arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2202.07957astro-ph.SR
收藏

日珥纵向振荡摆模型的推广和验证

Extension and validation of the pendulum model for longitudinal solar prominence oscillations

M. Luna, J. Terradas, J. Karpen, J. L. Ballester

摘要:

双折射的纵向振荡是太阳上常见的现象。这些振荡可用于推断灯丝磁场的几何形状和强度。以前的纵向振荡理论研究做了两个简化的假设:均匀重力和半圆形倾角的支持通量管。然而,重力是不均匀的,并且现实的倾角不是半圆形的。了解考虑太阳引力不均匀性对纵振荡的影响,并探讨不同通量管几何形状的单摆模型的有效性。我们首先推导出方程描述的等离子体沿通量管的运动,包括不均匀重力的影响,产生校正原来的钟摆模型。我们还计算了正常模式的完整的数值解,并将它们与新的钟摆近似进行比较。我们已经发现,非均匀重力引入了一个显着的修改中的钟摆模型。我们还发现了一个截止周期,即纵向振荡的周期不能超过167分钟。此外,考虑到不同的管的几何形状,周期几乎完全取决于曲率半径在底部的下降。我们的结论是,非均匀重力显着修改钟摆模型。这些修正对于日珥地震学是很重要的,因为曲率半径和最小磁场强度的推断值与旧模型有很大的不同。然而,我们发现,修正后的钟摆模型是相当强大的,仍然是有效的非圆形倾角。

英文摘要:

Longitudinal oscillations in prominences are common phenomena on the Sun. These oscillations can be used to infer the geometry and intensity of the filament magnetic field. Previous theoretical studies of longitudinal oscillations made two simplifying assumptions: uniform gravity and semi-circular dips on the supporting flux tubes. However, the gravity is not uniform and realistic dips are not semi-circular. To understand the effects of including the nonuniform solar gravity on longitudinal oscillations, and explore the validity of the pendulum model with different flux-tube geometries. We first derive the equation describing the motion of the plasma along the flux tube including the effects of nonuniform gravity, yielding corrections to the original pendulum model. We also compute the full numerical solutions for the normal modes, and compare them with the new pendulum approximation. We have found that the nonuniform gravity introduces a significant modification in the pendulum model. We have also found a cut-off period, i.e. the longitudinal oscillations cannot have a period longer than 167 minutes. In addition, considering different tube geometries, the period depends almost exclusively on the radius of curvature at the bottom of the dip. We conclude that nonuniform gravity significantly modifies the pendulum model. These corrections are important for prominence seismology, because the inferred values of the radius of curvature and minimum magnetic-field strength differ substantially from those of the old model. However, we find that the corrected pendulum model is quite robust and is still valid for non-circular dips.

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。

↑