The CoRoT space mission : early results Special feature Pulsation modes in rapidly rotating stellar models based on the self-consistent field method
The CoRoT space mission : early results Special feature Pulsation modes in rapidly rotating stellar models based on the self-consistent field method
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CoRoT 太空任务：早期结果 特点 基于自洽场方法的快速旋转恒星模型中的脉动模式
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
T. S. Metcalfe
中科院分区：
文献类型：
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作者：
D. R. Reese;K. Macgregor;S. Jackson;A. Skumanich;T. S. Metcalfe
语境。 CoRoT 和开普勒太空任务等新的观测手段以及地面网络正在并将以前所未有的精度收集恒星脉动数据。观察到脉动的恒星中有很大一部分正在快速旋转。目标。我们的目标是表征快速旋转恒星模型中的脉动模式，以便能够解释来自此类恒星的星震数据。方法。一种新的脉动代码被应用于基于自洽场（SCF）方法的恒星模型。结果。 SCF 模型中的脉动模式遵循与均匀旋转多方模型中类似的行为，前提是旋转轮廓差异不太大。脉动模态分为不同的类别，三种主要模态是岛模态、混沌模态和回音壁模态，它们是低、中、高模态的旋转对应物 - |m|值，分别。岛模式的频率遵循渐近模式，与多方模型中发现的非常相似。将这个渐近公式扩展到更高的方位角阶数，揭示了作为 m 函数的更微妙的行为，并提供了通过旋转产生的脉动模式的平均平流的第一个估计。基于变分原理的进一步计算证实了这一估计，并提供了可用于反演方法的旋转核。当旋转剖面变得高度差异时，在低方位角阶数下找到岛模式和回音壁模式变得越来越困难。在高方位角阶下，回音壁模态以及在某些情况下的岛模态会重新出现。结论。当旋转轮廓不太差异时，为岛模式频率找到的渐近公式可以作为快速旋转恒星模式识别方案的基础。
Context. New observational means such as the space missions CoRoT and Kepler and ground-based networks are and will be collecting stellar pulsation data with unprecedented accuracy. A significant fraction of the stars in which pulsations are observed are rotating rapidly. Aims. Our aim is to characterise pulsation modes in rapidly rotating stellar models so as to be able to interpret asteroseismic data from such stars. Methods. A new pulsation code is applied to stellar models based on the self-consistent field (SCF) method. Results. Pulsation modes in SCF models follow a similar behaviour to those in uniformly rotating polytropic models, provided that the rotation profile is not too differential. Pulsation modes fall into different categories, the three main ones being island, chaotic, and whispering gallery modes, which are rotating counterparts to modes with low, medium, and high − |m| values, respectively. The frequencies of the island modes follow an asymptotic pattern quite similar to what was found for polytropic models. Extending this asymptotic formula to higher azimuthal orders reveals more subtle behaviour as a function of m and provides a first estimate of the average advection of pulsation modes by rotation. Further calculations based on a variational principle confirm this estimate and provide rotation kernels that could be used in inversion methods. When the rotation profile becomes highly differential, it becomes more and more difficult to find island and whispering gallery modes at low azimuthal orders. At high azimuthal orders, whispering gallery modes, and in some cases island modes, reappear. Conclusions. The asymptotic formula found for frequencies of island modes can potentially serve as the basis of a mode identification scheme in rapidly rotating stars when the rotation profile is not too differential.