Distortion of high-degree solar p-mode eigenfunctions by latitudinal differential rotation
Distortion of high-degree solar p-mode eigenfunctions by latitudinal differential rotation
复制标题
纬度差分旋转对高阶太阳 p 模式本征函数的畸变
DOI：
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发表时间：
1989
期刊：
影响因子：
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通讯作者：
M. Woodard
中科院分区：
文献类型：
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作者：
M. Woodard
太阳非径向振荡的本征函数由于太阳自转而偏离了它们通常假定的球谐形式。本文讨论了在太阳赤道面上也是镜像对称的慢轴对称微分自转对振荡本征函数的影响。一个给定的振荡本征函数，受旋转扰动，可以表示为一个（假设的）太阳非旋转状态的本征函数的叠加。轴对称的假设意味着每个叠加函数具有相同的方位角阶m，而镜像对称则规定叠加中涉及的球谐度l的值要么全是奇数，要么全是偶数。这里的处理是进一步专门的情况下，高度的p-和f-模式的振荡，其影响的科里奥利加速度是小的。结果表明，通过忽略科里奥利效应和其他合理的近似，可以得到一个解析表达式的旋转扭曲模式本征函数，这是一个很好的近似为典型的太阳振荡度l大于100。讨论了计算得到的模式畸变对太阳自转测量的影响。参考文献5。
The eigenfunctions of nonradial oscillation of the sun depart from their customarily assumed spherical harmonic form as a result of solar rotation. This paper treats the effect on oscillation eigenfunctions of slow, axisymmetric differential rotation which is also mirror symmetric across the solar equatorial plane. A given oscillation eigenfunction, perturbed by rotation, can be expressed as a superposition of eigenfunctions of a (hypothetical) nonrotating state of the sun. The assumption of axialsymmetry implies that each of the superposed functions has the same azimuthal order, m, while mirror symmetry dictates that the values of l, the spherical harmonic degree, involved in the superposition be either all odd or all even. The treatment here is further specialized to the case of high-degree p- and f-mode oscillations, on which the effect of the Coriolis acceleration is small. It is shown that, by ignoring the Coriolis effect and making other sensible approximations, an analytic expression can be obtained for the rotationally distorted mode eigenfunctions, which is expected to be a good approximation for typical solar oscillations of degree l greater than 100. The effect of the calculated mode distortion on the measurement of solar rotation is explored. 5 refs.