论文标题
红色巨星偶极混合模式的混合特征的变化
Variations of the mixing character of dipolar mixed modes in red giant stars
论文作者
论文摘要
多亏了太空任务的高质量数据，在许多恒星中，混合模式的检测变得可能。在这项工作中，我们研究了偶极混合模式的混合特征如何随着恒星的演化以及每个恒星模型中的频率而变化。这是通过监测红色巨型模型中偶极混合模式的耦合强度和周期间距的变化来实现的。这些参数是通过将混合模式的渐近扩展与红色巨型模型网格的模型频率拟合，质量在1.0至2.0 $ m_ \ odot $和三种不同的化学丰度之间的模型频率。耦合强度和周期间距随着恒星进化而降低。我们发现它们趋势的斜率减少趋势取决于压力模式分量的径向顺序。对于一组红色巨型模型，在可观察到的频率范围内发现，与频率的耦合强度不可忽略的耦合强度最高可达40 \％。相反，没有发现随频率间距的显着变化。在大多数情况下，模式的混合特征的变化受模型质量和金属性影响。浮力也对混合特征有影响。如果在应用渐近扩张中未考虑频率的故障，则发现接近光度凸起的模型的估计耦合强度和周期间距的显着波动。
Thanks to the high quality data of space missions, the detection of mixed modes has become possible in numerous stars. In this work, we investigate how the mixing character of dipolar mixed modes changes with stellar evolution, as well as with frequency within each stellar model. This is achieved by monitoring the variations in the coupling strength and the period spacing of dipolar mixed modes in red-giant models. These parameters are measured by fitting the asymptotic expansion of mixed modes to the model frequencies of a grid of red-giant models with masses between 1.0 and 2.0 $M_\odot$ and three different chemical abundances. The coupling strength and the period spacing decrease with stellar evolution. We find that the slopes of their decreasing trends depend on the radial order of the pressure mode component. A non-negligible increase of the coupling strength with frequency by up to around 40\% is found in the observable frequency range for a set of red-giant models. On the contrary, no significant changes of the period spacing with frequency are found. The changes in the mixing character of the modes are in most cases affected by the model mass and metallicity. Buoyancy glitches also have an impact on the mixing character. Significant fluctuations in the estimated coupling strength and period spacing are found for models approaching the luminosity bump, if the glitch impact of the frequencies is not considered in the applied asymptotic expansion.
