THE PHOTOECCENTRIC EFFECT AND PROTO-HOT JUPITERS. III. A PAUCITY OF PROTO-HOT JUPITERS ON SUPER-ECCENTRIC ORBITS
THE PHOTOECCENTRIC EFFECT AND PROTO-HOT JUPITERS. III. A PAUCITY OF PROTO-HOT JUPITERS ON SUPER-ECCENTRIC ORBITS
复制标题
DOI：
10.1088/0004-637x/798/2/66
复制
发表时间：
2015-01-10
影响因子：
4.9
通讯作者：
Johnson, John Asher
中科院分区：
文献类型：
--
作者：
Dawson, Rebekah I.;Murray-Clay, Ruth A.;Johnson, John Asher
在距其主恒星0.1AU范围内运行的气态巨行星不太可能是原地形成的，这是行星迁移的证据。人们争论的是，这颗典型的热木星是顺利地从其形成位置通过原行星盘向内迁移，还是被另一颗天体扰动进入高度偏心的轨道，随后潮汐耗散在接近恒星通道时收缩并环流。苏格拉底和他的合作者预测，后一种模型应该会产生一群开普勒容易观测到的超级偏心的原始热木星。我们在开普勒样本中发现了这样的行星的稀少，这与96.9%的置信度的理论预测不一致。观测效应不太可能解释这种差异。我们发现，恒星-行星Kozai机制产生的轨道周期为P>；3天的热木星的比例不超过44%(在2西格玛时)。我们的结果可能表明，盘迁移是产生P>；3天热木星的主要途径。或者，典型的热木星可能已经被与行星而不是恒星伴星的相互作用扰动到高度偏心，并在多次散射后开始在1AU内部的潮汐环化。最后一种选择是，在高偏心率的潮汐环化过程的早期，潮汐环化比在低偏心率的过程中发生得更快，尽管这与目前的潮汐理论相反。
Gas giant planets orbiting within 0.1 AU of their host stars are unlikely to have formed in situ and are evidence for planetary migration. It is debated whether the typical hot Jupiter smoothly migrated inward from its formation location through the proto-planetary disk, or was perturbed by another body onto a highly eccentric orbit, which tidal dissipation subsequently shrank and circularized during close stellar passages. Socrates and collaborators predicted that the latter model should produce a population of super-eccentric proto-hot Jupiters readily observable by Kepler. We find a paucity of such planets in the Kepler sample, which is inconsistent with the theoretical prediction with 96.9% confidence. Observational effects are unlikely to explain this discrepancy. We find that the fraction of hot Jupiters with an orbital period P > 3 days produced by the star-planet Kozai mechanism does not exceed ( at two-sigma) 44%. Our results may indicate that disk migration is the dominant channel for producing hot Jupiters with P > 3 days. Alternatively, the typical hot Jupiter may have been perturbed to a high eccentricity by interactions with a planetary rather than stellar companion, and began tidal circularization much interior to 1 AU after multiple scatterings. A final alternative is that early in the tidal circularization process at high eccentricities tidal circularization occurs much more rapidly than later in the process at low eccentricities, although this is contrary to current tidal theories.