用于计算日震学的太阳结构模型的构建和表征
Constructing and Characterising Solar Structure Models for Computational Helioseismology
摘要：
在本文中，我们通过修改模型S（Christensen-Dalsgaard等人，1996，Science，272，1286）放弃流体静力平衡。然而，稳定化会影响我们希望尽可能接近模型S的本征模。为了恢复Model S的本征模，我们选择在稳定之前对Model S的声速进行额外的修正。没有稳定的模型可以完美的太阳一样，所以我们提出了三个稳定的模型略有不同的本征模式。该模型适用于研究球谐度在400 ~ 900范围内的f模和p1 ~ p4模。背景模型CSM具有用于稳定的修改的压力梯度，并且具有在模型S的2%内的本征频率。模型CSM_A在顶部1 Mm处的声速增加了10%，导致本征频率在模型S的2%以内，并且本征函数与CSM相比最接近于模型S的本征函数。模型CSM_B在顶部5 Mm处的声速降低3%，导致本征频率在模型S的1%内，本征函数仅受到轻微的不利影响。这些模型是有用的，以研究太阳波与嵌入的三维非均匀性，如对流和模型太阳黑子的相互作用。我们还计算了响应的稳定模型随机近地表源的激励，使用模拟的线性波的传播。我们发现模拟的波动功率谱与观测到的SOHO/MDI功率谱吻合得很好。总的来说，我们的对流稳定的背景模型提供了一个很好的基础，定量数值当地日震学。这些模型可从http://www.mps.mpg.de/projects/seismo/NA4/下载。
英文摘要：
In this paper, we construct background solar models that are stable against convection, by modifying the vertical pressure gradient of Model S (Christensen-Dalsgaard et al., 1996, Science, 272, 1286) relinquishing hydrostatic equilibrium. However, the stabilisation affects the eigenmodes that we wish to remain as close to Model S as possible. In a bid to recover the Model S eigenmodes, we choose to make additional corrections to the sound speed of Model S before stabilisation. No stabilised model can be perfectly solar-like, so we present three stabilised models with slightly different eigenmodes. The models are appropriate to study the f and p1 to p4 modes with spherical harmonic degrees in the range from 400 to 900. Background model CSM has a modified pressure gradient for stabilisation and has eigenfrequencies within 2% of Model S. Model CSM_A has an additional 10% increase in sound speed in the top 1 Mm resulting in eigenfrequencies within 2% of Model S and eigenfunctions that are, in comparison with CSM, closest to those of Model S. Model CSM_B has a 3% decrease in sound speed in the top 5 Mm resulting in eigenfrequencies within 1% of Model S and eigenfunctions that are only marginally adversely affected. These models are useful to study the interaction of solar waves with embedded three-dimensional heterogeneities, such as convective flows and model sunspots. We have also calculated the response of the stabilised models to excitation by random near-surface sources, using simulations of the propagation of linear waves. We find that the simulated power spectra of wave motion are in good agreement with an observed SOHO/MDI power spectrum. Overall, our convectively stabilised background models provide a good basis for quantitative numerical local helioseismology. The models are available for download from http://www.mps.mpg.de/projects/seismo/NA4/.
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