Embedded star clusters and the formation of the Oort cloud. III. Evolution of the inner cloud during the Galactic phase
Embedded star clusters and the formation of the Oort cloud. III. Evolution of the inner cloud during the Galactic phase
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嵌入式星团和奥尔特云的形成。
DOI：
10.1016/j.icarus.2008.02.016
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发表时间：
2008
期刊：
影响因子：
3.2
通讯作者：
H. Levison
中科院分区：
文献类型：
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作者：
R. Brasser;M. Duncan;H. Levison
在先前的出版物[Brasser，R.，邓肯，M. J.，Levison，H.F.，2006. Icarus 184，59-82]，内部奥尔特云的模型被建立起来，其中包括嵌入的星星团对彗星绕太阳轨道的影响。该论文的主要结论是，云的形成效率约为10%，云到太阳的距离仅取决于太阳遇到的气体和恒星的平均密度。在这里，我们报告的模拟结果，随后在当前的银河系环境中，一旦太阳离开嵌入式星星集群的这些彗星云的动态演变。目标是确定经过的银河场恒星和银河潮汐场的动力学影响是否足以从内云（a<20，000 Au）补充足够的物质到当前的外层云（半长轴a> 20，000 Au）。由于可见的新彗星直接来自外层云，因此仅存在对后者的质量估计，下限为1 M [弗朗西斯，P. J.，2005.占星术。J. 635，1348-1361]。知道内部云的膨胀量因此可以产生对所述（看不见的）内部云的质量的估计。我们的研究结果表明，通常只有10%的彗星从内云土地在外层云，并在4.5 Gyr后绑定。如果假设在极端情况下，外层云的全部或大部分来自内层云，那么内层云的质量典型值约为10 M。[Brasser，R.，邓肯，M. J.，Levison，H.F.，2006. Icarus 184，59-82]表明，来自土星-土星区域的彗星中有10%被植入内部奥尔特云，这意味着原始土星-土星区域的固体质量约为100 M，这是一个令人不安的大值。这种极端的情况可以用两种说法来弥补：要么是巨型分子云复合体对内部奥尔特云的影响一定比原先想象的要严重得多，要么是奥尔特云有一个两阶段的形成过程，其中外层云主要是由彗星组成的，这些彗星是在太阳离开它的原始诞生星团后散落的。
In a previous publication [Brasser, R., Duncan, M.J., Levison, H.F., 2006. Icarus 184, 59–82], models of the inner Oort cloud were built which included the effect of an embedded star cluster on cometary orbits about the Sun. The main conclusions of that paper were that the formation efficiency is about 10% and the median distance of the cloud to the Sun only depends on the mean density of gas and stars the Sun encountered. Here we report on the results of simulations which followed the ensuing dynamical evolution of these comet clouds in the current Galactic environment once the Sun left the embedded star cluster. The goal is to determine whether or not the dynamical influence of passing Galactic field stars and the Galactic tidal field is sufficient to replenish the current outer cloud (semi-major axis a>20,000 AU) with enough material from the inner cloud (a<20,000 AU). Since visible new comets come directly from the outer cloud, a mass estimate only exists for the latter, with a lower limit of 1 M⊕[Francis, P.J., 2005. Astrophys. J. 635, 1348–1361]. Knowing the amount of expansion of the inner cloud may therefore yield an estimate of the mass of said (unseen) inner cloud. Our results indicate that typically only 10% of the comets from the inner cloud land in the outer cloud and are bound after 4.5 Gyr. If one assumes that in the extreme case all or the majority of the current population of the outer cloud has come from the inner cloud, then a typical value of the mass of the inner cloud is about 10 M⊕. The results of [Brasser, R., Duncan, M.J., Levison, H.F., 2006. Icarus 184, 59–82] showed that ∼10% of comets from the Jupiter–Saturn region were implanted in the inner Oort cloud, which implies an uncomfortably large value of about 100 M⊕for the mass of solids in the primordial Jupiter–Saturn region. This extreme case might be remedied in two says: either the effect of Giant Molecular Cloud complexes on the inner Oort cloud must be much more severe than originally thought, or there was a two-stage formation process for the Oort cloud, in which the outer cloud was largely populated by comets scattered once the Sun had left its primordial birth cluster.
DOI：
10.1086/521815
发表时间：
2007-08
期刊：
The Astronomical Journal
影响因子：
--
作者：
A. Higuchi;E. Kokubo;H. Kinoshita;T. Mukai
通讯作者：
A. Higuchi;E. Kokubo;H. Kinoshita;T. Mukai