IMPULSIVELY GENERATED SAUSAGE WAVES IN CORONAL TUBES WITH TRANSVERSALLY CONTINUOUS STRUCTURING
IMPULSIVELY GENERATED SAUSAGE WAVES IN CORONAL TUBES WITH TRANSVERSALLY CONTINUOUS STRUCTURING
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具有横向连续结构的冠状管中脉冲产生的香肠波
DOI：
10.3847/1538-4357/833/1/51
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发表时间：
2016-10
影响因子：
4.9
通讯作者：
Guo Ming-Zhe
中科院分区：
文献类型：
--
作者：
Yu Hui;Li Bo;Chen Shao-Xia;Xiong Ming;Guo Ming-Zhe
被捕获的香肠波的纵向群速度的频率依赖性在确定脉冲产生的波列中起着重要作用，这些波列经常被用来解释日冕环中的准周期信号。通过求解在任意厚度过渡层中出现任意形状密度不均匀的情况下的色散关系，我们研究了无压日冕管中香肠模式的角频率(ω)与群速度()的关系。我们发现，群速度行为除了取决于横向长度尺度L和密度对比度外，还取决于密度不均匀的具体形式。对于抛物线轮廓，总是先随着ω减小，然后再增加，就像研究得很多的顶帽轮廓一样。但是，对于线性纵断面，曲线的行为更为复杂。当L的值较大时，曲线变得单调。另一方面，对于较高的密度对比度，当冕管扩散时，除了存在局部极小值外，还存在局部极大值。通过与时间相关的计算，我们发现群速度曲线的不同行为，特别是特征速度，反映在脉冲产生的波列的时间演化和Morlet谱中。我们的结论是，观测到的准周期波列不仅可以用来探测密度对比度和轮廓陡度等关键参数，而且还有可能区分横向密度分布的未知形式。
The frequency dependence of the longitudinal group speeds of trapped sausage waves plays an important role in determining impulsively generated wave trains, which have often been invoked to account for quasi-periodic signals in coronal loops. We examine how the group speeds ( ) depend on angular frequency (ω) for sausage modes in pressureless coronal tubes with continuous transverse density distributions by solving the dispersion relation pertinent to the case where the density inhomogeneity of arbitrary form occurs in a transition layer of arbitrary thickness. We find that in addition to the transverse lengthscale l and density contrast , the group speed behavior also depends on the detailed form of the density inhomogeneity. For parabolic profiles, always decreases with ω first before increasing again, as happens for the much studied top-hat profiles. For linear profiles, however, the behavior of the curves is more complex. When , the curves become monotonical for large values of l. On the other hand, for higher density contrasts, a local maximum exists in addition to a local minimum when coronal tubes are diffuse. With time-dependent computations, we show that the different behavior of group speed curves, the characteristic speeds and in particular, is reflected in the temporal evolution and Morlet spectra of impulsively generated wave trains. We conclude that the observed quasi-periodic wave trains not only can be employed to probe such key parameters as density contrasts and profile steepness, but also have the potential to discriminate between the unknown forms of the transverse density distribution.
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多波长准周期、快速传播的磁声波及其与其他磁结构相互作用的观测
影响因子：
2.8
作者：
Shen, Y. -D.;Liu, Y.;Su, J. -T.;Li, H.;Zhang, X. -F.;Tian, Z. -J.;Zhao, R. -J.;Elmhamdi, A.
通讯作者：
Elmhamdi, A.
DOI：
10.1088/0004-637x/781/2/111
发表时间：
2013-12
期刊：
The Astrophysical Journal
影响因子：
--
作者：
R. Soler;M. Goossens;J. Terradas;R. Oliver
通讯作者：
R. Soler;M. Goossens;J. Terradas;R. Oliver
影响因子：
20.9
作者：
V. Nakariakov;E. Verwichte
通讯作者：
V. Nakariakov;E. Verwichte
日冕等离子体喷射激发的快模磁声波的数值模拟
影响因子：
4.9
作者：
Yang Liping;Zhang Lei;He Jiansen;Peter Hardi;Tu Chuanyi;Wang Linghua;Zhang Shaohua;Feng Xueshang
通讯作者：
Feng Xueshang
影响因子：
2.8
作者：
V. Nakariakov;B. Roberts
通讯作者：
V. Nakariakov;B. Roberts