Semianalytic Expressions for the Isolation and Coupling of Mixed Modes
Semianalytic Expressions for the Isolation and Coupling of Mixed Modes
复制标题
混合模态隔离与耦合的半解析表达式
作者：
J. Ong;S. Basu
在巨星的振荡光谱中，非径向模式可以被看作是避免了交叉，这产生了一个特征性的“模式碰撞”，否则在各自的阶梯图中，渐进的p-和g-模式模式是一致的。相对于典型的观测误差，避免的交叉演化非常快，因此在确定恒星的精确年龄方面非常有用，特别是在亚巨星中。这种现象是由p模腔和g模腔中彼此接近谐振的模之间的耦合引起的。这些模腔之间的耦合的大多数理论分析依赖于杰弗里斯-温策尔-克拉默斯-布里渊方法，严格地说，这不适用于在亚巨星中观察到的低阶g模或在非常演化的红巨星中观察到的低阶p模。我们提出了一个非渐近处方隔离的两个模式腔，以及微扰（也是非渐近）描述它们之间的耦合，我们表明，在这些物理情况下，低阶g和p模式持有良好。最后，我们将讨论如何将这些结果可应用于亚巨星建模和确定其全球性的振荡频率。我们还公开了所有这些计算的代码。
In the oscillation spectra of giant stars, nonradial modes may be seen to undergo avoided crossings, which produce a characteristic “mode bumping” of the otherwise uniform asymptotic p- and g-mode patterns in their respective echelle diagrams. Avoided crossings evolve very quickly relative to typical observational errors and are therefore extremely useful in determining precise ages of stars, particularly in subgiants. This phenomenon is caused by coupling between modes in the p- and g-mode cavities that are near resonance with each other. Most theoretical analyses of the coupling between these mode cavities rely on the Jeffreys–Wentzel–Kramers–Brillouin approach, which is strictly speaking inapplicable to the low-order g modes observed in subgiants or the low-order p modes seen in very evolved red giants. We present both a nonasymptotic prescription for isolating the two mode cavities, as well as a perturbative (and also nonasymptotic) description of the coupling between them, which we show to hold good for the low-order g and p modes in these physical situations. Finally, we discuss how these results may be applied to modeling subgiant stars and determining their global properties from oscillation frequencies. We also make our code for all of these computations publicly available.
影响因子：
4.8
作者：
A. Stokholm;P. Nissen;V. Silva Aguirre-V.-Silva Aguirre-148319567;T. White;M. Lund;J. Mosumgaard;D. Huber;J. Jessen-Hansen-J.-Jessen-Hans
通讯作者：
A. Stokholm;P. Nissen;V. Silva Aguirre-V.-Silva Aguirre-148319567;T. White;M. Lund;J. Mosumgaard;D. Huber;J. Jessen-Hansen-J.-Jessen-Hans