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arXiv 1207.4352astro-ph.SRastro-ph.EP
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太阳内部磁结构的地震探测

Seismic probes of solar interior magnetic structure

Shravan Hanasoge, Aaron Birch, Laurent Gizon, Jeroen Tromp

摘要:

太阳黑子是太阳磁对流的突出表现,成像其地下结构是一个具有广泛物理意义的突出问题。传播通过这些结构的地震波的传播时间通常用作反演的输入。尽管存在强烈的各向异性磁波导,这些测量一直被解释为各向同性的波速和流动平流相关的多普勒频移的变化。在这里,我们采用偏微分方程约束优化,以确定适当的参数化的磁内部的结构特性。七个不同的波速度充分表征日震波传播:各向同性的声速,多普勒频移流平流速度和各向异性的磁速度。磁介质的结构通过磁声慢模式和快模式以及Alfvén波来感知,每种模式都以不同的波速传播。我们表明,即使在弱磁场的情况下,显着的错误可能会招致,如果这些各向异性不占反演。翻译不变性明显丧失。这些发展使得太阳磁对流的精确地震成像似乎是合理的。

英文摘要:

Sunspots are prominent manifestations of solar magnetoconvection and imaging their subsurface structure is an outstanding problem of wide physical importance. Travel times of seismic waves that propagate through these structures are typically used as inputs to inversions. Despite the presence of strongly anisotropic magnetic waveguides, these measurements have always been interpreted in terms of changes to isotropic wavespeeds and flow-advection related Doppler shifts. Here, we employ PDE-constrained optimization to determine the appropriate parameterization of the structural properties of the magnetic interior. Seven different wavespeeds fully characterize helioseismic wave propagation: the isotropic sound speed, a Doppler-shifting flow-advection velocity and an anisotropic magnetic velocity. The structure of magnetic media is sensed by magnetoacoustic slow and fast modes and Alfvén waves, each of which propagates at a different wavespeed. We show that even in the case of weak magnetic fields, significant errors may be incurred if these anisotropies are not accounted for in inversions. Translation invariance is demonstrably lost. These developments render plausible the accurate seismic imaging of magnetoconvection in the Sun.

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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