Can a binary star host three giant circumbinary planets?
Can a binary star host three giant circumbinary planets?
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双星可以拥有三颗巨大的绕双星行星吗？
DOI：
10.1093/mnras/stad2543
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发表时间：
2023
影响因子：
4.8
通讯作者：
Chen C
中科院分区：
文献类型：
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作者：
Chen C
我们研究了由三颗巨行星组成的倾斜环双星行星系统的轨道稳定性。行星之间的相互希尔半径为常数 (Δ)，范围为 Δ = 3.4–12.0，因此内对行星的周期比与外对行星的周期比相同。即使围绕共面双星的同一系统是稳定的，倾斜的环绕双星行星系统也可能不稳定。对于等质量的双星系统，我们发现三行星系统的稳定性在质量上与两行星系统相似，但三行星系统在平均运动共振区域更不稳定。对于质量不等的双星系统，三行星系统的不稳定性明显更大，因为内行星可能会经历冯·蔡佩尔-科扎伊-利多夫振荡。一般来说，在不稳定的系统中，内行星比外行星更容易被弹出。对于距离较近的系统（Δ ≲ 8），最可能的不稳定结果是一颗仍保持稳定的行星。对于更广泛分离的系统，Δ≳8，最可能的不稳定结果是两颗稳定的行星，只有一颗被弹出。观察到的具有显着偏心率的绕双星行星可能表明它是由不稳定的系统形成的。因此，如果双星质量接近相等并且行星间隔良好并且不接近平均运动共振，那么双星可以容纳三颗倾斜的巨行星。
We investigate the orbital stability of a tilted circumbinary planetary system with three giant planets. The planets are spaced by a constant number (Δ) of mutual Hill radii in the range Δ = 3.4–12.0 such that the period ratio of the inner pair is the same as that of the outer pair. A tilted circumbinary planetary system can be unstable even if the same system around a coplanar binary is stable. For an equal-mass binary, we find that the stability of a three-planet system is qualitatively similar to that of a two-planet system, but the three-planet system is more unstable in mean motion resonance regions. For an unequal-mass binary, there is significantly more instability in the three-planet system as the inner planets can undergo von Zeipel–Kozai–Lidov oscillations. Generally in unstable systems, the inner planets are more likely to be ejected than the outer planets. The most likely unstable outcome for closely spaced systems, with Δ ≲ 8, is a single remaining stable planet. For more widely separated systems, Δ ≳ 8, the most likely unstable outcome is two stable planets, only one being ejected. An observed circumbinary planet with significant eccentricity may suggest that it was formed from an unstable system. Consequently, a binary can host three tilted giant planets if the binary stars are close to equal mass and provided that the planets are well spaced and not close to a mean motion resonance.