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arXiv 1402.0833astro-ph.SR
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快速旋转A星中共振模耦合的证据以及低频和高频之间的关系

Evidence of resonant mode coupling and the relationship between low and high frequencies in a rapidly rotating A star

Michel Breger, Michael H. Montgomery

摘要:

在谐振模耦合理论中,母模和子模在频率和相位上直接相关。目前在快速旋转的盾牌座δ恒星KIC 8054146的振荡,使我们能够测试最普遍和通用方面的这样一个理论。分离母模和耦合(子)模的唯一直接方法是检查不同频率之间幅度变化的相关性。对于相关频率的主要家族,只有一个单一的模式和一个三重态是9个主要频率峰值的起源,范围从每天2.93到66.30个周期(以及几十个小振幅组合模式和预测和检测到的第三个高频三重态)。模式耦合模型正确地预测了耦合模式的大幅度变化作为父模式的幅度的乘积,而相位变化也被正确地建模。这与“正常”组合频率的行为不同,因为振幅大三个数量级,甚至可能超过母模的振幅。我们发现,两个占主导地位的低频率在5.86和2.93周期,每天在重力模式区域是不是谐波的对方,和他们的属性遵循那些几乎等距的高频三重态。我们注意到,以前令人困惑的情况下,发现两个强峰在低频区域的相关性几乎是一个因素的两倍,在其他三角洲盾牌座恒星以及。

英文摘要:

In the theory of resonant mode coupling, the parent and child modes are directly related in frequency and phase. The oscillations present in the fast rotating Delta Scuti star KIC 8054146 allow us to test the most general and generic aspects of such a theory. The only direct way to separate the parent and coupled (child) modes is to examine the correlations in amplitude variability between the different frequencies. For the dominant family of related frequencies, only a single mode and a triplet are the origins of nine dominant frequency peaks ranging from 2.93 to 66.30 cycles per day (as well as dozens of small-amplitude combination modes and a predicted and detected third high-frequency triplet). The mode-coupling model correctly predicts the large amplitude variations of the coupled modes as a product of the amplitudes of the parent modes, while the phase changes are also correctly modeled. This differs from the behavior of 'normal' combination frequencies in that the amplitudes are three orders of magnitude larger and may exceed even the amplitudes of the parent modes. We show that two dominant low frequencies at 5.86 and 2.93 cycles per day in the gravity-mode region are not harmonics of each other, and their properties follow those of the almost equidistant high-frequency triplet. We note that the previously puzzling situation of finding two strong peaks in the low-frequency region related by nearly a factor of two in frequency has been seen in other Delta Scuti stars as well.

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