Running The Gauntlet -- Survival of Small Circumbinary Planets Migrating Through Destabilising Resonances
Running The Gauntlet -- Survival of Small Circumbinary Planets Migrating Through Destabilising Resonances
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经受考验——小绕双星行星通过不稳定共振迁移的生存
DOI：
10.1093/mnras/stac090
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发表时间：
2021
影响因子：
6.5
通讯作者：
Evan Fitzmaurice
中科院分区：
文献类型：
--
作者：
D. Martin;Evan Fitzmaurice
所有已知的外双星都很大(RP≥3R⊕)。虽然观测偏差可能解释了这种小行星的稀缺，但在这篇文章中，我们提出了一个理论解释。大多数已知的行星都接近稳定极限，散布在潜在不稳定的5：1、6：1和7：1的平均运动与双星的共振之间。据信，这些行星不是在原地形成的，而是从圆盘中更远的地方迁移过来的，因此通过了这些共振。行星的移动速度预计与其质量成正比，较慢的速度使共振捕获和随后的抛射更有可能发生。因此，虽然大型行星可能能够成功地“冲刺”，但小型行星可能会受到威胁。这一假设是通过在截断和湍流的圆盘中迁移的N体积分来验证的。我们发现，令人惊讶的是，在完全不稳定的共振的内部，没有一颗已知的行星存在。我们证明了迁移中的行星在自然界中可能发生共振抛射，而且它确实对小行星造成了不成比例的影响，但它需要一个高度湍流的圆盘，其效率可能太低，不能完全解释Rp<；3R⊕行星的稀缺。
All of the known circumbinary planets are large (Rp ≥ 3R⊕). Whilst observational biases may account for this dearth of small planets, in this paper we propose a theoretical explanation. Most of the known planets are near the stability limit, interspersed between potentially unstable 5 : 1, 6 : 1 and 7 : 1 mean motion resonances with the binary. It is believed that these planets did not form in situ, but rather migrated from farther out in the disc, and hence passed through these resonances. Planets are expected to migrate at a speed proportional to their mass, and a slower rate makes resonant capture and subsequent ejection more likely. Therefore, whilst large planets may be able to successfully “run the gauntlet”, small planets may be imperiled. This hypothesis is tested using N-body integrations of migration in a truncated and turbulent disc. We discover that surprisingly none of the known planets exist interior to a fully unstable resonance. We demonstrate that resonant ejection of migrating planets may occur in nature, and that it does indeed disproportionately affect small planets, but it requires a highly turbulent disc and its efficiency is likely too low to fully explain a dearth of Rp < 3R⊕ planets.