15倍，大多数值在2至7分钟之间。灯丝失稳或耀斑（在检查的255个耀斑中，有6％，范围从C3到X2）激发了振荡。振荡幅度对耀斑幅度没有明确的依赖性。振荡发生在活动区域​​内闭合的环路中，或者发生在将活动区域连接到邻近区域或安静的太阳中的强通量斑块的环路中。一些磁性结构特别容易表现出振荡：两个有源区域显示两个，一个区域甚至三个，具有明显不同的间隔，并出现环路振荡。回路振荡不是累积的共振：由于该激励曲线，沿整个长度激发的回路振荡很可能接近基本共振模式，但是不对称激发的振荡清楚地表明传播波被衰减得太快而不能会产生共振，某些情况下会显示多个频率。我们讨论的证据是，所有振荡环都位于磁分离线附近，这些磁分离线概述了磁场的大规模拓扑。所有的磁性结构都比简单的双极区域复杂，涉及区域内部或附近的混合极性。这可能反映出令人兴奋的喷发仅发生在这样的环境中，但是这种极性混合也可能引入了所涉及的大规模分离。通常，响应于触发事件，振荡与回路位置的逐渐调节有关。我们在两个模型的背景下讨论了这些观测结果：（a）日冕环中的横向波充当波导，（b）对分离线附近的场线对场源变化的强烈敏感性。支持模型b的属性是（1）涉及分离场或接近分离场的环路，这些环路概述了磁场的大规模拓扑结构;（2）振荡和环路平移的组合发生;（3）小周期扩展和相似的衰减一个观察到的事件中一组振荡循环的时间尺度，以及（4）在两种情况下，存在倒相振荡且脚点靠近的循环。除了几乎所有的振荡都从触发事件开始，这暗示着向外推动的激波更符合模型a的事实之外，所有其他属性均与任一模型都兼容。从事件到事件的时间间隔的扩展表明，振荡可能反映了某些与爆发或质量抛射有关的驱动器机制的属性。

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  • 来源
    《Solar Physics》 |2002年第1期|69-98|共30页
  • 作者

    Carolus J. Schrijver; Markus J. Aschwanden; Alan M. Title;

  • 作者单位

    Department L9–41 Lockheed Martin Advanced Technology Center;

    Department L9–41 Lockheed Martin Advanced Technology Center;

    Department L9–41 Lockheed Martin Advanced Technology Center;

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