Title: Theoretical investigation of the occurrence of tidally excited oscillations in massive eccentric binary systems Show Chinese title

Title: 大质量椭圆双星系统中潮汐激发振荡现象的理论研究

Abstract: Massive and intermediate-mass stars reside in binary systems much more frequently than low-mass stars. Binaries containing massive main-sequence (MS) component(s) are often characterised by eccentric orbits, and can be observed as eccentric ellipsoidal variables (EEVs). The orbital phase-dependent tidal potential acting on the components of EEV can induce tidally excited oscillations (TEOs). We investigate how the history of resonances between the eigenmode spectra of the EEV components and the tidal forcing frequencies depends on the initial parameters of the system. We synthesised 20,000 evolutionary models of the EEVs across the MS. Later, we calculated the eigenfrequencies for each model. We focused only on the $l=2$, $m=0,+2$ modes. Knowing the temporal changes in the orbital parameters of simulated EEVs and the changes of the eigenfrequency spectra for both components, we were able to determine so-called `resonance curves', which describe the overall chance of a resonance occurring. We analysed the resonance curves by constructing basic statistics for them and analysing their morphology using machine learning methods, including the Uniform Manifold Approximation and Projection tool. The EEV resonance curves from our sample are characterised by striking diversity, including the occurrence of exceptionally long resonances or the absence of resonances for long evolutionary times. Both components may be subject to increased resonance rates as they approach the TAMS. On average, we should observe TEOs more frequently in EEVs containing massive components than intermediate-mass ones. TEOs will be particularly well-pronounced for EEVs with the component(s) close to the TAMS. Given the total number of resonances and their rates, TEOs may play an important role in the transport of angular momentum within massive and intermediate-mass stars (mainly near TAMS). Show Chinese abstract

Abstract: 大质量及中等质量恒星比低质量恒星更频繁地存在于双星系统中。包含大质量主序（MS）成分的双星通常具有偏心轨道，并可被观测为偏心椭球变星（EEVs）。作用于EEV分量上的轨道相位依赖性潮汐势可以激发潮汐激发振荡（TEOs）。我们研究了EEV分量的本征模谱与潮汐强迫频率之间的共振历史如何依赖于系统的初始参数。我们在主序阶段模拟了20,000个EEV演化模型，并计算了每个模型的本征频率。我们仅关注$l=2$和$m=0,+2$模式。通过已知的模拟EEV轨道参数的时间变化和两个分量的本征频率谱的变化，我们能够确定所谓的“共振曲线”，这些曲线描述了共振发生的总体可能性。我们通过构建基本统计量来分析这些共振曲线，并使用包括Uniform Manifold Approximation and Projection工具在内的机器学习方法来分析它们的形态。我们的样本中的EEV共振曲线表现出显著的多样性，包括出现异常长的共振或长时间演化中没有共振的情况。当两个分量接近终主序时，它们可能会经历增加的共振率。平均而言，在包含大质量分量的EEV中，我们应该比在中等质量EEV中更频繁地观察到TEOs。对于接近终主序的EEV分量，TEOs将表现得尤为明显。考虑到总的共振次数和共振率，TEOs可能在大质量和中等质量恒星（主要在接近终主序时）的角动量传输中发挥重要作用。