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arXiv 1108.4148astro-ph.SR
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脉冲驱动冷极喷流的SDO/AIA观测

Observations of a pulse driven cool polar jet by SDO/AIA

Abhishek K. Srivastava, Kris Murawski

摘要:

上下文2010年8月3日,我们使用SDO AIA 304 °A图像数据在北极冕洞(NPCH)观测到太阳喷流。喷流在太阳边缘上方倾斜上升,然后沿其传播路径回落。目标。我们通过实施一个现实的(VAL-C)太阳温度模型,数值模拟观察到的太阳射流。方法.我们数值求解二维理想磁流体动力学方程组来模拟观测到的太阳喷流。我们考虑一个本地化的速度脉冲,基本上是平行的背景磁场线,最初发射在顶部的太阳光球。脉冲在更高的高度变陡成冲击,这触发了等离子体扰动,表现出所观察到的喷流特征。脉冲的典型方向也清楚地显示了运动射流的前沿。结果我们的数值模拟表明,在太阳光球顶部发射的大振幅初始速度脉冲通常会产生所观察到的喷流特性,例如,向上和向后的平均速度、高度、宽度、寿命和弹道性质。结论.喷流观测和数值模拟之间的密切匹配提供了第一个强有力的证据,这种喷流的形成由一个单一的速度脉冲。这种强速度脉冲很可能是由极区低层大气重联触发喷流而产生的。喷流的向下流动的物质很可能在下一个即将到来的速度脉冲从低太阳大气中消失,因此,明显地发射一个单一的喷流向上在太阳大气中观察到。

英文摘要:

Context. We observe a solar jet at north polar coronal hole (NPCH) using SDO AIA 304 °A image data on 3 August 2010. The jet rises obliquely above the solar limb and then retraces its propagation path to fall back. Aims. We numerically model this observed solar jet by implementing a realistic (VAL-C) model of solar temperature. Methods. We solve two-dimensional ideal magnetohydrodynamic equations numerically to simulate the observed solar jet. We consider a localized velocity pulse that is essentially parallel to the background magnetic field lines and initially launched at the top of the solar photosphere. The pulse steepens into a shock at higher altitudes, which triggers plasma perturbations that exhibit the observed features of the jet. The typical direction of the pulse also clearly exhibits the leading front of the moving jet. Results. Our numerical simulations reveal that a large amplitude initial velocity pulse launched at the top of the solar photosphere produces in general the observed properties of the jet, e.g., upward and backward average velocities, height, width, life-time, and ballistic nature. Conclusions. The close matching between the jet observations and numerical simulations provides first strong evidence for the formation of this jet by a single velocity pulse. The strong velocity pulse is most likely generated by the low- atmospheric reconnection in the polar region which results in triggering of the jet. The downflowing material of the jet most likely vanishes in the next upcoming velocity pulses from lower solar atmosphere, and therefore distinctly launched a single jet upward in the solar atmosphere is observed.

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