The OSCROX stellar oscillaton code
The OSCROX stellar oscillaton code
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OSCROX 恒星振荡代码
DOI：
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发表时间：
2008
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影响因子：
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通讯作者：
I. Roxburgh
中科院分区：
文献类型：
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作者：
I. Roxburgh
摘要
本文介绍了用于计算球形星星低次绝热振荡的OSCROX程序。有两个主要版本：一个是拉格朗日变量（oscroxL），第二个是欧拉变量（oscroxE）。拉格朗日代码不需要Brunt Väisälä频率或等效密度梯度的值。当λ =1时，振动方程有精确积分和精确分波解，代码oscroxL 1和oscroxE 1包含了这些精确解。不同的代码得到的频率的差异给出了一些估计的结果中的不确定性，由于有限的精度流体静力学支持的恒星模型，和有限的精度的振荡方程的集成。
我们通过计算一个1.5 M主序星星星模型（ModelJC）在20-2500 μHz范围内的频率，比较了不同方法的结果。ModelJC是J. Christensen-Dalsgaard为了代码的交叉比较而提供的，是该模型的一个修改版本（ModelJCA）的改进的流体静力学支持，和一个高精度的n=3多变模型的星星具有相同的质量和半径。对于多变模型，所有代码计算的频率都在0.001 μHz之内，而对于1.5 M的主层序模型，主要由于模型中流体静力学支持的有限精度，频率差达到最大值0.04 μHz;对于JCA模型，频率差降低到0.01 μHz。
Abstract
This paper describes the OSCROX stellar oscillation code for the calculation of the adiabatic oscillations of low degree ℓ of a spherical star. There are two principal versions: one in Lagrangian variables (oscroxL), the second in Eulerian variables (oscroxE). The Lagrangian code does not require values of the Brunt Väisälä frequency or equivalently the density gradient. For ℓ=1 the oscillation equations have both an exact integral and an exact partial wave solution, and codes oscroxL1 and oscroxE1 incorporate these exact solutions. The difference in the frequencies obtained with the various codes gives some estimate of the uncertainty in the results due both to limited accuracy of hydrostatic support of the stellar model, and the limited accuracy of the integration of the oscillation equations.
We compare the results of the different methods by calculating the frequencies in the range 20–2500 μHz of a model of a 1.5 M⊙ main-sequence star (ModelJC) kindly provided by J. Christensen-Dalsgaard for the purposes of cross comparison of codes, a modified version of this model (ModelJCA) with improved hydrostatic support, and of a highly accurate n=3 polytropic model of a star with the same mass and radius. For the polytropic model the frequencies as calculated by all codes agree to within 0.001 μHz, whereas for the 1.5 M⊙ main sequence model the frequency differences reach a maximum of 0.04 μHz, due primarily to the limited accuracy of hydrostatic support in the model; this is reduced to 0.01 μHz for ModelJCA.