亚恒星伴星引起的椭球振荡：开普勒任务的展望
Ellipsoidal Oscillations Induced by Substellar Companions: A Prospect for the Kepler Mission
摘要：
开普勒卫星将发现数百颗太阳型恒星的亚恒星伴星。开普勒的极端测光精度使人们能够获得由各种物理过程引起的低振幅恒星变化。我们详细讨论了周期性的流量调制所产生的潮汐力的恒星由于一个亚恒星的同伴。在平衡潮近似下，导出了变率的解析表达式。我们通过线性非绝热恒星振荡方程的解析解和数值解证明，对于质量<1.4 Msun且表面对流区较厚的恒星，平衡潮汐公式非常适用。大质量恒星的辐射包层并不符合平衡潮汐近似，其通量变化比原始估计大$\ga$ 10倍。在所考虑的恒星质量的整个范围内，我们通过调整A。布里克希尔为脉动白矮星发展的。与其他周期性变化源相比，椭球光变曲线对时间和系统参数有明显的依赖性。我们认为，在开普勒的10^5颗目标恒星中，可能有多达100颗可以探测到巨行星引起的椭球振荡。（节录）
英文摘要：
Hundreds of substellar companions to solar-type stars will be discovered with the Kepler satellite. Kepler's extreme photometric precision gives access to low-amplitude stellar variability contributed by a variety of physical processes. We discuss in detail the periodic flux modulations arising from the tidal force on the star due to a substellar companion. An analytic expression for the variability is derived in the equilibrium-tide approximation. We demonstrate analytically and through numerical solutions of the linear, nonadiabatic stellar oscillation equations that the equilibrium-tide formula works extremely well for stars of mass <1.4 Msun with thick surface convection zones. More massive stars with largely radiative envelopes do not conform to the equilibrium-tide approximation and can exhibit flux variations $\ga$10 times larger than naive estimates. Over the full range of stellar masses considered, we treat the oscillatory response of the convection zone by adapting a prescription that A. J. Brickhill developed for pulsating white dwarfs. Compared to other sources of periodic variability, the ellipsoidal lightcurve has a distinct dependence on time and system parameters. We suggest that ellipsoidal oscillations induced by giant planets may be detectable from as many as ~100 of the 10^5 Kepler target stars. (Abridged)
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