Heavy-element accretion by proto-Jupiter in a massive planetesimal disc, revisited
Heavy-element accretion by proto-Jupiter in a massive planetesimal disc, revisited
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重新审视原木星在巨大星子盘中的重元素吸积
DOI：
10.1093/mnras/stac3568
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发表时间：
2022
影响因子：
4.8
通讯作者：
Kobayashi H
中科院分区：
文献类型：
--
作者：
Shibata S;Helled R;Kobayashi H
星子吸积是巨行星中重元素富集的关键来源。有人认为，木星丰富的包层是在其成长过程中星子吸积的结果，假设它形成于一个巨大的星子盘。在这项研究中，我们模拟了木星在这种情况下的形成。我们假设情景并进行体模拟来推断固体吸积速率。我们发现，在快速气体吸积阶段，原木星可以捕获十倍地球质量的星子。然而，如果几个胚胎在木星核心附近形成，这是一个巨大的星子盘的预期结果，胚胎的散射增加了星子的离心率和倾斜度，因此显著降低了吸积效率。我们还将我们的结果与已发表的半解析模型进行了比较，并表明这些模型不能再现当时的体模拟，特别是当行星盘具有较大的偏心和倾角时。我们表明，当对星子的动力学演化进行仔细模拟时，捕获的星子的总质量为smcap，tot为2M⊕> Mcap，tot为> 18M⊕。木星包层的金属丰度可以用我们的大质量盘模型中的星子吸积来解释，尽管由于星子的高偏心率和高倾角导致了低吸积效率。我们的研究证明了行星生长过程中星子吸积详细建模的重要性及其对气态行星重元素质量的影响。
Planetesimal accretion is a key source for heavy-element enrichment in giant planets. It has been suggested that Jupiter’s enriched envelope is a result of planetesimal accretion during its growth, assuming it formed in a massive planetesimal disc. In this study, we simulate Jupiter’s formation in this scenario. We assumein situformation and performN-body simulations to infer the solid accretion rate. We find that tens-Earth masses of planetesimals can be captured by proto-Jupiter during the rapid gas accretion phase. However, if several embryos are formed near Jupiter’s core, which is an expected outcome in the case of a massive planetesimal disc, scattering from the embryos increases the eccentricity and inclination of planetesimals and therefore significantly reduces the accretion efficiency. We also compare our results with published semi-analytical models and show that these models cannot reproduce theN-body simulations especially when the planetesimal disc has a large eccentricity and inclination. We show that when the dynamical evolution of planetesimals is carefully modelled, the total mass of captured planetesimalsMcap,totis 2M⊕≲Mcap,tot≲ 18M⊕. The metallicity of Jupiter’s envelope can be explained by the planetesimal accretion in our massive disc model despite the low accretion efficiency coming from the high eccentricity and inclination of planetesimals. Our study demonstrates the importance of detailed modelling of planetesimal accretion during the planetary growth and its implications to the heavy-element mass in gaseous planets.