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arXiv 2407.02568astro-ph.EP
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利用环带盘探测尘埃与气体性质

Probing Dust and Gas Properties Using Ringed Disks

Eve J. Lee

AI总结:

本文利用分辨良好的尘埃环和尘埃径向运动玩具模型,约束Class 0/I盘的Stokes数与湍流α,并解释环稳定性、行星迁移及系外行星分布。

摘要:

行星质量增长的速度以及它们可能停驻在距离宿主恒星多远的位置,敏感地取决于两个无量纲参数:Stokes数St和湍流α。然而,这些参数仍然高度不确定,因为难以或无法直接测量。在这里,我们展示如何利用具有环带结构的盘来分别获得St和α:我们构建了一个简单的玩具模型,将气动阻力下并与气体运动耦合的尘埃径向运动方程,与Class 0/I盘中测得的尘埃质量分布相结合。聚焦于具有良好分辨尘埃环的已知系统,我们发现与环的测量性质相符的St和α取值范围很小:10^-4 ≲ St ≲ 10^-2,且10^-5 ≲ α ≲ 10^-3。这些较低的St和α确保观测到的环对团块化保持稳定。即使在一个可能形成束缚团块的边缘情形中,通过卵石吸积实现的进一步质量增长也会受到抑制。此外,推导出的低α与近乎无黏的状态一致,在该状态下Type I迁移可能被提前终止。我们的分析预测,在观测到尘埃环的约数十au以外,行星数量极少;而在约10 AU以内,行星形成显著更活跃,这与当前的系外巨行星统计结果一致。最后,我们讨论了这些结果对大轨道距离处的小行星统计所具有的启示。

英文摘要:

How rapidly a planet grows in mass and how far they may park from the host star depend sensitively on two non-dimensional parameters: Stokes number St and turbulent $α$. Yet, these parameters remain highly uncertain being difficult or impossible to measure directly. Here, we demonstrate how the ringed disks can be leveraged to obtain St and $α$ separately by constructing a simple toy model that combines dust radial equation of motion under aerodynamic drag and coupling to gas motion with the measured distribution of dust masses in Class 0/I disks. Focusing on known systems with well-resolved dust rings, we find that the range of St and $α$ that are consistent with the measured properties of the rings are small: $10^{-4} \lesssim {\rm St} \lesssim 10^{-2}$ and $10^{-5} \lesssim α\lesssim 10^{-3}$. These low St and $α$ ensure the observed rings are stable against clumping. Even in one marginal case where the formation of bound clumps is possible, further mass growth by pebble accretion is inhibited. Furthermore, the derived low $α$ is consistent with the nearly inviscid regime where Type I migration can be prematurely halted. Our analysis predicts minimal planet population beyond $\sim$10s of au where we observe dust rings and significantly more vigorous planet formation inside $\sim$10 AU, consistent with current exo-giant statistics. We close with discussions on the implications of our results on small planet statistics at large orbital distances.

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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