论文标题

脉动二进制恒星中的反向潮汐

Inverse Tides in Pulsating Binary Stars

论文作者

Fuller, Jim

论文摘要

在紧密的二进制恒星中,脉动的潮气激发通常会消散能量,从而导致系统向圆形轨道演变,并带有对齐和同步的恒星旋转。但是,对于具有自振动搏动的恒星,我们证明了与不稳定脉动模式的潮汐相互作用可以朝相反的方向传递能量,从而迫使恒星远离同步性,并可能泵入偏心率和旋转轨道失误角度。仅当潮汐强制模式振幅与模式的饱和幅度相当时,这种“反向”潮汐过程仅发生,因此,它最有可能在轨道时期的主序列重力模式脉冲器中发生。我们检查了反向潮汐作用的长期演变,发现恒星旋转速率可能会被驱动到非常大或非常小的值,同时保持较大的自旋轨道未对准角。最近在近距离二进制中对脉动恒星进行的几项小型拼接分析表明,核心旋转期极慢,我们将其归因于反向潮汐的作用。

In close binary stars, the tidal excitation of pulsations typically dissipates energy, causing the system to evolve towards a circular orbit with aligned and synchronized stellar spins. However, for stars with self-excited pulsations, we demonstrate that tidal interaction with unstable pulsation modes can transfer energy in the opposite direction, forcing the spins of the stars away from synchronicity, and potentially pumping the eccentricity and spin-orbit misalignment angle. This "inverse" tidal process only occurs when the tidally forced mode amplitude is comparable to the mode's saturation amplitude, and it is thus most likely to occur in main sequence gravity mode pulsators with orbital periods of a few days. We examine the long-term evolution of inverse tidal action, finding the stellar rotation rate can potentially be driven to a very large or very small value, while maintaining a large spin-orbit misalignment angle. Several recent asteroseismic analyses of pulsating stars in close binaries have revealed extremely slow core rotation periods, which we attribute to the action of inverse tides.

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