论文标题

潮汐相互作用二进制恒星潜在可居住行星的轨道演变

Orbital evolution of potentially habitable planets of tidally interacting binary stars

论文作者

Graham, David E., Fleming, David P., Barnes, Rory

论文摘要

我们模拟了短期二进制恒星(轨道周期$ p_ {orb} \ lsim $ 8天)的耦合恒星和潮汐演变,以研究轨道振荡,启动周期和轨道稳定性的环形星球(CBPS)。我们考虑了两个潮汐模型,并表明两者都预测了二进制的半轴轴的外向进化,$ a_ {bin} $和偏心$ e_ {bin} $。这种轨道的演化驱动了最小CBP半轴轴的类似演变,以实现轨道稳定性。通过扩展以前的模型以包括质量浓度的演变,我们表明,CBP轨道稳定性极限中的最大值倾向于在行星形成后100 MYR发生,比以前的研究长100倍。该结果为假设提供了进一步的支持:二元恒星的早期恒星潮汐演化已从短期二进制中去除CBP。然后,我们将模型应用于Kepler-47 B(Kepler-47 B),这是一个接近其宿主星的稳定性极限的CBP,以表明,如果二进制的初始$ e_ {bin} \ gsim $ 0.24,那么地球将在过去的不稳定区域内绕轨道,并且可能无法生存。对于稳定的,稳定性极限未达到行星轨道的稳定的情况,我们发现$ a_ {bin} $和$ e_ {bin} $振荡的幅度分别可以降低10 \%和50 \%。最后,我们考虑使用$ p_ {orb} = $ 7.5天的相等质量星星,并将Hz与稳定性限制进行比较。我们发现,对于恒星质量,$ \ lsim0.0.12亿_ {\ odot} $,即使二进制轨道是圆形的,Hz也完全不稳定。对于$ e_ {bin} \ lsim $ 0.5,该限制增加到$ 107万美元_ {\ odot} $,而Hz对于出色的群众来说是不稳定的,高达445万美元_ {\ odot} $。这些结果可能有助于指导搜索潜在可居住的CBP,并在发现生命后表征它们的进化和可能性。

We simulate the coupled stellar and tidal evolution of short-period binary stars (orbital period $P_{orb} \lsim$8 days) to investigate the orbital oscillations, instellation cycles, and orbital stability of circumbinary planets (CBPs). We consider two tidal models and show that both predict an outward-then-inward evolution of the binary's semi-major axis $a_{bin}$ and eccentricity $e_{bin}$. This orbital evolution drives a similar evolution of the minimum CBP semi-major axis for orbital stability. By expanding on previous models to include the evolution of the mass concentration, we show that the maximum in the CBP orbital stability limit tends to occur 100 Myr after the planets form, a factor of 100 longer than previous investigations. This result provides further support for the hypothesis that the early stellar-tidal evolution of binary stars has removed CBPs from short-period binaries. We then apply the models to Kepler-47 b, a CBP orbiting close to its host stars' stability limit, to show that if the binary's initial $e_{bin} \gsim$0.24, the planet would have been orbiting within the instability zone in the past and probably wouldn't have survived. For stable, hypothetical cases in which the stability limit does not reach a planet's orbit, we find that the amplitudes of $a_{bin}$ and $e_{bin}$ oscillations can damp by up to 10\% and 50\%, respectively. Finally, we consider equal-mass stars with $P_{orb} =$ 7.5 days and compare the HZ to the stability limit. We find that for stellar masses $\lsim0.12M_{\odot}$, the HZ is completely unstable, even if the binary orbit is circular. For $e_{bin} \lsim$0.5, that limit increases to $0.17M_{\odot}$, and the HZ is partially destabilized for stellar masses up to $0.45M_{\odot}$. These results may help guide searches for potentially habitable CBPs, as well as characterize their evolution and likelihood to support life after they are found.

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