arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.15823astro-ph.EPastro-ph.GAastro-ph.SR
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热彗星,冷运动学:宿主恒星的高相空间密度反映了年龄偏差

Hot Jupiters, cold kinematics: High phase space densities of host stars reflect an age bias

Alexander J. Mustill, Michiel Lambrechts, Melvyn B. Davies

摘要:

上下文行星系的诞生环境被认为通过外部光蒸发和恒星飞掠影响行星形成和轨道演化。最近的工作声称观测支持这一点,在行星系的属性和当地的银河系的相空间密度的宿主恒星之间的相关性的形式。特别是,热彗星在高相空间密度区域的恒星周围被发现,这可能反映了高恒星密度的形成环境。目的。相反,我们调查是否高相空间密度可能有一个银河系的运动学起源:热木星主机可能偏向于年轻,因此运动学冷,因为潮汐螺旋导致Gyr时间尺度上的行星的破坏,和银河系中的恒星的速度色散增加类似的时间尺度。方法.我们使用6D的位置和运动学从盖亚的热木星主机和他们的邻居,并构建相空间密度的分布。我们研究了恒星的局部相空间密度和特有速度之间的相关性。结果我们发现相空间密度和宿主星的特有速度之间有很强的相关性。因此,大多数在“高密度”区域的恒星在运动学上是冷的,这可能是由于前面提到的偏向于在行星潮汐破坏之前探测年轻恒星周围的热彗星。结论.我们没有发现证据的数据热木星主机优先在相空间overdensities相比,其他恒星的类似运动学,也因此,他们的出生环境中的高恒星密度的起源。

英文摘要:

Context. The birth environments of planetary systems are thought to influence planet formation and orbital evolution, through external photoevaporation and stellar flybys. Recent work has claimed observational support for this, in the form of a correlation between the properties of planetary systems and the local Galactic phase space density of the host star. In particular, Hot Jupiters are found overwhelmingly around stars in regions of high phase space density, which may reflect a formation environment with high stellar density. Aims. We instead investigate whether the high phase space density may have a galactic kinematic origin: Hot Jupiter hosts may be biased towards being young and therefore kinematically cold, because tidal inspiral leads to the destruction of the planets on Gyr timescales, and the velocity dispersion of stars in the Galaxy increases on similar timescales. Methods. We use 6D positions and kinematics from Gaia for the Hot Jupiter hosts and their neighbours, and construct distributions of the phase space density. We investigate correlations between the stars' local phase space density and peculiar velocity. Results. We find a strong anticorrelation between the phase space density and the host star's peculiar velocity with respect to the Local Standard of Rest. Therefore, most stars in "high-density" regions are kinematically cold, which may be caused by the aforementioned bias towards detecting Hot Jupiters around young stars before the planets' tidal destruction. Conclusions. We do not find evidence in the data for Hot Jupiter hosts preferentially being in phase space overdensities compared to other stars of similar kinematics, nor therefore for their originating in birth environments of high stellar density.

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