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arXiv 1708.08159astro-ph.EP
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论动力学孤立热地球的起源

On the origin of dynamically isolated hot Earths

Arieh Königl, Steven Giacalone, Titos Matsakos

摘要:

最近在对开普勒行星候选目录数据的分析中发现了一个独特的行星系,其中包含动态孤立的地球大小的行星,轨道周期为$P_\mathrm{orb}\sim 1\,$天。我们认为,这些物体可能代表巨行星的残余岩石核心,这些行星以高偏心率轨道到达恒星附近,并在越过各自的罗氏极限(RL)$a_\mathrm{R,p}$后迅速被剥离其气体包层。在这张图片中,具有$P_\mathrm{orb}\gtrsim1\,$日的天体大多是“早期”的核心,它们起源于具有初始近星点距离$a_\mathrm{per,0}\le a_\mathrm{R,p}$的行星;它们具有高的初始偏心率,但它们的轨道在核心暴露后经历了快速的潮汐循环。相比之下,具有$P_\mathrm{orb}\lesssim 1\,$日的天体大多是起源于具有$a_\mathrm{per,0}>a_\mathrm{R,p}$的行星的“晚期”核心;这些行星经历了半径为$>a_\mathrm{per,0}$的轨道圆化,但最终通过潮汐轨道衰变达到$a_\mathrm{R,p}$。这幅图自然地解释了热地球的空间分布,以及它们与热彗星的推断发生率的相似性,它很好地符合轨道周期行星质量平面中所谓的亚木星沙漠的解释,即高偏心率行星迁移到RL附近。

英文摘要:

A distinct population of planetary systems that contain dynamically isolated, Earth-size planets with orbital periods $P_\mathrm{orb}\sim 1\,$day was recently identified in an analysis of data from the Kepler planet candidate catalog. We argue that these objects could represent the remnant rocky cores of giant planets that arrived at the stellar vicinity on high-eccentricity orbits and were rapidly stripped of their gaseous envelopes after crossing their respective Roche limits (RLs) $a_\mathrm{R,p}$. In this picture, objects with $P_\mathrm{orb}\gtrsim1\,$day are mostly "early" cores that originated in planets with an initial periastron distance $a_\mathrm{per,0}\le a_\mathrm{R,p}$; they had high initial eccentricities but their orbits underwent fast tidal circularization after the cores were exposed. Objects with $P_\mathrm{orb}\lesssim 1\,$day are, by contrast, mostly "late" cores that originated in planets with $a_\mathrm{per,0}>a_\mathrm{R,p}$; these planets underwent orbital circularization to a radius $>a_\mathrm{per,0}$ but eventually reached $a_\mathrm{R,p}$ through tidal orbital decay. This picture naturally accounts for the spatial distribution of hot Earths and for the similarity of their inferred occurrence rate to that of hot Jupiters, and it fits well with the interpretation of the so-called sub-Jovian desert in the orbital-period--planetary-mass plane in terms of high-eccentricity planet migration to the vicinity of the RL.

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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