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arXiv 1111.5464astro-ph.SR
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I型针状振荡的起源

The Origin of Type I Spicule Oscillations

D. B. Jess, D. J. Pascoe, D. J. Christian, M. Mathioudakis, P. H. Keys, F. P. Keenan

摘要:

我们使用高空间和时间分辨率的图像,获得与快速振荡在太阳大气仪器在邓恩太阳望远镜,揭示如何生成横波在I型针状体是一个直接的结果,发生在光球的纵向振荡。在这里,我们展示了如何压力振荡,周期在130 - 440秒的范围内,表现在小规模的光球磁亮点,并产生扭结波在太阳的外层大气中的横向速度接近当地的声速。通过比较我们的观察与先进的二维磁流体动力学模拟,我们提供的证据磁声振荡,在太阳表面产生的,漏斗向上沿I型针状结构,在经历的横向到横向模式转换成波在初始驱动频率的两倍。由此产生的扭结模在色球等离子体中可见,周期为65 - 220 s,振幅通常超过400 km。香肠模式振荡也出现作为光球驱动程序的结果,这是可见的模拟和观测的时间序列。我们的结论是,模式转换和周期修改是一个直接的后果,90度相移涵盖光球驱动器的相对两侧。这些波的色球能量通量估计约为300,000 W/m^2,这表明它们有足够的能量来加速太阳风,并将局部日冕加热到数百万度的温度。

英文摘要:

We use images of high spatial and temporal resolution, obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope, to reveal how the generation of transverse waves in Type I spicules is a direct result of longitudinal oscillations occurring in the photosphere. Here we show how pressure oscillations, with periodicities in the range 130 - 440 s, manifest in small-scale photospheric magnetic bright points, and generate kink waves in the Sun's outer atmosphere with transverse velocities approaching the local sound speed. Through comparison of our observations with advanced two-dimensional magneto-hydrodynamic simulations, we provide evidence for how magnetoacoustic oscillations, generated at the solar surface, funnel upwards along Type I spicule structures, before undergoing longitudinal-to-transverse mode conversion into waves at twice the initial driving frequency. The resulting kink modes are visible in chromospheric plasma, with periodicities of 65 -220 s, and amplitudes often exceeding 400 km. A sausage mode oscillation also arises as a consequence of the photospheric driver, which is visible in both simulated and observational time series. We conclude that the mode conversion and period modification is a direct consequence of the 90 degree phase shift encompassing opposite sides of the photospheric driver. The chromospheric energy flux of these waves are estimated to be approximately 300,000 W/m^2, which indicates that they are sufficiently energetic to accelerate the solar wind and heat the localized corona to its multi-million degree temperatures.

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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