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arXiv 2406.09337astro-ph.EP
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小质量行星与巨行星的不同行星偏心率-周期(PEP)分布

Different Planetary Eccentricity-Period (PEP) Distributions of Small- and Giant-Planets

Dolev Bashi, Tsevi Mazeh, Simchon Faigler

AI总结:

本文基于1040颗短周期系外行星的视向速度轨道数据,发现巨行星偏心率随周期增大呈上包络上升至0.8,而小质量行星偏心率在0.1-0.5间平坦分布,揭示两类行星不同的潮汐圆化与动力学演化机制。

摘要:

我们利用包含1040颗短周期(1≤P<200天)系外行星视向速度(RV)轨道的数据库,研究了行星偏心率-周期(PEP)分布。我们首先根据(最小)行星质量的分布将样本划分为低质量和高质量系外行星子样本,该质量分布呈现出明显的双高斯分布,分界点为0.165M_J。随后我们选取了216条轨道,其中低质量和高质量行星均有,其偏心率显著区别于圆轨道。131条巨行星偏心轨道显示出清晰的上包络,我们对其进行了定量建模,该包络从零偏心率单调上升,并在P~100天处达到0.8的偏心率。相反,85条低质量行星轨道在0.1至0.5之间呈现出平坦的偏心率分布,几乎不依赖于轨道周期。我们表明,这两种PEP分布之间的显著差异并非所用探测技术导致的结果。高质量行星的上包络在短周期双星中也有出现,是潮汐圆化的明确特征,该过程很可能发生在行星内部;而小质量行星的PEP分布表明圆化并不有效,这可能是由于与邻近行星的动力学相互作用所致。

英文摘要:

We used the database of $1040$ short-period ($1 \leq P < 200$ days) exoplanets radial-velocity (RV) orbits to study the planetary eccentricity-period (PEP) distribution. We first divided the sample into low- and high-mass exoplanet sub-samples based on the distribution of the (minimum) planetary masses, which displays a clear two-Gaussian distribution, separated at $0.165M_J$. We then selected $216$ orbits, low- and high-mass alike, with eccentricities significantly distinct from circular orbits. The $131$ giant-planet eccentric orbits display a clear upper envelope, which we model quantitatively, rises monotonically from zero eccentricity and reaches an eccentricity of $0.8$ at $P \sim 100$ days. Conversely, the $85$ low-mass planetary orbits display a flat eccentricity distribution between $0.1$ and $0.5$, with almost no dependence on the orbital period. We show that the striking difference between the two PEP distributions is not a result of the detection technique used. The upper envelope of the high-mass planets, also seen in short-period binary stars, is a clear signature of tidal circularization, which probably took place inside the planets, while the small-planet PEP distribution suggests that the circularization was not effective, probably due to dynamical interactions with neighboring planets.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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