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arXiv 1409.5673astro-ph.SR
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星震恒星活动关系

Asteroseismic stellar activity relations

A. Bonanno, E. Corsaro, C. Karoff

摘要:

在星震学中,对恒星演化状态的一个重要诊断是小的频率分离,它对恒星内部平均分子量的梯度很敏感。因此,用这个量来讨论经典的年龄-活动关系是很有趣的。此外,由于光球磁场往往会抑制声波振荡的振幅,因此必须通过考虑各种活动指标来量化这种影响的重要性。我们提出了一个新的类的年龄活动的关系,连接山。Wilson $S$折射率和平均散射在光变曲线中具有小的频率间隔和振幅的p模振荡。我们使用了贝叶斯推断计算的样本开普勒望远镜观测到的19个类太阳活动恒星的各种经验定律的后验概率。我们证明了山之间存在着明显的相关性。Wilson $S$指数和恒星的相对年龄(由小的频率间隔表示),以及$S$指数和振荡幅度之间的反相关。我们认为,恒星的平均活动水平表现出更强的相关性与小的频率分离比绝对年龄,通常被认为是在文献中。本文发现的唯象规律有可能成为联系恒星演化理论与全球磁场动力学的新的重要诊断。特别是我们认为,之间的关系山。Wilson $S$指数和振荡幅度与磁对流直接数值模拟的结果吻合较好。

英文摘要:

In asteroseismology an important diagnostic of the evolutionary status of a star is the small frequency separation which is sensitive to the gradient of the mean molecular weight in the stellar interior. It is thus interesting to discuss the classical age-activity relations in terms of this quantity. Moreover, as the photospheric magnetic field tends to suppress the amplitudes of acoustic oscillations, it is important to quantify the importance of this effect by considering various activity indicators. We propose a new class of age-activity relations that connects the Mt. Wilson $S$ index and the average scatter in the light curve with the small frequency separation and the amplitude of the p-mode oscillations. We used a Bayesian inference to compute the posterior probability of various empirical laws for a sample of 19 solar-like active stars observed by the Kepler telescope. We demonstrate the presence of a clear correlation between the Mt. Wilson $S$ index and the relative age of the stars as indicated by the small frequency separation, as well as an anti-correlation between the $S$ index and the oscillation amplitudes. We argue that the average activity level of the stars shows a stronger correlation with the small frequency separation than with the absolute age that is often considered in the literature. The phenomenological laws discovered in this paper have the potential to become new important diagnostics to link stellar evolution theory with the dynamics of global magnetic fields. In particular we argue that the relation between the Mt. Wilson $S$ index and the oscillation amplitudes is in good agreement with the findings of direct numerical simulations of magneto-convection.

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